Clinicopathologic Significance of Synchronous and Metachronous Adenomas in Colorectal Cancer

Abstract

Colorectal cancers (CRCs) evolve from a multiple-step tumorigenesis and, morphologically, are characterized by adenoma. Colorectal cancers with adenomas have distinct clinical features, including reports of improved survival. It is hypothesized that this survival advantage is related to biologic differences in CRC with adenomas rather than earlier diagnosis or earlier stage of disease presentation. A retrospective chart review of 569 patients treated from 1983 through 2002 was conducted. Data on age, sex, and survival; CRC stage, location, and recurrence; adenoma number, size, histology, and location; and colonoscopy history were analyzed. The mean patient age was 62 years (range, 17-90 years), and 54% of patients were men. The majority of CRCs were left-sided (67%). The American Joint Committee on Cancer stage distribution was 0/I (12%), II (21%), III (34%), and IV (33%). Colorectal cancer with synchronous adenoma was seen in 33% of cases; overall, CRC with adenoma comprised 42% of cases. The event-free survival and overall survival favored CRC with adenoma. After adjusting for age, disease stage, sex, and total number of colonoscopic examinations, the relative risk for an event was 1.51 (P < 0.003) for patients without adenomas versus those with adenomas. Colorectal cancer with adenoma represents a distinct population of patients with CRC. The apparent association seems to confer a survival advantage that is not based on age, sex, or disease stage. The survival benefit, although slightly less dramatic, remained significant even when controlled for the number of colonoscopies.