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.