Previous studies have shown conflicting results on the prognosis of colorectal mucinous adenocarcinoma. This study compared prognostic characteristics of patients diagnosed with mucinous and non-mucinous adenocarcinomas in a Canadian series. Analyses were based on 165 colorectal mucinous and 1215 non-mucinous adenocarcinoma patients who were registered at the Ottawa Regional Cancer Centre from 1994 to 1997, with follow-up extending to December 31, 2001. Differences in survival were examined using the relative survival analysis and the Cox proportional hazards model. For colon, rectum and both combined, the distribution for age at diagnosis, stage and treatment of patients with mucinous adenocarcinoma was similar to that of non-mucinous patients (all p≥0.12). Patients with mucinous histology had fewer well- or moderately-differentiated tumours than non-mucinous patients (all p<0.01). Overall, no statistically significant differences were noted in 5-year relative survival between mucinous and non-mucinous carcinoma for colon, rectum and their combination (p≥0.35 for each). However, when the stages were considered separately, patients with stage III mucinous carcinoma had worse survival than patients with non-mucinous carcinoma for both sites. Multivariate analysis of combined data for colon and rectal cancers indicated that independent significant prognostic factors were stage for mucinous, with age and grade as well as stage for non-mucinous carcinoma. In conclusion, no significant differences in stage distribution and overall survival were found between mucinous and non-mucinous patients for colorectal cancer.

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