Distinctive Oncological Features of Stage IIIA Colorectal Cancer: Analysis of Prognostic Factors for Selective Adjuvant Chemotherapy

Abstract

IntroductionIn the seventh TNM classification, stage IIIA includes tumors with early stage of bowel wall invasion and regional lymph node metastasis. We investigated the validity of the current TNM classification of patients with stage IIIA colorectal cancer and identified prognostic factors of them for ameliorating treatment strategies for them. MethodsThis study included the participation of four tertiary hospitals. A total of 4,236 patients with Stages I-IIIB colorectal cancer were analyzed. The primary end point was the 5-year relapse-free survival. ResultsThe 5-year relapse-free survival of patients with stage IIIA disease was similar to that of patients with stage IIA. The 5-year relapse-free survival was 88.9% in the chemotherapy group (n=152) and 82.3% in the no-chemotherapy group (n=36, P=0.111). Tumor differentiation (moderate or poor) and venous invasion were independent prognostic factors of relapse-free survival. ConclusionsThe relapse-free survival of patients with stage IIIA tumors was similar to that of patients with stage IIA tumors, and the prognosis of stage IIIA tumors varied significantly by the tumor factors identified. These factors can be used to predict the risk of disease recurrence and to optimize the use of adjuvant chemotherapy. J. Surg. Oncol. 2015 111:882-890. (c) 2014 Wiley Periodicals, Inc.