Multimodal Treatment of cT3 Rectal Cancer in a Prospective Multi-Center Observational Study: Can Neoadjuvant Chemoradiation Be Omitted in Patients with an MRI-Assessed, Negative Circumferential Resection Margin?

Abstract

Background/Aim: Neoadjuvant chemoradiation (nCRT) in rectal cancer is associated with significant long-term morbidity. It is unclear whether nCRT in resectable mesorectal fascia circumferential resection margin (mrCRM)-negative rectal cancer treated by adequate total mesorectal excision (TME) is beneficial. The aim was to determine if nCRT can be omitted in patients with MRI-assessed cT3 rectal cancer and a negative mrCRM undergoing good-quality TME. Methods: By means of a prospective nationwide registry (n = 43.147; prospective multi-center observational study), patients with cT3 rectal cancer <12 cm from the anal verge with a negative (>1 mm) MRI-assessed CRM undergoing radical resection from 2006 to 2008 were selected. Overall, 87 patients were available for the final analysis (TME-alone, n = 25; nCRT+TME, n = 62). Groups were balanced for age, sex, and ASA score, with a nonsignificant predominance of males in the nCRT+TME group. As main outcome measures, local and distant recurrence rates were compared between patients undergoing primary surgery (TME-alone) vs. neoadjuvant chemoradiation + surgery (nCRT+TME). Results: In the TME-alone group, tumors were located closer to the anal verge (p = 0.018) and demonstrated a smaller minimal circumferential distance from the resection margin (p = 0.036). TME quality was comparable, as was median follow-up (48.9 vs. 44.9 months; p = 0.268). Local recurrences occurred at a similar rate in the TME-alone (n = 1; 5.3%) and nCRT+TME groups (n = 3; 5.5%) (p = 0.994) and were diagnosed at 10 months (TME-alone) and at 8, 13, and 18 months (nCRT+TME). Distant recurrences occurred in 28.9 and 17.4% of the cases, respectively (p = 0.626). The analysis was limited to cT3 cancers with a negative mrCRM. In addition, caution is required when appraising these results because of the limited number of evaluable subjects (especially in the TME-alone group), which adds some uncertainty to the statistical analysis. Conclusions: In this cohort of patients with rectal cancer located <12 cm from the anal verge and a negative mrCRM undergoing adequate TME, omission of nCRT had no impact onto the local recurrence rate.