Oncologic impact of pathologic response on clinical outcome after preoperative chemoradiotherapy in locally advanced rectal cancer

PURPOSE Downstaging after chemoradiotherapy (CRT) for rectal cancer usually occurs. The present study aimed to evaluate pathologic y-stage (yp-stage) and its influence on local recurrence and systemic recurrence in rectal cancer patients treated with CRT followed by surgical resection. METHODS We retrospectively analyzed 261 patients underwent preoperative CRT and radical resection for rectal cancer between August 2004 and December 2010. Patients received preoperative CRT consisting of 5-fluorouracil and leucovorin delivered with concurrent pelvic radiation of 45.0-50.4 Gy, followed by radical surgery at 6-8 weeks after CRT. RESULTS Of the 261 patients, 24 (9.2%) had yp-stage 0, 83 (31.8%) had yp-stage I, 86 (32.9%) had yp-stage II, and 68 (26.1%) had yp-stage III. Patients with yp-stage III had a greater prevalence of preoperative CEA, poorly differentiated tumor, lymphovascular invasion (LVI) and perineural invasion (PNI) than patients with lower yp-stages. We found that yp-stage, preoperative CEA, LVI, PNI and tumor regression grade were significant prognostic factors for both local and systemic recurrence. In multivariate analysis, yp-stage, LVI and PNI were significant factors for local and systemic recurrence. During the median follow-up of 37.5 months, the five-year local recurrence-free survival rate was 100.0%, 95.0%, 89.3%, and 80.6% of yp-stage 0-III, respectively. The five-year systemic recurrence-free survival was 95.8%, 75.3%, 71.4%, and 48.8% of yp-stages 0-III, respectively. CONCLUSION The yp-stage after preoperative CRT for rectal cancer is closely correlated with local and systemic recurrence-free survival. Therefore, yp-stage should be considered as a prognostic factor for rectal cancer patients having a course of preoperative CRT.