Preoperative chemoradiotherapy (CRT) is the standard of care for locally advanced rectal cancer. Patients with a marked histological response have good outcomes with low risk of local and distant recurrence. Histological response can be evaluated on the basis of T or N downstaging, and tumor regression grade (TRG). Some patients with ypStage II are evaluated to have no downstaging because of the presence of small amounts of residual cancer cells in the T3 layer even if they have a marked reduction in tumor volume and a TRG of 2. We therefore studied whether the combination of ypStage and TRG could be used as prognostic factor.
We studied 191 patients with cT3/T4, Nx, or cT2, N + , M0 adenocarcinoma of the rectum who underwent surgery after CRT from 2007 to 2015. The total radiation dose was 40 or 45 Gy given in combination with oral UFT or S-1. Surgery was performed 6 to 8 weeks after the completion of radiotherapy. Survival analyses were performed according to ypStage and ypStage plus TRG.
Recurrence was found in 47 patients (25%). The initial site of recurrence was local in 5 patients (3%), the liver in 16 (8%), and the lung in 19 (10%). The ypStage was 0 in 39 patients (20%), I in 45 (24%), II in 62 (32%), and III in 45 (24%). Downstaging was noted in 44% of the patients. The TRG was 1 in 32 patients (17%), 2 in 49 (26%), 3 in 75 (39%), and 4 in 35 (18%). The median follow-up was 55 months, the 5y DFS was 71%, and the 5y OS was 85%. The 5y DFS according to ypStage was 82% in 0 or I cancer and 62% in II or III cancer, and the 5y OS was 90% and 82%, respectively. Survival rates was significantly higher in ypStage 0 or I cancer than in ypStage II or III cancer (p = 0.0003 and p = 0.0465). The 5y DFS was 83% in patients with ypStage 0 or I or ypStage II cancer with a TRG of 2, as compared with 58% in other patients. The 5y OS was 92% and 79%, respectively. Survival rates were significantly higher in patients with ypStage 0 or I or ypStage II cancer with a TRG of 2 (p
Outcomes were good even in patients with ypStage II cancer who had a TRG of 2. Combining the TRG histological response with ypStage may be a better prognostic indicator than ypStage alone.
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All authors have declared no conflicts of interest.