Pathological assessment of the AJCC tumor regression grading system after preoperative chemoradiotherapy for Chinese locally advanced rectal cancer

Abstract

We used American Joint Committee on Cancer (AJCC) Staging Manual system to assess the prognostic significance of tumor regression grading (TRG) for locally advanced rectal cancer (LARC) (T3/4 or N+) patients who were treated with preoperative chemoradiotherapy (CRT). The 4 AJCC-TRG classifications were evaluated on surgical specimens from 295 LARC patients receiving CRT. Overall survival (OS), disease-free survival (DFS), local recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS) were estimated using Kaplan- Meier method and Cox regression model. Classifications of TRG 0, 1, 2, and 3 were found in 27.5%, 19.3%, 45.7%, and 7.5% of the resected specimens, respectively. Three-year OS was 95.5% for TRG0, 91.5% for TRG1, 84.8% for TRG2, and 85.7% for TRG3 (P=0.035). Three-year DFS was 89.0% for TRG0, 74.4% for TRG1, 70.9% for TRG2, and 62% for TRG3 (P=0.018). By multivariate analysis, AJCC-TRG (P=0.033), residual lymph node metastasis (ypN+) (P<0.001) and pretreatment CA19-9 level (P=0.035) were significant predictors of OS. Pathological T category (P=0.006) and nodal status (P<0.001) after CRT were the most important independent prognostic factors for DFS. AJCC-TRG is a prognostic factor for LARC patients receiving CRT, independent of pathological staging.