Impact of specific modes of circumferential resection margin involvement in rectal cancer local recurrence: A retrospective study

Watch & wait - Post neoadjuvant imaging for rectal cancer

Rectal cancer management has evolved over the past decade with the emergence of total neoadjuvant therapy (TNT). For select patients who achieve a clinical complete response following TNT, organ preservation by means of the watch-and-wait (WW) strategy is an increasingly adopted alternative that preserves rectal function and quality of life without compromising oncologic outcomes. Recently, published 5-year results from the OPRA trial demonstrated that organ preservation can be achieved in approximately half of patients managed with the WW strategy, with most local regrowth events occurring within two years. Considering the potential for local regrowth, the implementation of the WW strategy mandates rigorous clinical and radiographic surveillance. Magnetic resonance imaging (MRI) serves as the conventional imaging modality for local staging and surveillance of rectal cancer given its excellent soft-tissue resolution. This review will discuss the current evidence for the WW strategy and the role of restaging rectal MRI in determining patient eligibility for this strategy. Restaging rectal MRI acquisition parameters and treatment response assessment, including important factors to assess, pitfalls, and classification systems, will be discussed in the context of the WW strategy.

Progress of MRI in predicting the circumferential resection margin of rectal cancer: A narrative review

Rectal cancer (RC) is the third most frequently diagnosed cancer worldwide, and the status of its circumferential resection margin (CRM) is of paramount significance for treatment strategies and prognosis. CRM involvement is defined as tumor touching or within 1 mm from the outermost part of tumor or outer border of the mesorectal or lymph node deposits to the resection margin. The incidence of involved CRM varied from 5.4 % to 36 %, which may associate with an in consistent definition of CRM, the quality of surgeries, and the different examination modalities. Although T and N status are essential factors in determining whether a patient should receive neoadjuvant therapy before surgery, CRM status is a powerful predictor of local and distant recurrence as well as survival rate. This review explores the significance of CRM, the various assessment methods, and the role of magnetic resonance imaging (MRI) and artificial intelligence-based MRI in predicting CRM status. MRI showed potential advantage in predicting CRM status with a high sensitivity and specificity compared to computed tomography (CT). We also discuss MRI advancements in RC imaging, including conventional MRI with body coil, high-resolution MRI with phased-array coil, and endorectal MRI. Along with a discussion of artificial intelligence-based MRI techniques to predict the CRM status of RCs before and after treatments.

Advances in MRI-Based Assessment of Rectal Cancer Post-Neoadjuvant Therapy: A Comprehensive Review

Rectal cancer presents significant diagnostic and therapeutic challenges, with neoadjuvant therapy playing a pivotal role in improving resectability and patient outcomes. MRI serves as a critical tool in assessing treatment response. However, differentiating viable tumor tissue from therapy-induced changes on MRI remains a complex task. In this comprehensive review, we explore treatment options for rectal cancer based on resectability status, focusing on the role of MRI in guiding therapeutic decisions. We delve into the nuances of MRI-based evaluation of treatment response following neoadjuvant therapy, paying particular attention to emerging techniques like radiomics. Drawing from our insights based on the literature, we provide essential recommendations for post-neoadjuvant therapy management of rectal cancer, all within the context of MRI-based findings.

Rectal cancer lexicon 2023 revised and updated consensus statement from the Society of Abdominal Radiology Colorectal and Anal Cancer Disease-Focused Panel

The Society of Abdominal Radiology's Colorectal and Anal Cancer Disease-Focused Panel (DFP) first published a rectal cancer lexicon paper in 2019. Since that time, the DFP has published revised initial staging and restaging reporting templates, and a new SAR user guide to accompany the rectal MRI synoptic report (primary staging). This lexicon update summarizes interval developments, while conforming to the original lexicon 2019 format. Emphasis is placed on primary staging, treatment response, anatomic terminology, nodal staging, and the utility of specific sequences in the MRI protocol. A discussion of primary tumor staging reviews updates on tumor morphology and its clinical significance, T1 and T3 subclassifications and their clinical implications, T4a and T4b imaging findings/definitions, terminology updates on the use of MRF over CRM, and the conundrum of the external sphincter. A parallel section on treatment response reviews the clinical significance of near-complete response and introduces the lexicon of "regrowth" versus "recurrence". A review of relevant anatomy incorporates updated definitions and expert consensus of anatomic landmarks, including the NCCN's new definition of rectal upper margin and sigmoid take-off. A detailed review of nodal staging is also included, with attention to tumor location relative to the dentate line and locoregional lymph node designation, a new suggested size threshold for lateral lymph nodes and their indications for use, and imaging criteria used to differentiate tumor deposits from lymph nodes. Finally, new treatment terminologies such as organ preservation, TNT, TAMIS and watch-and-wait management are introduced. This 2023 version aims to serve as a concise set of up-to-date recommendations for radiologists, and discusses terminology, classification systems, MRI and clinical staging, and the evolving concepts in diagnosis and treatment of rectal cancer.

Preoperative computed tomography assessment of circumferential resection margin in retroperitonealized colon cancer predicts disease-free survival

OBJECTIVES

The aim of this retrospective study was to predict circumferential resection margin (CRM) involvement on preoperative CT, and prognostic impact of CRM assessment by CT (ctCRM) in patients with retroperitonealized colon cancer.

METHODS

This study included patients who underwent resection for ascending or descending colon cancer between July 2010 and February 2013. Positive ctCRM was defined as tumor distance to the retromesenteric plane of ≤ 1 mm. The origin of positive CRM was divided into primary tumor or other tumor components including lymph nodes, tumor deposits, or extramural venous invasions. Logistic regression analysis was performed to identify preoperative factors to predict pathologic CRM (pCRM). A Cox proportional hazards model was used in multivariable analysis to determine the preoperative factors affecting disease-free survival (DFS).

RESULTS

A total of 274 patients (mean age, 64.0 years ± 11.0 [standard deviation]; 157 men) with retroperitonealized colon cancer were evaluated. Of 274 patients, 67 patients (24.5%) had positive CRM on surgical pathology. The accuracy of preoperative CT in predicting pCRM was 79.6% (218/274). Among preoperative factors, only CRM assessment on CT was independently associated with pCRM (p < 0.001). Positive ctCRM by primary tumor was an independent factor for DFS (HR, 3.362 [1.714-6.593]) and systemic recurrence (HR, 3.715 [1.787-7.724], but not for local recurrence on multivariable analyses.

CONCLUSIONS

Preoperative CT can accurately predict pCRM, and positive ctCRM by primary tumor is an independent risk factor for DFS and systemic recurrence, but not for local recurrence in retroperitonealized colon cancer.

KEY POINTS

• Preoperative CT can predict pathologic circumferential resection margin (CRM) with approximately 80% of accuracy in patients with retroperitonealized colon cancer. • Positive CRM by a primary tumor on preoperative CT is a poor prognostic factor for disease-free survival and systemic recurrence in patients with retroperitonealized colon cancer. • CRM involvement on CT was not associated with local recurrence in patients with retroperitonealized colon cancer.

The impact of subdivisions of microscopically positive (R1) margins on patterns of relapse in stage III colorectal cancer - A retrospective cohort study

AIM

Microscopically positive (R1) margins are associated with poorer outcomes in patients with colorectal cancer. However, the impact of subdivisions of R1 margins, be they to the primary tumour (R1 tumour) or to lymph node metastases (R1LNM), on patterns of relapse is unknown.

METHODS

Patients treated for stage III colorectal cancer from 01 January 2016 to 31 December 2019 in four specialist centres were identified from the Danish national cancer registry. Patients were stratified into three groups according to margin status (R0 vs. R1 tumour vs. R1LNM). The primary outcomes were local recurrence-free survival (LRFS), distant metastases-free survival (DMFS) and disease-specific survival (DSS).

RESULTS

A total of 1,164 patients were included, with R1 margins found in 237 (20.4%). Irrespective of tumour location, R1 tumour and R1LNM margins were independent prognostic factors for systemic relapse (R1 tumour HR 1.84, CI: 1.17-2.88, p = 0.008; R1LNM HR 1.59, CI: 1.12-2.27, p = 0.009) and disease-related death (R1 tumour HR 2.08, CI: 1.12-3.85, p = 0.020; R1LNM HR 1.84, CI: 1.12-3.02, p = 0.016). Whereas R1 tumour margins were associated with poorer 3-year LRFS in both colon and rectum cancer, R1LNM margins only reduced LRFS in patients with rectal cancer. Patterns of relapse differed between R1 subdivisions, with R1 tumour margins more likely to affect multiple anatomical sites, with a predilection for extra-hepatic/pulmonary metastases.

CONCLUSION

Subdivisions of R1 margins have a distinct impact on the oncological outcomes and patterns of disease relapse in patients with stage III colorectal cancer.

The significance of subdivisions of microscopically positive (R1) margins in colorectal cancer: A retrospective study of a national cancer registry

AIM

Microscopically positive (R1) margins are associated with poorer outcomes in patients with colorectal cancer. However, little is known of the differential impact of subdivisions of R1 margins, be they to the primary tumour (R1tumour) or to lymph node metastases/tumour deposits (R1LNM).

METHODS

Patients treated for Stage III colorectal cancer from 1 January 2016 to 31 December 2019 were identified from the Danish national cancer registry. Patients were stratified into three groups according to margin status (R0 vs. R1tumour vs. R1LNM). The primary outcome was overall survival.

RESULTS

In all, 4186 patients were included, comprising 3012 patients with colon cancer and 1174 patients with rectal cancer. The R1 resection rates were 16.5% and 18.2% in patients with colon and rectum cancer, respectively. In colon cancers, 3-year overall survival was reduced in patients with R1LNM (65.7%, 95% CI 62.8-68.6) or R1tumour margins (51.8%, 95% CI 47.3-56.3) compared with R0 resections (80.8%, 95% CI 79.9-81.6, P < 0.001). A similar impact on survival was seen in rectal cancers (R0, 84.2%, 95% CI 82.9-85.5; R1LNM, 72.2%, 95% CI 67.8-76.6; R1tumour, 56.6%, 95% CI 50.0-63.2, P < 0.001). Margin status was independently prognostic of survival in both colon (R1tumour, hazard ratio 2.08, 95% CI 1.50-2.89, P < 0.001; R1LNM, hazard ratio 1.48, 95% CI 1.11-1.97, P = 0.008) and rectal cancers (R1tumour, hazard ratio 2.35, 95% CI 1.42-3.90, P < 0.001; R1LNM, hazard ratio 1.54, 95% CI 0.95-2.48, P = 0.077).

CONCLUSION

R1 subdivisions have distinct impacts on survival in Stage III colorectal cancer. Further focused research in these patient subgroups is warranted.

What management for patients with R1 resection after total mesorectal excision for rectal cancer? A review of the literature

AIM OF THE STUDY

Treatment for rectal cancer is very standardized. However, for total mesorectal excision (TME) with positive margins at microscopic pathological examination (classified R1 ), there is no consensus regarding management. The objective of this update was, through a review of the literature, to identify the most suitable management to improve overall survival and/or recurrence-free survival after R1 TME for rectal cancer.

PATIENTS AND METHODS

Published national quality guidelines and original studies were searched on Pubmed. Only studies and recommendations concerning the specific management of patients who had undergone R1 TME resection were selected.

RESULTS

Five original non-randomized studies and seven published national quality guidelines were selected for review. For patients who have undergone R1 TME resection, the French and European published guidelines issued a Grade A recommendation in favor of post-operative radio-chemotherapy (RCT) for those in whom it had not already been performed pre-operatively. The French and European guidelines recommendation for adjuvant chemotherapy was based only on expert agreement. The original studies emphasized the survival benefit of adjuvant chemotherapy, as opposed to post-operative RCT, which did not seem to improve survival. Salvage surgery was not recommended in any of the studies.

CONCLUSION

After R1 TME resection for rectal cancer, adjuvant chemotherapy seems to be indicated when feasible, whereas post-operative RCT and salvage surgery do not appear to improve patient survival.