Assessing the predictive value of clinical complete response to neoadjuvant therapy for rectal cancer: an analysis of 488 patients

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.

Predictive Value of Magnetic Resonance Complete Response After Neoadjuvant Therapy for Rectal Cancer

INTRODUCTION

Previous research has demonstrated that after neoadjuvant therapy for rectal cancer, the sensitivity of magnetic resonance complete response (mrCR) for detecting pathologic complete response (pCR) in the surgical specimen ranges from 74 to 94%. Patient and provider interest in nonoperative management of rectal cancer that responds favorably to neoadjuvant therapy has grown, necessitating stronger evidence for how well radiographic complete response truly predicts pCR. We sought to determine the current association between mrCR and pCR in locally advanced rectal cancer.

METHODS

We conducted a retrospective cohort study of patients with rectal adenocarcinoma who underwent neoadjuvant chemoradiation followed by index proctectomy at a single academic referral center from January 2012 to December 2021. Our primary outcomes were mrCR, defined as the absence of residual disease on restaging MRI, and pCR, defined as the absence of residual adenocarcinoma in surgical pathology specimens.

RESULTS

Among 523 eligible patients, 157 met the inclusion criteria (38.9% females; 51.0% nonwhite; mean [SD] age, 58.6 [13.2] years). Overall, 8.9% of patients had mrCR and 7.0% had pCR. The sensitivity and positive predictive value of mrCR were 36.4% (95% CI: 10.9 to 69.2) and 28.6% (95% CI: 8.4 to 58.1). Our findings were qualitatively unchanged when only patients in the last 5 years of the study period were included. Study limitations include that neoadjuvant therapy regimens were not standardized and patients who were offered and elected to undergo nonoperative management were not included.

CONCLUSIONS

The value of mrCR in predicting pathologic response following neoadjuvant therapy in locally advanced rectal cancer is low, and mrCR should be interpreted with caution when counseling patients about nonoperative management. Early, frequent surveillance is critical in patients who elect nonoperative management after mrCR.

A management of patients achieving clinical complete response after neoadjuvant therapy and perspectives: on locally advanced rectal cancer

Neoadjuvant chemoradiotherapy (nCRT) followed by total mesorectal excision (TME) and selective use of adjuvant chemotherapy is currently considered the standard of care for locally advanced rectal cancer (LARC). Despite this, the concept of organ preservation is gradually challenging this approach. The management of complete clinical remission (cCR) lacks international consensus, leading scholars to develop their own perspectives based on well-designed studies and long-term data from large multicenter cohorts. To ensure appropriate treatment, this review focuses on the choice of neoadjuvant therapy, criteria for defining cCR, and treatment strategies for patients who achieve cCR after neoadjuvant therapy. By providing guidance on the accurate management of LARC patients after cCR, this review aims to prevent over- or under-treatment.

The Role of Frailty in the Treatment of Locally Advanced Rectal Cancer

Owing to the gradual aging of today's population, an increase in the prevalence of frailty syndrome has been noticed. This complex state of health, characterized by decreased resilience and tolerance with concurrent increased vulnerability to stressors and adverse health-related factors, has drawn researchers' attention in recent years. Rectal cancer, which constitutes ~30% of all colorectal cancers, is a disease noticeably related to the elderly. In its locally advanced form, it is conventionally treated with trimodal therapy-neoadjuvant chemoradiotherapy followed by total mesorectal excision and adjuvant chemotherapy. Despite its good clinical outcomes and improvement in rectal cancer local control, as evidenced by clinical trials, it remains unclear if all frail patients benefit from that approach since it may be associated with adverse side effects that cannot be handled by them. As old patients, and frail ones even more noticeably, are poorly represented in the clinical trials describing outcomes of the standard treatment, this article aims to review the current knowledge on the trimodal therapy of rectal cancer with an emphasis on novel approaches to rectal cancer that can be implemented for frail patients.

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.

Evaluation of transrectal ultrasound-guided tru-cut biopsy as a complementary method for predicting pathological complete response in rectal cancer after neoadjuvant treatment: a phase II prospective and diagnostic trial

IMPORTANCE

Patients with pathological complete response (pCR) of rectal cancer following neoadjuvant treatment had better oncological outcomes. However, reliable methods for accurately predicting pCR remain limited.

OBJECTIVE

To evaluate whether transrectal ultrasound-guided tru-cut biopsy (TRUS-TCB) adds diagnostic value to conventional modalities for predicting pathological complete response in patients with rectal cancer after neoadjuvant treatment.

DESIGN, SETTING, AND PARTICIPANTS

This study evaluated data of patients with rectal cancer who were treated with neoadjuvant treatment and reassessed using TRUS-TCB and conventional modalities before surgery. This study is registered with ClinicalTrials.gov.

MAIN OUTCOMES AND MEASURES

The primary outcome was accuracy, along with secondary outcomes including sensitivity, specificity, negative predictive value, and positive predictive value in predicting tumour residues. Final surgical pathology was used as reference standard.

RESULTS

Between June 2021 and June 2022, a total of 74 patients were enroled, with 63 patients ultimately evaluated. Among them, 17 patients (28%) exhibited a complete pathological response. TRUS-TCB demonstrated an accuracy of 0.71 (95% CI, 0.58-0.82) in predicting tumour residues. The combined use of TRUS-TCB and conventional modalities significantly improved diagnostic accuracy compared to conventional modalities alone (0.75 vs. 0.59, P =0.02). Furthermore, TRUS-TCB correctly reclassified 52% of patients erroneously classified as having a complete clinical response by conventional methods. The occurrence of only one mild adverse event was observed.

CONCLUSIONS AND RELEVANCE

TRUS-TCB proves to be a safe and accessible tool for reevaluation with minimal complications. The incorporation of TRUS-TCB alongside conventional methods leads to enhanced diagnostic performance.

Development and Validation of a Radiomics Model Based on Lymph-Node Regression Grading After Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer

PURPOSE

The response to neoadjuvant chemoradiotherapy (nCRT) varies among patients with locally advanced rectal cancer (LARC), and the treatment response of lymph nodes (LNs) to nCRT is critical in implementing a watch-and-wait strategy. A robust predictive model may help personalize treatment plans to increase the chance that patients achieve a complete response. This study investigated whether radiomics features based on prenCRT magnetic resonance imaging nodes could predict treatment response in preoperative LARC LNs.

METHODS AND MATERIALS

The study included 78 patients with clinical stage T3-T4, N1-2, and M0 rectal adenocarcinoma who received long-course neoadjuvant radiotherapy before surgery. Pathologists evaluated 243 LNs, of which 173 and 70 were assigned to training and validation cohorts, respectively. For each LN, 3641 radiomics features were extracted from the region of interest in high-resolution T2WI magnetic resonance imaging before nCRT. The least absolute shrinkage and selection operator regression model was used for feature selection and radiomics signature building. A prediction model based on multivariate logistic analysis, combining radiomics signature and selected LN morphologic characteristics, was developed and visualized by drawing a nomogram. The model's performance was assessed by receiver operating characteristic curve analysis and calibration curves.

RESULTS

The radiomics signature consists of 5 selected features that were effectively discriminated within the training cohort (area under the curve [AUC], 0.908; 95% CI, 0.857%-0.958%) and the validation cohort (AUC, 0.865; 95% CI, 0.757%-0.973%). The nomogram, which consisted of radiomics signature and LN morphologic characteristics (short-axis diameter and border contours), showed better calibration and discrimination in the training and validation cohorts (AUC, 0.925; 95% CI, 0.880%-0.969% and AUC, 0.918; 95% CI, 0.854%-0.983%, respectively). The decision curve analysis confirmed that the nomogram had the highest clinical utility.

CONCLUSIONS

The nodal-based radiomics model effectively predicts LNs treatment response in patients with LARC after nCRT, which could help personalize treatment plans and guide the implementation of the watch-and-wait approach in these patients.

Organ Preservation in MSS Rectal Cancer

Rectal cancer is a heterogeneous disease with complex genetic and molecular subtypes. Emerging progress of neoadjuvant therapy has led to increased pathological and clinical complete response (cCR) rates for microsatellite stable (MSS) rectal cancer, which responds poorly to immune checkpoint inhibitor alone. As a result, organ preservation of MSS rectal cancer as an alternative to radical surgery has gradually become a feasible option. For patients with cCR or near-cCR after neoadjuvant treatment, organ preservation can be implemented safely with less morbidity. Patient selection can be done either before the neoadjuvant treatment for higher probability or after with careful assessment for a favorable outcome. Those patients who achieved a good clinical response are managed with nonoperative management, organ preservation surgery, or radiation therapy alone followed by strict surveillance. The oncological outcomes of patients with careful selection and organ preservation seem to be noninferior compared with those of radical surgery, with lower postoperative morbidity. However, more studies should be done to seek better regression of tumor and maximize the possibility of organ preservation in MSS rectal cancer.

Stereotactic MR-guided adaptive radiotherapy (SMART) for primary rectal cancer: evaluation of early toxicity and pathological response

Background

The purpose of this study is to measure the effects of stereotactic MR-guided adaptive radiotherapy (SMART) for rectal cancer patients in terms of early toxicity and pathological response.

Materials and methods

For this prospective pilot study, patients diagnosed with locally advanced rectal cancer (LARC) with positive lymph node clinical staging underwent SMART on rectal lesion and mesorectum using hybrid MR-Linac (MRIdian ViewRay). Dose prescription at 80% isodose for the rectal lesion and mesorectum was 40 Gy (8 Gy/fr) and 25 Gy (5 Gy/fr), respectively, delivered on 5 days (3 fr/week). Response assessment by MRI was performed 3 weeks after SMART, then patients fit for surgery underwent total mesorectal excision. Primary endpoint was evaluation of adverse effect of radiotherapy. Secondary endpoint was pathological complete response rate. Early toxicity was graded according to the Common Terminology Criteria for Adverse Events (CTCAE v5.0).

Results

From October 2020 to January 2022, twenty patients underwent rectal SMART. No grade 3-5 toxicity was recorded. Twelve patients were eligible for total mesorectal excision (TME). Mean interval between the completion of SMART and surgery was 4 weeks. Pathological downstaging occurred in all patients; rate of pathological complete response (pCR) was 17%. pCR occurred with a prolonged time to surgery (> 7 weeks).

Conclusion

To our knowledge, this is the first study to use stereotactic radiotherapy for primary rectal cancer. SMART for rectal cancer is well tolerated and effective in terms of tumor regression, especially if followed by delayed surgery.

Limits of Clinical Restaging in Detecting Responders After Neoadjuvant Therapies for Rectal Cancer

BACKGROUND

Accurate clinical restaging is required to select patients who respond to neoadjuvant chemoradiotherapy for locally advanced rectal cancer and who may benefit from an organ preservation strategy.

OBJECTIVE

The purpose of this study was to review our experience with the clinical restaging of rectal cancer after neoadjuvant therapy to assess its accuracy in detecting major and pathological complete response to treatment.

DESIGN

This was a retrospective cohort study.

SETTING

This study was conducted at 2 high-volume Italian centers for Colorectal Surgery.

PATIENTS

Data were included from all consecutive patients who underwent neoadjuvant therapy and surgery for locally advanced rectal cancer from January 2012 to July 2020. Criteria to define clinical response were no palpable mass, a superficial ulcer <2 cm (major response), or no mucosal abnormality (complete response) at endoscopy and no metastatic nodes at MRI.

MAIN OUTCOME MEASURES

The main outcome measures were sensitivity, specificity, positive predictive values, and negative predictive values of clinical restaging in detecting pathological complete response (ypT0) or major pathological response (ypT0-1) after neoadjuvant therapy.

RESULTS

A total of 333 patients were included; 81 (24.3%) had a complete response whereas 115 (34.5%) had a pathological major response. Accuracy for clinical complete response was 80.8% and for major clinical response was 72.9%. Sensitivity was low for both clinical complete response (37.5%) in detecting ypT0 and clinical major response (59.3%) in detecting ypT0-1. Positive predictive value was 68.2% for ypT0 and 60.4% for ypT0-1.

LIMITATIONS

The main limitation of the study its retrospective nature.

CONCLUSION

Accuracy of actual clinical criteria to define pathological complete response or pathological major response is poor. Failure to achieve good sensitivity and precision is a major limiting factor in the clinical setting. Current clinical assessments need to be revised to account for indications for rectal preservation after neoadjuvant chemoradiotherapy. See Video Abstract at http://links.lww.com/DCR/C63 .

LMITES DE LA REESTADIFICACIN CLNICA EN LA DETECCIN DE RESPONDEDORES DESPUS DE TERAPIAS NEOADYUVANTES PARA EL CNCER DE RECTO

ANTECEDENTES:Se requiere una nueva reestadificación clínica precisa para seleccionar pacientes que respondan a la quimiorradioterapia neoadyuvante para el cáncer de recto localmente avanzado y que puedan beneficiarse de una estrategia de preservación de órganos.OBJETIVO:El propósito de este estudio fue revisar nuestra experiencia con la reestadificación clínica del cáncer de recto después de la terapia neoadyuvante para evaluar su precisión en la detección de una respuesta patológica importante y completa al tratamiento.DISEÑO:Estudio de cohorte retrospectivo.AJUSTE:Este estudio se realizó en dos centros italianos de alto volumen para cirugía colorrectal.PACIENTES:Incluimos datos de todos los pacientes consecutivos que se sometieron a terapia neoadyuvante y cirugía por cáncer de recto localmente avanzado desde enero de 2012 hasta julio de 2020. Los criterios para definir la respuesta clínica fueron ausencia de masa palpable, úlcera superficial <2 cm (respuesta mayor) o ausencia de anomalías en la mucosa. (respuesta completa) en la endoscopia, y sin ganglios metastásicos en la resonancia magnética.PRINCIPALES MEDIDAS DE RESULTADO:Exploramos la sensibilidad, la especificidad, los valores predictivos positivos y negativos de la reestadificación clínica para detectar una respuesta patológica completa (ypT0) o mayor (ypT0-1) después de la terapia neoadyuvante.RESULTADOS:Se incluyeron 333 pacientes; 81 (24,3%) tuvieron una respuesta completa mientras que 115 (34,5%) tuvieron una respuesta patológica mayor. La precisión de la respuesta clínica completa y la respuesta clínica importante fue del 80,8 % y el 72,9 %, respectivamente. La sensibilidad fue baja tanto para la respuesta clínica completa (37,5 %) en la detección de ypT0 como para la respuesta clínica mayor (59,3 %) en la detección de ypT0-1. El valor predictivo positivo fue del 68,2 % para ypT0 y del 60,4 % para ypT0-1.LIMITACIONES:Nuestro estudio tiene como principal limitación su carácter retrospectivo.CONCLUSIÓNES:La precisión de los criterios clínicos reales para definir una respuesta patológica completa o mayor es pobre. El hecho de no lograr una buena sensibilidad y precisión es un factor limitante importante en el entorno clínico. La indicación para la preservación rectal después de la quimiorradioterapia neoadyuvante necesita una mejora de la evaluación clínica actual. Consulte Video Resumen en http://links.lww.com/DCR/C63 . (Traducción-Dr. Mauricio Santamaria ).

Rectal Cancer: Clinical and Molecular Predictors of a Complete Response to Total Neoadjuvant Therapy

BACKGROUND

Total neoadjuvant therapy in rectal cancer may increase pathological complete response rates, potentially allowing for a nonoperative approach.

OBJECTIVE

The objective of this study was to identify patient and tumor characteristics that predict a complete response following total neoadjuvant therapy.

DESIGN

This was a retrospective cohort study.

SETTINGS

This study was conducted at a university-based National Cancer Institute-designated Comprehensive Cancer Center.

PATIENTS

The patients include those with stage 2 or 3 rectal adenocarcinoma.

INTERVENTIONS

Interventions included total neoadjuvant therapy, total mesorectal excision, and nonoperative management.

MAIN OUTCOME MEASURES

Complete response was defined as either patients with a clinical complete response undergoing nonoperative management who remained cancer-free or patients undergoing surgery with a pathological complete response.

RESULTS

Among 102 patients, median age was 54 years, 69% were male, median carcinoembryonic antigen level was 3.0 ng/mL, and the median distance of the tumor above the anorectal ring was 3 cm. Thirty-eight (37%) patients had a complete response, including 15 of 18 (83%) nonoperative patients who remained cancer free at a median of 22 months (range, 7-48 months) and 23 of 84 (27%) patients who underwent surgery and had a pathological complete response. The incomplete response group consisted of 61 patients who underwent initial surgery and 3 nonoperative patients with regrowth. There were no differences in gender, T-stage, or tumor location between groups. Younger age (median, 49 vs 55 years), normal carcinoembryonic antigen (71% vs 41%), clinical node-negative (24% vs 9%), smaller tumors (median 3.9 vs 5.4 cm), and wild-type p53 (79% vs 47%) and SMAD4 (100% vs 81%) were more likely to have a complete response (all p < 0.05).

LIMITATIONS

This was a retrospective study with a small sample size.

CONCLUSIONS

In patients with rectal cancer treated with total neoadjuvant therapy, more than one-third will achieve a pathological complete response or sustained clinical complete response with nonoperative management, making oncological resection superfluous in these patients. Smaller, wild-type p53 and SMAD4, and clinically node-negative cancers are predictive features of a complete response. See Video Abstract at http://links.lww.com/DCR/B889 .

CNCER DE RECTO PREDICTORES CLNICOS Y MOLECULARES DE UNA RESPUESTA COMPLETA A LA TERAPIA NEOADYUVANTE TOTAL

ANTECEDENTES:La terapia neoadyuvante total en el cáncer de recto puede aumentar las tasas de respuesta patológica completa y permitir potencialmente un enfoque no quirúrgico.OBJETIVO:El objetivo fue identificar las características tanto del paciente y del tumor que logren predecir una respuesta completa después de la terapia neoadyuvante total.DISEÑO:Este fue un estudio de cohorte retrospectivo.AJUSTES:Este estudio se realizó en un Centro Integral de Cáncer designado por el Instituto Nacional del Cáncer con sede universitaria.PACIENTES:Los pacientes incluyen aquellos con adenocarcinoma de recto en estadio 2 o 3.INTERVENCIONES:Terapia neoadyuvante total, escisión total del mesorrecto, manejo conservador no quirúrgico.PRINCIPALES MEDIDAS DE RESULTADO:La respuesta completa se definió como pacientes con una respuesta clínica completa sometidos a tratamiento no quirúrgico que permanecieron libres de cáncer o pacientes sometidos a cirugía con una respuesta patológica completa.RESULTADOS:Entre 102 pacientes, la mediana de edad fue de 54 años, el 69% fueron hombres, la mediana del nivel de antígeno carcinoembrionario fue de 3.0 ng/ml y la mediana de la distancia del tumor por encima del anillo anorrectal fue de 3 cm. Thirty-eight (37%) pacientes tuvieron una respuesta completa que incluyó a 15 de 18 (83%) pacientes con manejo no operatorio y que permanecieron libres de cáncer en una mediana de 22 meses (rango 7- 48 meses) y 23 de 84 (27%) pacientes que fueron sometidos a cirugía y tuvieron una respuesta patológica completa. El grupo de respuesta incompleta consistió en 61 pacientes que fueron sometidos inicialmente a cirugía y 3 pacientes no quirúrgicos con recrecimiento. No se encontró diferencias de género, estadio T o ubicación del tumor entre los grupos. Edad más joven (mediana 49 frente a 55), antígeno carcinoembrionario normal (71% frente a 41%), ganglios clínicos negativos (24% frente a 9%), tumores más pequeños (mediana de 3,9 frente a 5,4 cm) y p53 de tipo salvaje (79 % vs 47%) y SMAD4 (100% vs 81%) tenían más probabilidades de tener una respuesta completa (todos p < 0,05).LIMITACIONES:Este fue un estudio retrospectivo y con un tamaño de muestra pequeño.CONCLUSIONES:En pacientes con cáncer de recto tratados con terapia neoadyuvante total, más de un tercio logrará una respuesta patológica completa o una respuesta clínica completa sostenida con manejo no operatorio, logrando que la resección oncológica sea superflua en estos pacientes. Los cánceres más pequeños, clínicamente con ganglios negativos, con p53 de tipo salvaje y SMAD4, son características predictoras de una respuesta completa. Consulte Video Resumen en http://links.lww.com/DCR/B889 . (Traducción-Dr. Osvaldo Gauto ).

Assessing the predictive value of clinical factors to pathological complete response for locally advanced rectal cancer: An analysis of 124 patients

Purpose

To investigate the clinical factors affecting pathological complete response (pCR) after neoadjuvant chemoradiotherapy (nCRT) in locally advanced rectal cancer (LARC).

Methods

Clinical data of 124 LARC patients treated with nCRT and surgery in the fourth Hospital of Hebei Medical University from 2014 to 2019 were retrospectively analyzed. In this study, univariate analysis and logistic dichotomous multivariate regression analysis were used to study the clinical factors affecting pCR, and the receiver operator characteristic curve (ROC) analysis was used to further verify the accuracy of partial indexes in predicting pCR.

Results

Of the 124 enrolled patients, 19 patients (15.32%) achieved pCR. Univariate analysis showed that the number of cycles of consolidation chemotherapy, serum carcino-embryonic antigen (CEA) level before treatment, MRI longitudinal length of tumor, and extramural vascular invasion (EMVI) were statistically correlated with pCR. ROC analysis of the longitudinal length of tumor measured by MRI showed that the area under the curve (AUC) value, sensitivity and specificity were 0.735, 89.47% and 48.57% respectively, and the optimal cut-off value was 5.5cm. The ROC analysis showed that the AUC value, sensitivity and specificity of pCR prediction using CEA were 0.741, 63.16% and 90.48%, respectively, and the optimal cut-off value was 3.1ng/ml. Multivariate results showed that the number of cycles of consolidation chemotherapy, serum CEA level before treatment, and EMVI were independent predictors of pCR.

Conclusion

The number of cycles of consolidation chemotherapy, serum CEA level before treatment, and EMVI may be important determinants of LARC patients to reach pCR after nCRT.

Utility of Circulating Free DNA Fragmentomics in the Prediction of Pathological Response after Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer

BACKGROUND

A "Watch and Wait" (W&W) approach has become an alternative to surgery for locally advanced rectal cancer (LARC) after neoadjuvant chemoradiotherapy (nCRT). Precise prediction of pathological complete response (pCR) will improve patient selection for W&W. We investigated the utility of cell-free DNA (cfDNA) fragmentomics in predicting pCR.

METHODS

We recruited 119 LARC patients and evaluated nCRT response by pCR status and pathological or MRI tumor regression grade (mrTRG). Plasma samples before, during, and after nCRT were applied to deep targeted-panel sequencing, with 103 patients having complete samples. cfDNA fragment and 5'-end motif profiles were used to construct elastic-net logistic regression models to predict non-pCR. Predictive performance was measured by area under the receiver operator characteristic curve (AUC), sensitivity, and specificity.

RESULTS

In the training cohort, the model based on 5'-end motif profile plus mrTRG achieved the highest cross-validation AUC (0.92, 95% CI, 0.91-0.93). The AUC in a testing cohort was 0.96 (95% CI, 0.90-1.00). The models based on 5'-end motif profile alone or in combination with mrTRG both maintained good predictive ability for patients without detectable circulating tumor DNA (AUC 0.94, 95% CI, 0.93-0.95; AUC 0.95, 95% CI, 0.94-0.96). In an external validation cohort, the model trained with a local 5'-end motif profile obtained an AUC of 0.878 (95% CI, 0.801-0.956) in discriminating colorectal cancer from healthy subjects.

CONCLUSIONS

The combination of a 5'-end motif profile with mrTRG has the potential to predict the response to nCRT, and therefore may improve the patient selection for a W&W approach.

A nomogram prediction model for lymph node metastasis risk after neoadjuvant chemoradiotherapy in rectal cancer patients based on SEER database

Background

Rectal cancer patients who received neoadjuvant chemoradiotherapy (CRT) may have a lower cancer stage and a better prognosis. Some patients may be able to avoid invasive surgery. It is critical to accurately assess lymph node metastases (LNM) after neoadjuvant chemoradiotherapy. The goal of this study is to identify clinical variables associated with LNM and to develop a nomogram for LNM prediction in rectal cancer patients following nCRT.

Methods

From 2010 to 2015, patients were drawn from the Surveillance, Epidemiology, and End Results (SEER) database. To identify clinical factors associated with LNM, the least absolute shrinkage and selection operator (LASSO) aggression and multivariate logistic regression analyses were used. To predict the likelihood of LNM, a nomogram based on multivariate logistic regression was created using decision curve analyses.

Reslut

The total number of patients included in this study was 6,388. The proportion of patients with pCR was 17.50% (n=1118), and the proportion of patients with primary tumor pCR was 20.84% (n = 1,331). The primary tumor was pCR in 16.00% (n=213) of the patients. Age, clinical T stage, clinical N stage, and histology were found to be significant independent clinical predictors of LNM using LASSO and multivariate logistic regression analysis. The nomogram was developed based on four clinical factors. The 5-year overall survival rate was 78.9 percent for those with ypN- and 66.3 percent for those with ypN+, respectively (P<0.001).

Conclusion

Patients over 60 years old, with clinical T1-2, clinical N0, and adenocarcinoma may be more likely to achieve ypN0. The watch-and-wait (WW) strategy may be considered. Patients who had ypN0 or pCR had a better prognosis.

Circulating tumour DNA in the evolving treatment landscape of locally advanced rectal cancer: where does it fit in?

The management of locally advanced rectal cancer (LARC) requires multimodality treatment, typically with neoadjuvant chemoradiotherapy (CRT) followed by total mesorectal excision. However, the treatment landscape is rapidly evolving with total neoadjuvant therapy and non-operative management for selected patients emerging as other novel treatment approaches. With so many treatment options, there is a need for biomarkers to direct a more personalised treatment strategy for patients with LARC. In this review, we summarise the available data regarding the use of circulating tumour DNA (ctDNA) in patients with LARC, as both a marker of treatment response to neoadjuvant therapy and as a marker of minimal residual disease (MRD) after patients have completed definitive local treatment. To date, the ability of ctDNA status to predict for pathologic complete response at any timepoint during multimodality treatment has been variably reported. The most consistent finding across available studies is the ability of ctDNA to detect MRD after CRT and surgery, the presence of which confers a significantly poor prognosis, with increased risk of cancer recurrence and worse overall survival. It is yet to be determined if providing additional therapies to patients with MRD improves outcomes. The available studies assessing the potential utility of ctDNA in LARC are limited by significant heterogeneity in the choice of ctDNA assay, timepoint at which ctDNA was collected, treatment that patients received and length of follow-up, leading to uncertainties about how to implement it into daily clinical practice. As the treatment landscape evolves, larger randomised trials assessing the role of ctDNA in LARC are needed.

Adaptive Individualized high-dose preoperAtive (AIDA) chemoradiation in high-risk rectal cancer: a phase II trial

PURPOSE

To evaluate the pathological complete response (pCR) rate of locally advanced rectal cancer (LARC) after adaptive high-dose neoadjuvant chemoradiation (CRT) based on 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (18 F-FDG-PET/CT).

METHODS

The primary endpoint was the pCR rate. Secondary endpoints were the predictive value of 18 F-FDG-PET/CT on pathological response and acute and late toxicity. All patients performed 18 F-FDG-PET/CT at baseline (PET0) and after 2 weeks during CRT (PET1). The metabolic PET parameters were calculated both at the PET0 and PET1. The total CRT dose was 45 Gy to the pelvic lymph nodes and 50 Gy to the primary tumor, corresponding mesorectum, and to metastatic lymph nodes. Furthermore, a sequential boost was delivered to a biological target volume defined by PET1 with an additional dose of 5 Gy in 2 fractions. Capecitabine (825 mg/m2 twice daily orally) was prescribed for the entire treatment duration.

RESULTS

Eighteen patients (13 males, 5 females; median age 55 years [range, 41-77 years]) were enrolled in the trial. Patients underwent surgical resection at 8-9 weeks after the end of neoadjuvant CRT. No patient showed grade > 1 acute radiation-induced toxicity. Seven patients (38.8%) had TRG = 0 (complete regression), 5 (27.0%) showed TRG = 2, and 6 (33.0%) had TRG = 3. Based on the TRG results, patients were classified in two groups: TRG = 0 (pCR) and TRG = 1, 2, 3 (non pCR). Accepting p < 0.05 as the level of significance, at the Kruskal-Wallis test, the medians of baseline-MTV, interim-SUVmax, interim-SUVmean, interim-MTV, interim-TLG, and the MTV reduction were significantly different between the two groups. 18 F-FDG-PET/CT was able to predict the pCR in 77.8% of cases through compared evaluation of both baseline PET/CT and interim PET/CT.

CONCLUSIONS

Our results showed that a dose escalation on a reduced target in the final phase of CRT is well tolerated and able to provide a high pCR rate.

The watch-and-wait strategy versus radical resection for rectal cancer patients with a good response (≤ycT2) after neoadjuvant chemoradiotherapy

Purpose

This study aims to oncologic outcomes of the watch-and-wait (WW) strategy compared with radical resection (RR).

Methods

Patients with rectal cancer who received neoadjuvant chemoradiotherapy (nCRT) and achieved ≤ycT2 between 2008 and 2016 were included. The mean follow-up time was 61 months (range, 0-168 months). Recurrence-free survival (RFS), local recurrence-free survival (LRFS), distant metastasis-free survival (DMFS), and overall survival (OS) were compared. A total of 446 patients were included, and WW was adopted for 34 patients.

Results

WW patients were older (P = 0.022) and less advanced initial cT stage (P = 0.004). Ten patients in the WW group (29.4%) experienced local regrowth. Later, distant metastases occurred in 7 of these patients. The 5-year RFS (74.1% vs. 79.5%), DMFS (74.1% vs. 81.6%), and OS (90.4% vs. 87.7%) for the WW and RR groups were not statistically different. However, LRFS in the WW group was significantly lower (65.1% vs. 97.0%, P < 0.001). The initial cT stage was associated with RFS (P = 0.019) and LRFS (P = 0.037). WW was an independent risk factor for LRFS (P < 0.001) and DMFS (P = 0.024). After 1:4 propensity score matching between the WW and RR groups, there was no difference in RFS and OS. However, the 5-year LRFS (67.5% vs. 96.5%) and DMFS (73.2% vs. 86.4%) demonstrated a statistically significant difference between the groups.

Conclusion

By appointing the WW strategy, oncologic safety was not ensured. The WW strategy must be implemented with caution in patients with ≤ycT2 stage, particularly those with advanced initial cT stage.

Transanal Endoscopic Microsurgery Versus Total Mesorectal Excision in ypT0-1 Rectal Cancer After Preoperative Radiochemotherapy: Postoperative Morbidity, Functional Results, and Long-term Oncologic Outcome

BACKGROUND

In patients with locally advanced extraperitoneal rectal cancer, a multidisciplinary approach represents the standard treatment. However, considering the favorable prognosis in patients with major or complete response, radical surgery might represent overtreatment.

OBJECTIVE

This study aimed to evaluate postoperative short-term morbidity, functional outcome, and oncologic long-term outcome in patients with rectal cancer treated with local excision by transanal endoscopic microsurgery or radical surgery and to determine who achieved a complete or major pathological response (ypT0-1) after neoadjuvant treatment.

DESIGN

This was a retrospective study.

SETTING

The study was conducted at a single center.

PATIENTS

Patients who had received neoadjuvant treatment by local excision with a major or complete pathological response at histological examination (transanal endoscopic microsurgery group) were compared to patients treated by radical surgery with the same pathological response (total mesorectal excision group).

INTERVENTIONS

The interventions included local excision by transanal endoscopic microsurgery and radical surgery with total mesorectal excision.

MAIN OUTCOME MEASURES

Postoperative short-term morbidity, functional outcome 1 year after surgery, and oncologic long-term outcome were measured.

RESULTS

Ninety-three patients were included in the study (35 in the transanal endoscopic microsurgery group and 58 in the mesorectal excision group). In the total mesorectal excision group, a sphincter-saving approach was possible in 89.7% (vs 100%; p = 0.049); a protective temporary stoma was necessary in 74.1% of radical procedures (vs 0%; p < 0.001), and 13.8% of these became permanent. Short-term postoperative morbidity was lower after local excision (14.3% vs 46.6%; p = 0.002). One year after surgery, the transanal endoscopic microsurgery group recorded better evacuation and continence function than the total mesorectal excision group. Oncologic outcome was similar between the groups.

LIMITATIONS

This study had a retrospective design.

CONCLUSION

If a major or complete pathological response occurs after neoadjuvant treatment, an organ-sparing approach by local excision seems to offer the same oncologic results as radical surgery, but it has a better postoperative morbidity rate and better functional results. See Video Abstract at http://links.lww.com/DCR/B901 .Microcirugía endoscópica transanal versus escisión total del mesorrecto en cáncer de recto ypT0-1 después de radioquimioterapia preoperatoria: morbilidad posoperatoria, resultados funcionales y resultado oncológico a largo plazo.

ANTECEDENTES

En pacientes con cáncer rectal extraperitoneal localmente avanzado, un abordaje multidisciplinario con radioquimioterapia preoperatoria y cirugía con escisión total del mesorrecto representa el tratamiento estándar. En pacientes que obtienen una respuesta mayor o completa, la cirugía radical puede representar un sobretratamiento, considerando el pronóstico favorable de estos casos.

OBJETIVO

Evaluar la morbilidad posoperatoria a corto plazo, el resultado funcional y el resultado oncológico a largo plazo en pacientes con cáncer de recto tratados con escisión local mediante microcirugía endoscópica transanal o mediante cirugía radical y que obtuvieron una respuesta patológica completa o mayor (ypT0-1) después del tratamiento neoadyuvante.

DISEO

Este fue un estudio retrospectivo.

AJUSTE

El estudio se realizó en un solo centro.

ESCENARIO

El estudio se realizó en un solo centro.

PACIENTES

Se comparó a los pacientes tratados, tras tratamiento neoadyuvante (1996-2016), mediante escisión local con respuesta patológica mayor o completa al examen histológico (grupo de microcirugía endoscópica transanal), con los pacientes tratados mediante cirugía radical con la misma respuesta patológica (grupo de escisión mesorrectal total).

INTERVENCIONES

Extirpación local mediante microcirugía endoscópica transanal y cirugía radical con escisión mesorrectal total.

PRINCIPALES MEDIDAS DE RESULTADO

Morbilidad posoperatoria a corto plazo, resultado funcional a un año después de la cirugía (evaluado con una puntuación de evacuación y continencia) y resultado oncológico a largo plazo.

LIMITACIONES

Las limitaciones de este estudio incluyen su diseño retrospectivo.

CONCLUSIN

Si se produce una respuesta patológica mayor o completa después del tratamiento neoadyuvante, un abordaje con preservación de órganos mediante escisión local parece ofrecer los mismos resultados oncológicos que la cirugía radical, pero tiene una menor tasa de morbilidad postoperatoria y mejores resultados funcionales un año después de la cirugía. Consulte Video Resumen en http://links.lww.com/DCR/B901 . (Traducción-Dr. Felipe Bellolio ).

Correlation between T stage and lymph node metastasis in rectal cancer treated with preoperative chemoradiotherapy

Background:

Depth of tumor is a risk factor for lymph node metastasis in rectal cancer, but impact of yield pathologic T (ypT) stage on lymph node involvement in rectal cancer remains unclear. The aim of this study was to evaluate the correlation between ypT stage and lymph node metastasis.

Methods:

From January 2010 to December 2015, 602 patients who were diagnosed with rectal cancer and treated with neoadjuvant chemoradiotherapy (CRT) followed by radical operation were reviewed retrospectively. The correlations between ypT stage and lymph node status and survival were evaluated.

Results:

On pathology, 179 (29.7%) patients exhibited regional lymph node metastasis. Lymph node metastasis was seen in 8.5% of ypT0 patients, 20% of ypT1, 18.4% of ypT2, 47.5% of ypT3, and 27.3% of ypT4. Positive lymph node metastasis was correlated with ypT stage. In addition, the difference of lymph node metastasis in ypT stage subgroups was statistically significant (p < 0.001). Five-year disease-free survival was significantly different in the ypT stage subgroups (88.7% versus 86.7% versus 82.6% versus 64.7% versus 72.7%, p < 0.001), as was 5-year overall survival (96.2% versus 90.0% versus 95.8% versus 80.0% versus 90.9%, p < 0.001).

Conclusion:

YpT stage is associated with lymph node metastasis in rectal cancer treated with neoadjuvant CRT and radical operation, and ypT0 patients exhibited an 8.5% lymph node metastasis rate. Therefore, the decision for local excision or the watch-and-wait strategy for rectal cancer treated with neoadjuvant CRT and predicted to show a pathologic complete response should be considered with caution.

Clinical Robotic Surgery Association (India Chapter) and Indian rectal cancer expert group's practical consensus statements for surgical management of localized and locally advanced rectal cancer

INTRODUCTION

There are standard treatment guidelines for the surgical management of rectal cancer, that are advocated by recognized physician societies. But, owing to disparities in access and affordability of various treatment options, there remains an unmet need for personalizing these international guidelines to Indian settings.

METHODS

Clinical Robotic Surgery Association (CRSA) set up the Indian rectal cancer expert group, with a pre-defined selection criterion and comprised of the leading surgical oncologists and gastrointestinal surgeons managing rectal cancer in India. Following the constitution of the expert Group, members identified three areas of focus and 12 clinical questions. A thorough review of the literature was performed, and the evidence was graded as per the levels of evidence by Oxford Centre for Evidence-Based Medicine. The consensus was built using the modified Delphi methodology of consensus development. A consensus statement was accepted only if ≥75% of the experts were in agreement.

RESULTS

Using the results of the review of the literature and experts' opinions; the expert group members drafted and agreed on the final consensus statements, and these were classified as "strong or weak", based on the GRADE framework.

CONCLUSION

The expert group adapted international guidelines for the surgical management of localized and locally advanced rectal cancer to Indian settings. It will be vital to disseminate these to the wider surgical oncologists and gastrointestinal surgeons' community in India.

Lymph node regression grading of locally advanced rectal cancer treated with neoadjuvant chemoradiotherapy

Neoadjuvant chemoradiotherapy (nCRT) and total rectal mesenteric excision are the main standards of treatment for locally advanced rectal cancer (LARC). Lymph node regression grade (LRG) is an indicator of prognosis and response to preoperative nCRT based on postsurgical metastatic lymph node pathology. Common histopathological findings in metastatic lymph nodes after nCRT include necrosis, hemorrhage, nodular fibrosis, foamy histiocytes, cystic cell reactions, areas of hyalinosis, residual cancer cells, and pools of mucin. A number of LRG systems designed to classify the amount of lymph node regression after nCRT is mainly concerned with the relationship between residual cancer cells and regressive fibrosis and with estimating the number of lymph nodes existing with residual cancer cells. LRG offers significant prognostic information, and in most cases, LRG after nCRT correlates with patient outcomes. In this review, we describe the systematic classification of LRG after nCRT, patient prognosis, the correlation with tumor regression grade, and the typical histopathological findings of lymph nodes. This work may serve as a reference to help predict the clinical complete response and determine lymph node regression in patients based on preservation strategies, allowing for the formulation of more accurate treatment strategies for LARC patients, which has important clinical significance and scientific value.

Comparison of tumor regression grade and clinical stage based on MRI image as a selection criterion for non-radical management after concurrent chemoradiotherapy in locally advanced rectal cancer: a multicenter, retrospective, cross-sectional study

PURPOSE

There has been no comparative study on the clinical value of magnetic resonance tumor regression grade (mrTRG)1-2 and ycT0-1N0 for the prediction of ypT0-1N0 after concurrent chemoradiotherapy (CCRT) for rectal cancer. We compared the diagnostic performance between mrTRG1-2 and ycT0-1N0 for predicting ypT0-1N0 as a selection criterion for non-radical management after CCRT in locally advanced rectal cancer.

METHODS

This retrospective study enrolled 291 patients from three referral hospitals between January 2018 and March 2020. The diagnostic performance of ycT0-1N0 and mrTRG1-2 for the prediction of ypT0-1N0 was compared in terms of sensitivity, specificity, positive-predictive value, negative-predictive value, and area under the curve (AUC).

RESULTS

Sixty-eight patients (23.4%) achieved ypT0-1N0. Nineteen patients (6.5%) had ycT0-1N0, and 91 patients (31.2%) had mrTRG1-2. For predicting ypT0-1N0, ycT0-1N0 had a sensitivity of 16.2% (95% confidence interval [CI]: 8.36‒27.10) and positive-predictive value of 57.9% (95% CI: 36.57‒76.63), while mrTRG1-2 had a sensitivity of 58.8% (95% CI: 46.23‒70.63) and positive-predictive value of 44.0% (95% CI: 36.46‒51.74). When predicting ypT0-1N0, mrTRG1-2 showed a higher AUC (0.680, 95% CI: 0.604‒0.756) than ycT0-1N0 (0.563, 95% CI: 0.481‒0.645) (P < 0.001).

CONCLUSION

mrTRG1-2 might be a better indicator than ycT0-1N0 for the selection of non-radical management of advanced rectal cancer post-CCRT. However, additional diagnostic tools are required for predicting ypT0-1N0 because mrTRG1-2 or yc stage on MRI has insufficient evidence for diagnosing ypT0-1N0.

18F-FDG-PET/MRI texture analysis in rectal cancer after neoadjuvant chemoradiotherapy

OBJECTIVE

Reliable markers to predict the response to neoadjuvant chemoradiotherapy (nCRT) in locally advanced rectal cancer (LARC) are lacking. We aimed to assess the ability of 18F-FDG PET/MRI to predict response to nCRT among patients undergoing curative-intent surgery.

METHODS

Patients with histological-confirmed LARC who underwent curative-intent surgery following nCRT and restaging with 18F-FDG PET/MRI were included. Statistical correlation between radiomic features extracted in PET, apparent diffusion coefficient (ADC) and T2w images and patients' histopathologic response to chemoradiotherapy using a multivariable logistic regression model ROC-analysis.

RESULTS

Overall, 50 patients were included in the study. A pathological complete response was achieved in 28.0% of patients. Considering second-order textural features, nine parameters showed a statistically significant difference between the two groups in ADC images, six parameters in PET images and four parameters in T2w images. Combining all the features selected for the three techniques in the same multivariate ROC curve analysis, we obtained an area under ROC curve of 0.863 (95% CI, 0.760-0.966), showing a sensitivity, specificity and accuracy at the Youden's index of 100% (14/14), 64% (23/36) and 74% (37/50), respectively.

CONCLUSION

PET/MRI texture analysis seems to represent a valuable tool in the identification of rectal cancer patients with a complete pathological response to nCRT.

Tissue-Based Markers as a Tool to Assess Response to Neoadjuvant Radiotherapy in Rectal Cancer-Systematic Review

According to current guidelines, the current treatment for locally advanced rectal cancer is neoadjuvant therapy, followed by a total mesorectal excision. However, radiosensitivity tends to differ among patients due to tumor heterogeneity, making it difficult to predict the possible outcomes of the neoadjuvant therapy. This review aims to investigate different types of tissue-based biomarkers and their capability of predicting tumor response to neoadjuvant therapy in patients with locally advanced rectal cancer. We identified 169 abstracts in NCBI PubMed, selected 48 reports considered to meet inclusion criteria and performed this systematic review. Multiple classes of molecular biomarkers, such as proteins, DNA, micro-RNA or tumor immune microenvironment, were studied as potential predictors for rectal cancer response; nonetheless, no literature to date has provided enough sufficient evidence for any of them to be introduced into clinical practice.

Correlation of Tumor Response Between Flexible Sigmoidoscopy and Magnetic Resonance Imaging in Patients Undergoing Neoadjuvant Therapy for Locally Advanced Rectal Cancer: A Retrospective Review

BACKGROUND

The National Accreditation Program for Rectal Cancer recommends a pelvic MRI to assess the response to neoadjuvant therapy for advanced rectal cancers. However, there is no single restaging modality that can identify all patients with complete tumor response. At our institution, we perform both a pelvic MRI and a flexible sigmoidoscopy (FS) after neoadjuvant therapy prior to surgical resection.

OBJECTIVE

The objective is to elucidate the correlation of tumor response between FS and MRI in patients undergoing neoadjuvant therapy for locally advanced rectal cancer.

DESIGN

Single institution from 2010 to 2019. Retrospective cohort study comparing local tumor response on FS to MRI utilizing final pathology as the gold standard for comparison.

PATIENTS

Patients with confirmed locally advanced rectal adenocarcinoma (stage II or III) who underwent neoadjuvant therapy prior to surgical intervention and underwent flexible endoscopy and a standardized rectal cancer protocol MRI to evaluate tumor response.

RESULTS

A total of 48 patients were evaluated. Seven (14%) patients had a complete pathological response. MRI adequately reported 1 (14%), while FS found 4 (57.14%) out of the 7 complete responders. Nevertheless, this did not reach statistical significance (P = .06). On logistic regression analysis, flexible sigmoidoscopy had a 5.5 higher likelihood to report an accurate complete response (OR 5.5, 95% CI: 1.02-29.64; P = .047).

CONCLUSIONS

Flexible sigmoidoscopy should be used in conjunction with MRI in the work up of patients who have received neoadjuvant therapy for advanced rectal cancer prior to surgical resection.

Endoscopy-Based Deep Convolutional Neural Network Predicts Response to Neoadjuvant Treatment for Locally Advanced Rectal Cancer

Background and Aims: Although the wait and watch (W&W) strategy is a treatment choice for locally advanced rectal cancer (LARC) patients who achieve clinical complete response (cCR) after neoadjuvant therapy (NT), the issue on consistency between cCR and pathological CR (pCR) remains unsettled. Herein, we aimed to develop a deep convolutional neural network (DCNN) model using endoscopic images of LARC patients after NT to distinguish tumor regression grade (TRG) 0 from non-TRG0, thus providing strength in identifying surgery candidates. Methods: A total of 1000 LARC patients (6,939 endoscopic images) who underwent radical surgery after NT from April 2013 to April 2021 at the Sixth Affiliated Hospital, Sun Yat-sen University were retrospectively included in our study. Patients were divided into three cohorts in chronological order: the training set for constructing the model, the validation set, and the independent test set for validating its predictive capability. Besides, we compared the model's performance with that of three endoscopists on a class-balanced, randomly selected subset of 20 patients' LARC images (10 TRG0 patients with 70 images and 10 non-TRG0 patients with 72 images). The measures used to evaluate the efficacy for identifying TRG0 included overall accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the receiver operating characteristic curve (AUROC). Results: There were 219 (21.9%) cases of TRG0 in the included patients. The constructed DCNN model in the training set obtained an excellent performance with good accuracy of 94.21%, specificity of 94.39%, NPV of 98.11%, and AUROC of 0.94. The validation set showed accuracy, specificity, NPV, and AUROC of 92.13%, 93.04%, 96.69%, and 0.95, respectively; the corresponding values in the independent set were 87.14%, 92.98%, 91.37%, and 0.77, respectively. In the reader study, the model outperformed the three experienced endoscopists with an AUROC of 0.85. Conclusions: The proposed DCNN model achieved high specificity and NPV in detecting TRG0 LARC tumors after NT, with a better performance than experienced endoscopists. As a supplement to radiological images, this model may serve as a useful tool for identifying surgery candidates in LARC patients after NT.

Predicting response to neoadjuvant chemoradiotherapy in rectal cancer: from biomarkers to tumor models

Colorectal cancer (CRC) is a major contributor to cancer-associated morbidity worldwide and over one-third of CRC is located in the rectum. Neoadjuvant chemoradiotherapy (nCRT) followed by surgical resection is commonly applied to treat locally advanced rectal cancer (LARC). In this review, we summarize current and novel concepts of neoadjuvant therapy for LARC such as total neoadjuvant therapy and describe how these developments impact treatment response. Moreover, as response to nCRT is highly divergent in rectal cancers, we discuss the role of potential predictive biomarkers. We review recent advances in biomarker discovery, from a clinical as well as a histopathological and molecular perspective. Furthermore, the role of emerging predictive biomarkers derived from the tumor environment such as immune cell composition and gut microbiome is presented. Finally, we describe how different tumor models such as patient-derived cancer organoids are used to identify novel predictive biomarkers for chemoradiotherapy (CRT) in rectal cancer.

Predicting stage ypT0–1N0 for nonradical management in patients with middle or low rectal cancer who undergo neoadjuvant chemoradiotherapy: a retrospective cohort study

Purpose

It is important to discover predictive factors that can identify rectal cancer patients who will respond well to neoadjuvant concurrent chemoradiotherapy (CCRT) to develop management strategies, preserve sphincter and avoid over-treatment. This study explored clinical factors that would predict the adequacy of nonradical management after CCRT in patients with middle or low rectal cancer.

Methods

We retrospectively evaluated 447 patients with middle or low rectal cancer who were treated with curative surgery after neoadjuvant CCRT between January 2010 and December 2019. The good response group comprised patients with stages ypT0–1N0 on resection after CCRT; the remaining patients were included in the poor response group.

Results

Of 447 patients (mean age, 60.37 ± 11.85 years), 108 (24.2%) had ypT0–1N0 (71.3% with ypT0N0, 4.6% with ypTisN0, and 24.1% with ypT1N0). Overall, 19 patients with cT1–2 (50.0% vs. 21.8% with cT3–4, P < 0.001), 22 with well-differentiated tumors (51.2% vs. 21.3% with moderately/poorly differentiated tumors, P < 0.001), 16 with fungating tumors (47.1% vs. 22.3% with other types, P = 0.001), and 66 with anterior/posterior circumference direction (28.9% vs. 19.2% with lateral/encircling direction, P = 0.016) had stage ypT0–1N0. On multivariable analysis, cT1–2 (P = 0.021) and well-differentiated tumor (P = 0.001) were independent predictors of ypT0–1N0. Fungating tumors were not significantly associated with ypT0–1N0 (P = 0.054).

Conclusion

Stage cT1–2 and well differentiation are predictors of ypT0–1N0, while fungating tumors could be considered clinically meaningful, possibly identifying candidates for nonradical treatment post-CCRT.

Diagnostic performance of MRI and endoscopy for assessing complete response in rectal cancer after neoadjuvant chemoradiotherapy: a systematic review of the literature

BACKGROUND

The diagnostic performance of magnetic resonance imaging (MRI) modalities and/or endoscopy for assessing complete response in rectal cancer after neoadjuvant chemoradiotherapy (nCRT) is unclear.

PURPOSE

To summarize existing evidence on the diagnostic performance of diffusion-weighted MRI, perfusion-weighted MRI, T2-weighted MR tumor regression grade, and/or endoscopy for assessing complete tumor response after nCRT.

MATERIAL AND METHODS

MEDLINE and Embase databases were searched. The PRISMA guidelines were followed. Sensitivity, specificity, negative predictive, and positive predictive values were retrieved from included studies.

RESULTS

In total, 81 studies were eligible for inclusion. Evidence suggests that combined use of MRI and endoscopy tends to improve the diagnostic performance compared to single imaging modality. The positive predictive value of a complete response varies substantially between studies. There is considerable heterogeneity between studies.

CONCLUSION

Combined re-staging tends to improve diagnostic performance compared to single imaging modality, but the vast majority of studies fail to offer true clinical value due to the study heterogeneity.

Biomarkers in Locally Advanced Rectal Cancer: A Review

Locally advanced rectal cancers (LARC) are the subject of a rapidly evolving treatment paradigm. The critical timepoints where management decisions are required during the care of the LARC patient are: prior to the institution of any treatment, post neoadjuvant therapy and post-surgery. This article reviews the clinical, imaging, blood-based, tissue-based, and molecular biomarkers that can assist clinicians at these timepoints in the patient's management, in prognosticating for their LARC patients or in predicting responses to therapy in the multi-modality neoadjuvant treatment era.

Tumor Volume as Predictor of Pathologic Complete Response Following Neoadjuvant Chemoradiation in Locally Advanced Rectal Cancer

PURPOSE

Neoadjuvant chemoradiation followed by surgery is the current standard of care in the treatment of locally advanced rectal cancer. Those who achieved pathologic complete response, following this standard of care, complete pathologic response (pCR) had better outcome. Until now there are no reliable clinical parameters to predict this response. The purpose of the study was to evaluate whether tumor volume may serve as a predictive factor in patients treated with neoadjuvant chemoradiotherapy.

MATERIALS AND METHODS

Between September 2015 and September 2019, patients diagnosed with stage IIA to IIIC rectal adenocarcinoma, who were treated with neoadjuvant chemoradiation, were enrolled to this study. All patients underwent rectal ultrasound, pelvic magnetic resonance imaging, fluorodeoxyglucose-positron emission tomography-computed tomography and the diagnosis was confirmed by pathology report. Radiation therapy was consisted of 50 Gy delivered to the tumor site, 2 Gy a day, 5 times a week and to the pelvic lymph nodes for a total of 45 Gy in 1.8 Gy a day, 5 times a week. The gross tumor volume (GTV) was contoured by radiation oncology expert, reviewed by radiology and nuclear medicine expert and approved by radiation therapy tumor board. Chemotherapy was consisted of either capecitabine 875 mg/m2 twice a day or continuous. IV infusion of 5 fluorouracil 375 mg/m2 for 4 consecutive days in a 3 weeks apart. Operation, either low anterior or abdominoperineal resection was carried out 6 to 8 weeks following completion of treatment. Patients were assigned to either complete pathologic response (pCR) or non-pCR groups. GTV, among other clinical and treatment parameters, were evaluated for prediction of pCR. Statistical methods included independent t test, logistic regression, area under the curve-receiver operating characteristic, Bayesian independent statistics and multilayer perceptron model.

RESULTS

One hundred ninety-three patients were enrolled to this study, 6 were excluded due to metastatic disease detected at the time of operation. Seventy had stage II and 117 had stage III. Forty-four of 187 (23.5%) patients achieved pCR and 143 patients had either partial or no response/progressive disease. Among the 44 pCR group, 21 had stage II and 23 had stage III disease. Treatment interruption, defined as either a delay of up to 1 week in radiation, and a dose reduction to 75%, was occurred in 42 patients. Sex, ethnicity, distance from anal verge to tumor, height, weight, age, delivered radiation dose, radiotherapy techniques, clinical T and N stage and GTV were evaluated for prediction of pCR. GTV at the volume of <39.5 cm3 was the only significant predictive factor to detect pCR by logistic regression model (P<0.01) and by Bayesian independent test (P=0.026). Area under the receiver operating characteristic curve of GTV <39.5 cm3 showed area under the curve of 0.715 (P=0.009) for stage II and area under the curve of 0.62 (P>0.05) for stage III.

CONCLUSION

GTV may serve as a predictive factor for achieving pCR in locally advanced rectal cancer after neoadjuvant chemoradiotherapy.

Circulating Hybrid Cells: A Novel Liquid Biomarker of Treatment Response in Gastrointestinal Cancers

BACKGROUND

Real-time monitoring of treatment response with a liquid biomarker has potential to inform treatment decisions for patients with rectal adenocarcinoma (RAC), esophageal adenocarcinoma (EAC), and colorectal liver metastasis (CRLM). Circulating hybrid cells (CHCs), which have both immune and tumor cell phenotypes, are detectable in the peripheral blood of patients with gastrointestinal cancers, but their potential as an indicator of treatment response is unexplored.

METHODS

Peripheral blood specimens were collected from RAC and EAC patients after neoadjuvant therapy (NAT) or longitudinally during therapy and evaluated for CHC levels by immunostaining. Receiver operating characteristics (ROCs) and the Kaplan-Meier method were used to analyze the CHC level as a predictor of pathologic response to NAT and disease-specific survival (DSS), respectively.

RESULTS

Patients with RAC (n = 23) and EAC (n = 34) were sampled on the day of resection, and 11 patients (32%) demonstrated a pathologic complete response (pCR) to NAT. On ROC analysis, CHC levels successfully discriminated pCR from non-pCR with an area under the curve of 0.82 (95% confidence interval [CI], 0.71-0.92; P < 0.001). Additionally, CHC levels in the EAC patients correlated with residual nodal involvement (P = 0.026) and 1-year DSS (P = 0.029). The patients with RAC who were followed longitudinally during NAT (n = 2) and hepatic arterial infusion therapy for CRLM (n = 2) had CHC levels that decreased with therapy response and increased before clinical evidence of disease progression.

CONCLUSION

Circulating hybrid cells are a novel blood-based biomarker with potential for monitoring treatment response and disease progression to help guide decisions for further systemic therapy, definitive resection, and post-therapy surveillance. Additional validation studies of CHCs are warranted.

Association Between Three-Dimensional Transrectal Ultrasound Findings and Tumor Response to Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer: An Observational Study

Background

There is a significant demand for the development of non-surgical methods for the evaluation of complete response to tumor therapy. Predicting ability and image quality of routine imaging has not been satisfactory. To avoid the deficiencies, we assessed the capability of three-dimensional transrectal ultrasound in predicting the response to neoadjuvant chemoradiotherapy in rectal cancer patients.

Methods

The inclusion criteria were patients with locally advanced rectal adenocarcinoma, receiving capecitabine-based neoadjuvant chemoradiotherapy, distance from anal verge (≤6 cm), clinical stage T3-4 and/or N+ without evidence of distant metastasis, and restaging ycT0-3a (T3a <5 mm) after the end of neoadjuvant chemoradiotherapy. Three-dimensional transrectal ultrasound was performed 7 weeks after neoadjuvant chemoradiotherapy to discern the patients with complete response from the others. Eight main parameters were obtained from three-dimensional transrectal ultrasound: thickness of muscularis on the residual side, thickness of contralateral muscularis, angle of residual arc, regularity of the shape, integrity of the mucosal layer, blurring of the margin, internal echo, and posterior echo. The association between tumor response and three-dimensional transrectal ultrasound parameters was analyzed, and a model was developed by logistic regression.

Results

Between 2014 and 2019, 101 patients were recruited; 72 cases received total mesorectal excision, and 29 cases underwent watch-and-wait. Among the three-dimensional transrectal ultrasound parameters, the adjusted-thickness of the muscularis (P<0.01), angle of the residual arc (P<0.01), and regularity of the residual shape (P<0.01) were strongly associated with tumor response. In the dataset with total mesorectal excision cases (TME dataset), the residual adjusted-thickness (odds ratio [OR]=4.88, 95% confidence interval [CI]=1.44–16.6, P=0.01) and regularity of the residual shape (OR=5.00, 95% CI=1.13–22.2, P=0.03) were kept in the final logistic model. The area under the curve of the logistic model was 0.84. Among these parameters, residual adjusted-thickness correlated significantly with tumor response. Additionally, we observed similar results in the whole population of 101 cases (whole dataset) and in the cross-validation.

Conclusion

Three-dimensional transrectal ultrasound model is a valuable method for predicting tumor response in rectal cancer patients undergoing neoadjuvant chemoradiotherapy, which should be included as a factor for evaluating clinical complete response.

Trial Registration

This trial was registered with ClinicalTrials.gov, number NCT02605265. Registered 9 November 2015 - Retrospectively registered, https://clinicaltrials.gov/ct2/show/record/NCT02605265

Pathological Complete Response After Neoadjuvant Therapy in Rectal Adenocarcinoma: a 5-Year Follow-up

Neoadjuvant therapy is the gold standard treatment of locally advanced rectal cancer. It may induce complete sterilization of tumor cell and decreases its local recurrence rate. While 15–20% of patients were found to have pathological complete response (pCR) with combined multimodal therapy, Asian data were generally scarce. pCR rate can indicate the suitability of applying the “watch-and-wait” strategy, which advocates deferment of surgery that can alleviate surgery-associated morbidity.To determine the percentage of pCR of rectal cancer after neoadjuvant therapy. Patients diagnosed with rectal cancer underwent treatment from 2013 to 2017 were retrieved retrospectively. Demographic data, tumor localization, pre- and post-operative pathological reports, neoadjuvant therapy, and pCR status were collected from patients’ records. A total of 242 out of 259 patients were treated with definitive rectal surgery. Mean age was 67.1 years old. Chinese ethnicity and male gender were predominant (n = 131, 54.1% and n = 146, 64.3% respectively). More than half (n = 124, 51.2%) had tumor located at mid or low rectum. Histologically, moderate differentiated adenocarcinoma was predominant (n = 227, 93.8%). Merely half (n = 123, 50.8%) of the patients received neoadjuvant chemoradiation therapy, but only 12 (9.8%) had a pCR. From follow-up on these 12 pCR patients, most had 2-year disease-free survival but 1 (8.3%) of the pCR had distant metastasis within 1-year post-surgery. The pathological complete response rate in our center was lower than reported. Stringent patient selection with close follow-up for patients should be carried out if the “watch-and-wait” strategy is implemented in our population.

Neoadjuvant Therapy and Surgery in Rectal Adenocarcinoma: Analysis of Patients with Complete Tumor Remission

Introduction: the standard treatment for locally advanced extra-peritoneal rectal adenocarcinoma, consists of neoadjuvant treatment with radiotherapy and chemotherapy followed by total mesorectal excision.

Objective: evaluate, retrospectively, the patients submitted to neoadjuvant therapy and surgery that presents with total remission of the lesion in the anatomopathological examination.

Methods: between 2000 and 2010, 212 patients underwent surgery at the Coloproctology Unit at DMAD at FCM–UNICAMP. They were grouped as: rectosigmoidectomy and colorectal anastomosis (n = 54), rectosigmoidectomy with coloanal anastomosis (n = 41), 114 abdominoperineal resection of the rectum (n = 114) and other (n = 3).

Results: thirty (14.2%) patients (mean age 57.6 years; 60% males) showed complete remission of the rectal lesion. 4 (13.3%) had compromised lymph nodes and/or lymphatic invasion

At follow-up (mean 51.9 months), 4 (13.3%) presented with local recurrence (one patient) or distant metastases (two patients had liver metastasis, one had liver and lung, and one had bone metastasis). The mean survival was 86.7%.

Conclusion: patients with a complete tumor response show ed an increased survival rate, however, the same patients without evidence of residual tumors could develop local recurrence or distant metastases on a later follow-up.

Functional outcome and quality of life following treatment for rectal cancer

Introduction Over the last decades, treatment for rectal cancer has substantially improved with development of new surgical options and treatment modalities. With the improvement of survival, functional outcome and quality of life are getting more attention.

Study objective To provide an overview of current modalities in rectal cancer treatment, with particular emphasis on functional outcomes and quality of life.

Results Functional outcomes after rectal cancer treatment are influenced by patient and tumor characteristics, surgical technique, the use of preoperative radiotherapy and the method and level of anastomosis. Sphincter preserving surgery for low rectal cancer often results in poor functional outcomes that impair quality of life, referred to as low anterior resection syndrome. Abdominoperineal resection imposes the need for a permanent stoma but avoids the risk of this syndrome. Contrary to general belief, long-term quality of life in patients with a permanent stoma is similar to those after sphincter preserving surgery for low rectal cancer.

Conclusion All patients should be informed about the risks of treatment modalities. Decision on rectal cancer treatment should be individualized since not all patients may benefit from a sphincter preserving surgery “at any price”. Non-resection treatment should be the future focus to avoid the need of a permanent stoma and bowel dysfunction.

Transanal minimally invasive surgery for rectal cancer

Due to the increased uptake of rectal cancer screening and the increasing rates of complete clinical response to chemoradiotherapy, more early-stage and down-staged rectal cancers are being treated. This has triggered surgeons to question the necessity for proctectomy and its associated morbidity and consider local excision and organ preservation in selected cases. Transanal minimally invasive surgery (TAMIS) has evolved as an oncologically safe yet cost-effective platform for local excision of rectal tumors using traditional laparoscopic instruments. This review highlights the recent advances and current role of TAMIS in the treatment of rectal cancer.

Response to neoadjuvant treatment among rectal cancer patients in a population-based cohort

BACKGROUND

In rectal cancer, prediction of tumor response and pathological complete response (pCR) to neoadjuvant treatment could contribute to refine selection of patients who might benefit from a delayed- or no-surgery approach. The aim of this study was to explore the association of clinical and molecular characteristics of rectal cancer with response to neoadjuvant treatment and to compare patient survival according to level of response.

METHODS

Resected rectal cancer patients were selected from a population-based cohort study. Molecular tumor markers were determined from the surgical specimen. Tumor response and pCR were defined as downstaging in T or N stage and absence of tumor cells upon pathological examination, respectively. The associations of patient and tumor characteristics with tumor response and pCR were explored, and patient survival was determined by degree of response to neoadjuvant treatment.

RESULTS

Among 1536 patients with rectal cancer, 602 (39%) received neoadjuvant treatment. Fifty-five (9%) patients presented pCR, and 239 (49%) and 250 (53%) patients showed downstaging of the T and N stages, respectively. No statistically significant associations were observed between patient or tumor characteristics and tumor response or pCR. Patients who presented any type of response to neoadjuvant treatment had significantly better cancer-specific and overall survival compared with non-responders.

CONCLUSION

In this study, patient characteristics were not associated with response to neoadjuvant treatment, and molecular characteristics determined after surgical resection of the tumor were not predictive of pCR or tumor downstaging. Future studies should include molecular biomarkers from biopsy samples before neoadjuvant treatment.

A Diagnostic Biopsy-Adapted Immunoscore Predicts Response to Neoadjuvant Treatment and Selects Patients with Rectal Cancer Eligible for a Watch-and-Wait Strategy

PURPOSE

No biomarker to personalize treatment in locally advanced rectal cancer (LARC) is currently available. We assessed in LARC whether a diagnostic biopsy-adapted immunoscore (ISB) could predict response to neoadjuvant treatment (nT) and better define patients eligible to an organ preservation strategy ("Watch-and-Wait").

EXPERIMENTAL DESIGN

Biopsies from two independent cohorts (n 1 = 131, n 2 = 118) of patients with LARC treated with nT followed by radical surgery were immunostained for CD3+ and CD8+ T cells and quantified by digital pathology to determine ISB. The expression of immune-related genes post-nT was investigated (n = 64 patients). Results were correlated with response to nT and disease-free survival (DFS). The ISB prognostic performance was further assessed in a multicentric cohort (n = 73 patients) treated by Watch-and-Wait.

RESULTS

ISB positively correlated with the degree of histologic response (P < 0.001) and gene expression levels for Th1 orientation and cytotoxic immune response, post-nT (P = 0.006). ISB high identified patients at lower risk of relapse or death compared with ISB low [HR, 0.21; 95% confidence interval (CI), 0.06-0.78; P = 0.009]. Prognostic performance of ISB for DFS was confirmed in a validation cohort. ISB was an independent parameter, more informative than pre- (P < 0.001) and post-nT (P < 0.05) imaging to predict DFS. ISB combined with imaging post-nT discriminated very good responders that could benefit from organ preservation strategy. In the "Watch-and-Wait" cohort (n = 73), no relapse was observed in patients with ISB high (23.3%).

CONCLUSIONS

ISB predicts response to nT and survival in patients with LARC treated by surgery. Its usefulness in the selection of patients eligible for a Watch-and-Wait strategy is strongly suggested.

Watch and wait approach in rectal cancer: Current controversies and future directions

According to the main international clinical guidelines, the recommended treatment for locally-advanced rectal cancer is neoadjuvant chemoradiotherapy followed by surgery. However, doubts have been raised about the appropriate definition of clinical complete response (cCR) after neoadjuvant therapy and the role of surgery in patients who achieve a cCR. Surgical resection is associated with significant morbidity and decreased quality of life (QoL), which is especially relevant given the favourable prognosis in this patient subset. Accordingly, there has been a growing interest in alternative approaches with less morbidity, including the organ-preserving watch and wait strategy, in which surgery is omitted in patients who have achieved a cCR. These patients are managed with a specific follow-up protocol to ensure adequate cancer control, including the early identification of recurrent disease. However, there are several open questions about this strategy, including patient selection, the clinical and radiological criteria to accurately determine cCR, the duration of neoadjuvant treatment, the role of dose intensification (chemotherapy and/or radiotherapy), optimal follow-up protocols, and the future perspectives of this approach. In the present review, we summarize the available evidence on the watch and wait strategy in this clinical scenario, including ongoing clinical trials, QoL in these patients, and the controversies surrounding this treatment approach.

Nonsurgical Management of Rectal Cancer

Neoadjuvant chemoradiotherapy followed by surgical resection is the standard of care for locally advanced rectal adenocarcinoma. Up to one third of patients achieve pathologic complete response (CR) with neoadjuvant therapy. Promising disease-free and overall survival outcomes have been reported in patients who achieve clinical CR after neoadjuvant therapy without surgical resection. Furthermore, patients who have local recurrence have acceptable disease control outcomes with salvage resection. With consideration of morbidities associated with surgical resection and similar clinical outcomes, interest in nonsurgical management of low rectal cancers has emerged. Randomized clinical trials are being conducted to evaluate a nonsurgical approach in rectal cancer. Lack of consensus on the definition of clinical CR, molecular biomarkers, and standardized nonsurgical management protocols is a significant barrier for routine clinical implementation of a nonsurgical management approach. This article aims to provide a concise review of the clinical experience and practical approach to the nonsurgical management of locoregional rectal adenocarcinoma.

Organ-saving surgery for rectal cancer after neoadjuvant chemoradiation: Analysis of failures and long-term results

BACKGROUND

To analyze long-term results and risk of relapse in the clinical TNM stages II and III, mid-low rectal cancer patients (RC pts), treated with transanal local excision (LE) after major response to neoadjuvant chemoradiation (n-CRT).

METHODS

Thirty-two out of 345 extraperitoneal cT3-4 or N+ RC pts (9.3%) underwent LE.

INCLUSION CRITERIA

extraperitoneal RC, adenocarcinoma, ECOG Performance Status ≤2. Pts with distant metastases were excluded.

RESULTS

All pts showed histologically clear margins of resection and 81.2% were restaged ypT0/mic/1. Nine out of 32 (28.1%) pts relapsed: 7 (21.8%) showed a local recurrence, of which 5 (15.6%) at the endorectal suture, 1 (3.1%) pelvic and 1 (3.1%) mesorectal. Two pts (6.2%) relapsed distantly. Among the pT0/1, 11.5% relapsed vs 100% of the pT2 and pT4 ones. The six pts relapsing locally or in the mesorectal fat underwent a salvage total mesorectal excision surgery. The old patient with pelvic recurrence relapsed after 108 months and underwent a re-irradiation; the two pts with distant metastases were treated with chemotherapy followed by radical surgery.

CONCLUSIONS

Presently combined approach seems a valid option in major responders, confirming its potential curative impact in the ypT0/mic/1 pts. A strict selection of pts is basic to obtain favourable results.

How to measure tumour response in rectal cancer? An explanation of discrepancies and suggestions for improvement

Various methods categorize tumour response after neoadjuvant therapy, including down-staging and tumour regression grading. Response categories allow comparison of different treatments within clinical trials and predict outcome. A reproducible response categorization could identify subgroups with high or low risk for the most appropriate subsequent treatments, like watch and wait. Lack of standardization and interpretation difficulties currently limit the usability of these approaches. In this review we describe these difficulties for the evaluation of chemoradiation in rectal cancer. An alternative approach of tumour response is based on patterns of residual disease, including fragmentation. We summarise the evidence behind this alternative method of response categorisation, which explains a number of very relevant clinical discrepancies. These issues include differences between downstaging and tumour regression, high local regrowth in advanced tumours during watchful waiting procedures, the importance of resection margins, the limited value of post-treatment biopsies and the relatively poor outcome of patients with a near complete pathological response. Recognition of these patterns of response can allow meaningful development of novel biomarkers in the future.