A National Cancer Database Analysis of the Characteristics and Outcome of Colon Cancer According to Type of Preexisting Adenoma.

Background: The vast majority of colon cancers occur in pre-existing adenomas. Little is known about the impact of adenoma type on behavior and outcome of subsequent carcinomas. The present study aimed to assess characteristics, behavior, and outcome of colon adenocarcinoma based on histologic type of pre-existing adenoma.

Methods: US-National Cancer Database was searched between 2005 and 2019 for patients with colonic adenocarcinoma with known adenoma type who underwent colectomy. Patients were divided into 3 groups according to type of adenoma in which carcinoma developed: tubular adenoma (TA), villous adenoma (VA), and tubulovillous adenoma (TVA)-associated carcinomas. The main outcome of the study was 5-year overall survival (OS).

Results: 66,854 patients were included. 79.3% of carcinomas originated from TVA, 10.2% from VA, and 0.5% from TA. Patients with adenocarcinoma in VA were more often female whereas carcinomas in TA affected patients of Asian race more often. Approximately one-third of carcinomas in villous and tubulovillous adenomas were in the cecum whereas one-third of carcinomas in tubular adenomas were in the sigmoid colon. More TA-associated carcinomas were of clinical T1-2 stage (30.2% vs. 20.8%; P < .001), clinical N0 stage (69% vs. 62.2%, P < .001), and high grade (15.9% vs. 11.5%, P < .001) compared to VA-associated carcinomas. Patients with TA-associated carcinomas had longer mean OS than patients with VA and TVA-associated carcinomas (130.1 vs. 116.9 vs. 123.5 months, P < .0001).

Conclusions: Adenocarcinomas that arose in TA had more T1-2 stage and N0 stage, higher grade, and longer OS than did adenocarcinomas that arose in VA and TVA.