Purpose: This study was performed to determine cost-effective colonoscopy guidelines for patients with prior colorectal adenocarcinoma.
Method: A retrospective review was performed of patients who had been treated for colorectal adenocarcinoma and later underwent follow-up colonoscopy from 1984 to 1994.
Results: During this study period, 389 patients previously treated for colorectal adenocarcinoma underwent follow-up colonoscopy. All patients had perioperative colon evaluation for other neoplasms. Ages ranged from 26 to 89 (mean, 65.8) years, and 46.8 percent were female. Recurrent or metachronous cancer or a neoplastic polyp constituted a positive examination. Results of 389 first follow-up colonoscopies were compared with 259 second (66.6 percent), 165 third (42.4 percent), and 83 fourth (21.3 percent) follow-up examinations. Median interval between all colonoscopies was 13 months. Positive examination rates for the first two yearly examinations were 18.3 and 18.5 percent, respectively. Slightly lower, third-year and fourth-year positive examination rates were 16.4 and 14.5 percent, respectively. Four-year examinations yielded the following: first year--1 carcinoid, a new adenocarcinoma, and 100 polyps; second year--1 anastomotic recurrence and 68 polyps; third year --55 polyps; and fourth year--1 recurrent cancer and 17 polyps.
Conclusions: These data suggest that 1) annual follow-up colonoscopy for two years after colorectal cancer surgery is beneficial for detecting recurrent and metachronous neoplasms and 2) the interval between subsequent examinations may be increased depending on the result of the most recent examination.