Factors Associated With Performing IPAA After Total Colectomy for Ulcerative Colitis

BACKGROUND

IPAA is considered the procedure of choice for restorative surgery after total colectomy for ulcerative colitis. Previous studies have examined the rate of IPAA within individual states but not at the national level in the United States.

OBJECTIVE

This study aimed to assess the rate of IPAA after total colectomy for ulcerative colitis in a national population and identify factors associated with IPAA.

DESIGN

This was a retrospective cohort study.

SETTINGS

This study was performed in the United States.

PATIENTS

Patients who were aged 18 years or older and who underwent total colectomy between 2009 and 2019 for a diagnosis of ulcerative colitis were identified within a commercial database. This database excluded patients with public insurance, including all patients older than 65 years with Medicare.

MAIN OUTCOME MEASURES

The primary outcome was IPAA. Multivariable logistic regression was used to assess the association between covariates and the likelihood of undergoing IPAA.

RESULTS

In total, 2816 patients were included, of whom 1414 (50.2%) underwent IPAA, 928 (33.0%) underwent no further surgery, and 474 (16.8%) underwent proctectomy with end ileostomy. Younger age, lower comorbidities, elective case, and laparoscopic approach in the initial colectomy were significantly associated with IPAA but socioeconomic status was not.

LIMITATIONS

This retrospective study included only patients with commercial insurance.

CONCLUSIONS

A total of 50.2% of patients who had total colectomy for ulcerative colitis underwent IPAA, and younger age, lower comorbidities, and elective cases are associated with a higher rate of IPAA placement. This study emphasizes the importance of ensuring follow-up with colorectal surgeons to provide the option of restorative surgery, especially for patients undergoing urgent or emergent colectomies. See Video Abstract .

FACTORES ASOCIADOS CON LA REALIZACIN DE ANASTOMOSIS ANALBOLSA ILEAL DESPUS DE UNA COLECTOMA TOTAL POR COLITIS ULCEROSA

ANTECEDENTES:La anastomosis ileo-anal se considera el procedimiento de elección para la cirugía reparadora tras la colectomía total por colitis ulcerosa. Estudios previos han examinado la tasa de anastomosis ileo-anal dentro de los estados individuales, pero no a nivel nacional en los Estados Unidos.OBJETIVO:Evaluar la tasa de anastomosis bolsa ileal-anal después de la colectomía total para la colitis ulcerosa en una población nacional e identificar los factores asociados con la anastomosis bolsa ileal-anal.DISEÑO:Se trata de un estudio de cohortes retrospectivo.LUGAR:Este estudio se realizó en los Estados Unidos.PACIENTES:Los pacientes que tenían ≥18 años de edad que se sometieron a colectomía total entre 2009 y 2019 para un diagnóstico de colitis ulcerosa fueron identificados dentro de una base de datos comercial. Esta base de datos excluyó a los pacientes con seguro público, incluidos todos los pacientes >65 años con Medicare.MEDIDAS DE RESULTADO PRINCIPALES:El resultado primario fue la anastomosis ileal bolsa-anal. Se utilizó una regresión logística multivariable para evaluar la asociación entre las covariables y la probabilidad de someterse a una anastomosis ileal.RESULTADOS:En total, se incluyeron 2.816 pacientes, de los cuales 1.414 (50,2%) se sometieron a anastomosis ileo-anal, 928 (33,0%) no se sometieron a ninguna otra intervención quirúrgica y 474 (16,8%) se sometieron a proctectomía con ileostomía terminal. La edad más joven, las comorbilidades más bajas, el caso electivo, y el abordaje laparoscópico en la colectomía inicial se asociaron significativamente con la anastomosis ileal bolsa-anal, pero no el estatus socioeconómico.LIMITACIONES:Este estudio retrospectivo incluyó sólo pacientes con seguro comercial.CONCLUSIONES:Un 50,2% de los pacientes se someten a anastomosis ileo-anal y la edad más joven, las comorbilidades más bajas y los casos electivos se asocian con una mayor tasa de colocación de anastomosis ileo-anal. Esto subraya la importancia de asegurar el seguimiento con cirujanos colorrectales para ofrecer la opción de cirugía reparadora, especialmente en pacientes sometidos a colectomías urgentes o emergentes. (Traducción-Dr. Yolanda Colorado ).

Prediction of Pathologic Complete Response for Rectal Cancer Based on Pretreatment Factors Using Machine Learning

BACKGROUND

Pathologic complete response after neoadjuvant therapy is an important prognostic indicator for locally advanced rectal cancer and may give insights into which patients might be treated nonoperatively in the future. Existing models for predicting pathologic complete response in the pretreatment setting are limited by small data sets and low accuracy.

OBJECTIVE

We sought to use machine learning to develop a more generalizable predictive model for pathologic complete response for locally advanced rectal cancer.

DESIGN

Patients with locally advanced rectal cancer who underwent neoadjuvant therapy followed by surgical resection were identified in the National Cancer Database from years 2010 to 2019 and were split into training, validation, and test sets. Machine learning techniques included random forest, gradient boosting, and artificial neural network. A logistic regression model was also created. Model performance was assessed using an area under the receiver operating characteristic curve.

SETTINGS

This study used a national, multicenter data set.

PATIENTS

Patients with locally advanced rectal cancer who underwent neoadjuvant therapy and proctectomy.

MAIN OUTCOME MEASURES

Pathologic complete response defined as T0/xN0/x.

RESULTS

The data set included 53,684 patients. Pathologic complete response was experienced by 22.9% of patients. Gradient boosting showed the best performance with an area under the receiver operating characteristic curve of 0.777 (95% CI, 0.773-0.781), compared with 0.684 (95% CI, 0.68-0.688) for logistic regression. The strongest predictors of pathologic complete response were no lymphovascular invasion, no perineural invasion, lower CEA, smaller size of tumor, and microsatellite stability. A concise model including the top 5 variables showed preserved performance.

LIMITATIONS

The models were not externally validated.

CONCLUSIONS

Machine learning techniques can be used to accurately predict pathologic complete response for locally advanced rectal cancer in the pretreatment setting. After fine-tuning a data set including patients treated nonoperatively, these models could help clinicians identify the appropriate candidates for a watch-and-wait strategy. See Video Abstract .

EL CNCER DE RECTO BASADA EN FACTORES PREVIOS AL TRATAMIENTO MEDIANTE EL APRENDIZAJE AUTOMTICO

ANTECEDENTES:La respuesta patológica completa después de la terapia neoadyuvante es un indicador pronóstico importante para el cáncer de recto localmente avanzado y puede dar información sobre qué pacientes podrían ser tratados de forma no quirúrgica en el futuro. Los modelos existentes para predecir la respuesta patológica completa en el entorno previo al tratamiento están limitados por conjuntos de datos pequeños y baja precisión.OBJETIVO:Intentamos utilizar el aprendizaje automático para desarrollar un modelo predictivo más generalizable para la respuesta patológica completa para el cáncer de recto localmente avanzado.DISEÑO:Los pacientes con cáncer de recto localmente avanzado que se sometieron a terapia neoadyuvante seguida de resección quirúrgica se identificaron en la Base de Datos Nacional del Cáncer de los años 2010 a 2019 y se dividieron en conjuntos de capacitación, validación y prueba. Las técnicas de aprendizaje automático incluyeron bosque aleatorio, aumento de gradiente y red neuronal artificial. También se creó un modelo de regresión logística. El rendimiento del modelo se evaluó utilizando el área bajo la curva característica operativa del receptor.ÁMBITO:Este estudio utilizó un conjunto de datos nacional multicéntrico.PACIENTES:Pacientes con cáncer de recto localmente avanzado sometidos a terapia neoadyuvante y proctectomía.PRINCIPALES MEDIDAS DE VALORACIÓN:Respuesta patológica completa definida como T0/xN0/x.RESULTADOS:El conjunto de datos incluyó 53.684 pacientes. El 22,9% de los pacientes experimentaron una respuesta patológica completa. El refuerzo de gradiente mostró el mejor rendimiento con un área bajo la curva característica operativa del receptor de 0,777 (IC del 95%: 0,773 - 0,781), en comparación con 0,684 (IC del 95%: 0,68 - 0,688) para la regresión logística. Los predictores más fuertes de respuesta patológica completa fueron la ausencia de invasión linfovascular, la ausencia de invasión perineural, un CEA más bajo, un tamaño más pequeño del tumor y la estabilidad de los microsatélites. Un modelo conciso que incluye las cinco variables principales mostró un rendimiento preservado.LIMITACIONES:Los modelos no fueron validados externamente.CONCLUSIONES:Las técnicas de aprendizaje automático se pueden utilizar para predecir con precisión la respuesta patológica completa para el cáncer de recto localmente avanzado en el entorno previo al tratamiento. Después de realizar ajustes en un conjunto de datos que incluye pacientes tratados de forma no quirúrgica, estos modelos podrían ayudar a los médicos a identificar a los candidatos adecuados para una estrategia de observar y esperar. (Traducción-Dr. Ingrid Melo ).

Prediction of Ureteral Injury During Colorectal Surgery Using Machine Learning

BACKGROUND

Ureteral injury (UI) is a rare but devastating complication during colorectal surgery. Ureteral stents may reduce UI but carry risks themselves. Risk predictors for UI could help target the use of stents, but previous efforts have relied on logistic regression (LR), shown moderate accuracy, and used intraoperative variables. We sought to use an emerging approach in predictive analytics, machine learning, to create a model for UI.

METHODS

Patients who underwent colorectal surgery were identified in the National Surgical Quality Improvement Program (NSQIP) database. Patients were split into training, validation, and test sets. The primary outcome was UI. Three machine learning approaches were tested including random forest (RF), gradient boosting (XGB), and neural networks (NN), and compared with traditional LR. Model performance was assessed using area under the curve (AUROC).

RESULTS

The data set included 262,923 patients, of whom 1519 (.578%) experienced UI. Of the modeling techniques, XGB performed the best, with an AUROC score of .774 (95% CI .742-.807) compared with .698 (95% CI .664-.733) for LR. Random forest and NN performed similarly with scores of .738 and .763, respectively. Type of procedure, work RVUs, indication for surgery, and mechanical bowel prep showed the strongest influence on model predictions.

CONCLUSIONS

Machine learning-based models significantly outperformed LR and previous models and showed high accuracy in predicting UI during colorectal surgery. With proper validation, they could be used to support decision making regarding the placement of ureteral stents preoperatively.

Exploring Stakeholders' Perspectives on Implementing Universal Germline Testing for Colorectal Cancer: Findings From a Clinical Practice Survey

PURPOSE

New guidelines recommend considering germline genetic testing for all patients with colorectal cancer (CRC). However, there is a lack of data on stakeholders' perspectives on the advantages and barriers of implementing universal germline testing (UGT). This study assessed the perspectives of members of the Collaborative Group of the Americas on Inherited Gastrointestinal Cancer (CGA-IGC) regarding the implementation of UGT for patients with CRC, including readiness, logistics, and barriers.

METHODS

A cross-sectional survey was sent to 317 active members of CGA-IGC. The survey included sections on demographics, clinical practice specialty, established institutional practices for testing, and questions pertaining to support of and barriers to implementing UGT for patients with CRC.

RESULTS

Eighty CGA-IGC members (25%) participated, including 42 genetic counselors (53%) and 14 gastroenterologists (18%). Forty-seven (59%) reported an academic medical center as their primary work setting, and most participants (56%) had more than 10 years of clinical practice. Although most participants (73%) supported UGT, 54% indicated that changes in practice would be required before adopting UGT, and 39% indicated that these changes would be challenging to implement. There was support for both genetics and nongenetics providers to order genetic testing, and a majority (57%) supported a standardized multigene panel rather than a customized gene panel. Key barriers to UGT implementation included limited genetics knowledge among nongenetics providers, time-consuming processes for obtaining consent, ordering tests, disclosing results, and lack of insurance coverage.

CONCLUSION

This study demonstrates wide support among hereditary GI cancer experts for implementation of UGT for patients with CRC. However, alternative service delivery models using nongenetics providers should be considered to address the logistical barriers to UGT implementation, particularly the growing demand for genetic testing.

Estimating Risk of Locoregional Failure and Overall Survival in Anal Cancer Following Chemoradiation: A Machine Learning Approach

BACKGROUND

Optimal treatment of anal squamous cell carcinoma (ASCC) is definitive chemoradiation. Patients with persistent or recurrent disease require abdominoperineal resection (APR). Current models for predicting need for APR and overall survival are limited by low accuracy or small datasets. This study sought to use machine learning (ML) to develop more accurate models for locoregional failure and overall survival for ASCC.

METHODS

This study used the National Cancer Database from 2004-2018, divided into training, validation, and test sets. We included patients with stage I-III ASCC who underwent chemoradiation. Our primary outcomes were need for APR and 3-year overall survival. Random forest (RF), gradient boosting (XGB), and neural network (NN) ML-based models were developed and compared with logistic regression (LR). Accuracy was assessed using area under the receiver operating characteristic curve (AUROC).

RESULTS

APR was required in 5.3% (1,015/18,978) of patients. XGB performed best with AUROC of 0.813, compared with 0.691 for LR. Tumor size, lymphovascular invasion, and tumor grade showed the strongest influence on model predictions. Mortality was 23.6% (7,988/33,834). AUROC for XGB and LR were similar at 0.766 and 0.748, respectively. For this model, age, radiation dose, sex, and insurance status were the most influential variables.

CONCLUSIONS

We developed and internally validated machine learning-based models for predicting outcomes in ASCC and showed higher accuracy versus LR for locoregional failure, but not overall survival. After external validation, these models may assist clinicians with identifying patients with ASCC at high risk of treatment failure.

New Opportunities for Minimizing Toxicity in Rectal Cancer Management

Advances in multimodal management of locally advanced rectal cancer (LARC), consisting of preoperative chemotherapy and/or radiotherapy followed by surgery with or without adjuvant chemotherapy, have improved local disease control and patient survival but are associated with significant risk for acute and long-term morbidity. Recently published trials, evaluating treatment dose intensification via the addition of preoperative induction or consolidation chemotherapy (total neoadjuvant therapy [TNT]), have demonstrated improved tumor response rates while maintaining acceptable toxicity. In addition, TNT has led to an increased number of patients achieving a clinical complete response and thus eligible to pursue a nonoperative, organ-preserving, watch and wait approach, thereby avoiding toxicities associated with surgery, such as bowel dysfunction and stoma-related complications. Ongoing trials using immune checkpoint inhibitors in patients with mismatch repair-deficient tumors suggest that this subgroup of patients with LARC could potentially be treated with immunotherapy alone, sparing them the toxicity associated with preoperative treatment and surgery. However, the majority of rectal cancers are mismatch repair-proficient and less responsive to immune checkpoint inhibitors and require multimodal management. The synergy noted in preclinical studies between immunotherapy and radiotherapy on immunogenic tumor cell death has led to the design of ongoing clinical trials that explore the benefit of combining radiotherapy, chemotherapy, and immunotherapy (mainly of immune checkpoint inhibitors) and aim to increase the number of patients eligible for organ preservation.

Current chemoprevention approaches in Lynch syndrome and Familial adenomatous polyposis: a global clinical practice survey

Background

International chemoprevention preferences and approaches in Lynch syndrome (LS) and APC-associated polyposis, including Familial adenomatous polyposis (FAP) and attenuated FAP (AFAP) have not been previously explored.

Aim

To describe current chemoprevention strategies for patients with LS or FAP/AFAP (referred to collectively as FAP) practiced by members of four international hereditary cancer societies through administration of a survey.

Results

Ninety-six participants across four hereditary gastrointestinal cancer societies responded to the survey. Most respondents (91%, 87/96) completed information regarding their demographics and practice characteristics relating to hereditary gastrointestinal cancer and chemoprevention clinical practices. Sixty-nine percent (60/87) of respondents offer chemoprevention for FAP and/or LS as a part of their practice. Of the 75% (72/96) of survey respondents who were eligible to answer practice-based clinical vignettes based off of their responses to ten barrier questions regarding chemoprevention, 88% (63/72) of those participants completed at least one case vignette question to further characterize chemoprevention practices in FAP and/or LS. In FAP, 51% (32/63) would offer chemoprevention for rectal polyposis, with sulindac - 300 mg (18%, 10/56) and aspirin (16%, 9/56) being the most frequently selected options. In LS, 93% (55/59) of professionals discuss chemoprevention and 59% (35/59) frequently recommend chemoprevention. Close to half of the respondents (47%, 26/55) would recommend beginning aspirin at time of commencement of the patient's first screening colonoscopy (usually at age 25yrs). Ninety-four percent (47/50) of respondents would consider a patient's diagnosis of LS as an influential factor for aspirin use. There was no consensus on the dose of aspirin (≤100 mg, >100 mg - 325 mg or 600 mg) to offer patients with LS and there was no agreement on how other factors, such as BMI, hypertension, family history of colorectal cancer, and family history of heart disease, would affect the recommendation for aspirin use. Possible harm among older patients (>70 years) was identified as the most common reason to discourage aspirin use.

Conclusion

Although chemoprevention is widely discussed and offered to patients with FAP and LS by an international group of hereditary gastrointestinal cancer experts, there is significant heterogeneity in how it is applied in clinical practice.

Improved Prediction of Surgical-Site Infection After Colorectal Surgery Using Machine Learning

BACKGROUND

Surgical-site infection is a source of significant morbidity after colorectal surgery. Previous efforts to develop models that predict surgical-site infection have had limited accuracy. Machine learning has shown promise in predicting postoperative outcomes by identifying nonlinear patterns within large data sets.

OBJECTIVE

This study aimed to seek usage of machine learning to develop a more accurate predictive model for colorectal surgical-site infections.

DESIGN

Patients who underwent colorectal surgery were identified in the American College of Surgeons National Quality Improvement Program database from years 2012 to 2019 and were split into training, validation, and test sets. Machine-learning techniques included random forest, gradient boosting, and artificial neural network. A logistic regression model was also created. Model performance was assessed using area under the receiver operating characteristic curve.

SETTINGS

A national, multicenter data set.

PATIENTS

Patients who underwent colorectal surgery.

MAIN OUTCOME MEASURES

The primary outcome (surgical-site infection) included patients who experienced superficial, deep, or organ-space surgical-site infections.

RESULTS

The data set included 275,152 patients after the application of exclusion criteria. Of all patients, 10.7% experienced a surgical-site infection. Artificial neural network showed the best performance with area under the receiver operating characteristic curve of 0.769 (95% CI, 0.762-0.777), compared with 0.766 (95% CI, 0.759-0.774) for gradient boosting, 0.764 (95% CI, 0.756-0.772) for random forest, and 0.677 (95% CI, 0.669-0.685) for logistic regression. For the artificial neural network model, the strongest predictors of surgical-site infection were organ-space surgical-site infection present at time of surgery, operative time, oral antibiotic bowel preparation, and surgical approach.

LIMITATIONS

Local institutional validation was not performed.

CONCLUSIONS

Machine-learning techniques predict colorectal surgical-site infections with higher accuracy than logistic regression. These techniques may be used to identify patients at increased risk and to target preventive interventions for surgical-site infection. See Video Abstract at http://links.lww.com/DCR/C88 .

PREDICCIN MEJORADA DE LA INFECCIN DEL SITIO QUIRRGICO DESPUS DE LA CIRUGA COLORRECTAL MEDIANTE EL APRENDIZAJE AUTOMTICO

ANTECEDENTES:La infección del sitio quirúrgico es una fuente de morbilidad significativa después de la cirugía colorrectal. Los esfuerzos anteriores para desarrollar modelos que predijeran la infección del sitio quirúrgico han tenido una precisión limitada. El aprendizaje automático se ha mostrado prometedor en la predicción de los resultados posoperatorios mediante la identificación de patrones no lineales dentro de grandes conjuntos de datos.OBJETIVO:Intentamos utilizar el aprendizaje automático para desarrollar un modelo predictivo más preciso para las infecciones del sitio quirúrgico colorrectal.DISEÑO:Los pacientes que se sometieron a cirugía colorrectal se identificaron en la base de datos del Programa Nacional de Mejoramiento de la Calidad del Colegio Estadounidense de Cirujanos de los años 2012 a 2019 y se dividieron en conjuntos de capacitación, validación y prueba. Las técnicas de aprendizaje automático incluyeron conjunto aleatorio, aumento de gradiente y red neuronal artificial. También se creó un modelo de regresión logística. El rendimiento del modelo se evaluó utilizando el área bajo la curva característica operativa del receptor.CONFIGURACIÓN:Un conjunto de datos multicéntrico nacional.PACIENTES:Pacientes intervenidos de cirugía colorrectal.PRINCIPALES MEDIDAS DE RESULTADO:El resultado primario (infección del sitio quirúrgico) incluyó pacientes que experimentaron infecciones superficiales, profundas o del espacio de órganos del sitio quirúrgico.RESULTADOS:El conjunto de datos incluyó 275.152 pacientes después de la aplicación de los criterios de exclusión. El 10,7% de los pacientes presentó infección del sitio quirúrgico. La red neuronal artificial mostró el mejor rendimiento con el área bajo la curva característica operativa del receptor de 0,769 (IC del 95 %: 0,762 - 0,777), en comparación con 0,766 (IC del 95 %: 0,759 - 0,774) para el aumento de gradiente, 0,764 (IC del 95 %: 0,756 - 0,772) para conjunto aleatorio y 0,677 (IC 95% 0,669 - 0,685) para regresión logística. Para el modelo de red neuronal artificial, los predictores más fuertes de infección del sitio quirúrgico fueron la infección del sitio quirúrgico del espacio del órgano presente en el momento de la cirugía, el tiempo operatorio, la preparación intestinal con antibióticos orales y el abordaje quirúrgico.LIMITACIONES:No se realizó validación institucional local.CONCLUSIONES:Las técnicas de aprendizaje automático predicen infecciones del sitio quirúrgico colorrectal con mayor precisión que la regresión logística. Estas técnicas se pueden usar para identificar a los pacientes con mayor riesgo y para orientar las intervenciones preventivas para la infección del sitio quirúrgico. Consulte Video Resumen en http://links.lww.com/DCR/C88 . (Traducción-Dr Yolanda Colorado ).

Colorectal cohort analysis from the Intraperitoneal Chemotherapy After Cytoreductive Surgery for Peritoneal Metastasis (ICARuS) clinical trial

160

Background: ICARuS is a randomized phase II, multicenter trial to evaluate the relative efficacy of Hyperthermic Intraperitoneal Chemotherapy (HIPEC) with mitomycin C vs. Early Postoperative Intraperitoneal Chemotherapy (EPIC) with floxuridine (FUDR), after cytoreductive surgery (CRS), for the treatment of peritoneal metastases (PM) from colorectal (CRC) or appendiceal cancer (AC). PRODIGE7 results failed to demonstrate benefit of HIPEC therapy after complete gross resection of CRC PM, prompting termination of CRC accrual and early cohort analysis. Methods: Patients with isolated, confirmed PM were eligible for 1:1 randomization to CRS plus HIPEC with mitomycin C or CRS plus EPIC with FUDR. Patients were stratified by recent systemic chemotherapy and disease (AC vs. CRC). The trial was originally powered to evaluate 212 patients for a 20% gain in a primary endpoint of 3-year progression free survival (PFS: HR = 1.75). Results: Seventy-five CRC patients were included between 4/2013 and 12/2018 for HIPEC (N = 40) or EPIC (N = 35) treatment. Baseline characteristics were well balanced. After a median follow up of 36 months, the median PFS was 7.7 months (95% CI: 6.3-11.1) in the HIPEC arm and 8.8 months (95% CI: 7.1-21.9) in the EPIC arm, HR = 0.69 (95% CI: 0.42-1.14) p = 0.14. In the 42 left-sided primary cancers, the median PFS was 8.4 months (95% CI: 6.4-17.7) in the HIPEC arm and 12.5 months (95% CI: 8.1-NR) in the EPIC arm, HR = 0.60 (95% CI: 0.29-1.22) p = 0.14. In the 33 right-sided primary cancers, the median PFS was 6.5 months (95% CI: 5.5-14.1) in the HIPEC arm and 8 months (95% CI: 5.8-24.1) in the EPIC arm, HR = 0.80 (95% CI: 0.39-1.64) p = 0.53. PFS was significantly better in the EPIC arm among patients with BRAF wildtype (WT) tumors and patients with higher PM burden (PCI > 7). There was no difference between HIPEC and EPIC in the primary toxicity endpoint of complications grade 3 or above (23 vs. 34%, p = 0.3). Conclusions: Three-year PFS did not significantly differ between treatment arms. The lack of survival benefit of HIPEC in the entire cohort and in subset analysis is consistent with the findings of PRODIGE7. ICARuS remains open to accrual for AC. These data support further investigation of the potential benefit of EPIC with CRS in carefully selected patients with CRC PM. Clinical trial information: NCT01815359 .

Racial and regional disparities in the management of locally advanced rectal cancer

14

Background: Surgical margins following rectal cancer resection impact oncologic outcomes and may reflect adequacy of care. We examined the relationship between race, ethnicity, or region of care with margin positivity following rectal cancer resection. Methods: We queried the National Cancer Database (NCDB) for patients diagnosed with stage II-IV rectal cancer between 2004-2018 who underwent surgical resection and excluded patients with missing data for race/ethnicity and radiation therapy/surgery status, and/or who had local excision only. We performed a propensity-score analysis via inverse probability of treatment weighting (IPTW) of margin positivity rate as outcome and race/ethnicity and region as predictors of interest. We controlled for age, sex, Charlson-Deyo Score, pathologic stage, pathologic grade, time from diagnosis to surgical resection, surgery type, sequence of radiation and surgery, facility type, insurance type, level of education, distance between patient and facility, and region of the United States. Results: Our query yielded 73,269 patients. Median patient age was 63 (IQR: 54-72) years and 40% were female. 81%,8%, 6%, and 5% were non-Hispanic White, non-Hispanic Black, Hispanic, and non-Hispanic Other, respectively. After IPTW adjustment, non-Hispanic Black patients had 19% higher odds of margin positivity relative to non-Hispanic White patients (OR: 1.185, 95% CI: 1.094-1.284; p<.0001) Patients in the Northeast United States had a 10% lower odds of margin positivity compared to those in the South (OR: 0.900, 95% CI: 0.842-0.962; p=0.0019). Conclusions: Being non-Hispanic Black was significantly associated with a higher likelihood of positive margin following rectal cancer resection when compared to their non-Hispanic White counterparts. Patients in the South also experienced significantly higher rates of positive margin when compared to Northeast patients. Further investigation into potential interactions between racial and regional disparities and other contributors is warranted.[Table: see text]

Development and Validation of Machine Learning Models to Predict Readmission After Colorectal Surgery

BACKGROUND

Readmission after colorectal surgery is common and often implies complications for patients and costs for hospitals. Previous works have created predictive models using logistic regression for this outcome but have shown limited accuracy. Machine learning has shown promise in improving predictions by identifying non-linear patterns in data. We sought to create a more accurate predictive model for readmission after colorectal surgery using machine learning.

METHODS

Patients who underwent colorectal surgery were identified in the National Quality Improvement Program (NSQIP) database including years 2012-2019 and split into training, validation, and test sets. The primary outcome was readmission within 30 days of surgery. Three types of machine learning models were created, including random forest (RF), gradient boosting (XGB), and neural network (NN). A logistic regression (LR) model was also created for comparison. Model performance was evaluated using area under the receiver operating characteristic curve (AUROC).

RESULTS

The dataset included 213,827 patients after application of exclusion criteria. A total of 23,083 (10.8%) of patients experienced readmission. NN obtained an AUROC of 0.751 (95% CI 0.743-0.759), compared with 0.684 (95% CI 0.676-0.693) for LR. RF and XGB performed similarly with AUROCs of 0.749 (95% CI 0.741-0.757) and 0.745 (95% CI 0.737-0.753) respectively. Ileus, index admission length of stay, organ-space surgical site infection present at time of surgery, and ostomy placement were identified as the most contributory variables.

CONCLUSIONS

Machine learning approaches outperformed traditional statistical methods in the prediction of readmission after colorectal surgery. After external validation, this improved prediction model could be used to target interventions to reduce readmission rate.

Predictors of operative difficulty in robotic low anterior resection for rectal cancer

AIM

This study evaluates the relationship of tumour and anatomical features with operative difficulty in robotic low anterior resection performed by four experienced surgeons in a high-volume colorectal cancer practice.

METHODS

Data from 382 patients who underwent robotic low anterior resection by four expert surgeons between January 2016 and June 2019 were included in the analysis. Operating time was used as a measure of operative difficulty. Univariate and multivariate mixed models were used to identify associations between baseline characteristics and operating time, with surgeon as a random effect, thereby controlling for variability in surgeon speed and proficiency. In an exploratory analysis, operative difficulty was defined as conversion to laparotomy, a positive margin or an incomplete mesorectum.

RESULTS

Median operating time was 4.28 h (range 1.95-11.33 h) but varied by surgeon from 3.45 h (1.95-6.10 h) to 5.93 h (3.33-11.33 h) (P < 0.001). Predictors of longer operating time in multivariate analysis were male sex, higher body mass index, neoadjuvant radiotherapy, low tumour height, greater sacral height and larger mesorectal area at the S5 vertebral level. Conversion occurred in two cases (0.5%), and incomplete mesorectum and positive margins were found in nine (2.4%) and 19 (5.0%) patients, respectively. Neoadjuvant radiotherapy and larger pelvic outlet were the only characteristics associated with the exploratory measure of difficulty.

CONCLUSION

Predicting operative difficulty based on easy to identify, preoperative radiological and clinical variables is feasible in robotic anterior resection.

Colorectal cancer incidences in Lynch syndrome: a comparison of results from the prospective lynch syndrome database and the international mismatch repair consortium

OBJECTIVE

To compare colorectal cancer (CRC) incidences in carriers of pathogenic variants of the MMR genes in the PLSD and IMRC cohorts, of which only the former included mandatory colonoscopy surveillance for all participants.

METHODS

CRC incidences were calculated in an intervention group comprising a cohort of confirmed carriers of pathogenic or likely pathogenic variants in mismatch repair genes (path_MMR) followed prospectively by the Prospective Lynch Syndrome Database (PLSD). All had colonoscopy surveillance, with polypectomy when polyps were identified. Comparison was made with a retrospective cohort reported by the International Mismatch Repair Consortium (IMRC). This comprised confirmed and inferred path_MMR carriers who were first- or second-degree relatives of Lynch syndrome probands.

RESULTS

In the PLSD, 8,153 subjects had follow-up colonoscopy surveillance for a total of 67,604 years and 578 carriers had CRC diagnosed. Average cumulative incidences of CRC in path_MLH1 carriers at 70 years of age were 52% in males and 41% in females; for path_MSH2 50% and 39%; for path_MSH6 13% and 17% and for path_PMS2 11% and 8%. In contrast, in the IMRC cohort, corresponding cumulative incidences were 40% and 27%; 34% and 23%; 16% and 8% and 7% and 6%. Comparing just the European carriers in the two series gave similar findings. Numbers in the PLSD series did not allow comparisons of carriers from other continents separately. Cumulative incidences at 25 years were < 1% in all retrospective groups.

CONCLUSIONS

Prospectively observed CRC incidences (PLSD) in path_MLH1 and path_MSH2 carriers undergoing colonoscopy surveillance and polypectomy were higher than in the retrospective (IMRC) series, and were not reduced in path_MSH6 carriers. These findings were the opposite to those expected. CRC point incidence before 50 years of age was reduced in path_PMS2 carriers subjected to colonoscopy, but not significantly so.

Differential Performance of Machine Learning Models in Prediction of Procedure-Specific Outcomes

BACKGROUND

Procedure-specific complications can have devastating consequences. Machine learning-based tools have the potential to outperform traditional statistical modeling in predicting their risk and guiding decision-making. We sought to develop and compare deep neural network (NN) models, a type of machine learning, to logistic regression (LR) for predicting anastomotic leak after colectomy, bile leak after hepatectomy, and pancreatic fistula after pancreaticoduodenectomy (PD).

METHODS

The colectomy, hepatectomy, and PD National Surgical Quality Improvement Program (NSQIP) databases were analyzed. Each dataset was split into training, validation, and testing sets in a 60/20/20 ratio, with fivefold cross-validation. Models were created using NN and LR for each outcome. Models were evaluated primarily with area under the receiver operating characteristic curve (AUROC).

RESULTS

A total of 197,488 patients were included for colectomy, 25,403 for hepatectomy, and 23,333 for PD. For anastomotic leak, AUROC for NN was 0.676 (95% 0.666-0.687), compared with 0.633 (95% CI 0.620-0.647) for LR. For bile leak, AUROC for NN was 0.750 (95% CI 0.739-0.761), compared with 0.722 (95% CI 0.698-0.746) for LR. For pancreatic fistula, AUROC for NN was 0.746 (95% CI 0.733-0.760), compared with 0.713 (95% CI 0.703-0.723) for LR. Variables related to intra-operative information, such as surgical approach, biliary reconstruction, and pancreatic gland texture were highly important for model predictions.

DISCUSSION

Machine learning showed a marginal advantage over traditional statistical techniques in predicting procedure-specific outcomes. However, models that included intra-operative information performed better than those that did not, suggesting that NSQIP procedure-targeted datasets may be strengthened by including relevant intra-operative information.

Survival After Induction Chemotherapy and Chemoradiation Versus Chemoradiation and Adjuvant Chemotherapy for Locally Advanced Rectal Cancer

BACKGROUND

Total neoadjuvant therapy (TNT) improves tumor response in locally advanced rectal cancer (LARC) patients compared to neoadjuvant chemoradiotherapy alone. The effect of TNT on patient survival has not been fully investigated.

MATERIALS AND METHODS

This was a retrospective case series of patients with LARC at a comprehensive cancer center. Three hundred and eleven patients received chemoradiotherapy (chemoRT) as the sole neoadjuvant treatment and planned adjuvant chemotherapy, and 313 received TNT (induction fluorouracil and oxaliplatin-based chemotherapy followed by chemoradiotherapy in the neoadjuvant setting). These patients then underwent total mesorectal excision or were entered in a watch-and-wait protocol. The proportion of patients with complete response (CR) after neoadjuvant therapy (defined as pathological CR or clinical CR sustained for 2 years) was compared by the χ2 test. Disease-free survival (DFS), local recurrence-free survival, distant metastasis-free survival, and overall survival were assessed by Kaplan-Meier analysis and log-rank test. Cox regression models were used to further evaluate DFS.

RESULTS

The rate of CR was 20% for chemoRT and 27% for TNT (P=.05). DFS, local recurrence-free survival, metastasis-free survival, and overall survival were no different. Disease-free survival was not associated with the type of neoadjuvant treatment (hazard ratio [HR] 1.3; 95% confidence interval [CI] 0.93-1.80; P = .12).

CONCLUSIONS

Although TNT does not prolong survival than neoadjuvant chemoradiotherapy plus intended postoperative chemotherapy, the higher response rate associated with TNT may create opportunities to preserve the rectum in more patients with LARC.

Adoption of Organ Preservation and Surgeon Variability for Patients with Rectal Cancer Does Not Correlate with Worse Survival

BACKGROUND AND OBJECTIVES

Watch-and-wait is variably adopted by surgeons and the impact of this on outcomes is unknown. We compared the disease-free survival and organ preservation rates of locally advanced rectal cancer patients treated by expert colorectal surgeons at a comprehensive cancer center.

METHODS

This study included retrospective data on patients diagnosed with stage II/III rectal adenocarcinoma from January 2013 to June 2017 who initiated neoadjuvant therapy (either with chemoradiation, chemotherapy, or a combination of both) and were treated by an expert colorectal surgeon.

RESULTS

Overall, 444 locally advanced rectal cancer patients managed by five surgeons were included. Tumor distance from the anal verge, type of neoadjuvant therapy, and organ preservation rates varied by treating surgeon. There was no difference in disease-free survival after stratifying by the treating surgeon (p = 0.2). On multivariable analysis, neither the type of neoadjuvant therapy nor the treating surgeon was associated with disease-free survival.

CONCLUSIONS

While neoadjuvant therapy type and organ preservation rates varied among surgeons, there were no meaningful differences in disease-free survival. These data suggest that among expert colorectal surgeons, differing thresholds for selecting patients for watch-and-wait do not affect survival.

Comparing outcomes of robotic versus open mesorectal excision for rectal cancer

Background

The outcomes of robot-assisted mesorectal excision for rectal cancer, compared with open resection, have not been fully characterized.

Methods

A retrospective analysis of pathologic, short-term, and long-term outcomes in patients with rectal adenocarcinoma who underwent total or tumour-specific mesorectal excision at a high-volume cancer centre between 2008 and 2017 was conducted. Outcomes after robotic and open surgery were compared on an intention-to-treat basis.

Results

Out of 1048 resections performed, 1018 patients were reviewed, with 638 who underwent robotic surgery and 380 open surgery. Robotic surgery was converted to the open approach in 17 (2.7 per cent) patients. Patients who underwent robotic surgery were younger (median 54 (range 22–91) years versus median 58 (range 18–97) years; P < 0.001), had higher tumours (median 80 (range 0–150) mm from the anal verge versus median 70 (0–150) mm; P = 0.001), and were less likely to have received neoadjuvant therapy (64 per cent versus 73 per cent; P = 0.003). For patients who underwent a robotic total mesorectal excision, the operating time was longer (median 283.5 (range 117–712) min versus median 249 (range 70–661) min; P < 0.001). However, the rate of complications was lower (29 per cent versus 45 per cent; P < 0.001) and length of hospital stay was shorter (median 5 (range 1–32) days versus median 7 (range 0–137) days; P < 0.001). Median follow-up of survivors was 2.9 years. The proportion of patients with a positive circumferential resection margin did not differ between the groups, nor did the rate of local recurrence (robotic versus open: 3.7 per cent, 95 per cent c.i. 1.9 to 5.6 versus 2.8 per cent, 95 per cent c.i. 1.0 to 4.6; P = 0.400), systemic recurrence (robotic versus open: 11.7 per cent, 95 per cent c.i. 8.5 to 14.8 versus 13.0 per cent, 95 per cent c.i. 9.2 to 16.5; P = 0.300), or overall survival (robotic versus open: 97.8 per cent, 95 per cent c.i. 96.3 to 99.3 versus 93.5 per cent, 95 per cent c.i. 90.8 to 96.2; P = 0.050). The same results were documented in a subanalysis of 370 matched patients, including 185 who underwent robotic surgery and 185 open surgery, for the overall incidence of any postoperative complications, overall survival, disease-free survival, local recurrence, and systemic recurrence.

Conclusion

In patients with rectal cancer who are candidates for curative resection, robotic mesorectal excision is associated with lower complication rates, shorter length of stay, and equivalent oncologic outcomes, compared with open mesorectal excision.

Primary Tumor-Related Complications and Salvage Outcomes in Patients with Metastatic Rectal Cancer and an Untreated Primary Tumor

BACKGROUND

For rectal cancer with unresectable metastases, current practice favors omitting interventions directed at the primary tumor in asymptomatic patients.

OBJECTIVE

This study aimed to determine the proportion of patients with primary tumor-related complications, characterize salvage outcomes, and measure survival in patients with metastatic rectal cancer who did not undergo upfront intervention for their primary tumor.

DESIGN

This is a retrospective analysis.

SETTING

This study was conducted at a comprehensive cancer center.

PATIENTS

Patients who presented between January 1, 2008, and December 31, 2015, with synchronous stage IV rectal cancer, an unresected primary tumor, and no prior primary tumor-directed intervention were selected.

MAIN OUTCOME MEASURES

The main outcome measured was the rate of primary tumor-related complications in the cohort that did not receive any primary tumor-directed intervention. The Kaplan-Meier method and Cox regression analysis were used to determine whether complications are associated with survival.

RESULTS

The cohort comprised 358 patients with a median age of 56 years (22-92). Median follow-up was 26 months (range, 1-93 months). Among the 168 patients (46.9%) who eventually underwent elective resection of the primary tumor, the surgery was performed with curative intent in 66 patients (18.4%) and preemptive intent in 102 patients (28.5%). Of the 190 patients who did not undergo an upfront or elective intervention for the primary tumor, 68 (35.8%) experienced complications. Nonsurgical intervention for complications was attempted in 34 patients with an overall success rate of 61.8% (21/34). Surgical intervention was performed in 47 patients (including 13 patients for whom nonsurgical intervention failed): diversion in 26 patients and resection in 21 patients. Of those 47 patients, 42 (89.4%) ended up with a colostomy or ileostomy.

LIMITATIONS

This study was conducted at a single center.

CONCLUSION

A significant proportion of patients with metastatic rectal cancer and untreated primary tumor experience primary tumor-related complications. These patients should be followed closely, and preemptive intervention (resection, diversion, or radiation) should be considered if the primary tumor progresses despite systemic therapy. See Video Abstract at http://links.lww.com/DCR/B400. COMPLICACIONES RELACIONADAS CON EL TUMOR PRIMARIO Y RESULTADOS DE RESCATE EN PACIENTES CON CÁNCER DE RECTO METASTÁSICO Y UN TUMOR PRIMARIO NO TRATADO: Para el cáncer de recto con metástasis no resecables, la práctica actual favorece la omisión de las intervenciones dirigidas al tumor primario en pacientes asintomáticos.Determinar la proporción de pacientes con complicaciones relacionadas con el tumor primario, caracterizar los resultados de rescate y medir la supervivencia en pacientes con cáncer rectal metastásico que no se sometieron a una intervención inicial para su tumor primario.Análisis retrospectivo.Centro oncológico integral.Pacientes que se presentaron entre el 1 de enero de 2008 y el 31 de diciembre de 2015 con cáncer de recto en estadio IV sincrónico, un tumor primario no resecado y sin intervención previa dirigida al tumor primario.Tasa de complicaciones relacionadas con el tumor primario en la cohorte que no recibió ninguna intervención dirigida al tumor primario. Se utilizó el método de Kaplan-Meier y el análisis de regresión de Cox para determinar si las complicaciones están asociadas con la supervivencia.La cohorte estuvo compuesta por 358 pacientes con una mediana de edad de 56 años (22-92). La mediana de seguimiento fue de 26 meses (rango, 1 a 93 meses). Entre los 168 pacientes (46,9%) que finalmente se sometieron a resección electiva del tumor primario, la cirugía se realizó con intención curativa en 66 pacientes (18,4%) y con intención preventiva en 102 pacientes (28,5%). De los 190 pacientes que no se sometieron a una intervención inicial o electiva para el tumor primario, 68 (35,8%) experimentaron complicaciones. Se intentó una intervención no quirúrgica para las complicaciones en 34 pacientes con una tasa de éxito global del 61,8% (21 de 34). La intervención quirúrgica se realizó en 47 pacientes (incluidos 13 pacientes en los que falló la intervención no quirúrgica): derivación en 26 pacientes y resección en 21 pacientes. De esos 47 pacientes, 42 (89,4%) terminaron con una colostomía o ileostomía.Único centro.Una proporción significativa de pacientes con cáncer de recto metastásico y primario no tratado experimentan complicaciones relacionadas con el tumor primario. Se debe hacer un seguimiento estrecho de estos pacientes y considerar la posibilidad de una intervención preventiva (resección, derivación o radiación) si el tumor primario progresa a pesar de la terapia sistémica. Consulte Video Resumen en http://links.lww.com/DCR/B400.

Monitoring an Ongoing Enhanced Recovery After Surgery (ERAS) Program: Adherence Improves Clinical Outcomes in a Comparison of Three Thousand Colorectal Cases

AIM

In 2014, Memorial Sloan Kettering Cancer Center was identified as an outlier for increased length of stay (LOS) after colorectal surgery. We subsequently implemented a comprehensive Enhanced Recovery After Surgery (ERAS) program in January 2016, which is continually monitored to target areas for improvement. The primary aim of this study was to evaluate the impact of a newly established ERAS program in a high-volume colorectal center over time.

METHOD

This was a retrospective cohort study, comparing 3000 sequential cancer patients who underwent elective colorectal surgery before and after ERAS implementation. Patients were divided into three groups (Pre-, Early, and Late ERAS). Adherence to ERAS process measures and outcomes (LOS, complications, and 30-day readmission) were compared among the three time periods.

RESULTS

Adherence to ERAS metrics significantly increased over time, from a median of 25% Pre-ERAS to 67% Early and 75% Late ERAS (p < 0.0001). Mean LOS decreased from 5.2 days Pre-ERAS to 4.5 Early and 4.0 Late ERAS (p < 0.0001). There were no differences in rates of complications or readmissions, and patients with shorter LOS had lower readmission rates. With ERAS, the readmission rate was 4.4% for patients discharged within 3 days, versus >10% for LOS ≥5 days (p < 0.0001).

CONCLUSION

Initiation of an ERAS program at a high-volume colorectal center was associated with decreased LOS, without increasing morbidity. Increased ERAS adherence was associated with a further decrease in LOS. Multidisciplinary monitoring to promote protocol adherence is necessary for maintaining a safe and effective ERAS program.

Risk of Metachronous Colorectal Neoplasm after a Segmental Colectomy in Lynch Syndrome Patients According to Mismatch Repair Gene Status

BACKGROUND

Because of increased risk of metachronous colorectal cancer (CRC), all patients with Lynch syndrome (LS) are offered a total colectomy. However, because metachronous CRC rate by mismatch repair (MMR) gene is uncertain, and total colectomy negatively impacts quality of life, it remains unclear whether segmental resection is indicated for lower penetrance MMR genes. We evaluated metachronous CRC incidence according to MMR gene in LS patients who underwent a segmental colectomy.

STUDY DESIGN

Single-center, retrospective cohort study in patients with an earlier colectomy for CRC and an MMR germline mutation in MLH1, MSH2, MSH6, or PMS2 followed prospectively in a hereditary CRC family registry. All patients underwent surveillance colonoscopy. Metachronous CRC was defined as one detected more than 1 year after index resection. Primary end point was cumulative incidence of metachronous CRC overall and by MMR gene.

RESULTS

One hundred and ten patients were included: 35 with MLH1 likely pathogenic/pathogenic (LP/P) variants (32%), 42 MSH2 (38%), 20 MSH6 (18%), and 13 PMS2 (12%). Median follow-up 4.26 years (range 0.53 to 19.92 years). Overall, metachronous CRC developed in 22 patients (20%). At 10-year follow-up, incidence was 12% (95% CI 6% to 23%), with no metachronous CRC detected in patients with a PMS2 or MSH6 LP/P variant.

CONCLUSIONS

After index segmental resection, metachronous CRC is less likely to develop in LS patients with MSH6 or PMS2 LP/P variant than in MLH1 or MSH2 carriers. Our data support segmental resection and long-term colonoscopic surveillance rather than total colectomy in carefully selected, well-informed LS patients with MSH6 or PMS2 LP/P variant.

A rectal cancer organoid platform to study individual responses to chemoradiation

Rectal cancer (RC) is a challenging disease to treat that requires chemotherapy, radiation and surgery to optimize outcomes for individual patients. No accurate model of RC exists to answer fundamental research questions relevant to patients. We established a biorepository of 65 patient-derived RC organoid cultures (tumoroids) from patients with primary, metastatic or recurrent disease. RC tumoroids retained molecular features of the tumors from which they were derived, and their ex vivo responses to clinically relevant chemotherapy and radiation treatment correlated with the clinical responses noted in individual patients' tumors. Upon engraftment into murine rectal mucosa, human RC tumoroids gave rise to invasive RC followed by metastasis to lung and liver. Importantly, engrafted tumors displayed the heterogenous sensitivity to chemotherapy observed clinically. Thus, the biology and drug sensitivity of RC clinical isolates can be efficiently interrogated using an organoid-based, ex vivo platform coupled with in vivo endoluminal propagation in animals.

Changes in the multidisciplinary management of rectal cancer from 2009 to 2015 and associated improvements in short-term outcomes

AIM

Significant recent changes in management of locally advanced rectal cancer (LARC) include preoperative staging, use of extended neoadjuvant therapies and minimally invasive surgery (MIS). This study was aimed at characterizing these changes and associated short-term outcomes.

METHOD

We retrospectively analysed treatment and outcome data from patients with T3/4 or N+ LARC ≤ 15 cm from the anal verge who were evaluated at a comprehensive cancer centre in 2009-2015.

RESULTS

In total, 798 patients were identified and grouped into five cohorts based on treatment year: 2009-2010, 2011, 2012, 2013 and 2014-2015. Temporal changes included increased reliance on MRI staging, from 57% in 2009-2010 to 98% in 2014-2015 (P < 0.001); increased use of total neoadjuvant therapy, from 17% to 76% (P < 0.001); and increased use of MIS, from 33% to 70% (P < 0.001). Concurrently, median hospital stay decreased (from 7 to 5 days; P < 0.001), as did the rates of Grade III-V complications (from 13% to 7%; P < 0.05), surgical site infections (from 24% to 8%; P < 0.001), anastomotic leak (from 11% to 3%; P < 0.05) and positive circumferential resection margin (from 9% to 4%; P < 0.05). TNM downstaging increased from 62% to 74% (P = 0.002).

CONCLUSION

Shifts toward MRI-based staging, total neoadjuvant therapy and MIS occurred between 2009 and 2015. Over the same period, treatment responses improved, and lengths of stay and the incidence of complications decreased.

Assessment of the Value of Comorbidity Indices for Risk Adjustment in Colorectal Surgery Patients

BACKGROUND AND PURPOSE

Comorbidity indices (CIs) are widely used in retrospective studies. We investigated the value of commonly used CIs in risk adjustment for postoperative complications after colorectal surgery.

METHODS

Patients undergoing colectomy without stoma for colonic neoplasia at a single institution from 2009 to 2014 were included. Four CIs were calculated or obtained for each patient, using administrative data: Charlson-Deyo (CCI-D), Charlson-Romano (CCI-R), Elixhauser Comorbidity Score, and American Society of Anesthesiologists classification. Outcomes of interest in the 90-day postoperative period were any surgical complication, surgical site infection (SSI), Clavien-Dindo (CD) grade 3 or higher complication, anastomotic leak or abscess, and nonroutine discharge. Base models were created for each outcome based on significant bivariate associations. Logistic regression models were constructed for each outcome using base models alone, and each index as an additional covariate. Models were also compared using the DeLong and Clarke-Pearson method for receiver operating characteristic (ROC) curves, with the CCI-D as the reference.

RESULTS

Overall, 1813 patients were included. Postoperative complications were reported in 756 (42%) patients. Only 9% of patients had a CD grade 3 or higher complication, and 22.8% of patients developed an SSI. Multivariable modeling showed equivalent performance of the base model and the base model augmented by the CIs for all outcomes. The ROC curves for the four indices were also similar.

CONCLUSIONS

The inclusion of CIs added little to the base models, and all CIs performed similarly well. Our study suggests that CIs do not adequately risk-adjust for complications after colorectal surgery.

Assessment of a Watch-and-Wait Strategy for Rectal Cancer in Patients With a Complete Response After Neoadjuvant Therapy

Importance

The watch-and-wait (WW) strategy aims to spare patients with rectal cancer unnecessary resection.

Objective

To analyze the outcomes of WW among patients with rectal cancer who had a clinical complete response to neoadjuvant therapy.

Design, Setting, and Participants

This retrospective case series analysis conducted at a comprehensive cancer center in New York included patients who received a diagnosis of rectal adenocarcinoma between January 1, 2006, and January 31, 2015. The median follow-up was 43 months. Data analyses were conducted from June 1, 2016, to October 1, 2018.

Exposures

Patients had a clinical complete response after completing neoadjuvant therapy and agreed to a WW strategy of active surveillance and possible salvage surgery (n = 113), or patients underwent total mesorectal excision and were found to have a pathologic complete response (pCR) at resection (n = 136).

Main Outcomes and Measures

Kaplan-Meier estimates were used for analyses of local regrowth and 5-year rates of overall survival, disease-free survival, and disease-specific survival.

Results

Compared with the 136 patients in the pCR group, the 113 patients in the WW group were older (median [range], 67.2 [32.1-90.9] vs 57.3 [25.0-87.9] years, P < .001) with cancers closer to the anal verge (median [range] height from anal verge, 5.5 [0.0-15.0] vs 7.0 [0.0-13.0] cm). All 22 local regrowths in the WW group were detected on routine surveillance and treated by salvage surgery (20 total mesorectal excisions plus 2 transanal excisions). Pelvic control after salvage surgery was maintained in 20 of 22 patients (91%). No pelvic recurrences occurred in the pCR group. Rectal preservation was achieved in 93 of 113 patients (82%) in the WW group (91 patients with no local regrowths plus 2 patients with local regrowths salvaged with transanal excision). At 5 years, overall survival was 73% (95% CI, 60%-89%) in the WW group and 94% (95% CI, 90%-99%) in the pCR group; disease-free survival was 75% (95% CI, 62%-90%) in the WW group and 92% (95% CI, 87%-98%) in the pCR group; and disease-specific survival was 90% (95% CI, 81%-99%) in the WW group and 98% (95% CI, 95%-100%) in the pCR group. A higher rate of distant metastasis was observed among patients in the WW group who had local regrowth vs those who did not have local regrowth (36% vs 1%, P < .001).

Conclusions and Relevance

A WW strategy for select rectal cancer patients who had a clinical complete response after neoadjuvant therapy resulted in excellent rectal preservation and pelvic tumor control; however, in the WW group, worse survival was noted along with a higher incidence of distant progression in patients with local regrowth vs those without local regrowth.

Role of the Interval from Completion of Neoadjuvant Therapy to Surgery in Postoperative Morbidity in Patients with Locally Advanced Rectal Cancer

BACKGROUND

Increasing the interval from completion of neoadjuvant therapy to surgery beyond 8 weeks is associated with increased response of rectal cancer to neoadjuvant therapy. However, reports are conflicting on whether extending the time to surgery is associated with increased perioperative morbidity.

METHODS

Patients who presented with a tumor within 15 cm of the anal verge in 2009-2015 were grouped according to the interval between completion of neoadjuvant therapy and surgery: < 8 weeks, 8-12 weeks, and 12-16 weeks.

RESULTS

Among 607 patients, the surgery was performed at < 8 weeks in 317 patients, 8-12 weeks in 229 patients, and 12-16 weeks in 61 patients. Patients who underwent surgery at 8-12 weeks and patients who underwent surgery at < 8 weeks had comparable rates of complications (37% and 44%, respectively). Univariable analysis identified male sex, earlier date of diagnosis, tumor location within 5 cm of the anal verge, open operative approach, abdominoperineal resection, and use of neoadjuvant chemoradiotherapy alone to be associated with higher rates of complications. In multivariable analysis, male sex, tumor location within 5 cm of the anal verge, open operative approach, and neoadjuvant chemoradiotherapy administered alone were independently associated with the presence of a complication. The interval between neoadjuvant therapy and surgery was not an independent predictor of postoperative complications.

CONCLUSIONS

Delaying surgery beyond 8 weeks from completion of neoadjuvant therapy does not appear to increase surgical morbidity in rectal cancer patients.

Effect of Neoadjuvant Systemic Chemotherapy With or Without Chemoradiation on Bowel Function in Rectal Cancer Patients Treated With Total Mesorectal Excision

BACKGROUND

Neoadjuvant chemoradiation (CRT) impairs bowel function in patients with rectal cancer treated with total mesorectal excision (TME). The impact of other forms of neoadjuvant therapy such as neoadjuvant chemotherapy alone (NC) and induction chemotherapy followed by CRT (total neoadjuvant therapy or TNT) on postoperative bowel function has not been investigated.

METHODS

We conducted a retrospective review of 176 rectal cancer patients treated between November 1, 2011, and August 31, 2017. All patients completed the MSKCC Bowel Function Instrument (BFI), a validated bowel function questionnaire, at least 6 months after TME and/or ileostomy reversal. Differences in BFI scores were compared across four groups (surgery alone, CRT, NC, and TNT) and also according to exposure to neoadjuvant RT and neoadjuvant chemotherapy. A multivariable linear regression model was used to evaluate the independent relationship between exposure to neoadjuvant RT or chemotherapy and BFI.

RESULTS

BFI total scores were significantly different between the four groups (p = 0.008). Exposure to RT correlated with worse BFI total scores (p = 0.002), and no differences were found in BFI total score after exposure to neoadjuvant chemotherapy (p = 0.92). In a linear regression model, only exposure to RT (β = - 5.1; 95% CI - 8.9 to - 1.3; p = 0.008) and tumor distance from the anal verge (β = 1.23; 95% CI 0.48 to 1.97; p = 0.001) were significantly correlated with BFI total score.

CONCLUSION

NC, whether administered alone or added to CRT, does not seem to impair bowel function. These data should be used to counsel rectal cancer patients when discussing neoadjuvant therapy options.

A perioperative multidisciplinary care bundle reduces surgical site infections in patients undergoing synchronous colorectal and liver resection

BACKGROUND

Surgical site infections (SSIs) are a major cause of morbidity, mortality, and healthcare costs, and patients undergoing simultaneous colorectal/liver resections are at an especially high SSI risk.

METHODS

Data were collected on all patients undergoing synchronous colorectal/liver resection from 2011 to 2016 (n = 424). The intervention, implemented in 2013, included 13 multidisciplinary perioperative components. The primary endpoints were superficial/deep and organ space SSIs. Secondary endpoints were hospital length of stay (LOS) and 30-day readmission rate. To control for changes in SSI rates independent of the intervention, interrupted time series analysis was conducted.

RESULTS

Overall, superficial/deep, and organ space SSIs decreased by 60.5% (p < 0.001), 80.6% (p < 0.001), and 47.6% (p = 0.008), respectively. In the pre-intervention cohort (n = 231), there were 79 (34.2%), 31 (13.4%), and 48 (20.8%) total, superficial/deep, and organs space SSIs, respectively. In the post-intervention cohort (n = 193), there were 26 (13.5%), 5 (2.6%), and 21 (10.9%) total, superficial/deep, and organs space SSIs, respectively. Median LOS decreased from 9 to 8 days (p < 0.001). Readmission rates did not change (p = 0.6). Interrupted time series analysis found no significant trends in SSI rate within the pre-intervention (p = 0.35) and post-intervention (p = 0.55) periods.

CONCLUSION

In combined colorectal/liver resection patients, implementation of a multidisciplinary care bundle was associated with a 61% reduction in SSIs, with the greatest impact on superficial/deep SSI, and modest reduction in LOS. The absence of trends within each time period indicated that the intervention was likely responsible for SSI reduction. Future efforts should target further reduction in organ space SSI.

SMAD4 Loss in Colorectal Cancer Patients Correlates with Recurrence, Loss of Immune Infiltrate, and Chemoresistance

PURPOSE

SMAD4 has shown promise in identifying patients with colorectal cancer at high risk of recurrence or death.Experimental Design: A discovery cohort and independent validation cohort were classified by SMAD4 status. SMAD4 status and immune infiltrate measurements were tested for association with recurrence-free survival (RFS). Patient-derived xenografts from SMAD4-deficient and SMAD4-retained tumors were used to examine chemoresistance.

RESULTS

The discovery cohort consisted of 364 patients with stage I-IV colorectal cancer. Median age at diagnosis was 53 years. The cohort consisted of 61% left-sided tumors and 62% stage II/III patients. Median follow-up was 5.4 years (interquartile range, 2.3-8.2). SMAD4 loss, noted in 13% of tumors, was associated with higher tumor and nodal stage, adjuvant therapy use, fewer tumor-infiltrating lymphocytes (TIL), and lower peritumoral lymphocyte aggregate (PLA) scores (all P < 0.04). SMAD4 loss was associated with worse RFS (P = 0.02). When stratified by SMAD4 and immune infiltrate status, patients with SMAD4 loss and low TIL or PLA had worse RFS (P = 0.002 and P = 0.006, respectively). Among patients receiving 5-fluorouracil (5-FU)-based systemic chemotherapy, those with SMAD4 loss had a median RFS of 3.8 years compared with 13 years for patients with SMAD4 retained. In xenografted mice, the SMAD4-lost tumors displayed resistance to 5-FU. An independent cohort replicated our findings, in particular, the association of SMAD4 loss with decreased immune infiltrate, as well as worse disease-specific survival.

CONCLUSIONS

Our data show SMAD4 loss correlates with worse clinical outcome, resistance to chemotherapy, and decreased immune infiltrate, supporting its use as a prognostic marker in patients with colorectal cancer.

Use of the Xi robotic platform for total abdominal colectomy: a step forward in minimally invasive colorectal surgery

BACKGROUND

The use of the da Vinci robotic platform for total colectomy has been limited by the need to reposition the patient-side surgical cart from one side of the patient to the other, which increases operative time. In this study, we examined the feasibility of robotic total colectomy using the da Vinci Xi model, which offers a rotating boom-mounted system and laser-targeted trocar positioning.

METHODS

The study cohort consisted of 23 patients who underwent minimally invasive total colectomy for cancer or polyposis syndromes at a comprehensive cancer center between 2015 and 2017. Of the 23 colectomies, 15 were robotic and eight were laparoscopic. For the robotic colectomies, trocars were placed in the supraumbilical region and all four quadrants. The da Vinci Xi robot was placed between the patient's legs, and the boom was rotated from left to right and then to the middle in order to work sequentially on the right colon, the left colon, and the pelvis. Operating time and short-term outcomes were compared between the patients who underwent robotic surgery and the patients who underwent laparoscopic surgery.

RESULTS

The two groups of patients were comparable in age, gender, BMI, physical status, and disease types. In the robotic group, median length of stay (4 vs. 6 days, p = 0.047) was significantly shorter and median operative time (243 vs. 263 min, p = 0.97) and median estimated blood loss (50 vs. 100 ml; p = 0.08) were similar between the groups.

CONCLUSIONS

With the da Vinci Xi boom-mounted system, total abdominal colectomy can be performed without the need to move the patient-side surgical cart and is associated with shorter length of stay and similar operative time compared to the laparoscopic approach.

Effectiveness of a multidisciplinary patient care bundle for reducing surgical-site infections

BACKGROUND

Surgical-site infection (SSI) is associated with significant healthcare costs. To reduce the high rate of SSI among patients undergoing colorectal surgery at a cancer centre, a comprehensive care bundle was implemented and its efficacy tested.

METHODS

A pragmatic study involving three phases (baseline, implementation and sustainability) was conducted on patients treated consecutively between 2013 and 2016. The intervention included 13 components related to: bowel preparation; oral and intravenous antibiotic selection and administration; skin preparation, disinfection and hygiene; maintenance of normothermia during surgery; and use of clean instruments for closure. SSI risk was evaluated by means of a preoperative calculator, and effectiveness was assessed using interrupted time-series regression.

RESULTS

In a population with a mean BMI of 30 kg/m² , diabetes mellitus in 17·5 per cent, and smoking history in 49·3 per cent, SSI rates declined from 11·0 to 4·1 per cent following implementation of the intervention bundle (P = 0·001). The greatest reductions in SSI rates occurred in patients at intermediate or high risk of SSI: from 10·3 to 4·7 per cent (P = 0·006) and from 19 to 2 per cent (P < 0·001) respectively. Wound care modifications were very different in the implementation phase (43·2 versus 24·9 per cent baseline), including use of an overlying surface vacuum dressing (17·2 from 1·4 per cent baseline) or leaving wounds partially open (13·2 from 6·7 per cent baseline). As a result, the biggest difference was in wound-related rather than organ-space SSI. The median length of hospital stay decreased from 7 (i.q.r. 5-10) to 6 (5-9) days (P = 0·002). The greatest reduction in hospital stay was seen in patients at high risk of SSI: from 8 to 6 days (P < 0·001). SSI rates remained low (4·5 per cent) in the sustainability phase.

CONCLUSION

Meaningful reductions in SSI can be achieved by implementing a multidisciplinary care bundle at a hospital-wide level.

Adoption of Total Neoadjuvant Therapy for Locally Advanced Rectal Cancer

Importance

Treatment of locally advanced rectal (LARC) cancer involves chemoradiation, surgery, and chemotherapy. The concept of total neoadjuvant therapy (TNT), in which chemoradiation and chemotherapy are administered prior to surgery, has been developed to optimize delivery of effective systemic therapy aimed at micrometastases.

Objective

To compare the traditional approach of preoperative chemoradiation (chemoRT) followed by postoperative adjuvant chemotherapy with the more recent TNT approach for LARC.

Design, Setting, and Participants

A retrospective cohort analysis using Memorial Sloan Kettering Cancer Center (MSK) records from 2009 to 2015 was carried out. A total of 811 patients who presented with LARC (T3/4 or node-positive) were identified.

Exposures

Of the 811 patients, 320 received chemoRT with planned adjuvant chemotherapy and 308 received TNT (induction fluorouracil- and oxaliplatin-based chemotherapy followed by chemoRT).

Main Outcomes and Measures

Treatment and outcome data for the 2 cohorts were compared. Dosing and completion of prescribed chemotherapy were assessed on the subset of patients who received all therapy at MSK.

Results

Of the 628 patients overall, 373 (59%) were men and 255 (41%) were women, with a mean (SD) age of 56.7 (12.9) years. Of the 308 patients in the TNT cohort, 181 (49%) were men and 127 (49%) were women. Of the 320 patients in the chemoRT with planned adjuvant chemotherapy cohort, 192 (60%) were men and 128 (40%) were women. Patients in the TNT cohort received greater percentages of the planned oxaliplatin and fluorouracil prescribed dose than those in the chemoRT with planned adjuvant chemotherapy cohort. The complete response (CR) rate, including both pathologic CR (pCR) in those who underwent surgery and sustained clinical CR (cCR) for at least 12 months posttreatment in those who did not undergo surgery, was 36% in the TNT cohort compared with 21% in the chemoRT with planned adjuvant chemotherapy cohort.

Conclusions and Relevance

Our findings provide additional support for the National Comprehensive Cancer Network (NCCN) guidelines that categorize TNT as a viable treatment strategy for rectal cancer. Our data suggest that TNT facilitates delivery of planned systemic therapy. Long-term follow-up will determine if this finding translates into improved survival. In addition, given its high CR rate, TNT may facilitate nonoperative treatment strategies aimed at organ preservation.

Influence of timing of surgery on perioperative morbidity after neoadjuvant therapy for locally advanced rectal cancer

754

Background: Timing of surgery following completion of neoadjuvant therapy (NT) for locally advanced rectal cancer (LARC) has important implications for treatment response. However, it was recently reported in the GRECCAR 6 trial that delayed surgery beyond 8 weeks from completion of NT is associated with increased complications. Within a cohort of LARC patients treated with NT (CRT alone, Total NT (TNT) and chemotherapy alone) we examine perioperative complications based on time from NT to surgery. Methods: Patients with Stage II/III LARC ≤15cm from the anal verge who received NT from 06/01/09 – 03/01/15 were identified and preoperative morbidity collected on those undergoing rectal resection. Patients were grouped according to time of surgery from completion of NT (5-8 weeks – early surgery / 8-12 weeks – late surgery). Results: 798 patients were identified and 547 underwent rectal resection within 12 weeks of completing NT (440 LAR and 107 APR). Surgery was performed 5-8 following NT in 252 pts and 8-12 weeks following NT in 246 pts. 204 patients (41%) had a post-op complication: 53 (10%) Grade 3-5 complication and 83 (17%) SSI. There were no statistically significant differences in rates of all complications (44% vs 38%), grade 3-5 complications (9% vs 11%), SSI (17% vs 17%), and LOS (median 6 days vs 6 days) between the early and late surgery groups. Similar results were obtained when evaluating the subgroups by type of NT (CRT alone, chemo alone or TNT), surgical approach (open vs minimally invasive and sphincter preservation vs colostomy), post-treatment TNM stage and year of treatment (all NS). In addition, we did not observe differences in rates of downstaging responses: T downstaging (63% vs 64%), N downstaging (61% vs 54%), > 95% regression (34% vs 34%) or pCR rates (18% vs 18%) between the early and later surgery groups. Conclusions: In patients undergoing radical surgery for LARC post NT, we do not observe an effect of timing of surgery on surgical complications. Although timing of surgery is reported to influence response rates, we did not reproduce these findings, likely as a consequence of the high rate of deferral of surgery/ non-operative management in this cohort.

Rectal Gastrointestinal Stromal Tumor (GIST) in the Era of Imatinib: Organ Preservation and Improved Oncologic Outcome

BACKGROUND

Approximately 5% of gastrointestinal stromal tumors (GISTs) originate in the rectum, and historically, radical resection was commonly performed. Little is known about the outcome for rectal GIST in the era of imatinib.

METHODS

Using a prospectively maintained database, this study retrospectively analyzed 47 localized primary rectal GISTs treated at our center from 1982 to 2016, stratified by when imatinib became available in 2000. Overall survival (OS), disease-specific survival (DSS), and recurrence-free survival (RFS) were analyzed by the Kaplan-Meier method.

RESULTS

Rectal GISTs represented 7.1% of 663 primary GISTs. The findings showed 17 patients in the pre-imatinib era and 30 patients in the imatinib era. The two groups had similar follow-up evaluation, age, gender, Miettinen risk, and distance to the anal verge. In the imatinib era, tumors were smaller at diagnosis (median 4 vs. 5 cm; p = 0.029), and 24 of the 30 patients received perioperative imatinib. In the high-risk patients, organ preservation and negative margins were more common among the 13 patients treated with neoadjuvant imatinib than among the 21 patients treated directly with surgery. High-risk patients who received perioperative imatinib (n = 15) had greater (or nearly significantly greater) 5-year OS, DSS, local RFS, and distant RFS than those who did not (n = 19) (91, 100, 100, and 71% vs. 47, 65, 74, and 41%; p = 0.049, 0.052, 0.077, 0.051, respectively). In the imatinib era, no patient has had a local recurrence or death due to GIST.

CONCLUSIONS

The use of imatinib is associated with organ preservation and improved oncologic outcome for patients with rectal GIST.

Total neoadjuvant chemotherapy to facilitate delivery and tolerance of systemic chemotherapy and response in locally advanced rectal cancer

3519

Background: The most common therapy for locally advanced (T3/4 or N+) rectal cancer (LARC) consists of preoperative chemoradiotherapy (chemoRT) followed by surgery and adjuvant chemotherapy. Recently, use of total neoadjuvant therapy (TNT) with preoperative chemotherapy in addition to chemoRT prior to resection has been accepted as an alternative. Methods: Of 811 consecutive patients (pts) who presented with LARC at our cancer center in 2009-2015, 320 received chemoRT with planned adjuvant chemotherapy, and 308 received TNT (induction FOLFOX/CAPOX chemotherapy followed by chemoRT). Treatment and outcome data for those two cohorts were compared. Results: Pts in the TNT cohort received greater percentages of the planned oxaliplatin and fluorouracil prescribed dose than those in the chemoRT with planned adjuvant chemotherapy cohort (p < 0·005 and p < 0·001, respectively). The complete response (CR) rate, which includes pathological CR (pCR) and clinical CR (cCR) at 6 months post-treatment, was 21% in the chemoRT with planned adjuvant chemotherapy cohort and 36% in the TNT cohort. The median follow-up was 40 months in the chemoRT with planned adjuvant chemotherapy cohort and 23 months in the TNT cohort. Fewer distant recurrences were seen in patients who had T downstaging (p < 0·001), N downstaging (p < 0·005), a cCR (p = 0·005), or a pCR (p < 0·005). There was no statistically significant difference in distant-recurrence-free survival between the two cohorts. Conclusions: Our findings provide additional support for the National Comprehensive Cancer Network (NCCN) guidelines for rectal cancer treatment, which categorizes TNT as a viable treatment strategy that facilitates superior compliance and delivery of systemic therapy. Given its high CR rate, TNT may be beneficial as part of a nonoperative treatment strategy aimed at organ preservation.

Total neoadjuvant therapy for locally advanced rectal cancer

662

Background: Current therapy for locally advanced rectal cancer (LARC) consists of 6 months of perioperative therapy, either with pre-operative chemo-radiotherapy (CRT) and post operative adjuvant chemotherapy (PAC) or total neoadjuvant therapy (TNT) with induction chemotherapy (ICT) followed by CRT then surgery. The aim of our study was to report on the safety, efficacy and complete response rates comparing TNT to PAC in a larger series of LARC patients (pts) at Memorial Sloan Kettering Cancer Center (MSKCC). Methods: Pts treated at MSKCC (2009-15) were analyzed based on the intended treatment schedule (TNT or PAC). 730 LARC pts were treated with CRT, of these 320 received neoadjuvant CRT and 308 received TNT. Results: In the TNT group 205 pts (73%) underwent surgery within 26 weeks of completion of treatment, of which 38 (19%) had a pCR. Of the 78 pts who did not undergo surgery within 26 weeks, 68 (87%) had a complete clinical response (cCR). In the PAC group 293 pts (92%) underwent surgery within 26 weeks and 45 (15%) had a pCR. Of the 27 pts who did not undergo surgery within 26 weeks 22 (81%) had a cCR. The median follow up was 25 mo in the TNT group and 29 mo in the PAC group. There was no statistically significant difference in the distant metastasis free survival between the treatment regimens, despite a higher number of cT4 and cN + tumors in the TNT group. Fewer distant recurrences were seen in pts who had evidence of T downstaging (P < 0.001), N downstaging (P < 0.005), the presence of a cCR (P = 0.005) or a pCR (P < 0.005). Of the pts who received all treatment at MSKCC, comparison of dose of 5-FU and oxaliplatin between the preoperative (N = 249) and postoperative regimens (N = 101) was notable for a higher average dose received of both 5FU and oxaliplatin (p < 0.005 and p < 0.001) in the ICT group. Conclusions: These data add weight to the evidence already included in the NCCN guidelines that pre-operative chemotherapy as part of TNT is a viable treatment strategy with superior compliance and delivery of systemic therapy. Given the high complete response rate, TNT may be used as part of an organ preservation treatment strategy.

Poorly differentiated clusters as a prognostic marker at the invasive front of colon cancer

621

Background: Histology at the invasive front of colon cancer can predict malignant potential. However, the optimal histological marker is yet to be established. This study compares the various invasive front histologic markers. Methods: A single-institution prospective database was queried for consecutive patients who underwent curative resection for Stage I-III colon adenocarcinoma from 2007-14. Histologic features were reviewed by a pathologist, including poorly differentiated clusters (PDC), tumor budding (BD), perineural invasion (PN), desmoplastic reaction (DR) and Crohn’s like reaction (CLR) at the invasive front, and WHO grade of the whole tumor. PDC was defined as cancer clusters of ≥ 5 cancer cells that lack a gland-like structure, and was graded into G1 ( < 5), G2 (5-9) and G3 ( ≥ 10) by the highest number of the clusters /HPF. Clinical outcome included recurrence free survival (RFS) and peak hazard function of recurrence and death identified using the kernel-smoothing method. Predictive accuracy was measured with concordance probability estimate (CPE) for proportional hazards regression. Inter-observer agreement was assessed by weighted kappa values on diagnoses rendered by 3 pathologists on 50 randomly selected cases. Results: The study cohort consisted of 851 patients with a median follow up of 36 months. PDC, BD, PN, DR and CLR at the invasive front were significantly associated with RFS. When analyzed by stage, PDC, BD and PN were associated with RFS both in Stage II and Stage III, while the others were prognostic only in Stage III. CPE was the highest in PDC (0.642), indicating the best predictive accuracy, while it was the lowest in WHO grade (0.526). Weighted kappa was also the highest for PDC, indicating the best inter-observer agreement (PDC: 0.824, WHO grade: 0.568). The smoothed graph of the hazard function showed that the risk of recurrence was not only the highest but peaked earlier for PDC G3 (between0 and 12 months) than PDC G2 (between12 and 24 months) and G1 (no evident peak). Conclusions: Of the commonly evaluated histologic markers at the invasive front, PDC grade is the most predictive and reproducible. Further confirmatory investigations are warranted to determine if PDC can replace WHO grade.

Evolution in multimodality management of locally advanced rectal cancer

684

Background: This study reports the evolving multimodality management of locally advanced rectal cancer (LARC) and associated outcomes at a high volume center. Methods: Patients with Stage II/III LARC <15cm from the anal verge evaluated by the colorectal surgery service were identified from a prospective database. Clinical management including neoadjuvant therapy (NT) and surgical treatment along with pathologic and perioperative outcomes were collected. Results: Between June 2009 and March 2015, 798 patients were evaluated and received NT for LARC. Majority were staged cT3/T4 (84%) or cN+ (78%), and 635 had surgery within 26wks following NT. Reliance on MRI staging increased from 57% to 98% during the study period (P < 0.001). There was increased usage of total NT (NEO) with pre-op chemotherapy (CT) and chemoradiotherapy (CRT) (17% to 76%, p < 0.001) with a concomitant decrease in use of CRT alone (77% to 16%, p < 0.001) and post-op CT (70% to 15%, p < 0.001). The proportion undergoing surgery beyond 8wks after NT rose from 41% to 62% (P < 0.001) and beyond 8 wks after CRT rose from 45% to 72% (p < 0.001). The percentage of patients not undergoing resection by 26wks (nonoperative management) rose from 12% to 27%, P < 0.001). Minimally invasive surgery (MIS) increased from 33% to 71% (P < 0.001); in 2014-15 98% of MIS was robot-assisted. Over the study period there was a decrease in LOS (mean 8.1 to 6.5 days, p < 0.001), grade III-V complications (13% to 7%, p < 0.05), surgical site infections (25% to 8%, p < 0.001), and anastomotic leak (11% to 3%, p < 0.05). The proportion undergoing ileostomy closure within 15 wks rose from 7% to 73% (P < 0.001). Involved CRM rates decreased from 9% to 3% (P < 0.01). TNM downstaging increased from 62% to 74% (p = 0.002). Complete response rates (clinical and pathologic) at 26wks was 26% in 2009-10 and 32% in 2014/5 (p = 0.067). Conclusions: Over the past decade, there has been a shift to MRI staging, total NT (NEO), and MIS rectal resection at 8-12 weeks. This has been associated with higher response rates, shorter LOS, and fewer complications.

SMAD4 loss in colorectal cancer: Correlation with recurrence, chemoresistance, and immune infiltrate

587

Background: Few markers reliably identify colorectal cancer (CRC) patients at risk of recurrence and death. SMAD4 loss occurs in 10-20% of cases and has shown promise in identifying high-risk stage II/III patients. We examined SMAD4 status and association with clinical/pathologic features in 446 stage I-IV CRC patients at Memorial Sloan Kettering (MSK). Methods: Patients undergoing curative resection were included (1981-2010). Familial polyposis syndrome patients and those with inadequate tissue were excluded. Tissue microarrays were constructed (n=364). Immunohistochemistry for SMAD4 and mismatch repair (MMR) proteins was completed. SMAD4 nuclear stain intensity was scored (scale=0-3; 0=loss). On whole sections, MMR proteins (present or absent), tumor-infiltrating lymphocytes (TILs) and peritumoral lymphocyte aggregates (PLAs) were scored (scale=0-3). Associations between clinical/pathologic features and SMAD4 loss vs. retention were analyzed. Kaplan-Meier estimates and log-rank test were used for recurrence-free and overall survival analyses (RFS and OS). Results: SMAD4 loss was noted in 13%. Median age at diagnosis was 53 years, and 51% were male. The cohort consisted of 61% hindgut tumors and 62% stage II/III patients. With up to 33 years of follow-up, the mean was 6 years. SMAD4 loss correlated with higher tumor and nodal stage, adjuvant therapy use, and lower TIL and PLA scores (p<0.04 for all). Unlike prior studies, no significant differences in OS based on SMAD4 status across the entire cohort were noted; however, older patients (>median) were noted to have worse OS with SMAD4 loss (p<0.01). SMAD4 loss did correlate with worse RFS (p=0.02), persisting even when excluding MMR-deficient patients. Additionally, SMAD4 loss was associated with worse RFS in both the adjuvant chemotherapy group (median RFS=3.8 vs. 13 years; p=0.06) and the resection-only group (median RFS=4.2 years vs. not yet reached; p< 0.01). Conclusions: SMAD4 loss correlates with worse RFS and resistance to adjuvant therapy. SMAD4 loss also correlates with lower TIL and PLA scores. Future work will address chemoresistance mechanisms, relevance to adjuvant therapy use, and loss of immune infiltrate in SMAD4-null tumors.

Incisional hernias after laparoscopic and robotic right colectomy

PURPOSE

Incisional hernia (IH) is a common complication after colectomy, with impacts on both health care utilization and quality of life. The true incidence of IH after minimally invasive colectomy is not well described. The purpose of this study was to examine IH incidence after minimally invasive right colectomies (RC) and to compare the IH rates after laparoscopic (L-RC) and robotic (R-RC) colectomies.

METHODS

This is a retrospective review of patients undergoing minimally invasive RC at a single institution from 2009 to 2014. Only patients undergoing RC for colonic neoplasia were included. Patients with previous colectomy or intraperitoneal chemotherapy were excluded. Three L-RC patients were included for each R-RC patient. The primary outcome was IH rate based on clinical examination or computed tomography (CT). Univariate and multivariate time-to-event analyses were used to assess predictors of IH.

RESULTS

276 patients where included, of which 69 had undergone R-RC and 207 L-RC. Patient and tumor characteristics were similar between the groups, except for higher tumor stage in L-RC patients. Both the median time to diagnosis (9.2 months) and the overall IH rate were similar between the groups (17.4 % for R-RC and 22.2 % for L-RC), as were all other postoperative complications. In multivariable analyses, the only significant predictor of IH was former or current tobacco use (hazard raio 3.0, p = 0.03).

CONCLUSIONS

This study suggests that the incidence of IH is high after minimally invasive colectomy and that this rate is equivalent after R-RC and L-RC. Reducing the IH rate represents an important opportunity for improving quality of life and reducing health care utilization after minimally invasive colectomy.

Abstract LB-A24: Molecular alteration of SMAD4 in hindgut-derived colorectal tumors identifies a distinct subset of patients and is associated with worse recurrence-free survival

This abstract has been withheld from publication due to its inclusion in the AACR-NCI-EORTC Molecular Targets Conference 2015 Official Press Program. It will be posted online at the time of its presentation in a press conference or in a session: 10:00 AM ET Friday, November 6.

Citation Format: Jesse Joshua Smith, Lik Hang Lee, Xi Chen, Chao Wu, Raphael Pelossof, Garrett M. Nash, Larissa R. Temple, Jose G. Guillem, Martin R. Weiser, Philip B. Paty, Jinru Shia, Julio Garcia-Aguilar, Charles L. Sawyers. Molecular alteration of SMAD4 in hindgut-derived colorectal tumors identifies a distinct subset of patients and is associated with worse recurrence-free survival. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr LB-A24.

Mosaic partial deletion of the PTEN gene in a patient with Cowden syndrome

Cowden syndrome is an autosomal dominant condition caused by pathogenic mutations in the phosphatase and tensin homolog (PTEN) gene. Only a small proportion of identified pathogenic mutations have been reported to be large deletions and rearrangements. We report on a female patient with a previous history of breast ductal carcinoma in situ who presented to our institution for management of gastrointestinal hamartomatous polyposis. Although several neoplastic predisposition syndromes were considered, genetic evaluation determined that the patient met clinical diagnostic criteria for Cowden syndrome. Array-based comparative genomic hybridization was performed and revealed a mosaic partial deletion of the PTEN gene. Follow-up clinical history including bilateral thyroid nodules, dermatological findings, and a new primary "triple-negative" adenocarcinoma of the contralateral breast are discussed. We highlight the need for recognition and awareness of mosaicism as it may provide an explanation for variable phenotypic presentations and may alter the genetic counseling risk assessment of affected individuals and family members.

Total proctocolectomy for rectal cancer in Lynch syndrome: indications and considerations

SUMMARY 

Patients with Lynch syndrome and rectal cancer present a unique clinical challenge. Management of the primary rectal cancer and prophylactic removal of the colon should be considered. In patients requiring a mesorectal excision, a combined prophylactic colon removal can be considered. Although surveillance of the colon with frequent colonoscopies is an alternative, concerns of metachronous colon cancer development support prophylactic removal of the colon as an alternative. Since data are not available to confirm superiority of either approach, the final decision is greatly dependent upon a patient's wishes and preferences. Patients interested in pursuing simultaneous prophylactic colon removal can be offered total proctocolectomy with either ileal pouch anal-anastomosis as a sphincter-preserving alternative or a total proctocolectomy with end ileostomy.

Organ preservation in patients with rectal cancer with clinical complete response after neoadjuvant therapy

509

Background: Nonoperative management (NOM) of rectal cancer following a clinical complete response (cCR) to neoadjuvant therapy is a non-standard approach. We review our experience with NOM to evaluate safety and efficacy. Methods: A retrospective review of prospectively collected data between 2006 and 2014 was conducted. We compared patients completing neoadjuvant therapy for stage I to III rectal cancers who: a) achieved cCR and were treated with NOM, or b) underwent standard total mesorectal excision (TME) and achieved a pathologic complete response (pCR). Kaplan-Meier estimates and the log-rank test were used. Results: Seventy-three patients underwent NOM after cCR. From 369 rectal resections performed, 72 (20%) achieved pCR and form the comparison group. Median follow-up across both groups was 3.3 years. Rectal preservation was achieved in 56 (77%) of the patients treated with NOM. Of the 19 NOM patients with local regrowth, 18 were salvaged successfully with standard TME (n=16) or local excision (n=2), with one patient pending a salvage operation (n=1). No significant differences were noted in the number of distant recurrences between the NOM and pCR groups. Four-year disease-specific survival and overall survival between the two groups were not significantly different. Conclusions: In this highly selected group of patients with cCR to neoadjuvant treatment, NOM with surgical salvage of local tumor regrowth achieved local control in all patients. The oncologic outcome for NOM patients at 4 years was comparable to patients with pCR after rectal resection. These data continue to suggest that NOM does not compromise oncologic outcome, and that preservation of the rectum is achieved in a majority of patients. [Table: see text]

Neoadjuvant chemotherapy first, followed by chemoradiation and then surgery, in the management of locally advanced rectal cancer

Standard therapy for locally advanced rectal cancer (LARC) is preoperative chemoradiotherapy and postoperative chemotherapy. At Memorial Sloan-Kettering Cancer Center (MSKCC) the authors began offering FOLFOX (5-fluorouracil, leucovorin, and oxaliplatin) as initial treatment for patients with high-risk LARC to target micrometastases while treating the primary tumor. The purpose of this study is to report the safety and efficacy of initial FOLFOX given before chemoradiotherapy on tumor downsizing and pathologic complete response (pathCR) in LARC. The records of patients with stage II/III rectal cancer treated at MSKCC between 2007 and 2012 were reviewed. Of approximately 300 patients with LARC treated at MSKCC, 61 received FOLFOX as initial therapy. Of these 61 patients, 57 received induction FOLFOX (median 7 cycles) followed by chemoradiation, and 4 experienced an excellent response, declined chemoradiation, and underwent total mesorectal excision (TME). Twelve of the 61 patients did not undergo TME: 9 had a complete clinical response (CCR), 1 declined despite persistent tumor, 1 declined because of comorbidities, and 1 developed metastatic disease. Among the 61 patients receiving initial FOLFOX, 22 (36%) had either a pathCR (n=13) or a CCR (n=9). Of the 49 patients who underwent TME, all had R0 resections and 23 (47%) had tumor response greater than 90%, including 13 (27%) who experienced a pathCR. Of the 28 patients who received all 8 cycles of FOLFOX, 8 experienced a pathCR (29%) and 3 a CCR (11%). No serious adverse events occurred that required a delay in treatment during FOLFOX or chemoradiation. FOLFOX and chemoradiation before planned TME results in tumor regression, a high rate of delivery of planned therapy, and a substantial rate of pathCRs, and offers a good platform for nonoperative management in select patients.

Neoadjuvant chemotherapy without routine use of radiation therapy for patients with locally advanced rectal cancer: a pilot trial

PURPOSE

Although neoadjuvant chemoradiotherapy achieves low local recurrence rates in clinical stages II to III rectal cancer, it delays administration of optimal chemotherapy. We evaluated preoperative infusional fluorouracil, leucovorin, and oxaliplatin (FOLFOX)/bevacizumab with selective rather than consistent use of chemoradiotherapy.

PATIENTS AND METHODS

Thirty-two patients with clinical stages II to III rectal cancer participated in this single-center phase II trial. All were candidates for low anterior resection with total mesorectal excision (TME). Patients were to receive six cycles of FOLFOX, with bevacizumab included for cycles 1 to 4. Patients with stable/progressive disease were to have radiation before TME, whereas responders were to have immediate TME. Postoperative radiation was planned if R0 resection was not achieved. Postoperative FOLFOX × 6 was recommended, but adjuvant regimens were left to clinician discretion. The primary outcome was R0 resection rate.

RESULTS

Between April 2007 and December 2008, 32 (100%) of 32 study participants had R0 resections. Two did not complete preoperative chemotherapy secondary to cardiovascular toxicity. Both had preoperative chemoradiotherapy and then R0 resections. Of 30 patients completing preoperative chemotherapy, all had tumor regression and TME without preoperative chemoradiotherapy. The pathologic complete response rate to chemotherapy alone was 8 of 32 (25%; 95% CI, 11% to 43%). The 4-year local recurrence rate was 0% (95% CI, 0% to 11%); the 4-year disease-free survival was 84% (95% CI, 67% to 94%).

CONCLUSION

For selected patients with clinical stages II to III rectal cancer, neoadjuvant chemotherapy and selective radiation does not seem to compromise outcomes. Preoperative Radiation or Selective Preoperative Radiation and Evaluation Before Chemotherapy and TME (PROSPECT), a randomized phase III trial to validate this experience, is now open in the US cooperative group network.