Watch and wait after neoadjuvant treatment in rectal cancer: comparison of outcomes in patients with and without a complete response at first reassessment in the International Watch & Wait Database (IWWD)

Great Debates: Surgery or Watch and Wait After Total Neoadjuvant Therapy for Rectal Cancer

Locally advanced rectal cancer has traditionally been treated with multimodal therapy including neoadjuvant chemoradiotherapy followed by surgical resection. More recent data suggests that in appropriate patients, total neoadjuvant treatment (TNT) makes it possible to adopt a "watch and wait" approach. Advocates for watch and wait argue that patients with a complete or near-complete clinical response to TNT have comparable overall and disease-free survival to their counterparts who undergo surgical resection, and also have a better quality of life, fewer complications, and potentially avoid a stoma. The dogma of surgery as regional curative intent therapy has been challenged by similar recurrence rates among those treated with total mesorectal excision (TME) and those treated with watch and wait. Furthermore, those who develop local recurrence in the watch and wait groups are equally salvageable, either by surgery, brachytherapy, or chemotherapy. While watch and wait is not appropriate in all patients, this manuscript highlights the benefits and drawbacks of both therapeutic modalities.

A Review of Neoadjuvant Therapy and the Watch-and-Wait Protocol in Rectal Cancer: Current Evidence and Future Directions

The treatment of rectal cancer underwent a significant change with the introduction of total mesorectal excision (TME), which substantially improved recurrence rates. However, TME is associated with complications such as fecal incontinence and poor bladder control, especially in tumors located near the anal verge. The watch-and-wait (WW) protocol has emerged as an alternative for patients achieving a clinical complete response (cCR) following neoadjuvant radiochemotherapy. This narrative review, developed according to the Scale for the Assessment of Narrative Review Articles guidelines, evaluates neoadjuvant treatments and the WW protocol for rectal cancer. Literature was sourced from the PubMed database using specific search terms related to neoadjuvant therapy and the WW protocol, resulting in 63 articles selected for discussion. Neoadjuvant treatment, including chemoradiation and short-course radiotherapy, is indicated for T3 and T4 rectal adenocarcinomas. Studies like the German Rectal Cancer Study Group and the PRODIGE 23 trial have shown the benefits of preoperative treatment, including improved disease-free survival and reduced local recurrence rates. However, challenges in adopting the WW protocol include the risk of local regrowth and distant metastasis. Immune checkpoint inhibitors have shown promise in mismatch repair-deficient patients, yet the data are insufficient to fully endorse WW for these cases. The WW protocol is viable for selected rectal cancer patients, with ongoing debates regarding criteria for inclusion. Key challenges include accurately identifying cCR and managing patients with near-complete responses. MRI and endoscopic evaluation are crucial for assessing treatment response, although achieving a pathological complete response remains uncertain. The WW strategy offers a potential organ-preserving approach in rectal cancer management but requires careful patient selection and comprehensive risk-benefit discussions. Further research is needed to refine criteria for inclusion and optimize treatment protocols, enhancing outcomes while minimizing invasive interventions.

Watch and Wait for Near-Complete Responders-A Word of Caution

This Viewpoint discusses the establishment of a cutoff point as the watch and wait approach is increasingly used in patients with locally advanced rectal cancer.

Outcome of Patients with Locally Advanced Rectal Cancer Pursuing Non-Surgical Strategy in National Cancer Database

BACKGROUND

Survival data on patients with locally advanced rectal cancer (LARC) undergoing non-operative management (NOM) in a real-world setting are lacking.

METHODS

We analyzed LARC patients from the National Cancer Database with the following features: treated between 2010 and 2020, age 18-65 years, Charlson comorbidity index (CCI) ≤ 1, received neoadjuvant multiagent chemotherapy plus radiation ≥ 45 Gray, and underwent surgery or NOM. Patients were stratified into two groups: (A) clinical T1-3 tumors with positive nodes (cT1-3N+) and (B) clinical T4 tumors, N+/- (cT4N+/-). We performed a comparative analysis of overall survival (OS) with NOM versus surgery by the Kaplan-Meier method and propensity score matching. Additionally, a multivariable analysis explored the association between NOM and OS.

RESULTS

NOM exhibited significantly lower OS than surgery in both groups. In cT1-3N+ patients, NOM resulted in a 5-year OS of 73.9% (95% confidence interval [CI] = 69.7-77.6%) versus 84.5% (95% CI = 83.6-85.3%) with surgery (p < 0.001). In the cT4N+/- group, NOM yielded a 5-year OS of 44.5% (95% CI = 37.0-51.8%) versus 72.5% (95% CI = 69.9-74.8%) with surgery (p < 0.001). Propensity score matching and multivariable analyses revealed similar conclusions.

CONCLUSION

Patients with LARC undergoing NOM versus surgery in real-world settings appear to have inferior survival.

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

BACKGROUND

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

OBJECTIVE

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

DESIGN

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

SETTING

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

MAIN OUTCOME MEASURES

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

RESULTS

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

LIMITATIONS

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

CONCLUSIONS

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

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

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

Current treatment of pT1 rectal cancers in Denmark: A retrospective national cohort study

AIM

Organ preservation strategies for patients with rectal cancer are increasingly common. In appropriately selected patients, local excision (LE) of pT1 cancers can reduce morbidity without compromising cancer-related outcomes. However, determining the need for completion surgery after LE can be challenging, and it is unknown if prior LE compromises subsequent total mesorectal excision (TME). The aim of this study is to describe the current management of patients with pT1 rectal cancers.

METHOD

This is a retrospective national cohort study of the Danish Colorectal Cancer Group database, including patients with newly diagnosed pT1 cancers between 2016 and 2020. Patients were stratified according to treatment into LE alone, completion TME after LE or upfront TME. The treatment and outcomes of these groups were compared.

RESULTS

A total of 1056 patients were included. Initial LE was performed in 715 patients (67.7%), of whom 194 underwent completion TME (27.1%). The remaining 341 patients underwent upfront TME (32.3%). Patients undergoing LE alone were more likely to be male with low rectal cancers and greater comorbidity. No differences in specimen quality or perioperative outcomes were noted between patients undergoing completion or upfront TME. Eighty-five patients (15.9%) had lymph node metastases (LNM). Pathological risk factors poorly discriminated between patients with and without LNM, with similar rates seen in patients with zero (14.1%), one (12.0%) or two (14.4%) risk factors.

CONCLUSION

LE is a key component of the treatment of pT1 rectal cancer and does not appear to affect the outcomes of completion TME. Patient selection for completion TME remains a major challenge, with current stratification methods appearing to be inadequate.

A prospective study on using shear wave elastography to predict the ypT0 stage of rectal cancer after neoadjuvant therapy: a new support for the watch-and-wait approach?

Introduction

The diagnostic accuracy of traditional imaging examination in predicting ypT stage of rectal cancer after neoadjuvant therapy is significantly reduced, which would affect patients' subsequent treatment choices. This study aimed to investigate the use of endorectal shear wave elastography (SWE) for diagnosing ypT0 stage of rectal cancer after neoadjuvant chemoradiotherapy (nCRT).

Methods

Sixty patients with rectal cancer were prospectively recruited in this study. Data on endorectal ultrasound (ERUS) and SWE parameters were collected before nCRT and 6-8 weeks after nCRT. Postoperative pathological results were the gold standard for evaluating the diagnostic accuracy of SWE and ERUS in predicting the ypT0 stage of rectal cancer after nCRT. Receiver operating characteristic (ROC) curve analysis was used to determine the cut-off values of the SWE parameters that best corresponded to the ypT0 stage and analyze the sensitivity, specificity, and accuracy.

Results

The diagnostic accuracies of using ERUS to predict the ypT and ypT0 stages of rectal cancer after nCRT were 58.1% (18/31) and 64.3% (9/14), respectively. The ROC curve was constructed with the lesion's Emean, Emean corrected (EC), Emean difference (ED), Emean corrected differencede (ECD), Emean descendding rate (EDR) and Emean corrected descendding rate (ECDR) values after nCRT, the cut-off values of diagnosing the ypT0 stage were 64.40 kPa, 55.45 kPa, 72.55 kPa, 73.75 kPa, 50.15%, and 55.93%, respectively; the area under the curve (AUC) for diagnosing the ypT0 stage was 0.924, 0.933, 0.748, 0.729, 0.857 and 0.861, respectively. The EC value showed the best diagnostic performance.

Conclusion

SWE could improve the accuracy of conventional ERUS in diagnosing the ypT0 stage of rectal cancer after nCRT. It is expected to become a new method to help predict pathological complete responses in clinical practice and provide new evidence for the watch-and-wait approach.

Patient-Relevant Costs for Organ Preservation versus Radical Resection in Locally Advanced Rectal Cancer

Total neoadjuvant therapy (TNT) is an evolving treatment schedule for locally advanced rectal cancer (LARC), allowing for organ preservation in a relevant number of patients in the case of complete response. Patients who undergo this so-called "watch and wait" approach are likely to benefit regarding their quality of life (QoL), especially if definitive ostomy could be avoided. In this work, we performed the first cost-effectiveness analysis from the patient perspective to compare costs for TNT with radical resection after neoadjuvant chemoradiation (CRT) in the German health care system. Individual costs for patients insured with a statutory health insurance were calculated with a Markov microsimulation. A subgroup analysis from the prospective "FinTox" trial was used to calibrate the model's parameters. We found that TNT was less expensive (-1540 EUR) and simultaneously resulted in a better QoL (+0.64 QALYs) during treatment and 5-year follow-up. The average cost for patients under TNT was 4711 EUR per year, which was equivalent to 3.2% of the net household income. CRT followed by resection resulted in higher overall costs for ostomy care, medication and greater loss of earnings. Overall, TNT appeared to be more efficacious and cost-effective from a patient's point of view in the German health care system.

Recent advances in rectal cancer treatment - are we on the right track?

Background

Staging and treatment of rectal cancer have evolved over several decades with considerably fewer locoregional recurrences but no marked improved survival since systemic recurrence risks remain virtually unchanged. This development will briefly be summarised followed by a thorough discussion of two recent developments.

Methods

A systematic approach towards the literature is aimed at focusing on organ preservation and the delivery of all non-surgical treatments prior to surgery or total neoadjuvant treatment (TNT).

Results

Organ preservation, that is to defer surgery if the tumour happens to disappear completely after any pre-treatment given to locally advanced tumours to decrease recurrence risks has increased in popularity and is, if not universally, widely accepted. To give neo-adjuvant treatment to intentionally obtain a clinically complete remission to avoid surgery is practised in some environments but is mostly still experimental. TNT, that is to provide both radiotherapy and chemotherapy aimed at killing microscopic disease in the pelvis or elsewhere has been subject to several trials. Collectively, they show that the chance of achieving a complete response, pathologically or clinically, has approximately doubled, increasing the chance for organ preservation, and the risk of distant metastasis has decreased at least in some trials. The best schedule remains to be established.

Conclusions

To obtain substantial progress and also improve survival, the systemic treatments need to be improved even if preoperative delivery is more effective and better tolerated than postoperative. The locoregional treatment may be further optimised through better risk prediction.

Adoption of Total Neoadjuvant Therapy in the Treatment of Locally Advanced Rectal Cancer

Local and metastatic recurrence are primary concerns following the treatment of locally advanced rectal cancer (LARC). Chemoradiation (CRT) can reduce the local recurrence rates and has subsequently moved to the neoadjuvant setting from the adjuvant setting. Pathological complete response (pCR) rates have also been noted to be greater in patients treated with neoadjuvant CRT prior to surgery. The standard approach to treating LARC would often involve CRT followed by surgery and optional adjuvant chemotherapy and remained the treatment paradigm for almost two decades. However, patients were often unable to complete adjuvant chemotherapy due to a decreased tolerance of chemotherapy following surgery, which led to upfront treatment with both CRT and chemotherapy, and total neoadjuvant therapy, or TNT, was created. The efficacy outcomes of local recurrence, disease-free survival, and pCR have improved in patients receiving TNT compared to the standard approach. Additionally, more recent data suggest a possible improvement in overall survival as well. Patients with a complete clinical response following TNT have the opportunity for watch-and-wait surveillance, allowing some patients to undergo organ preservation. Here, we discuss the clinical trials and studies that led to the adoption of TNT as the standard of care for LARC, with the possibility of watch-and-wait surveillance for patients achieving complete responses. We also review the possibility of overtreating some patients with LARC.

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

Importance

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

Objective

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

Design, Setting, and Participants

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

Intervention

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

Main Outcomes and Measures

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

Results

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

Conclusions and Relevance

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

Trial Registration

ClinicalTrials.gov Identifier: NCT02008656.

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

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

Validated Pretreatment Prediction Models for Response to Neoadjuvant Therapy in Patients with Rectal Cancer: A Systematic Review and Critical Appraisal

Pretreatment response prediction is crucial to select those patients with rectal cancer who will benefit from organ preservation strategies following (intensified) neoadjuvant therapy and to avoid unnecessary toxicity in those who will not. The combination of individual predictors in multivariable prediction models might improve predictive accuracy. The aim of this systematic review was to summarize and critically appraise validated pretreatment prediction models (other than radiomics-based models or image-based deep learning models) for response to neoadjuvant therapy in patients with rectal cancer and provide evidence-based recommendations for future research. MEDLINE via Ovid, Embase.com, and Scopus were searched for eligible studies published up to November 2022. A total of 5006 studies were screened and 16 were included for data extraction and risk of bias assessment using Prediction model Risk Of Bias Assessment Tool (PROBAST). All selected models were unique and grouped into five predictor categories: clinical, combined, genetics, metabolites, and pathology. Studies generally included patients with intermediate or advanced tumor stages who were treated with neoadjuvant chemoradiotherapy. Evaluated outcomes were pathological complete response and pathological tumor response. All studies were considered to have a high risk of bias and none of the models were externally validated in an independent study. Discriminative performances, estimated with the area under the curve (AUC), ranged per predictor category from 0.60 to 0.70 (clinical), 0.78 to 0.81 (combined), 0.66 to 0.91 (genetics), 0.54 to 0.80 (metabolites), and 0.71 to 0.91 (pathology). Model calibration outcomes were reported in five studies. Two collagen feature-based models showed the best predictive performance (AUCs 0.83-0.91 and good calibration). In conclusion, some pretreatment models for response prediction in rectal cancer show encouraging predictive potential but, given the high risk of bias in these studies, their value should be evaluated in future, well-designed studies.