A Modified Classification of Prognostic Factors Based on Pathological Stage and Tumor Regression Grade in Patients with Rectal Cancer Who Receive Preoperative Chemoradiotherapy

Abstract

Objective: The histologic response to neoadjuvant chemoradiotherapy (CRT) has been intimately related to outcomes in locally advanced rectal cancer. However, reliable prognostic factors have yet to be established. Subjects and Methods: The study group comprised 198 patients with locally advanced rectal cancer who received CRT. A modified classification based on the combination of ypStage and tumor regression grade (TRG) was developed. yp Stage II with TRG 2 was classified as yp TRGstage IIA, and yp Stage II with TRG 3 or 4 was classified as yp TRGstage IIB. yp Stage 0 and yp Stage I were classified as yp TRGstage I, and yp Stage III was classified as yp TRGstage III. Results: The 5-year disease-free survival (DFS) was 83% in yp TRG stage I, 86% in yp TRG stage IIA, 57% in yp TRG stage IIB, and 60% in yp TRG stage III (p = 0.0001). The 5-year DFS in yp TRG stage IIA did not differ significantly from that in yp Stage 0 (p = 0.865) or yp Stage I (p = 0.585). The 5-year DFS in yp Stage IIB did not differ from that in yp Stage III (p = 0.912). Multivariate analysis showed that yp TRG stage was an independent risk factor for DFS. Conclusion: A modified classification allows patients with yp Stage II locally advanced rectal cancer to be clearly divided into two groups: responders and nonresponders.