Clinical Characteristics of Synchronous Adenomas Designated as Risk Factors of Metachronous Malignancy in Colorectal Cancer

Jung, Sang Hun; Kim, Hee Cheol; Yu, Chang Sik; Kim, Jin Cheon

Abstract

PURPOSE: More than 80% of colorectal cancers are known to occur from adenomas, but only a subset of adenomas undergoes malignant transformation. The aim of this retrospective study was to assess clinicopathologic characteristics of synchronous adenomas associated with metachronous malignant neoplasms in colorectal cancer patients.
METHODS
Three hundred sixty-eight colorectal cancer patients with synchronous adenomas who underwent a complete polypectomy were consecutively enrolled between 1995 and 2002. The patients with familial adenomatous polyposis (FAP), hereditary nonpolyposis colorectal cancer (HNPCC), and synchronous colorectal cancers with invasion beyond the submucosa, and patients who underwent a total colectomy were excluded.
RESULTS
The mean age were 60 years (range, 27~83), and the male- to-female ratio was 2.6:1. The mean number of synchronous adenomos was 2.4 (1~22). The incidence of metachronous adenomas was 44.3% (163 patients), and that of metachronous malignant neoplasms was 5.2% (19 patients), consisting of 9 carcinomas and 10 malignant polyps (or adenomas with malignant change). In the multivariate analysis, the variables associated a metachronous adenoma were sex (male), location of the primary tumor, and multiple synchronous adenomas. The independent risk factors of metachronous malignant neoplasms were synchronous neoplastic adenomas (OR, 3.8; 95% CI, 1.24~11.83) and large adenomas (OR, 3.64; 95% CI, 1.17~11.27). The mean free-inverval of matachronous malignant neoplasms was 24 months (range, 12~52).
CONCLUSIONS
Colorectal cancer patients with synchronous adenomas are prone to be at risk for recurrent adenomas and malignant tumors. High- risk patients for metachnonous malignant neoplasms should be considered for frequent colonoscopy follow-up.