Complete clinical response after neoadjuvant chemoradiation therapy for distal rectal cancer: characterization of clinical and endoscopic findings for standardization

Risks of Organ Preservation in Rectal Cancer: Data From Two International Registries on Rectal Cancer

PURPOSE

Organ preservation has become an attractive alternative to surgery (total mesorectal excision [TME]) among patients with rectal cancer after neoadjuvant therapy who achieve a clinical complete response (cCR). Nearly 30% of these patients will develop local regrowth (LR). Although salvage resection is frequently feasible, there may be an increased risk for development of subsequent distant metastases (DM). The aim of this study is to compare the risk of DM between patients with LR after Watch and Wait (WW) and patients with near-complete pathologic response (nPCR) managed by TME at the time of reassessment of response.

METHODS

Data from patients enrolled in the International Watch & Wait Database (IWWD) with cCR managed by WW and subsequent LR were compared with patients managed by TME (with ≤10% cancer cells-nPCR) from the Spanish Rectal Cancer Project (VIKINGO project). The primary end point was DM-free survival at 3 years from decision to WW or TME. The secondary end point was possible risk factors associated with DM.

RESULTS

Five hundred and eight patients with LR were compared with 893 patients with near-complete response after TME. Overall, DM rate was significantly higher among LRs (22.8% v 10.2%; P ≤ .001). Independent risk factors for DM included LR (v TME at reassessment; P = .001), ypT3-4 status (P = .016), and ypN+ status (P = .001) at the time of surgery. 3-year DM-free survival was significantly worse for patients with LR (75% v 87%; P = .001). When stratified for pathologic stage, patients with LR did significantly worse through all stages (P ≤ .009).

CONCLUSION

Patients with LR appear to have a higher risk for subsequent DM development than patients with nPCR managed by TME at restaging irrespective of final pathology. Leaving the primary undetectable tumor in situ until development of LR may result in worse oncologic outcomes.

Sustained Organ Preservation in Patients With Rectal Cancer After Sequential Short-Course Radiation Therapy and Chemotherapy

BackgroundNonoperative management in patients with rectal cancer with complete response to radiation therapy and chemotherapy is of increasing interest. Most of the data on nonoperative management have centered around patients treated with long-course chemoradiotherapy. The ability of short-course radiation-based treatment courses to achieve durable complete responses with sustained organ preservation is less defined. This study updates our institution's long-term experience with nonoperative management following upfront short-course radiation therapy and sequential/consolidation chemotherapy.MethodsWe retrospectively reviewed patients with nonmetastatic rectal cancer treated with sequential short-course radiation therapy and chemotherapy who reached complete response and were subsequently followed with nonoperative management. We report on disease control outcomes, including rates of regrowth and results of salvage surgery. We investigated characteristics associated with local tumor regrowth.ResultsOur study included 52 patients. The 2-year freedom from local regrowth for the entire cohort was 75%. Notably, patients with high-risk disease characteristics at diagnosis exhibited a trend toward a higher rate of local tumor regrowth. No patient with sustained clinical complete response developed metastatic disease. Of the twelve patients undergoing surgical salvage for regrowth of disease, ten were resected with complete/near-complete total mesorectal surgical specimens with negative margins.ConclusionsThe optimal approach to achieving sustained organ preservation through the use of radiation therapy and chemotherapy is not well defined. Our findings show the viability of neoadjuvant therapy incorporating short-course radiation therapy to achieve durable complete responses.

Advantages of a Point-of-care Digital Rectoscope for Colorectal Surgical Practice: A Video-supported Case Series

PURPOSE

Point-of-care (POC) diagnostic tools can support timely and efficient clinical decision-making. The introduction of a POC digital rectoscope has the potential to enhance colorectal surgical practice by enabling immediate bedside endoscopic evaluation in different settings.

METHODS

This case series describes 5 cases, with video documentation illustrating the potential benefits of using a portable digital rectoscope in outpatient follow-up, inpatient postoperative care, and emergency settings.

RESULTS

In a tertiary referral center, POC rectoscopy effectively supported the detection of anastomotic leakage and rectal perforation, response evaluation after neoadjuvant treatment for rectal cancer, and facilitated follow-up after treatment for anastomotic leakage.

CONCLUSIONS

POC digital rectoscopy shows promise in enhancing the diagnostic efficiency of colorectal care. Further studies are warranted to evaluate its clinical impact and cost-effectiveness for the illustrated indications.

The Landmark Series: Organ Preservation in Rectal Cancer-The Watch and Wait Strategy

Radical treatment of rectal cancer has evolved quite significantly over the last few decades with the development of optimal local disease staging with magnetic resonance (MR), refined surgical techniques including total mesorectal excision (TME) with or without sphincter-preservation, and multimodality treatment with the use of chemotherapy and radiation. While oncological outcomes have shown some significant improvements in terms of local disease control and distant metastases rates, complication rates and functional sequelae remain quite significant for patients undergoing TME surgery. In this setting, organ-preserving alternatives, including transanal local excision (TAE) and Watch and Wait (WW), have become increasingly attractive to patients in an attempt to avoid major surgery (TME) as an alternative treatment strategy with no oncological compromise. In the present narrative review, the fundamentals of selection and outcomes of patients undergoing WW will be covered to provide updated information for colorectal surgeons and surgical oncologists interested in this treatment alternative in clinical practice.

Clinical Prediction Models for Contact X-Ray Brachytherapy in Managing Rectal Cancers: A Scoping Review

BACKGROUND

Currently, there are no clinically predictive models that can prognosticate the response of rectal cancers to Contact X-ray brachytherapy (CXB). This review aims to critically evaluate existing models that have attempted to predict the response of rectal cancer to external beam radiotherapy, with the objective of laying the foundation for the development of a CXB-specific prediction model.

METHODS

A random-effects meta-analysis was employed to calculate pooled estimates of the discriminative ability of published models. Using the Prediction Model Risk Of Bias Assessment Tool (PROBAST), each model was evaluated for its risk of bias and applicability. Additionally, the frequency of commonly utilised predictive factors was documented.

RESULTS

Twelve papers discussed fifteen models based on pre-treatment factors. Models predicting response based on the Tumour regression grade (TRG) classified responders as patients who achieved a complete response or near complete response and achieved a pooled AUC of 0.82 (95% CI 0.74-0.89). Models that predicted pathologic complete response (pCR) had a pooled AUC of 0.76 (95% CI 0.71-0.82). The most utilised predictive parameters were age, tumour grade and T stage. However, these models were prone to significant risk of bias and had limited applicability to the general population.

CONCLUSIONS

Although the existing models were statistically robust, they lacked broad applicability. This was primarily due to a lack of external validation, which limits their clinical utility. A future CXB-specific model should prioritise dedicated data collection based on pre-calculated sample size and include the predictive factors identified in this review.

Safety and clinical efficacy of neoadjuvant chemoradiation therapy with immunotherapy for organ preservation in ultra-low rectal cancer: preliminary results of the CHOICE-I trial: a prospective cohort study

OBJECTIVE

To explore the safety and efficacy of neoadjuvant chemoradiotherapy (nCRT) combined with a PD-1 antibody in improving complete clinical response (cCR) and organ preservation in patients with ultra-low rectal cancer.

METHODS

This was a prospective phase II, single-arm, open-label trial. Patients with confirmed pMMR status T 1-3a N 0-1 M 0 retcal adenocarcinoma were included. Long-course chemoradiotherapy was delivered to a dose of 50 Gy. A PD-1 antibody was added 2 weeks after the first radiotherapy session, and two courses were administered. After chemoradiotherapy, CapeOX plus PD-1 antibody was administered to patients for two cycles. After evaluation, patients with cCR were managed with a watch-and-wait (W&W) approach. Local excision or a W&W approach was performed for patients with near complete clinical response (ncCR) as per multidisciplinary team decision. Radical surgery was recommended for poorly regressed or progressed tumors.

RESULTS

Twenty-five patients were enrolled, but two patients withdrew from the study. A total of 23 patients completed the entire neoadjuvant therapy. Ten and five patients achieved cCR and ncCR, respectively, and the rest had a partial clinical response. Patients with cCR were managed with W&W. Four patients with ncCR underwent local excision and were managed using W&W. Eight patients with partial clinical response underwent anus-preserving surgery. At the last follow-up, the rectum and anus preservation rates were 63.4% (14/22) and 95.5% (21/22), respectively.

CONCLUSION

nCRT combined with immunotherapy tended to achieve better cCR and rectum preservation rates with good tolerance in patients.

ACCORD study: a national multi-centre study of the watch and wait approach in patients with rectal cancer in Aotearoa New Zealand

AIM

The adoption of a watch and wait (W&W) approach in patients with rectal cancer, and a complete clinical response (cCR) following neoadjuvant therapy, is increasing worldwide. Despite this, pragmatic unbiased outcome data is limited. This study aimed to investigate national outcomes associated with W&W in Aotearoa New Zealand (AoNZ).

METHODS

A national retrospective study of patients with adenocarcinoma of the rectum managed with a W&W approach between January 2015 and December 2022 in AoNZ was performed by STRATA, a student and trainee led collaborative network. The Cancer Registry and the New Zealand Ministry of Health National Minimum Data Set were linked to identify patients who had rectal cancer and who were treated with neoadjuvant therapy but not rectal resection. Research teams across 17 AoNZ hospitals then screened these patients for inclusion and data collection.

RESULTS

One thousand five hundred and eighteen patients were screened across 17 hospitals, 133 met inclusion criteria. Median age was 71 years. Median follow-up was 2.2 years. The 2-year cumulative incidence of local regrowth was 18.2% (95% CI 10.7%-25.1%), of which 92% was present in the bowel wall, and 68% underwent surgery, all with curative intent. The 2-year cumulative distant metastasis rate was 8.8% (95% CI 3.0%-14.2%) and the 2-year overall survival was 94.8% (95% CI 90.4%-99.4%).

CONCLUSION

This nationwide study of a W&W approach has clinical outcomes similar to the international literature. This data will help guide further implementation of a W&W approach in the management of patients with rectal cancer and inform both clinicians and patients.

A new treatment strategy for mid-low rectal cancer patients exhibiting a clinical complete or near-complete response to neoadjuvant chemoradiotherapy: Transanal endoscopic microsurgery --A multicenter prospective case-control clinical trial by MONT-R

BACKGROUND

Total mesorectal excision is the standard surgery for locally advanced rectal cancer (LARC) after neoadjuvant chemoradiotherapy (nCRT), but it may lead to high complication rates and poor quality of life. This study evaluates whether transanal endoscopic microsurgery (TEM), as a partial resection procedure, can enhance quality of life for clinical complete response (cCR) or near-cCR patients without compromising survival.

METHODS

Between May 2017 to September 2021, 80 patients with T3-4N0M0 or TanyN+M0 mid-low rectal cancer achieving cCR or near-cCR post-nCRT were prospectively included at 6 Chinese centers. Patients underwent either TEM (Group A, n = 38) or radical surgery (Group B, n = 41). Clinicopathological, oncological, and functional outcomes were analyzed.

RESULTS

Postoperative histology revealed 22 ypT0 (57.9 %), 5 ypT1 (13.2 %), 10 ypT2 (26.3 %), and 1 ypT3 (2.6 %) cases in group A and 20 pCR (48.8 %), 1 T0N1 (2.4 %), 5 T1N0 (12.2 %), 12 T2-3N0 (29.3 %), 3 T2-3N1 (7.3 %) cases in group B. After a 60-month median follow-up, local recurrence occurred in 2 patients (5.26 %) in Group A and none in Group B. Distant metastases occurred in 8 patients (21.05 %) in group A and 7 (17.07 %) in group B. There was no significant difference between the two groups in 5-year disease-free survival (P = 0.658) or 5-year overall survival (P = 0.465). Group A showed significantly faster recovery (P < 0.001) and better sphincter function per Wexner (1 vs. 4, P = 0.001) and LARS (0 vs. 17, P < 0.001) scores than Group B.

CONCLUSION

TEM may be an effective approach for assessing residual tumors in LARC patients with cCR or near-cCR. This approach offers an option for those requiring sphincter preservation, with no significant compromise in long-term oncological outcomes observed in our study.

Do not expect an endoluminal complete response to identify a pathologic complete response in rectal cancer!

PURPOSE

To examine the relationship between endoluminal and pathologic complete response after chemoradiotherapy for rectal cancer and identify predictors of a pathologic complete response.

METHOD

The anatomic pathology reports of 102 consecutive patients with rectal cancer who underwent neoadjuvant chemoradiotherapy followed by proctectomy between 2013 and 2017 were reviewed for the presence or absence of endoluminal complete response. The presence of endoluminal complete response was compared with the anatomopathological stage. The residual lesion area was compared with the final pathologic stage to identify predictors of complete response.

RESULTS

Of 102 patients, 20 (19.6 %) achieved a pathologic complete response (ypT0N0). Of these, 9 (45 %) did not achieve an endoluminal complete response. The presence of endoluminal complete response had a sensitivity of 55.00 %, specificity of 96.34 %, and accuracy of 88.24 % to identify ypT0N0. The presence of endoluminal complete response, residual lesion area ≤ 4 cm2, and tumor located in the mid-rectum were associated with pathologic complete response (ypT0N0).

CONCLUSION

Almost half of the patients who had a pathologic complete response did not achieve an endoluminal complete response. Tumors located in the mid-rectum with a residual size of ≤ 4 cm2 and the presence of endoluminal complete response were significantly associated with the achievement of ypT0N0.

Is Early, Postinduction Restaging of Rectal Cancer Undergoing Total Neoadjuvant Therapy Associated With Ultimate Treatment Response?

BACKGROUND

Among patients with rectal cancer treated with total neoadjuvant therapy, it is unclear whether early, postinduction restaging is associated with final tumor response. If so, interim restaging may alter rectal cancer decision-making.

OBJECTIVE

To determine whether postinduction restaging with endoscopy and MRI is associated with final tumor response.

DESIGN

Retrospective cohort study.

SETTINGS

US tertiary care institution accredited by the National Accreditation Program for Rectal Cancer.

PATIENTS

Patients with biopsy-proven rectal cancer who underwent total neoadjuvant therapy with interim (postinduction) restaging.

MAIN OUTCOME MEASURES

Association between response assessment on postinduction restaging and final treatment response.

RESULTS

One hundred seven patients were analyzed. Patients with postinduction magnetic resonance tumor response grade 1 and 2 or complete endoscopic response were significantly more likely (OR 5.4, p < 0.01 and OR 3.7, p = 0.03, respectively) to ultimately achieve a final complete response. Likewise, the odds of a final incomplete response were significantly higher for patients with postinduction composite partial (OR 4.1, p < 0.01) or minimal (OR 12.0, p < 0.01) responses.

LIMITATIONS

Retrospective analysis and lack of detailed subclassification of partial endoscopic response may have limited the conclusions of these data. The limited sample size may also have biased these conclusions.

CONCLUSIONS

Tumor response to induction therapy is associated with the ultimate treatment response to total neoadjuvant therapy among complete or minimal responders; the significance of a partial interim response remains unclear. See Video Abstract .

EST ASOCIADA LA REESTADIFICACIN TEMPRANA POSTINDUCCIN DEL CANCER DE RECTO SOMETIDO A TERAPIA NEOADYUVANTE TOTAL CON LA RESPUESTA TERAPUTICA FINAL

ANTECEDENTES:Entre los pacientes con cáncer de recto tratados con terapia neoadyuvante total, no está claro si la re-estadificación temprana posterior a la inducción está asociada con la respuesta tumoral final. De ser así, la re-estadificación provisoria podría alterar la toma de decisiones sobre el cáncer rectal.OBJETIVO:Determinar si la re-estadificación posterior a la inducción con endoscopia y resonancia magnética están asociadas con la respuesta tumoral final.DISEÑO:Estudio de cohorte retrospectivoESCENARIO:Institución de atención terciaria de Estados Unidos, certificada por el Programa Nacional de Acreditación para el Cáncer de Recto.PACIENTES:Pacientes con cáncer rectal confirmado por biopsia que fueron sometidos a terapia neoadyuvante total con re-estadificación provisoria (posterior a la inducción).PRINCIPALES MEDIDAS DE RESULTADOS:La asociación entre la evaluación de la respuesta en la re-estadificación posterior a la inducción y la respuesta al final del tratamiento.RESULTADOS:Se estudiaron 107 pacientes. Aquellos que presentaban respuesta tumoral a la resonancia magnética post-inducción grado 1-2 o respuesta endoscópica completa tuvieron significativamente más probabilidades (OR (odds ratio) 5,4 [ p < 0,01] y OR: 3,7 [ p = 0,03], respectivamente) de lograr finalmente una respuesta completa final. Asimismo, las probabilidades de una respuesta incompleta final fueron significativamente mayores para los pacientes con respuestas parciales compuestas post-inducción (OR: 4,1, p < 0,01) o mínimas (OR: 12,0, p < 0,01).LIMITACIONES:El análisis retrospectivo y la falta de una subclasificación detallada de la respuesta endoscópica parcial pueden haber limitado las conclusiones de estos datos. El tamaño limitado de la muestra también puede haber sesgado las conclusiones mencionadas.CONCLUSIÓN:La respuesta tumoral a la terapia de inducción está asociada con la respuesta final al tratamiento con terapia neoadyuvante total entre los respondedores completos o mínimos; la importancia de una respuesta parcial provisional sigue sin estar clara. (Traducción-Dr. Xavier Delgadillo ).

Is clinical complete response as accurate as pathological complete response in patients with mid-low locally advanced rectal cancer?

PURPOSE

The standard treatment for locally advanced rectal cancer involves neoadjuvant chemoradiation followed by total mesorectal excision surgery. A subset of patients achieves pathologic complete response (pCR), representing the optimal treatment outcome. This study compares the long-term oncological outcomes of patients who achieved pCR with those who attained clinical complete response (cCR) after total neoadjuvant therapy, managed using a watch-and-wait approach.

METHODS

This study retrospectively evaluated patients with mid-low locally advanced rectal cancer who underwent neoadjuvant treatment from January 1, 2005, to May 1, 2023. The pCR and cCR groups were compared based on demographic, clinical, histopathological, and long-term survival outcomes.

RESULTS

The median follow-up times were 54 months (range, 7-83 months) for the cCR group (n=73), 96 months (range, 7-215 months) for the pCR group (n=63), and 72 months (range, 4-212 months) for the pathological incomplete clinical response (pICR) group (n=627). In the cCR group, 15 patients (20.5%) experienced local regrowth, and 5 (6.8%) developed distant metastasis (DM). The pCR group had no cases of local recurrence, but 3 patients (4.8%) developed DM. Among the pICR patients, 58 (9.2%) experienced local recurrence, and 92 (14.6%) had DM. Five-year disease-free survival rates were 90.0% for cCR, 92.0% for pCR, and 69.5% for pICR (P=0.022). Five-year overall survival rates were 93.1% for cCR, 92.0% for pCR, and 78.1% for pICR. There were no significant differences in outcomes between the cCR and pCR groups (P=0.810); however, the pICR group exhibited poorer outcomes (P=0.002).

CONCLUSIONS

This study shows no significant long-term oncological differences between patients who exhibited cCR and those who experienced pCR.

Evaluating the predictive value of endoscopic findings for residual colorectal cancer following neoadjuvant combination immunotherapy

BACKGROUND

Endoscopy allows for the direct observation of primary tumor characteristics and responses after neoadjuvant treatment. However, reports on endoscopic evaluation following neoadjuvant immunotherapy remain limited.

AIM

To examine the predictive value of endoscopic findings of primary tumors for responses to neoadjuvant immunotherapy.

METHODS

This retrospective study, conducted at a tertiary center in China, evaluated 74 patients with colorectal cancer, including 17 with deficient mismatch repair (dMMR) and 15 with proficient mismatch repair (pMMR) tumors. Patients underwent neoadjuvant immunotherapy followed by surgery. Endoscopic findings before and after neoadjuvant immunotherapy were reviewed and compared with the pathology of the resected specimens.

RESULTS

In the pMMR group (n = 57 evaluable patients), endoscopy identified 11/17 patients who achieved a complete response (CR), while misidentifying 1/40 patients with residual disease as CR (64.7% vs 2.5%, P < 0.01). Conversely, 22/40 patients with residual disease were accurately identified as achieving a partial response (PR), with 1/17 patients who achieved CR misclassified as PR (55.0% vs 5.9%, P < 0.01). The sensitivity, specificity, and accuracy of endoscopic diagnosis for pathological CR were 64.7%, 97.5%, and 87.7%, respectively. In the dMMR cohort, endoscopy classified 9/17 patients as CR and 2 of the remaining patients with residual tumors as PR (64.3% vs 66.7%, P = 0.73). The method demonstrated 100% sensitivity and 82.4% accuracy in diagnosing pathological CR.

CONCLUSION

Endoscopic evidence of CR or PR was well correlated with postoperative pathological outcomes in the pMMR cohort. Despite endoscopic indications of tumor residue, a complete pathological response post-surgery was possible in the dMMR cohort.

Economic Evaluation of 'Watch and Wait' Following Neoadjuvant Therapy in Locally Advanced Rectal Cancer: A Systematic Review

BACKGROUND

Owing to multimodal treatment and complex surgery, locally advanced rectal cancer (LARC) exerts a large healthcare burden. Watch and wait (W&W) may be cost saving by removing the need for surgery and inpatient care. This systematic review seeks to identify the economic impact of W&W, compared with standard care, in patients achieving a complete clinical response (cCR) following neoadjuvant therapy for LARC.

METHODS

The PubMed, OVID Medline, OVID Embase, and Cochrane CENTRAL databases were systematically searched from inception to 26 April 2024. All economic evaluations (EEs) that compared W&W with standard care were included. Reporting and methodological quality was assessed using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS), BMJ and Philips checklists. Narrative synthesis was performed. Primary and secondary outcomes were (incremental) cost-effectiveness ratios and the net financial cost.

RESULTS

Of 1548 studies identified, 27 were assessed for full-text eligibility and 12 studies from eight countries (2016-2024) were included. Seven cost-effectiveness analyses (complete EEs) and five cost analyses (partial EEs) utilized model-based (n = 7) or trial-based (n = 5) analytics with significant variations in methodological design and reporting quality. W&W showed consistent cost effectiveness (n = 7) and cost saving (n = 12) compared with surgery from third-party payer and patient perspectives. Critical parameters identified by uncertainty analysis were rates of local and distant recurrence in W&W, salvage surgery, perioperative mortality and utilities assigned to W&W and surgery.

CONCLUSION

Despite heterogenous methodological design and reporting quality, W&W is likely to be cost effective and cost saving compared with standard care following cCR in LARC. Clinical Trials Registration PROSPERO CRD42024513874.

What Predicts Complete Response to Total Neoadjuvant Therapy in Locally Advanced Rectal Cancer?

BACKGROUND

Total neoadjuvant therapy in the treatment of stage II and III rectal cancer involves the administration of either induction or consolidation chemotherapy with chemoradiation before surgery. Total neoadjuvant therapy is associated with an increased complete response rate, which is defined as the proportion of patients who either had a pathological complete response after surgery or sustained a clinical complete response for at least 1 year under surveillance.

OBJECTIVE

To identify the predictors of complete response to total neoadjuvant therapy and compare different diagnostic tools in predicting complete response.

DESIGN

Retrospective cohort study.

SETTINGS

A single tertiary care center.

PATIENTS

Patients with stage II and III rectal cancer who were diagnosed between January 2015 and December 2021.

INTERVENTION

Total neoadjuvant therapy.

MAIN OUTCOME MEASURES

Complete response rate, predictors of complete response, sensitivity and specificity of sigmoidoscopy, and MRI in predicting complete response.

RESULTS

One hundred nineteen patients (mean age 56 [±11.3] years, 47 [39.5%] women, 100 [84%] stage III rectal cancer) were included. The median tumor size was 5.1 (4-6.5) cm, and 63 (52.9%) were low rectal tumors. Twenty-one patients (17.6%) had extramural vascular invasion and 62 (52.1%) had elevated CEA at baseline. One hundred eight patients (90.8%) received consolidation chemotherapy. After total neoadjuvant therapy, 88 of 119 patients (73.9%) underwent surgery, of whom 20 (22.7%) had pathological complete response. Thirty-one patients (26.1%) underwent watch-and-wait, of whom 24 (77.4%) had sustained clinical complete response. Overall, the complete response rate was 37%. Low rectal tumors (OR 1.5 [95% CI, 1.03-2.4], p = 0.04) and absence of extramural vascular invasion (OR 2.2 [95% CI, 1.1-5.6], p = 0.01) were predictors of complete response. In predicting complete response, sigmoidoscopy was more sensitive (76.0% vs 62.5%) and specific (72.5% vs 69.2%) than MRI. The specificity further increased when 2 techniques were combined (82.5%).

LIMITATIONS

Retrospective study.

CONCLUSIONS

The complete response rate after total neoadjuvant therapy was 37%. Low rectal tumors and the absence of extramural vascular invasion were predictors of complete response. Sigmoidoscopy was better in predicting incomplete response, whereas combination (MRI and sigmoidoscopy) was better in predicting complete response. See Video Abstract.

QU PREDICE LA RESPUESTA COMPLETA A LA TERAPIA NEOADYUVANTE TOTAL EN EL CNCER DE RECTO LOCALMENTE AVANZADO

ANTECEDENTES:La terapia neoadyuvante total en el tratamiento del cáncer de recto en estadios II-III implica la administración de quimioterapia de inducción o de consolidación con quimio radiación antes de la cirugía. La terapia neoadyuvante total se asocia con una mayor tasa de respuesta completa, que se define como la proporción de pacientes que tuvieron una respuesta patológica completa después de la cirugía o una respuesta clínica completa sostenida al menos durante un año bajo vigilancia.OBJETIVO:Identificar los predictores de respuesta completa a la terapia neoadyuvante total y comparar diferentes herramientas de diagnóstico para predecir la respuesta completa.DISEÑO:Estudio de cohorte retrospectivo.LUGARES:Un único centro de atención terciaria.PACIENTES:Pacientes con cáncer de recto en estadio II-III diagnosticados entre enero de 2015 y diciembre de 2021.INTERVENCIÓN(S):Terapia neoadyuvante total.PRINCIPALES MEDIDAS DE RESULTADO:Tasa de respuesta completa, predictores de respuesta completa, sensibilidad y especificidad de la sigmoidoscopia y la resonancia magnética para predecir la respuesta completa.RESULTADOS:Se incluyeron 119 pacientes [edad media 56 (±11,3) años, 47 (39,5%) mujeres, 100 (84%) cáncer de recto en estadio III]. La mediana del tamaño tumoral fue de 5,1 (4-6,5) cm, 63 (52,9%) fueron tumores rectales bajos. Veintiún (17,6%) pacientes tenían invasión vascular extramural (EMVI), 62 (52,1%) tenían CEA elevado al inicio del estudio. Ciento ocho (90,8%) pacientes recibieron quimioterapia de consolidación. Después de la TNT, 88 (73,9%) de 119 pacientes fueron intervenidos quirúrgicamente, de los cuales 20 (22,7%) tuvieron respuesta patológica completa. Treinta y un (26,1%) pacientes fueron sometidos a observación y espera, de los cuales 24 (77,4%) tuvieron una respuesta clínica completa sostenida. La tasa de respuesta completa general fue del 37%. Los tumores rectales bajos [OR 1,5 (IC 95% 1,03-2,4), p = 0,04] y la ausencia de EMVI [OR 2,2 (IC 95% 1,1-5,6), p = 0,01] fueron predictores de respuesta completa. Para predecir la respuesta completa, la sigmoidoscopia fue más sensible (76,0 % frente a 62,5 %) y específica (72,5 % frente a 69,2 %) que la resonancia magnética. La especificidad aumentó aún más cuando se combinaron dos técnicas (82,5%).LIMITACIONES:Estudio retrospectivo.CONCLUSIONES:La tasa de respuesta completa después de la terapia neoadyuvante total fue del 37%. Los tumores rectales bajos y la ausencia de EMVI fueron predictores de respuesta completa. La sigmoidoscopia fue mejor para predecir la respuesta incompleta, mientras que la combinación (MRI y sigmoidoscopia) fue mejor para predecir la respuesta completa. (Traducción-Dr Osvaldo Gauto ).

Short-term outcomes from the 'Watch and Wait' (WoW) study: prospective cohort study

BACKGROUND

Despite absence of level 1 evidence on the long-term oncological safety of non-operative management for rectal cancer (watch and wait), increased implementation has occurred globally over the past decades. In Sweden, a pan-national prospective non-randomized study was initiated in 2017 to assess its implementation.

METHOD

Patients with biopsy-proven rectal cancer receiving neoadjuvant therapy according to national guidelines in whom a clinical complete response was detected at reassessment were eligible for inclusion following informed consent. Only patients with an opportunistic watch-and-wait approach were included. Inclusion and follow-up, according to the study protocol, was managed at the participating study centres. The primary outcome measure of the study is 3-year disease-free survival. Here, the secondary short-term outcomes local regrowth rate, distant metastasis rate and outcomes after surgery for regrowth, at 6 months follow-up, are reported.

RESULTS

Between January 2017 and February 2023, 211 patients with a clinical complete response were included in the study. Thirty-three (16%) patients developed suspicious regrowth within 6 months of inclusion. Thirty-two of 33 patients had abdominal resectional surgery for regrowth. The curative intention rate was 94% for patients with regrowth. Three patients (1.4%) developed distant metastases within 6 months of inclusion.

CONCLUSION

This Swedish national study on watch and wait reports regrowth rates after 6 months are in line with previous reports in the literature. Nearly all patients with early regrowth could be treated with salvage surgery and curative intent.

Nonoperative management of rectal cancer

The management of locally advanced rectal cancer has changed drastically in the last few decades due to improved surgical techniques, development of multimodal treatment approaches and the introduction of a watch and wait (WW) strategy. For patients with a complete response to neoadjuvant treatment, WW offers an opportunity to avoid the morbidity associated with total mesorectal excision in favor of organ preservation. Despite growing interest in WW, prospective data on the safety and efficacy of nonoperative management are limited. Challenges remain in optimizing multimodal treatment regimens to maximize tumor regression and in improving the accuracy of patient selection for WW. This review summarizes the history of treatment for rectal cancer and the development of a WW strategy. It also provides an overview of clinical considerations for patients interested in nonoperative management, including restaging strategies, WW selection criteria, surveillance protocols and long-term oncologic outcomes.

Computed Tomography Scan and Clinical-based Complete Response Prediction in Locally Advanced Rectal Cancer after Neoadjuvant Chemoradiotherapy: A Machine Learning Approach

Background

Treatment of locally advanced rectal cancer (LARC) involves neoadjuvant chemoradiotherapy (nCRT), followed by total mesorectal excision. Examining the response to treatment is one of the most important factors in the follow-up of patients; therefore, in this study, radiomics patterns derived from pretreatment computed tomography images in rectal cancer and its relationship with treatment response measurement criteria have been investigated.

Methods

Fifty patients with rectal adenocarcinoma who were candidates for nCRT and surgery were included. The information obtained from the tumor surgical pathology report, including pathological T and N, the degree of tumor differentiation, lymphovascular invasion, and perineural invasion along with radiomics characteristics to each patient, was assessed. Modeling with disturbed forest model was used for radiomics data. For other variables, Shapiro-Wilk, Chi-Square, and Pearson Chi-square tests were used.

Results

The participants of this study were 50 patients (23 males [46%] and 27 females [54%]). There was no significant difference in the rate of response to neoadjuvant treatment in between age and gender groups. According to the modeling based on combined clinical and radiomics data together, area under the curves for the nonresponders and complete respond group (responder group) was 0.97 and 0.99, respectively.

Conclusion

Random forests modeling based on combined radiomics and clinical characteristics of the pretreatment tumor images has the ability to predict the response or non-response to neoadjuvant treatment in LARC to an acceptable extent.

Challenges of Surveillance in Implementing Nonoperative Management for Rectal Cancer

Importance

Close surveillance for detection of local tumor regrowth is critical for patients opting for nonoperative management after neoadjuvant therapy for rectal cancer. However, there are minimal data regarding the feasibility and adherence to National Comprehensive Cancer Network (NCCN) surveillance guidelines for these patients.

Objective

To determine adherence rates to NCCN-recommended surveillance in patients undergoing nonoperative management for rectal cancer.

Design, Setting, and Participants

This retrospective cohort study included patients treated at a single academic center (University of Rochester, Rochester, New York) from 2012 to 2023, with analysis completed from March through May 2024. Patients with clinical stage I to III rectal cancer who underwent treatment with neoadjuvant therapy, achieved a clinical complete response (or initially near complete clinical response), and elected for nonoperative management were enrolled.

Exposure

Achievement of recommended surveillance.

Main Outcomes and Measures

The primary outcome was adherence to surveillance guidelines for patients undergoing nonoperative management for rectal cancer. Secondary outcomes included assessment of oncologic outcomes stratified by adherence to surveillance.

Results

Eighty-five patients (54 male [63.5%]; median [IQR] age, 63.0 [54.0-73.0] years) were managed nonoperatively and followed for a median of 4.04 years (95% CI, 3.17-4.58 years). The 5-year overall survival was 82.3% (95% CI, 71.8%-94.5%), the 5-year disease-specific survival was 95.1% (95% CI, 89.6%-100.0%), the rate of local regrowth was 24.7% (21 patients), and the rate of distant metastases was 12.9% (11 patients). Among the 77 patients with more than 6 months of follow-up in their first year of surveillance, only 39.0% of patients (30 patients) achieved NCCN-recommended surveillance in the first year, and this decreased to 15.0% (3 patients) by year 5. However, the time to local regrowth and distant metastasis were similar regardless of the level of surveillance.

Conclusions and Relevance

In this cohort study of patients with rectal cancer undergoing surveillance after nonoperative management, most did not achieve NCCN-recommended guidelines, although outcomes were not associated with surveillance intensity. This highlights the need for prospective evaluation of a surveillance regimen that is both feasible for patients and health care systems increasingly using nonoperative management. In addition, studies are warranted to explore patient preferences in rectal cancer care and to identify barriers to optimal surveillance.

What To Do With Suspected Nodal Regrowth on MRI During Follow-Up in an Organ Preservation Approach for Rectal Cancer?

BACKGROUND

For nodal regrowth in patients with rectal cancer following watch-and-wait, standardized protocols on diagnostic procedures and subsequent treatment are lacking.

OBJECTIVE

To evaluate the diagnosis and treatment of suspected nodal regrowth following an organ preservation approach.

SETTINGS

Patients were included from national and institutional watch-and-wait databases.

DESIGN

Thirty-five rectal cancer patients with suspected nodal regrowth on MRI were retrospectively identified during watch-and-wait follow-up.

PATIENTS

Twenty-seven of 35 patients followed the watch-and-wait schedule after neoadjuvant (chemo)radiotherapy and 8 of 35 patients followed the watch-and-wait schedule after local excision for early rectal cancer.

MAIN OUTCOME MEASURES

Diagnostic procedures, treatment, and histopathological outcome.

RESULTS

The median follow-up was 34 months. The median time from the end of (chemo)radiotherapy or local excision to the first detection of suspected nodal regrowth on MRI following watch-and-wait was 9 and 10 months. After the first detection, 17 of 35 patients underwent immediate treatment without further diagnostics, of whom 7 also had luminal regrowth. In 18 of 35 patients, additional diagnostic procedures were performed. In 4 of 18 patients, PET-CT or endorectal ultrasound-guided biopsy was performed, and treatment was initiated on the basis of increased nodal regrowth suspicion. In 14 of 18 patients, MRI was repeated after 8 to 12 weeks: growth of suspected lymph nodes was the most decisive factor to proceed to treatment. In 8 patients, repeated MRI was combined with PET-CT and/or endorectal ultrasound-guided biopsy: in half of them, it contributed to treatment initiation. In total, 34 of 35 patients were treated: 9 received (re-)irradiation and 33 underwent total mesorectal excision. In 27 of 33 patients, nodal regrowth was pathologically confirmed in the total mesorectal excision-resection specimen; 5 of 6 patients without nodal involvement had pathologically confirmed luminal regrowth.

LIMITATIONS

Highly selected study population.

CONCLUSIONS

During watch-and-wait follow-up of patients with rectal cancer in an organ preservation strategy, MRI plays an important role in the diagnosis of nodal regrowth. Repeated MRI after an interval can be helpful in making treatment decisions, and the role of PET-CT and endorectal ultrasound-guided biopsy appears limited. See Video Abstract .

QU HACER ANTE LA SOSPECHA DE UN NUEVO CRECIMIENTO GANGLIONAR EN LA RESONANCIA MAGNTICA DURANTE EL SEGUIMIENTO EN UN ENFOQUE DE PRESERVACIN DE RGANOS PARA EL CNCER DE RECTO

ANTECEDENTES:Para el recrecimiento ganglionar en pacientes con cáncer de recto posterior a watch-and-wait (W&W), faltan protocolos estandarizados de sobre procedimientos de diagnóstico y tratamiento subsecuente.OBJETIVO:Evaluar el diagnóstico y tratamiento de sospecha de recrecimiento ganglionar posterior a tratamiento de preservación del órgano.ENTORNO CLINICO:Se incluyeron pacientes de la base de datos W&W nacionales e institucionales.DISEÑO:Se identificaron retrospectivamente 35 pacientes con cáncer de recto con sospecha de recrecimiento ganglionar en la resonancia magnética durante el seguimiento de W&W.PACIENTES:27 de 35 pacientes siguieron el programa W&W después de (quimio)radioterapia neoadyuvante y 8 de 35 siguieron el programa W&W después de la escisión local en cáncer rectal temprano.PRINCIPALES MEDIDAS DE RESULTADO:Procedimientos de diagnóstico, tratamiento y resultado histopatológico.RESULTADOS:La mediana de seguimiento fue de 34 meses. La mediana de tiempo desde el final de la (quimio)radioterapia o la escisión local hasta la primera detección de un presunto recrecimiento ganglionar en la resonancia magnética después de W&W fue de 9 y 10 meses. Después de la primera detección, 17 de 35 pacientes fueron sometidos a tratamiento inmediato sin diagnóstico adicional, de los cuales 7 también tuvieron un nuevo crecimiento luminal. En 18 de 35 pacientes se realizaron procedimientos de diagnóstico adicionales. En 4 de 18 pacientes se realizó PET-CT o biopsia guiada por ecografía endorrectal (ERUS) y se inició tratamiento en base a una mayor sospecha de recrecimiento ganglionar. En 14 de 18 pacientes, la resonancia magnética se repitió después de 8 a 12 semanas: el crecimiento de los ganglios linfáticos sospechosos fue el factor más decisivo para proceder al tratamiento. En 8 pacientes, la resonancia magnética repetida se combinó con PET-CT y/o biopsia guiada por ERUS: en la mitad de ellos contribuyó al inicio del tratamiento. En total, se trataron 34 de 35 pacientes: 9 recibieron (re)irradiación y 33 se sometieron a escisión total de mesorrecto. En 27 de 33 pacientes se confirmó patológicamente el recrecimiento ganglionar en la muestra de escisión total de mesorrecto; 5 de 6 pacientes sin afectación ganglionar tuvieron un recrecimiento luminal patológicamente confirmado.LIMITACIONES:Población de estudio altamente seleccionada.CONCLUSIONES:Durante el seguimiento de W&W de pacientes con cáncer de recto en estrategia de preservación de órganos, la resonancia magnética juega un papel importante en el diagnóstico del recrecimiento ganglionar. La repetición de la resonancia magnética después de un intervalo puede ser útil para tomar decisiones de tratamiento, y el papel de la PET-CT y la biopsia guiada por ERUS parece limitado. (Traducción- Dr. Francisco M. Abarca-Rendon ).

Watch and wait in rectal cancer patients with residual mucin on magnetic resonance imaging following neoadjuvant therapy

BACKGROUND

Neoadjuvant therapy leads to a clinical complete response in a considerable proportion of patients with locally advanced rectal cancer, allowing for possible nonoperative management. The presence of mucin on magnetic resonance imaging (MRI) after neoadjuvant therapy leads to uncertainty about residual disease and appropriateness of a watch-and-wait strategy in patients with no evidence of disease on proctoscopy (endoscopic clinical complete response).

METHODS

MRI reports for locally advanced rectal cancer patients seen between July 2016 and January 2020 at Memorial Sloan Kettering Cancer Center were queried for presence of mucin in the tumor bed on MRI following neoadjuvant therapy. Clinicodemographic, pathologic, and outcome data were compiled and analyzed.

RESULTS

Of 71 patients with mucin on posttreatment MRI, 20 had a clinical complete response, and 51 had abnormalities on endoscopy and/or physical exam. One patient with a clinical complete response opted out of watch-and-wait; thus, 19 (27%) patients entered watch-and-wait, and 52 (73%) patients were planned for surgery (non-watch-and-wait). Of the 19 watch-and-wait patients, 15 (79%) have had no local regrowth with median follow-up of 50 months (range = 29-76 months), while 4 (21%) experienced regrowth between 9 and 29 months after neoadjuvant therapy. Of the 52 patients who were planned to have surgery (non-watch-and-wait), 49 underwent resection while 3 developed metastatic disease that precluded curative-intent surgery. Of the 49 patients who underwent surgery, 5 (10%) had a pathologic complete response (including the patient with an endoscopic clinical complete response).

CONCLUSIONS

The presence of mucin after neoadjuvant therapy for locally advanced rectal cancer does not preclude watch-and-wait management in otherwise appropriate candidates who achieve an endoscopic clinical complete response.

The Rise of Patients Declining Rectal Cancer Surgery in the Era of Total Neoadjuvant Therapy

BACKGROUND

The treatment landscape for rectal cancer is rapidly evolving, particularly with the increasing use of neoadjuvant therapies. Still, up to 50% of patients with stage II-III disease require surgical resection post-neoadjuvant therapy to achieve the best oncologic outcomes. Many patients, however, hope to avoid surgery. This study aimed to assess trends and factors associated with declining recommended oncologic resection after systemic therapy nationally and in our institution.

PATIENTS AND METHODS

This is a retrospective analysis using the National Cancer Database from 2009 to 2021 and an institutional cohort at an academic center between 2009 and 2022 including adults with stage I-III rectal adenocarcinoma who underwent neoadjuvant therapy and were suitable for surgery.

RESULTS

Of 96,997 patients nationally, the rate of declining surgery increased from 2.3% in 2009 to 6.3% in 2021, a trend mirrored in our institutional cohort of 365 patients (0% in 2009/2010 to approximately 6-12% in 2021/2022). Locally, patients who declined surgery had higher rates of tobacco use, temporary loss to follow-up during therapy, and a more robust, albeit incomplete, tumor response to neoadjuvant therapy compared with controls who underwent surgery. Despite a stoma being the most cited reason for declining surgery, 30.4% of patients who declined oncologic resection died with a stoma.

CONCLUSIONS

Our findings underscore a notable trend of patients declining oncologic resections following neoadjuvant therapy for rectal cancer. By shedding light on the outcomes of patients who opt against surgery, we address a critical gap in the literature essential for informing patients about potential risks.

Evaluating complete response rates and predictors in total neoadjuvant therapy for rectal cancer

BACKGROUND

There is a paradigm shift in the management of locally advanced rectal cancer (LARC) from conventional neoadjuvant treatment to total neoadjuvant therapy (TNT). Despite its growing acceptance, there are limited studies that have examined its effects on disease presentation. In addition, it is important to determine the factors that play a role in complete response (CR). Our previous data from 119 patients revealed that the CR rate was 37%, and low rectal tumors and the absence of extramural vascular invasion (EMVI) were predictors of CR. Unfortunately, there continues to be a lack of data, and reliable markers are still needed to consistently identify the best respondents. Therefore, this study aimed to determine the factors associated with CR. Moreover, this study hypothesized that both predictive factors and the CR ratio might evolve over time because of the growing patient population.

METHODS

This retrospective study included patients who completed TNT for LARC at our tertiary care center between 2015 and 2022. The primary outcome was to determine the predictors of CR. The secondary outcomes were the 2-year disease-free survival (DFS) rate and overall survival (OS) rate. CR consists of patients who sustained clinical CR (cCR) for at least 12 months under watch and wait or had pathologic CR (pCR) after surgery.

RESULTS

Of 339 patients with LARC, 208 (61.3%) successfully completed TNT. Among 208 patients, 57 (27.4%) achieved cCR, and 166 (80.0%) sustained cCR without tumor regrowth after 1 year. The remaining 151 patients (72.6%) underwent surgery, and 42 patients had pCR. The final CR rate was 42.3%. The median age of the patients was 56 years (IQR, 49-66). Moreover, 132 participants (63.5%) were male, whereas 76 participants (36.5%) were female. The median tumor size was 4.95 cm (IQR, 3.60-6.43), with most tumors in the low rectum (119 [57.2%]). Based on the MRI findings, the mesorectal facia (MRF) involvement rate was 25.0% (n = 52), and EMVI was observed in 43 patients (20.7%). Low rectal tumors, the absence of MRF involvement, and the absence of EMVI were predictors of CR. With a median follow-up of 24.7 months, 2-year DFS and OS were significantly higher among patients with CR than among patients with incomplete response (91.3% vs 71.0% [P < .01] and 98.8% vs 90.2% [P = .03], respectively).

CONCLUSION

An increasing CR rate was observed in our updated dataset compared with that in our previous study. In addition to previously identified predictors, low tumor location, and the absence of EMVI, the absence of MRF involvement was determined as a predictor of CR. Our findings offer valuable insights into clinical practice and help clinicians set clear expectations when counseling patients.

Tumor response rates based on initial TNM stage and tumor size in locally advanced rectal cancer: a useful tool for shared decision-making

BACKGROUND

It is accepted that tumor stage and size can influence response to neoadjuvant therapy in locally advanced rectal cancer (LARC). Studies on organ preservation to date have included a wide variety of size and TNM stage tumors. The aim of this study was to report tumor response based on each relevant TNM stage and tumor size.

METHODS

Patients treated with LARC from 2014 to 2021 with cT2-3NxM0 tumors who received neoadjuvant chemoradiotherapy with or without induction chemotherapy were included. Tumors were staged and tumor size calculated on pelvic MRI at the time of diagnosis (cTNM). Tumor size was based on the largest dimension taken on the longest axis of each tumor. Clinical response was defined on the basis of post-treatment pelvic MRI and pathological response following surgery, when performed. Statistical analysis was performed using IBM SPSS Statistics™, version 20. Data from 432 patients were analyzed as follows: cT2N0 (n = 51), cT2N+ (n = 36), cT3N0 (n = 76), cT3N+ (n = 270).

RESULTS

The rate of complete or near-complete response (cCR or nCR) varied from 77% in cT2N0 ≤ 3 cm to 20% in cT3N+ > 4 cm. Organ preservation without recurrence at 2 years was achieved in 86% of patients with cT2N0, 50% in cT2N+, 39% in cT3N0, and 12% in cT3N+.

CONCLUSION

There is significant variation in tumor response according to tumor stage and size. Tumor response appears inversely proportional to increasing TNM stage and tumor size. This data can support both refinement of selective patient recruitment to organ preservation programs and shared decision-making.

Predictive value of flexible proctosigmoidoscopy and laboratory findings for complete clinical responses after neoadjuvant chemoradiotherapy in patients with locally advanced primary rectal cancer: a retrospective cohort study

PURPOSE

Colorectal cancer is the second leading cause of cancer death worldwide. Standard treatments for locally advanced rectal cancer include neoadjuvant chemoradiotherapy and total mesorectal excision (TME), which are associated with significant morbidity. After neoadjuvant therapy, one-third of patients achieve a pathological complete response (pCR) and are eligible for a watch-and-wait approach without TME. The purpose of this study was to determine the potential predictors of pCR before surgery.

METHODS

The demographic, clinical, and endoscopic data of 119 patients with primary locally advanced rectal cancer without distant metastasis who underwent restaging endoscopy and TME 6-8 weeks after the end of neoadjuvant therapy were collected. The absence of tumor cells in the histological examination of the TME specimen after neoadjuvant therapy was considered pCR. Binary logistic regression and receiver operating characteristic curves were utilized for analysis.

RESULTS

According to the multivariate logistic regression analysis, flattening of marginal tumor swelling (p value < 0.001, odds ratio = 100.605) emerged as an independent predictor of pCR in rectal cancer patients. Additionally, receiver operating characteristic curve analysis revealed that lower preoperative carcinoembryonic antigen and erythrocyte sedimentation rate levels predict pCR, with cutoffs of 2.15 ng/ml and 19.0 mm/h, respectively.

CONCLUSION

Carcinoembryonic antigen and erythrocyte sedimentation rate, along with the presence of flattening of marginal tumor swelling, can predict pCR after neoadjuvant chemoradiotherapy in patients with primary rectal cancer. These factors offer a potential method for selecting candidates for conservative treatment based on endoscopic and laboratory findings.

Nonoperative management and local excision after neoadjuvant chemoradiation therapy for rectal cancer

Locally advanced extraperitoneal rectal cancer represents a significant clinical challenge, and currently, the standard treatment is based on neoadjuvant chemoradiation therapy (CRT) followed by radical surgical resection with total mesorectal excision (TME). In the last 30 years, its management has undergone significant changes due to the improvement of complementary radio- and chemotherapy treatments, the improvement of minimally invasive surgical approaches and the diffusion of organ-sparing approaches, such as nonoperative management, commonly called "watch and wait" (NOM) and local excision (LE), in highly selected patients who achieve a major or complete response to neoadjuvant CRT. This review aimed to critically examine the efficacy and oncological safety of NOM and LE compared to those of standard TME in rectal cancer patients after neoadjuvant CRT. Both the pros and cons of these approaches were strictly analyzed, providing a comprehensive and critical overview of these novel management strategies for rectal cancer.

Colorectal cancer

Despite decreased incidence rates in average-age onset patients in high-income economies, colorectal cancer is the third most diagnosed cancer in the world, with increasing rates in emerging economies. Furthermore, early onset colorectal cancer (age ≤50 years) is of increasing concern globally. Over the past decade, research advances have increased biological knowledge, treatment options, and overall survival rates. The increase in life expectancy is attributed to an increase in effective systemic therapy, improved treatment selection, and expanded locoregional surgical options. Ongoing developments are focused on the role of sphincter preservation, precision oncology for molecular alterations, use of circulating tumour DNA, analysis of the gut microbiome, as well as the role of locoregional strategies for colorectal cancer liver metastases. This overview is to provide a general multidisciplinary perspective of clinical advances in colorectal cancer.

Gross morphologic features of surgical specimen in rectal cancer patients with pathological complete response following neoadjuvant chemoradiotherapy: A cross-sectional study

BACKGROUND

pathological complete response (pCR) is achieved in 10%-30% of rectal cancer patients following neoadjuvant chemoradiotherapy and surgery. Residual mucosal abnormalities, which make patients ineligible for nonoperative management, may not be an accurate indicator of the pCR. The purpose of this study was to report the gross findings of rectal cancer patients with pathological complete responses.

METHODS

This study was conducted at Tehran University of Medical Sciences, Tehran, Iran. A total of 130 patients with rectal adenocarcinoma, treated by neoadjuvant chemoradiotherapy, followed by surgical resection between March 2007, and March 2017, with a surgical pathology report of pCR, were included. Patients' demographics and pretreatment tumor characteristics were collected from the medical records. Data regarding residual mucosal abnormalities were extracted from postoperative surgical pathology reports. Abnormal findings were reported as "ulcer" or " non-ulcerative lesion".

RESULTS

One hundred and fifteen patients (88.5%; 95% CI: 81.7%-93.4%) had at least one abnormal finding in the gross examination, including ulcer or non-ulcerative lesion (any mucosal abnormalities other than ulcers, including polyps, telangiectasia, etc.). Patients with higher-stage tumors had a higher chance of having an ulcerative lesion (p = 0.05). Younger patients tended to have deeper layers of involvement (p = 0.013). Patients with different gross findings were not significantly different regarding baseline characteristics, except for the pretreatment stage, where patients with a higher stage had higher odds of having ulcerative lesions.

CONCLUSIONS

Most rectal cancer patients achieving a pCR exhibit abnormalities on gross examination. The higher pretreatment stages were significantly associated with gross abnormalities especially ulcers.

Non-operative management of rectal cancer: Highlighting the controversies

There remains much ambiguity on what non-operative management (NOM) of rectal cancer truly entails in terms of the methods to be adopted and the best algorithm to follow. This is clearly shown by the discordance between various national and international guidelines on NOM of rectal cancer. The main aim of the NOM strategy is organ preservation and avoiding unnecessary surgical intervention, which carries its own risk of morbidity. A highly specific and sensitive surveillance program must be devised to avoid patients undergoing unnecessary surgical interventions. In many studies, NOM, often interchangeably called the Watch and Wait strategy, has been shown as a promising treatment option when undertaken in the appropriate patient population, where a clinical complete response is achieved. However, there are no clear guidelines on patient selection for NOM along with the optimal method of surveillance.

An International Expert-Based Consensus on the Definition of a Clinical Near-Complete Response After Neoadjuvant (Chemo)radiotherapy for Rectal Cancer

BACKGROUND

A variety of definitions for a clinical near-complete response after neoadjuvant (chemo) radiotherapy for rectal cancer are currently used. This variety leads to inconsistency in clinical practice, long-term outcome, and trial enrollment.

OBJECTIVE

The aim of this study was to reach expert-based consensus on the definition of a clinical near-complete response after (chemo) radiotherapy.

DESIGN

A modified Delphi process, including a systematic review, 3 surveys, and 2 meetings, was performed with an international expert panel consisting of 7 surgeons and 4 radiologists. The surveys consisted of individual features, statements, and feature combinations (endoscopy, T2-weighted MRI, and diffusion-weighted MRI).

SETTING

The modified Delphi process was performed in an online setting; all 3 surveys were completed online by the expert panel, and both meetings were hosted online.

MAIN OUTCOME MEASURES

The main outcome was to reach consensus (80% or more agreement).

RESULTS

The expert panel reached consensus on a 3-tier categorization of the near-complete response category based on the likelihood of the response to evolve into a clinical complete response after a longer waiting interval. The panelists agreed that a near-complete response is a temporary entity only to be used in the first 6 months after (chemo)radiotherapy. Furthermore, consensus was reached that the lymph node status should be considered when deciding on a near-complete response and that biopsies are not always needed when a near-complete response is found. No consensus was reached on whether primary staging characteristics have to be taken into account when deciding on a near-complete response.

LIMITATIONS

This 3-tier subcategorization is expert-based; therefore, there is no supporting evidence for this subcategorization. Also, it is unclear whether this subcategorization can be generalized into clinical practice.

CONCLUSIONS

Consensus was reached on the use of a 3-tier categorization of a near-complete response, which can be helpful in daily practice as guidance for treatment and to inform patients with a near-complete response on the likelihood of successful organ preservation. See Video Abstract.

UN CONSENSO INTERNACIONAL BASADO EN EXPERTOS ACERCA DE LA DEFINICIN DE UNA RESPUESTA CLNICA CASI COMPLETA DESPUS DE QUIMIORADIOTERAPIA NEOADYUVANTE CONTRA EL CNCER DE RECTO

ANTECEDENTES:Actualmente, se utilizan una variedad de definiciones para una respuesta clínica casi completa después de quimioradioterapia neoadyuvante contra el cáncer de recto. Esta variedad resulta en inconsistencia en la práctica clínica, los resultados a largo plazo y la inscripción en ensayos.OBJETIVO:El objetivo de este estudio fue llegar a un consenso de expertos sobre la definición de una respuesta clínica casi completa después de quimioradioterapia.DISEÑO:Se realizó un proceso Delphi modificado que incluyó una revisión sistemática, 3 encuestas y 2 reuniones con un panel internacional de expertos compuesto por siete cirujanos y 4 radiólogos. Las encuestas consistieron en características individuales, declaraciones y combinaciones de características (endoscopía, T2W-MRI y DWI).AJUSTE:El proceso Delphi modificado se realizó en un entorno en línea; el panel de expertos completó las tres encuestas en línea y ambas reuniones se realizaron en línea.PRINCIPALES MEDIDAS DE RESULTADO:El resultado principal fue llegar a un consenso (≥80% de acuerdo).RESULTADOS:El panel de expertos llegó a un consenso sobre una categorización de tres niveles de la categoría de respuesta casi completa basada en la probabilidad de que la respuesta evolucione hacia una respuesta clínica completa después de un intervalo de espera más largo. Los panelistas coincidieron en que una respuesta casi completa es una entidad temporal que sólo debe utilizarse en los primeros 6 meses después de la quimioradioterapia. Además, se llegó a un consenso en que se debe considerar el estado de los nódulos linfáticos al decidir sobre una respuesta casi completa y que no siempre se necesitan biopsias cuando se encuentra una respuesta casi completa. No se llegó a un consenso sobre si se deben tener en cuenta las características primarias de estadificación al decidir una respuesta casi completa.LIMITACIONES:Esta subcategorización de 3 niveles está basada en expertos; por lo tanto, no hay evidencia que respalde esta subcategorización. Además, no está claro si esta subcategorización puede generalizarse a la práctica clínica.CONCLUSIONES:Se alcanzó consenso sobre el uso de una categorización de 3 niveles de una respuesta casi completa que puede ser útil en la práctica diaria como guía para el tratamiento y para informar a los pacientes con una respuesta casi completa sobre la probabilidad de una preservación exitosa del órgano. (Traducción - Dr. Aurian Garcia Gonzalez).

Outcomes of rectal cancer patients who refuse surgery after incomplete clinical response to neoadjuvant therapy

BACKGROUND AND OBJECTIVES

Total mesorectal excision (TME) remains the standard of care for patients with rectal cancer who have an incomplete response to total neoadjuvant therapy (TNT). A minority of patients will refuse curative intent resection. The aim of this study is to examine the outcomes for these patients.

METHODS

A retrospective cohort study of stage 1-3 rectal adenocarcinoma patients who underwent neoadjuvant chemoradiation therapy or TNT at a single institution. Patients either underwent TME, watch-and-wait protocol, or if they refused TME, were counseled and watched (RCW). Clinical outcomes and resource utilization were examined in each group.

RESULTS

One hundred seventy-one patients (Male 59%) were included with a median surveillance of 43 months. Twenty-nine patients (17%) refused TME and had shortened overall survival (OS). Twelve patients who refused TME converted to a complete clinical response (cCR) on subsequent staging with a prolonged OS. 92% of these patients had a near cCR at initial staging endoscopy. Increased physician visits and testing was utilized in RCW and WW groups.

CONCLUSION

A significant portion of patients convert to cCR and have prolonged OS. Lengthening the time to declare cCR may be considered in select patients, such as those with a near cCR at initial endoscopic staging.

First clinical experience following the consensus guide for calibrating a proton stopping power ratio curve in a new proton centre

BACKGROUND AND PURPOSE

This work introduces the first assessment of CT calibration following the ESTRO's consensus guidelines and validating the HLUT through the irradiation of biological material.

METHODS

Two electron density phantoms were scanned with two CT scanners using two CT scan energies. The stopping power ratio (SPR) and mass density (MD) HLUTs for different CT scan energies were derived using Schneider's and ESTRO's methods. The comparison metric in this work is based on the Water-Equivalent Thickness (WET) difference between the treatment planning system and biological irradiation measurement. The SPR HLUTs were compared between the two calibration methods. To assess the accuracy of using MD HLUT for dose calculation in the treatment planning system, MD vs SPR HLUT was compared. Lastly, the feasibility of using a single SPR HLUT to replace two different energy CT scans was explored.

RESULTS

The results show a WET difference of less than 3.5% except for the result in the Bone region between Schneider's and ESTRO's methods. Comparing MD and SPR HLUT, the results from MD HLUT show less than a 3.5% difference except for the Bone region. However, the SPR HLUT shows a lower mean absolute percentage difference as compared to MD HLUT between the measured and calculated WET difference. Lastly, it is possible to use a single SPR HLUT for two different CT scan energies since both WET differences are within 3.5%.

CONCLUSION

This is the first report on calibrating an HLUT following the ESTRO's guidelines. While our result shows incremental improvement in range uncertainty using the ESTRO's guideline, the prescriptional approach of the guideline does promote harmonization of CT calibration protocols between different centres.

Interdisciplinary Spanish consensus on a watch-and-wait approach for rectal cancer

Watch-and-wait has emerged as a new strategy for the management of rectal cancer when a complete clinical response is achieved after neoadjuvant therapy. In an attempt to standardize this new clinical approach, initiated by the Spanish Cooperative Group for the Treatment of Digestive Tumors (TTD), and with the participation of the Spanish Association of Coloproctology (AECP), the Spanish Society of Pathology (SEAP), the Spanish Society of Gastrointestinal Endoscopy (SEED), the Spanish Society of Radiation Oncology (SEOR), and the Spanish Society of Medical Radiology (SERAM), we present herein a consensus on a watch-and-wait approach for the management of rectal cancer. We have focused on patient selection, the treatment schemes evaluated, the optimal timing for evaluating the clinical complete response, the oncologic outcomes after the implementation of this strategy, and a protocol for surveillance of these patients.

Surgical and local control outcomes after sequential short-course radiation therapy and chemotherapy for rectal cancer

Background

Total neoadjuvant therapy (TNT) is an accepted approach for the management of locally advanced rectal cancer (LARC) and is associated with a decreased risk of development of metastatic disease compared to standard neoadjuvant therapy. However, questions remain regarding surgical outcomes and local control in patients who proceed to surgery, particularly when radiation is given first in the neoadjuvant sequence. We report on our institution's experience with patients who underwent short-course radiation therapy, consolidation chemotherapy, and surgery.

Methods

We retrospectively reviewed surgical specimen outcomes, postoperative complications, and local/pelvic control in a large cohort of patients with LARC who underwent neoadjuvant therapy incorporating upfront short-course radiation therapy followed by consolidation chemotherapy.

Results

In our cohort of 83 patients who proceeded to surgery, a complete/near-complete mesorectal specimen was achieved in 90 % of patients. This outcome was not associated with the time interval from completion of radiation to surgery. Postoperative complications were acceptably low. Local control at two years was 93.4 % for all patients- 97.6 % for those with low-risk disease and 90.4 % for high-risk disease.

Conclusion

Upfront short-course radiation therapy and consolidation chemotherapy is an effective treatment course. Extended interval from completion of short-course radiation therapy did not impact surgical specimen quality.

Brachytherapy for rectal and anal cancer: Where are we and current perspectives?

Anal and rectal cancers were some of the first disease sites treated with brachytherapy due to the anatomic ease of implantation. As external beam radiotherapy grew in popularity the use of ano-rectal brachytherapy declined. However, the past few years have seen a steady resurgence in the use of brachytherapy in the ano-rectum supported by the use of large clinical series and randomized trials. The increasing acceptance by the surgical community of organ preservation as a valid treatment strategy for rectal cancer has encouraged the use of nonsurgical approaches and brachytherapy has shown itself to be a valuable tool for this. The current role of anal and rectal brachytherapy is presented with perspectives on its future use.

Endoscopic Predictors of Residual Tumor After Total Neoadjuvant Therapy: A Post Hoc Analysis From the Organ Preservation in Rectal Adenocarcinoma Trial

BACKGROUND

Restaging endoscopy plays a critical role in selecting patients with locally advanced rectal cancer who respond to neoadjuvant therapy for nonoperative management.

OBJECTIVE

This study evaluated the restaging endoscopic features that best predict the presence of residual tumor in the bowel wall.

DESIGN

This was a post hoc analysis of a prospective randomized trial.

SETTINGS

The Organ Preservation in Rectal Adenocarcinoma Trial randomly assigned patients across 18 institutions with stage II/III rectal adenocarcinoma to receive either induction or consolidation total neoadjuvant therapy. Surgeons completed a restaging tumor assessment form, which stratified patients across 3 tiers of clinical response.

PATIENTS

Patients enrolled in the Organ Preservation in Rectal Adenocarcinoma Trial with a completed tumor assessment form were included.

MAIN OUTCOME MEASURES

The main outcome was residual tumor, which was defined as either an incomplete clinical response or local tumor regrowth within 2 years of restaging. Independent predictors of residual tumor were identified using backward-selected multivariable logistic regression analysis. Subgroup analyses for complete and near complete clinical responders were performed.

RESULTS

Surgeons completed restaging forms for 263 patients at a median of 7.7 weeks after neoadjuvant therapy; 128 patients (48.7%) had a residual tumor. On multivariable regression analysis, several characteristics of a near complete response, including ulcer (OR 6.66; 95% CI, 2.54-19.9), irregular mucosa (OR 3.66; 95% CI, 1.61-8.68), and nodularity (OR 2.96; 95% CI, 1.36-6.58), remained independent predictors of residual tumor. A flat scar was associated with lower odds of harboring residual disease (OR 0.32; 95% CI, 0.11-0.93) for patients categorized as clinical complete responders.

LIMITATIONS

Limitations include analysis of endoscopic features at a single time point and ambiguities in tumor assessment form response criteria.

CONCLUSIONS

Patients with ulcer, nodularity, or irregular mucosa, on restaging endoscopy have higher odds of residual tumor. Recognizing negative prognostic implications of these features will help surgeons better select candidates for nonoperative management and suggests that patients with high-risk characteristics would benefit from close interval surveillance. See Video Abstract .

PREDICTORES ENDOSCPICOS DE TUMOR RESIDUAL DESPUS DE TERAPIA NEOADYUVANTE TOTAL UN ANLISIS POST HOC DEL ENSAYO DE PRESERVACIN DE RGANOS EN ADENOCARCINOMA RECTAL

ANTECEDENTES:La reestadificación por endoscopia juega un papel crítico en la selección de pacientes con cáncer de recto localmente avanzado que responden a la terapia neoadyuvante para el manejo no quirúrgico.OBJETIVO:Este estudio evaluó las características endoscópicas de reestadificación que mejor predicen la presencia de tumor residual en la pared intestinal.DISEÑO:Este fue un análisis post hoc de un ensayo prospectivo aleatorizado.ESCENARIO:El ensayo Organ Preservation in Rectal Adenocarcinoma aleatorizó a pacientes de 18 instituciones con adenocarcinoma de recto en estadio II/III para recibir terapia neoadyuvante total de inducción o consolidación. Los cirujanos completaron un formulario de reestadificación de evaluación del tumor, que estratificó a los pacientes en tres niveles de respuesta clínica.PACIENTES:Se incluyeron pacientes inscritos en el ensayo de preservación de órganos en adenocarcinoma rectal con un formulario de evaluación del tumor completado.PRINCIPALES MEDIDAS DE RESULTADO:El resultado principal fue presencia de tumor residual, que se definió como una respuesta clínica incompleta o un nuevo crecimiento local del tumor dentro de los dos años posteriores a la reestadificación. Los predictores independientes de tumor residual se identificaron mediante un análisis de regresión logística multivariable seleccionado hacia atrás. Se realizaron análisis de subgrupos para pacientes con respuesta clínica completa y casi completa.RESULTADOS:Los cirujanos completaron formularios de reestadificación para 263 pacientes en una mediana de 7.7 semanas después de la terapia neoadyuvante; 128 (48.7%) tenían tumor residual. En el análisis de regresión multivariable, varias características de una respuesta casi completa, incluyendo úlcera (OR 6.66; IC 95% 2.54-19.9), mucosa irregular (OR 3.66; IC 95% 1.61-8.68) y nodularidad (OR 2.96; IC 95% 1.36 -6.58) siguieron siendo predictores independientes de tumor residual. Una cicatriz plana se asoció con menores probabilidades de albergar enfermedad residual (OR 0.32; IC del 95 %: 0.11-0.93) para los pacientes clasificados como respondedores clínicos completos.LIMITACIONES:Las limitaciones de este estudio incluyen el análisis de las características endoscópicas en un solo momento y las ambigüedades en los criterios de respuesta.en la forma de evaluación del tumorCONCLUSIONES:Los pacientes con úlcera, nodularidad o mucosa irregular en la endoscopia de reestadificación tienen mayores probabilidades de tumor residual. El reconocer las implicaciones pronósticas negativas de estas características ayudará a los cirujanos a seleccionar mejor a los candidatos para el tratamiento no quirúrgico y sugiere que los pacientes con características de alto riesgo se beneficiarían de una vigilancia a intervalos estrechos. (Traducción-Dr. Jorge Silva Velazco ).

Whether the watch-and-wait strategy has application value for rectal cancer with clinical complete response after neoadjuvant chemoradiotherapy? A network meta-analysis

The aim was to evaluate the efficacy and safety between the watch-and-wait strategy (WW), radical surgery (RS), and local excision (LE) for rectal cancer with clinical complete response (cCR) after neoadjuvant radiotherapy (nCRT). We searched MEDLINE, EMBASE, the Cochrane Library, and clinical trials to compare WW with RS and LE for patients with cCR until March 2023 and collected the following data: local recurrence (LR), distant metastasis (DM), cancer-related death (CRD), overall survival (OS), and disease-free survival (DFS). In total, 2240 patients from 21 studies were included. Pairwise meta-analysis revealed no statistically significant differences between the three groups in terms of CRD and 2-, 3-, and 5-year OS (P < 0.05). The RS group was significantly better than the WW group in terms of the LR rate (odds ratio [OR] = 0.12, 95 % confidence interval [CI]: 0.06-0.21, P < 0.001, I2 = 0 %], 3-year DFS (OR = 1.56, 95 % CI: 1.10-2.21, P = 0.01, I2 = 38 %), and 5-year DFS (OR = 2.30, 95 % CI: 1.53-3.46, P < 0.001, I2 = 34 %). The results of network meta-analysis were also similar. After sensitivity analysis, the 5-year OS of the RS group was significantly better than that of the WW group (OR = 2.77, 95 % CI: 1.28-6.00, P = 0.009, I2 = 33 %). Nevertheless, neither regression analysis nor subgroup analysis provided meaningful results. However, the cumulative meta-analysis of LR, DM, and 3- and 5-year DFS revealed significant turning points (P < 0.05). Our meta-analysis recommends using the WW strategy for patients with cCR having poor underlying conditions and high surgical risk; however, there is a risk of higher LR and worse survival after 3 years.

Protocol for a national audit of the watch-and-wait approach in patients with rectal cancer in Aotearoa New Zealand: The ACCORD study

AIM

The watch-and-wait approach is increasingly being used in the management of rectal cancer as many patients achieve a clinical complete response after neoadjuvant treatment This national, multicentre, retrospective cohort study aims to understand the use of the watch-and-wait approach in the management of rectal cancer in Aotearoa New Zealand and its associated outcomes.

METHOD

This retrospective cohort study will include patients aged 18 years and over with biopsy proven rectal adenocarcinoma diagnosed between January 2015 and December 2022 who have a clinical complete response following neoadjuvant treatment (including short-course radiotherapy, long-course chemoradiotherapy or total neoadjuvant treatment) and have been managed with a watch-and-wait approach. Data will be collected from centres that manage rectal cancer in Aotearoa New Zealand with the eligible population being identified using data linkage with the National Cancer Registry.

CONCLUSION

This multicentre, national cohort study will investigate the use of the watch-and-wait strategy for rectal cancer in Aotearoa New Zealand. Through novel data linkage approaches, these data and methods will lay the foundation for a future prospective registry and outcome-tracking initiative.

Endoscopic resection of residual rectal neoplasia after definitive chemoradiotherapy for rectal cancer

The conventional approach to treating locally advanced rectal cancer, commonly defined as cT3 or cT4 primary tumors or with nodal metastases, involves chemoradiation (CRT) followed by surgical resection. There is a growing recognition of the potential for nonsurgical management following CRT or total neoadjuvant therapy (TNT), which allows for organ preservation. "Watch and wait" strategy may be considered if complete clinical response is achieved. In cases when adenoma or superficial cancer is present, a novel approach known as "salvage endoscopic resection of the residual disease" is emerging as a viable nonsurgical option for carefully selected patients. This review discusses available evidence and future potential for endoscopic management of residual neoplasia after oncological treatment of rectal cancer.

Organ Preservation and Survival by Clinical Response Grade in Patients With Rectal Cancer Treated With Total Neoadjuvant Therapy: A Secondary Analysis of the OPRA Randomized Clinical Trial

Importance

Assessing clinical tumor response following completion of total neoadjuvant therapy (TNT) in patients with locally advanced rectal cancer is paramount to select patients for watch-and-wait treatment.

Objective

To assess organ preservation (OP) and oncologic outcomes according to clinical tumor response grade.

Design, Setting, and Participants

This was secondary analysis of the Organ Preservation in Patients with Rectal Adenocarcinoma trial, a phase 2, nonblinded, multicenter, randomized clinical trial. Randomization occurred between April 2014 and March 2020. Eligible participants included patients with stage II or III rectal adenocarcinoma. Data analysis occurred from March 2022 to July 2023.

Intervention

Patients were randomized to induction chemotherapy followed by chemoradiation or chemoradiation followed by consolidation chemotherapy. Tumor response was assessed 8 (±4) weeks after TNT by digital rectal examination and endoscopy and categorized by clinical tumor response grade. A 3-tier grading schema that stratifies clinical tumor response into clinical complete response (CCR), near complete response (NCR), and incomplete clinical response (ICR) was devised to maximize patient eligibility for OP.

Main Outcomes and Measures

OP and survival rates by clinical tumor response grade were analyzed using the Kaplan-Meier method and log-rank test.

Results

There were 304 eligible patients, including 125 patients with a CCR (median [IQR] age, 60.6 [50.4-68.0] years; 76 male [60.8%]), 114 with an NCR (median [IQR] age, 57.6 [49.1-67.9] years; 80 male [70.2%]), and 65 with an ICR (median [IQR] age, 55.5 [47.7-64.2] years; 41 male [63.1%]) based on endoscopic imaging. Age, sex, tumor distance from the anal verge, pathological tumor classification, and clinical nodal classification were similar among the clinical tumor response grades. Median (IQR) follow-up for patients with OP was 4.09 (2.99-4.93) years. The 3-year probability of OP was 77% (95% CI, 70%-85%) for patients with a CCR and 40% (95% CI, 32%-51%) for patients with an NCR (P < .001). Clinical tumor response grade was associated with disease-free survival, local recurrence-free survival, distant metastasis-free survival, and overall survival.

Conclusions and Relevance

In this secondary analysis of a randomized clinical trial, most patients with a CCR after TNT achieved OP, with few developing tumor regrowth. Although the probability of tumor regrowth was higher for patients with an NCR compared with patients with a CCR, a significant proportion of patients achieved OP. These findings suggest the 3-tier grading schema can be used to estimate recurrence and survival outcomes in patients with locally advanced rectal cancer who receive TNT.

Trial Registration

ClinicalTrials.gov Identifier: NCT02008656.

Local Regrowth and the Risk of Distant Metastases Among Patients Undergoing Watch-and-Wait for Rectal Cancer: What Is the Best Control Group? Multicenter Retrospective Study

BACKGROUND

A proportion of rectal cancer patients who achieve a clinical complete response may develop local regrowth. Although salvage appears to provide appropriate local control, the risk of distant metastases is less known.

OBJECTIVE

To compare the risk of distant metastases between patients who achieve a clinical complete response (watch-and-wait strategy) and subsequent local regrowth and patients managed by surgery after chemoradiation.

DESIGN

Retrospective multicenter cohort study.

SETTINGS

This study used data of patients from 3 institutions who were treated between 1993 and 2019.

PATIENTS

Patients with initial clinical complete response (after neoadjuvant therapy) followed by local regrowth and patients with near-complete pathological response (≤10%) after straightforward surgery after chemoradiation were included.

MAIN OUTCOME MEASURES

Univariate and multivariate analyses were performed to identify risk factors for distant metastases. Kaplan-Meier curves were created (log-rank test) to compare survival outcomes. Analyses were performed using time zero as last day of radiation therapy or as date of salvage resection in the local regrowth group.

RESULTS

Twenty-one of 79 patients with local regrowth developed distant metastases, whereas only 10 of 74 after upfront total mesorectal excision following neoadjuvant chemoradiation therapy ( p  = 0.04). Local regrowth and final pathology (ypT3-4) were the only independent risk factors associated with distant metastases. When using date of salvage resection as time zero, distant metastases-free survival rates were significantly inferior for patients with local regrowth (70% vs 86%; p  = 0.01).

LIMITATIONS

Small number of patients, many neoadjuvant therapies, and selection bias.

CONCLUSIONS

Patients undergoing watch-and-wait strategy who develop local regrowth are at higher risk for development of distant metastases compared to patients with near-complete pathological response managed by upfront surgery after chemoradiation. See Video Abstract.

NUEVO CRECIMIENTO LOCAL Y EL RIESGO DE METSTASIS A DISTANCIA ENTRE PACIENTES SOMETIDOS A OBSERVACIN Y ESPERA POR CNCER DE RECTO CUL ES EL MEJOR GRUPO DE CONTROL ESTUDIO RETROSPECTIVO MUTICNTRICO

ANTECEDENTES:Una proporción de pacientes que logran una respuesta clínica completa pueden desarrollar un nuevo crecimiento local. Si bien el rescate parece proporcionar un control local apropiado, el riesgo de metástasis a distancia es menos conocido.OBJETIVO:Comparar el riesgo de metástasis a distancia entre los pacientes que logran una respuesta clínica completa (estrategia de observación y espera) y el nuevo crecimiento local posterior con los pacientes tratados con cirugía después de la quimiorradiación.DISEÑO:Estudio de cohorte multicéntrico retrospectivo.CONFIGURACIÓN:Este estudio utilizó datos de pacientes de 3 instituciones que fueron tratados entre 1993 y 2019.PACIENTES:Pacientes con respuesta clínica completa inicial (después de la terapia neoadyuvante) seguida de crecimiento local nuevo y pacientes con respuesta patológica casi completa (≤10 %) después de cirugía directa después de quimiorradiación.PRINCIPALES MEDIDAS DE RESULTADO:Se realizó un análisis univariante/multivariante para identificar los factores de riesgo de metástasis a distancia. Se crearon curvas de Kaplan-Meier (prueba de rango logarítmico) para comparar los resultados de supervivencia. El análisis se realizó utilizando el tiempo cero como último día de radioterapia (1) o como fecha de resección de rescate (2) en el grupo de recrecimiento local.RESULTADOS:Veintiuno de 79 pacientes con recrecimiento local desarrollaron metástasis a distancia, mientras que solo 10 de 74 después de una cirugía sencilla (p = 0,04). El recrecimiento local y la patología final (ypT3-4) fueron los únicos factores de riesgo independientes asociados con las metástasis a distancia. Cuando se utilizó la fecha de la resección de rescate como tiempo cero, las tasas de supervivencia sin metástasis a distancia fueron significativamente inferiores para los pacientes con recrecimiento local (70 frente a 86 %; p = 0,01).LIMITACIONES:Pequeño número de pacientes, muchas terapias neoadyuvantes, sesgo de selección.CONCLUSIONES:Los pacientes sometidos a observación y espera que desarrollan un nuevo crecimiento local tienen un mayor riesgo de desarrollar metástasis a distancia en comparación con los pacientes con una respuesta patológica casi completa manejados con cirugía por adelantado después de la quimiorradiación. (Traducción-Dr. Xavier Delgadillo ).

The Predictors of Complete Pathologic Response in Rectal Cancer during the Total Neoadjuvant Therapy Era: A Systematic Review

The modern rectal cancer treatment paradigm offers additional opportunities for organ preservation, most notably via total neoadjuvant therapy (TNT) and consideration for a watch-and-wait (WW) surveillance-only approach. A major barrier to widespread implementation of a WW approach to rectal cancer is the potential discordance between a clinical complete response (cCR) and a pathologic complete response (pCR). In the pre-TNT era, the identification of predictors of pCR after neoadjuvant therapy had been previously studied. However, the last meta-analysis to assess the summative evidence on this important treatment decision point predates the acceptance and dissemination of TNT strategies. The purpose of this systematic review was to assess preoperative predictors of pCR after TNT to guide the ideal selection criteria for WW in the current era. An exhaustive literature review was performed and the electronic databases Embase, Ovid, MEDLINE, PubMed, and Cochrane were comprehensively searched up to 27 June 2023. Search terms and their combinations included "rectal neoplasms", "total neoadjuvant therapy", and "pathologic complete response". Only studies in English were included. Randomized clinical trials or prospective/retrospective cohort studies of patients with clinical stage 2 or 3 rectal adenocarcinoma who underwent at least 8 weeks of neoadjuvant chemotherapy in addition to chemoradiotherapy with pCR as a measured study outcome were included. In this systematic review, nine studies were reviewed for characteristics positively or negatively associated with pCR or tumor response after TNT. The results were qualitatively grouped into four categories: (1) biochemical factors; (2) clinical factors; (3) patient demographics; and (4) treatment sequence for TNT. The heterogeneity of studies precluded meta-analysis. The level of evidence was low to very low. There is minimal data to support any clinicopathologic factors that either have a negative or positive relationship to pCR and tumor response after TNT. Additional data from long-term trials using TNT is critical to better inform those considering WW approaches following a cCR.

Clinical Tools for Rectal Cancer Response Assessment following Neoadjuvant Treatment in the Era of Organ Preservation

Local tumor response evaluation following neoadjuvant treatment(s) in rectal adenocarcinoma requires a multi-modality approach including physical and endoscopic evaluations, rectal protocoled MRI, and cross-sectional imaging. Clinical tumor response exists on a spectrum from complete clinical response (cCR), defined as the absence of clinical evidence of residual tumor, to near-complete response (nCR), which assumes a significant reduction in tumor burden but with increased uncertainty of residual microscopic disease, to incomplete clinical response (iCR), which incorporates all responses less than nCR that is not progressive disease. This article aims to review the clinical tools currently routinely available to evaluate treatment response and offers a potential management approach based on the extent of local tumor response.

The Crying Need for a Better Response Assessment in Rectal Cancer

OPINION STATEMENT

Since total neoadjuvant treatment achieves almost 30% pathologic complete response, organ preservation has been increasingly debated for good responders after neoadjuvant treatment for patients diagnosed with rectal cancer. Two organ preservation strategies are available: a watch and wait strategy and a local excision strategy including patients with a near clinical complete response. A major issue is the selection of patients according to the initial tumor staging or the response assessment. Despite modern imaging improvement, identifying complete response remains challenging. A better selection could be possible by radiomics analyses, exploiting numerous image features to feed data characterization algorithms. The subsequent step is to include baseline and/or pre-therapeutic MRI, PET-CT, and CT radiomics added to the patients' clinicopathological data, inside machine learning (ML) prediction models, with predictive or prognostic purposes. These models could be further improved by the addition of new biomarkers such as circulating tumor biomarkers, molecular profiling, or pathological immune biomarkers.

Endoscopic and imaging outcomes of PD-1 therapy in localised dMMR colorectal cancer

BACKGROUND

Neoadjuvant immune checkpoint blockade (IO) is emerging as a therapeutic option for patients with deficient mismatch repair (dMMR) colorectal cancer (CRC) given high pathological response rates. The aim of the study was to characterise imaging and endoscopic response to IO.

METHODS

A retrospective analysis of patients with localised dMMR CRC that received at least one cycle of neoadjuvant anti-PD-1 therapy was conducted. Endoscopy, imaging, and pathological outcomes were reviewed to determine response to treatment according to standardised criteria.

RESULTS

Thirty-eight patients had received IO for the treatment of localised CRC (median eight cycles). Among evaluable cases (n = 31 for endoscopy and n = 34 for imaging), the best endoscopic response was complete response (CR) in 45% of cases, and the best radiographic response was CR in 23% of cases. Imaging CR rate after ≤4 cycles of IO (n = 1) was 6% compared to 44% after >4 IO cycles (n = 7). Among 28 patients with imaging and endoscopy available, a discrepancy in best response was noted in 15 (54%) cases. At a median follow-up of 28.2 months from IO start, 18 patients underwent surgical resection of which 11 (61%) had pathological CR (pCR). Despite pCR or no evidence of progression ≥6 months after completion of IO among non-operatively managed patients, 72% and 42% of patients had non-CR on imaging and endoscopy, respectively.

CONCLUSIONS

Discrepancies between imaging and endoscopy are prevalent, and irregularities identified on these modalities can be identified despite pathological remission. Improved clinical response criteria are warranted.

Nonoperative Management of dMMR/MSI-H Colorectal Cancer following Neoadjuvant Immunotherapy: A Narrative Review

Immunotherapy with PD-1 blockade has achieved a great success in colorectal cancers (CRCs) with high microsatellite instability (MSI-H) and deficient mismatch repair (dMMR), and has become the first-line therapy in metastatic setting. Studies of neoadjuvant immunotherapy also report exciting results, showing high rates of clinical complete response (cCR) and pathological complete response. The high efficacy and long duration of response of immunotherapy has prompt attempts to adopt watch-and-wait strategy for patients achieving cCR following the treatment. Thankfully, the watch-and-wait approach has been proposed for nearly 20 years for patients undergoing chemoradiotherapy and has gained ground among patients as well as clinicians. In this narrative review, we combed through the available information on immunotherapy for CRC and on the watch-and-wait strategy in chemoradiotherapy, and looked forward to a future where neoadjuvant immunotherapy as a curative therapy would play a big part in the treatment of MSI-H/dMMR CRC.

Sense and non-sense of imaging in the era of organ preservation for rectal cancer

This review summarizes the current applications and benefits of imaging modalities for organ preservation in the treatment of rectal cancer. The concept of organ preservation in the treatment of rectal cancer has revolutionized the way rectal cancer is managed. Initially, organ preservation was limited to patients with locally advanced rectal cancer who needed neoadjuvant therapy to reduce tumor size before surgery and achieved complete response. However, neoadjuvant therapy is now increasingly utilized for smaller and less aggressive tumors to achieve primary organ preservation. Additionally, more intensive neoadjuvant strategies are employed to improve complete response rates and increase the chances of successful organ preservation. The selection of patients for organ preservation is a critical component of treatment, and imaging techniques such as digital rectal exam, endoscopy, and MRI are commonly used for this purpose. In this review, we provide an overview of what imaging modalities should be chosen and how they can aid in the selection and follow-up of patients undergoing organ-preserving strategies.