Mucinous histology predicts for reduced fluorouracil responsiveness and survival in advanced colorectal cancer

Background: Mucinous carcinoma of the colon and rectum (mucinous CRC) is a histological subtype of colorectal adenocarcinoma for which there is little data on chemotherapy responsiveness. The purpose of this study was to investigate specifically the efficacy of fluorouracil -based first-line chemotherapy in patients with advanced mucinous CRC. Patients and methods: All patients with advanced mucinous CRC enrolled in three prospective randomized trials evaluating infused 5-fluorouracil as first-line treatment were compared with patients with non-mucinous subtypes enrolled in the same trials in a case-control study. Prognostic factors associated with overall response rate (ORR), progression -free survival (PFS) and overall survival (OS) were identified using univariate and multivariate logistic and/or Cox proportional hazards analyses. Results: The study included 135 patients (45 cases and 90 controls). The response rates for cases and controls were 22% [95% confidence interval (CI), 11% to 38%] and 47% (95% Cl, 36. 1 % to 58.2%), respectively (P=0.0058). Median OS for the mucinous CRC patients was 11.8 months (95% Cl 8.87-14.8) compared with 17.9 months (95% Cl, 13.38-22.39) in the control group (Univariate analysis, P=0.056); after correcting for significant prognostic factors by multivariate Cox regression analysis, P = 0.0372 and hazard ratio (HR) = 1.497 (1.02-2.19). Conclusion: Patients with advanced mucinous CRC have a poorer response to fluorouracil -based first-line chemotherapy and reduced survival compared with patients with non-mucinous CRC.