Abstract
We conducted a surveillance study on 1,548 patients and observed them for a period of over 5 years after their first total colonoscopy (TCS) had been performed from 1985 to 2004, and had undergone TCS subsequently at least twice. We divided them into 4 groups ; non-neoplasm, small adenoma (less than 5 mm), adenoma (over 5 mm), and cancer at the first TCS and analyzed the cumulative hazard rate and risk factor after the neoplastic lesions (diagnosed as adenoma or cancer by pathologic diagnosis) were resected. Although the cumulative hazard rate of neoplastic lesions of the adenoma group was at a higher rate in the observation period of 5 to 10 years compared with the normal group, there was no significant difference in the observation period for more than 10 years. We detected 3 risk factors ; patients aged over 50, patients that had adenomas over 5 mm in diameter and patients with more than 2 lesions.
We considered 7.5% to be a permissible range, which was the proportion of those with adenomas over 10 mm and cancer in our hospital, and calculated the optimal surveillance TCS. We recommend that TCS should be performed once every 3-5 years on male patients in their 50s.
