Long-term outcome of neoadjuvant chemoradiotherapy based on the depth of invasion in mrT3 low rectal cancer / 中国肿瘤临床

ABSTRACT

Objective:To investigate the prognosis of cT3 and the subgroups of low rectal cancer patients who underwent neoadju-vant chemoradiotherapy (CRT) and evaluate whether all patients with cT3 low rectal cancer should undergo CRT. Methods:A total of 223 patients with cT3 low rectal cancer treated in the Department of Colorectal Surgery of Fujian Medical University Union Hospital from January 2008 to December 2012 were divided into neoadjuvant chemoradiotherapy group (CRT group) (115 cases) and no neoad-juvant chemoradiotherapy group (nCRT group) (108 cases) according to whether the patients underwent CRT. Afterward, the patients were retrospectively divided into three subgroups (mrT3a, mrT3b, and mrT3c) according to the proposed criteria of the Radiologic Soci-ety of North America (RSNA) by measuring the depth of mesorectal invasion (DMI) (DMI10 mm). The prog-noses of the two groups and their subgroups were compared. Results:The CRT and nCRT groups revealed no significant differences in the 3-year disease-free survival rate and the local recurrence rate for all the mrT3 patients (78.2%vs. 71.9%, P=0.608;4.4%vs. 8.5%, P=0.120) and mrT3a patients (82.4%vs. 81.8%, P=0.837;5.8%vs. 5.9%, P=0.658). On the contrary, for the mrT3b patients, the CRT and nCRT groups revealed significant differences in the 3-year disease-free survival rate (84.4%vs. 42.4%, P=0.032) and local recurrence rate (0.0%vs. 18.2%, P=0.014). For the mrT3b,c patients, the CRT and nCRT groups revealed no significant difference in the 3-year dis-ease-free survival rate (72.8%vs. 42.4%, P=0.060) but revealed a significant difference in the local recurrence rate (2.4%vs. 18.2%, P=0.021). COX regression analysis was utilized for 3-year disease-free survival, DMI and circumferential resection margin (CRM) were significant in the univariate analysis. Additionally, the multivariate analysis indicated that CRM is an independent impact factor (OR=2.249, CI 1.067-4.742, P=0.033). Conclusion:CRT can improve the prognosis of patients with mrT3b,c low rectal cancer but may not significantly influence the prognosis of patients with mrT3a and CRM-negative low rectal cancer;surgical treatment can be performed in these patients without CRT.