Organ Preservation in Rectal Cancer

Can Pretreatment MRI and Planning CT Radiomics Improve Prediction of Complete Pathological Response in Locally Advanced Rectal Cancer Following Neoadjuvant Treatment?

OBJECTIVE(S)

The treatment response to neoadjuvant chemoradiation (nCRT) differs largely in individuals treated for rectal cancer. In this study, we investigated the role of radiomics to predict the pathological response in locally advanced rectal cancers at different treatment time points: (1) before the start of any treatment using baseline T2-weighted MRI (T2W-MR) and (2) at the start of radiation treatment using planning CT.

METHODS

Patients on nCRT followed by surgery between June 2017 to December 2019 were included in the study. Histopathological tumour response grading (TRG) was used for classification, and gross tumour volume was defined by the radiation oncologists. Following resampling, 100 and 103 pyradiomic features were extracted from T2W-MR and planning CT images, respectively. Synthetic minority oversampling technique (SMOTE) was used to address class imbalance. Four machine learning classifiers built clinical, radiomic, and merged models. Model performances were evaluated on a held-out test dataset following 3-fold cross-validation using area under the receiver operator characteristic curves (AUC) with bootstrap 95% confidence intervals.

RESULTS

One hundred and fifty patients were included; 58/150 with TRG 1 were classified as complete responders, and rest were incomplete responders (IR). Clinical models performed better (AUC = 0.68) compared to radiomics models (AUC = 0.62). Overall, the clinical + T2W-MR model showed best performance (AUC = 0.72) in predicting the pathological response prior to therapy. Clinical + Planning CT-merged models could only achieve the highest AUC of 0.66.

CONCLUSION

Merging clinical and baseline T2W-MR radiomics enhances predicting pathological response in rectal cancer. Validation in larger cohorts is warranted, especially for watch and wait strategies.

Pathologic Complete Response, Total Neoadjuvant Therapy and the Survival Paradox in Locally Advanced Rectal Cancer

BACKGROUND

Pathologic complete response (pCR) after preoperative chemoradiation (nCRT) correlates with improved overall survival for patients with locally advanced rectal cancers (LARCs). Escalation protocols including total neoadjuvant therapy (TNT), which delivers multi-agent chemotherapy and chemoradiation before surgery, are associated with increased complete response rates. However, TNT is not associated with improved overall survival. The authors hypothesized that the route to pCR may be an important predictor of oncologic outcome.

METHODS

Adults with LARC between 2006 and 2017 were identified in the National Cancer Database. The cohort was limited to those who received neoadjuvant radiation (45-70 Gy) and underwent proctectomy.

RESULTS

Of 25,880 patients, 16 % received TNT and 84 % had nCRT followed by either multi-agent (27 %), single-agent (14 %), or no adjuvant chemotherapy (44 %). Overall, 18 % achieved pCR, with higher rates in the TNT cohort than in the nCRT (18 %) or multi-agent (14 %) chemotherapy cohorts. With control for covariates, the OS in the pCR cohort was similar for the patients that received single-agent therapy and those that received multi-agent adjuvant therapy, and superior to the TNT and no adjuvant therapy cohorts. Conversely, among the patients who did not achieve pCR, those who received single-agent chemotherapy had OS comparable with those who had multi-agent adjuvant therapy and TNT, which was better than no adjuvant therapy.

CONCLUSION

Patients achieving pCR after TNT had worse OS than those who had CRT alone, suggesting that the neoadjuvant route by which pCR is achieved is prognostically relevant. Therefore, in the era of neoadjuvant therapy escalation, pCR does not necessarily portend a uniformly favorable prognosis.

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.

Treatment stratification and prognosis assessment using circulating tumor DNA in locally advanced rectal cancer: A systematic review and meta-analysis

BACKGROUND

Circulating tumor DNA (ctDNA) is an emerging biomarker for locally advanced rectal cancer (LARC), giving hope for stratified treatment. As the completed studies have small sample sizes and different experimental methods, systematic review and meta-analysis were performed to explore their role in predicting pathological complete response (pCR), tumor recurrence, and prognosis.

METHODS

PubMed, Embase, and the Web of Science were searched for potentially eligible studies published up to September 6, 2022. Pooled relative risk (RR) was calculated to predict pCR and tumor recurrence, and pooled hazard ratio (HR) was calculated to evaluate the prognosis of overall survival (OS), recurrence-free survival (RFS), and metastasis-free survival (MRS).

RESULTS

Twelve studies published between 2018 and 2022 included 931 patients, and 2544 serum samples were eventually included in the meta-analysis. The pooled revealed that ctDNA-negative patients were more likely to have a pCR (RR = 1.64, 95% confidence interval [CI]: 1.26-2.12). The pooled revealed that ctDNA-positive patients were at high risk of recurrence (RR = 3.37, 95% CI: 2.34-4.85) and had a poorer prognosis for OS (HR = 3.03, 95% CI: 1.86-4.95), RFS (HR = 7.08, 95% CI: 4.12-12.14), and MRS (HR = 2.77, 95% CI: 2.01-3.83).

CONCLUSION

ctDNA may be useful for stratifying treatment and assessing prognosis in patients with LARC, but its clinical application still needs to be confirmed in a prospective multicenter study with large samples.

MRI assessment of rectal cancer response to neoadjuvant therapy: a multireader study

OBJECTIVES

A watch and wait strategy with the goal of organ preservation is an emerging treatment paradigm for rectal cancer following neoadjuvant treatment. However, the selection of appropriate patients remains a challenge. Most previous efforts to measure the accuracy of MRI in assessing rectal cancer response used a small number of radiologists and did not report variability among them.

METHODS

Twelve radiologists from 8 institutions assessed baseline and restaging MRI scans of 39 patients. The participating radiologists were asked to assess MRI features and to categorize the overall response as complete or incomplete. The reference standard was pathological complete response or a sustained clinical response for > 2 years.

RESULTS

We measured the accuracy and described the interobserver variability of interpretation of rectal cancer response between radiologists at different medical centers. Overall accuracy was 64%, with a sensitivity of 65% for detecting complete response and specificity of 63% for detecting residual tumor. Interpretation of the overall response was more accurate than the interpretation of any individual feature. Variability of interpretation was dependent on the patient and imaging feature investigated. In general, variability and accuracy were inversely correlated.

CONCLUSIONS

MRI-based evaluation of response at restaging is insufficiently accurate and has substantial variability of interpretation. Although some patients' response to neoadjuvant treatment on MRI may be easily recognizable, as seen by high accuracy and low variability, that is not the case for most patients.

KEY POINTS

• The overall accuracy of MRI-based response assessment is low and radiologists differed in their interpretation of key imaging features. • Some patients' scans were interpreted with high accuracy and low variability, suggesting that these patients' pattern of response is easier to interpret. • The most accurate assessments were those of the overall response, which took into consideration both T2W and DWI sequences and the assessment of both the primary tumor and the lymph nodes.

Watch-and-Wait is an Option in Rectal Cancer Patients: From Controversy to Common Clinical Practice

Overview of the introduction of organ preservation in rectal cancer patients and future challenges.

Prevalent Pseudoprogression and Pseudoresidue in Patients With Rectal Cancer Treated With Neoadjuvant Immune Checkpoint Inhibitors

BACKGROUND

Immune checkpoint inhibitor (ICI) treatment in patients with microsatellite instability-high/mismatch repair deficient (MSI-H/dMMR) tumors holds promise in reshaping organ preservation in rectal cancer. However, the benefits are accompanied by distinctive patterns of response, introducing a dilemma in the response evaluation for clinical decision-making.

PATIENTS AND METHODS

Patients with locally advanced rectal cancer with MSI-H/dMMR tumors receiving neoadjuvant ICI (nICI) treatment (n=13) and matched patients receiving neoadjuvant chemoradiotherapy (nCRT; n=13) were included to compare clinical response and histopathologic features.

RESULTS

Among the 13 patients receiving nICI treatment, in the final radiologic evaluation prior to surgery (at a median of 103 days after initiation of therapy), progressive disease (n=3), stable disease (n=1), partial response (n=7), and complete response (n=2) were observed. However, these patients were later confirmed as having pathologic complete response, resulting in pseudoprogression and pseudoresidue with incidences of 23.1% (n=3) and 76.9% (n=10), respectively, whereas no pseudoprogression was found in the 13 patients receiving nCRT. We further revealed the histopathologic basis underlying the pseudoprogression and pseudoresidue by discovering the distinctive immune-related regression features after nICI treatment, including fibrogenesis, dense lymphocytes, and plasma cell infiltration.

CONCLUSIONS

Pseudoprogression and pseudoresidue were unique and prevalent response patterns in MSI-H/dMMR rectal cancer after nICI treatment. Our findings highlight the importance of developing specific strategies for response evaluation in neoadjuvant immunotherapy to identify patients with a good response in whom sphincter/organ-preserving or watch-and-wait strategies may be considered.

A Pilot, Prospective, Observational Study to Investigate the Value of NGS in Liquid Biopsies to Predict Tumor Response After Neoadjuvant Chemo-Radiotherapy in Patients With Locally Advanced Rectal Cancer: The LiBReCa Study

Introduction

Circulating tumor DNA (ctDNA) correlates with the response to therapy in different types of cancer. However, in patients with locally advanced rectal cancer (LARC), little is known about how ctDNA levels change with neoadjuvant chemoradiation (Na-ChRT) and how they correlate with treatment response. This work aimed to explore the value of serial liquid biopsies in monitoring response after Na-ChRT with the hypothesis that this could become a reliable biomarker to identify patients with a complete response, candidates for non-operative management.

Materials and Methods

Twenty-five consecutive LARC patients undergoing long-term Na-ChRT therapy were included. Applying next-generation sequencing (NGS), we characterized DNA extracted from formalin-fixed paraffin embedded diagnostic biopsy and resection tissue and plasma ctDNA collected at the following time points: the first and last days of radiotherapy (T0, Tend), at 4 (T4), 7 (T7) weeks after radiotherapy, on the day of surgery (Top), and 3–7 days after surgery (Tpost-op). On the day of surgery, a mesenteric vein sample was also collected (TIMV). The relationship between the ctDNA at those time-points and the tumor regression grade (TRG) of the surgical specimen was statistically explored.

Results

We found no association between the disappearance of ctDNA mutations in plasma samples and pathological complete response (TRG1) as ctDNA was undetectable in the majority of patients from Tend on. However, we observed that the poor (TRG 4) response to Na-ChRT was significantly associated with a positive liquid biopsy at the Top.

Conclusions

ctDNA evaluation by NGS technology may identify LARC patients with poor response to Na-ChRT. In contrast, this technique does not seem useful for identifying patients prone to developing a complete response.

Non-operative management after chemoradiotherapy plus consolidation or sandwich (induction with bevacizumab and consolidation) chemotherapy in patients with locally advanced rectal cancer: a multicentre, randomised phase II trial (NOMINATE trial)

INTRODUCTION

Total mesorectal excision (TME) and postoperative adjuvant chemotherapy following neoadjuvant chemoradiotherapy (CRT) is the standard treatment for locally advanced rectal cancer (LARC). However, neoadjuvant CRT has no recognised impact on reducing distant recurrence, and patients suffer from a long-lasting impairment in quality of life (QOL) associated with TME. Total neoadjuvant therapy (TNT) is an alternative approach that could reduce distant metastases and increase the proportion of patients who could safely undergo non-operative management (NOM). This study is designed to compare two TNT regimens in the context of NOM for selecting a more optimal regimen for patients with LARC.

METHODS AND ANALYSIS

NOMINATE trial is a prospective, multicentre, randomised phase II selection design study. Patients must have clinical stage II or III (T3-T4Nany) LARC with distal location (≤5 cm from the anal verge or for those who are candidates for abdominoperineal resection or intersphincteric resection). Patients will be randomised to either arm A consisting of CRT (50.4 Gy with capecitabine) followed by consolidation chemotherapy (six cycles of CapeOx), or arm B consisting of induction chemotherapy (three cycles of CapeOx plus bevacizumab) followed by CRT and consolidation chemotherapy (three cycles of CapeOx). In the case of clinical complete response (cCR) or near cCR, patients will progress to NOM. Response assessment involves a combination of digital rectal examination, endoscopy and MRI. The primary endpoint is the proportion of patients achieving pathological CR or cCR≥2 years, defined as the absence of local regrowth within 2 years after the start of NOM among eligible patients. Secondary endpoints include the cCR rate, near cCR rate, rate of NOM, overall survival, distant metastasis-free survival, locoregional failure-free survival, time to disease-related treatment failure, TME-free survival, permanent stoma-free survival, safety of the treatment, completion rate of the treatment and QOL. Allowing for a drop-out rate of 10%, 66 patients (33 per arm) from five institutions will be accrued.

ETHICS AND DISSEMINATION

The study protocol was approved by Wakayama Medical University Certified Review Board in December 2020. Trial results will be published in peer-reviewed international journals and on the jRCT website.

TRIAL REGISTRATION NUMBER

jRCTs051200121.

Outcomes of Patients With Local Regrowth After Nonoperative Management of Rectal Cancer After Neoadjuvant Chemoradiotherapy

BACKGROUND

Clinical complete responders after chemoradiation for rectal cancer are increasingly being managed by a watch-and-wait strategy. Nonetheless, a significant proportion will experience a local regrowth, and the long-term oncological outcomes of these patients is not totally known.

OBJECTIVE

The purpose of this study was to analyze the outcomes of patients who submitted to a watch-and-wait strategy and developed a local regrowth, and to compare these results with sustained complete clinical responders.

DESIGN

This was a retrospective study.

SETTING

Single institution, tertiary cancer center involved in alternatives to organ preservation.

PATIENTS

Patients with a biopsy-proven rectal adenocarcinoma (stage II/III or low lying cT2N0M0 at risk for an abdominoperineal resection) treated with chemoradiation who were found at restage to have a clinical complete response.

INTERVENTIONS

Rectal cancer patients treated with chemoradiation who underwent a watch-and-wait strategy (without a full thickness local excision) and developed a local regrowth were compared to the remaining patients of the watch-and-wait strategy.

MAIN OUTCOME MEASURES

Overall survival between groups, incidence of regrowth' and results of salvage surgery.

RESULTS

There were 67 patients. Local regrowth occurred in 20 (29.9%) patients treated with a watch-and-wait strategy. Mean follow-up was 62.7 months. Regrowth occurred at mean 14.2 months after chemoradiation, half of them within the first 12 months. Patients presented with comparable initial staging, lateral pelvic lymph-node metastasis, and extramural venous invasion. The regrowth group had a statistically nonsignificant higher incidence of mesorectal fascia involvement (35.0% vs 13.3%, p = 0.089). All regrowths underwent salvage surgery, mostly (75%) a sphincter-sparing procedure. 5-year overall survival was 71.1% in patients with regrowth and 91.1% in patients with a sustained complete clinical response (p = 0.027).

LIMITATIONS

This study was limited by its retrospective evaluation of patient selection for a watch-and-wait strategy and outcomes, as well as its small sample size.

CONCLUSIONS

Local regrowth is a frequent event when following a watch-and-wait policy (29.9%); however, patients could undergo salvage surgical treatment with adequate pelvic control. In this series, overall survival showed a statistically significant difference from patients managed with a watch-and-wait strategy who experienced a local regrowth compared to those who did not. See Video Abstract at http://links.lww.com/DCR/B773.RESULTADOS DE LOS PACIENTES CON REBROTE LOCAL, DESPUÉS DEL MANEJO NO QUIRÚRGICO DEL CÁNCER DE RECTO, DESPUÉS DE LA QUIMIORRADIOTERAPIA NEOADYUVANTEANTECEDENTES:Los respondedores clínicos completos, después de la quimiorradiación para el cáncer de recto, se tratan cada vez más mediante una estrategia de observación y espera. No obstante, una proporción significativa experimentará un rebrote local y los resultados oncológicos a largo plazo de estos pacientes, no se conocen por completo.OBJETIVO:El propósito de este estudio, fue analizar los resultados de los pacientes sometidos a una estrategia de observación y espera, que desarrollaron un rebrote local, y comparar estos resultados con respondedores clínicos completos sostenidos.DISEÑO:Este fue un estudio retrospectivo.ENTORNO CLINICO.Institución única, centro oncológico terciario involucrado en alternativas a la preservación de órganos.PACIENTES:Pacientes con un adenocarcinoma de recto comprobado por biopsia (estadio II / III o posición baja cT2N0M0, en riesgo de resección abdominoperineal), tratados con quimiorradiación, y que durante un reestadiaje, presentaron una respuesta clínica completa.INTERVENCIONES:Los pacientes con cáncer de recto tratados con quimiorradiación, sometidos a una estrategia de observación y espera (sin una escisión local de espesor total) y que desarrollaron un rebrote local, se compararon con los pacientes restantes de la estrategia de observación y espera.PRINCIPALES MEDIDAS DE VALORACION:Supervivencia global entre los grupos, incidencia de rebrote y resultados de la cirugía de rescate.RESULTADOS:Fueron 67 pacientes. El rebrote local ocurrió en 20 (29,9%) pacientes tratados con una estrategia de observación y espera. El seguimiento medio fue de 62,7 meses. El rebrote se produjo a la media de 14,2 meses después de la quimiorradiación, la mitad de ellos dentro de los primeros 12 meses. Los pacientes se presentaron con una estadificación inicial comparable, metástasis en los ganglios linfáticos pélvicos laterales e invasión venosa extramural. El grupo de rebrote tuvo una mayor incidencia estadísticamente no significativa de afectación de la fascia mesorrectal (35,0 vs 13,3%, p = 0,089). Todos los rebrotes se sometieron a cirugía de rescate, en su mayoría (75%) con procedimiento de preservación del esfínter. La supervivencia global a 5 años fue del 71,1% en pacientes con rebrote y del 91,1% en pacientes con una respuesta clínica completa sostenida (p = 0,027).LIMITACIONES:Evaluación retrospectiva de la selección de pacientes para una estrategia y resultados de observar y esperar, tamaño de muestra pequeño.CONCLUSIONES:El rebrote local es un evento frecuente después de la política de observación y espera (29,9%), sin embargo los pacientes podrían someterse a un tratamiento quirúrgico de rescate con un adecuado control pélvico. En esta serie, la supervivencia global mostró una diferencia estadísticamente significativa de los pacientes manejados con una estrategia de observación y espera que experimentaron un rebrote local, en comparación con los que no lo hicieron. Consulte Video Resumen en http://links.lww.com/DCR/B773. (Traducción-Dr. Fidel Ruiz Healy).

The "Immunoscore" in rectal cancer: could we search quality beyond quantity of life?

Because of the function and anatomical environment of the rectum, therapeutic strategies for local advanced rectal cancer (LARC) must deal with two challenging stressors that are a high-risk of local and distal recurrences and a high-risk of poor quality of life (QoL). Over the last three decades, advances in screening tests, therapies, and combined-modality treatment options and strategies have improved the prognosis of patients with LARC. However, owing to the heterogeneous nature of LARC and genetic status, the patient may not respond to a specific therapy and may be at increased risk of side-effects without the life-prolonging benefit. Indeed, each therapy can cause its own side-effects, which may worsen by a combination of treatments resulting in long-term poor QoL. In LARC, QoL has become even more essential with the increasing incidence of rectal cancer in young individuals. Herein, we analyzed the value of the Immunoscore-Biopsy (performed on tumor biopsy at diagnosis) in predicting outcomes, alone or in association with clinical and imaging data, for each therapy used in LARC.

Role of MRI‑based radiomics in locally advanced rectal cancer (Review)

Colorectal cancer is the third most common type of cancer, with high morbidity and mortality rates. In particular, locally advanced rectal cancer (LARC) is difficult to treat and has a high recurrence rate. Neoadjuvant chemoradiotherapy (NCRT) is one of the standard treatment programs of LARC. If the response to treatment and prognosis in patients with LARC can be predicted, it will guide clinical decision‑making. Radiomics is characterized by the extraction of high‑dimensional quantitative features from medical imaging data, followed by data analysis and model construction, which can be used for tumor diagnosis, staging, prediction of treatment response and prognosis. In recent years, a number of studies have assessed the role of radiomics in NCRT for LARC. MRI‑based radiomics provides valuable data and is expected to become an imaging biomarker for predicting treatment response and prognosis. The potential of radiomics to guide personalized medicine is widely recognized; however, current limitations and challenges prevent its application to clinical decision‑making. The present review summarizes the applications, limitations and prospects of MRI‑based radiomics in LARC.

Does restaging MRI radiomics analysis improve pathological complete response prediction in rectal cancer patients? A prognostic model development

PURPOSE

Our study investigated the contribution that the application of radiomics analysis on post-treatment magnetic resonance imaging can add to the assessments performed by an experienced disease-specific multidisciplinary tumor board (MTB) for the prediction of pathological complete response (pCR) after neoadjuvant chemoradiotherapy (nCRT) in locally advanced rectal cancer (LARC).

MATERIALS AND METHODS

This analysis included consecutively retrospective LARC patients who obtained a complete or near-complete response after nCRT and/or a pCR after surgery between January 2010 and September 2019. A three-step radiomics features selection was performed and three models were generated: a radiomics model (rRM), a multidisciplinary tumor board model (yMTB) and a combined model (CM). The predictive performance of models was quantified using the receiver operating characteristic (ROC) curve, evaluating the area under curve (AUC).

RESULTS

The analysis involved 144 LARC patients; a total of 232 radiomics features were extracted from the MR images acquired post-nCRT. The yMTB, rRM and CM predicted pCR with an AUC of 0.82, 0.73 and 0.84, respectively. ROC comparison was not significant (p = 0.6) between yMTB and CM.

CONCLUSION

Radiomics analysis showed good performance in identifying complete responders, which increased when combined with standard clinical evaluation; this increase was not statistically significant but did improve the prediction of clinical response.