Mucinous histology to predict disease-free survival in microsatellite stable stage III colon cancer patients treated with adjuvant FOLFOX chemotherapy.

Abstract

e14084 Background: The prognostic role of mucinous histology of the colon cancer has been studied for decades and remained controversial. The aim of this retrospective study was to investigate whether mucinous adenocarcinoma (MA) is associated with a worse prognosis than that of non-mucinous adenocarcinoma (NMA) in patients with stage III colon cancer. Methods: This study enrolled unselected 402 patients with stage III colorectal cancer treated with adjuvant FOLFOX after curative resection (R0). Clinicopathological information was retrospectively reviewed. Tumors were analyzed for microsatellite instability (MSI) by polymerase chain reaction (PCR) to determine MSI-high (MSI-H) or microsatellite stable (MSS). Kaplan-Meier method, log-rank test, and Cox proportional hazards regression models were used. Results: Among 402 patients, 42 patients (10.4%) were MA and 26 patients (6.5%) were MSI-H. Compared with MSS tumors, MSI-H tumors was associated with a higher rate of MA (26.9% vs 9.3%, P=0.005). In MSS tumors (n=376), 3-year disease-free survival (DFS) rate was 79% and 55% in NMA and MA, respectively (log rank, P=0.014). In MSI-H tumors (n=26), no statistically significant difference of DFS between MA and NMA was found. In multivariate analysis, MA remained an independent significant poor prognostic factor for DFS (HR=1.9; 95% CI, 1.003-3.717; P=0.049) in MSS patients. Conclusions: Mucinous histology is an independent poor prognostic factor for DFS in patients with microsatellite stable stage III colon cancer after adjuvant FOLFOX chemotherapy. [Table: see text]