A Comparison of the Cumulative Incidence of Metachronous Colorectal Neoplasms Between Males and Females, and Between Elderly and Non-elderly During Colonoscopy Surveillance

Abstract

A total of 3,164 patients undergoing follow-up colonoscopies (period 82.3 months, frequency 3.90 times) were divided into four groups: 1,982 males (group M) and 1,182 females (group F), and another 1,381 under 65 years old (group Y) and 1,783 over 65 years old (group O). The cumulative incidence of patients with adenoma was significantly higher in group M than in group F (p < 0.001), and also in group O than in group Y (p < 0.01) by the Log-rank test. The cumulative incidence of patients with advanced adenoma was significantly higher in group O than in group Y (p < 0.001), although there was no difference in cumulative incidence between group M and group F (p = 0.07) by the Log-rank test. The patients who were followed up were sub-divided into three groups according to initial colonoscopic findings: normal colon or diminutive adenomas (group 1), small or large adenomas <20 mm (group 2), and Tis, T1 cancer, or adenomas >20 mm (group 3). Among the sub-groups, metachronous adenoma and advanced adenoma showed the same trends between groups M and F, and between groups Y and O. In conclusion, the cumulative incidence of patients with adenoma was significantly higher in males than females, and in those with advanced adenoma the cumulative incidence was significantly higher in elderly than non-elderly patients.