Preventive effects of gender and metabolic syndrome in 40s on colorectal cancer by colonoscopy.
59 Background: This study was aimed at measuring the preventive effect of colonoscopy for CRC development depending on age of index colonoscopy, gender and metabolic syndrome among persons aged 40 to 59 years. Methods: Between January 2005 and December 2006, data for the population aged from 40 to 59 who underwent colonoscopy (CSP cohort) claimed were collected from National Health Insurance Service (NHIS). Non-CSP (N-CSP) subjects were also collected by 1:5 propensity score matching with parameters of age, sex, and metabolic profiles, smoking, alcohol and past history of cancer. After one year of washout period, the risk of developing CRC was estimated by the occurrence of new case from January 2009 to December 2014 using the link of National CRC Registry to NHIS database. Compared with N-CSP cohort, hazard ratios (HRs) were obtained via conditional logistic regression analysis to estimate the risk of CRC in CSP cohort by age groups. Results: A total of 2,339,359 subjects were included (CSP cohort: 395,738 and matched N-CSP cohort: 1,943,621). The HRs for developing CRC by ages of 40-44, 45-49, 50-54, and 55-59 years in a CSP cohort were 0.864 ( P = NS), 0.591 ( P < 0.001), 0.599 ( P < 0.001), and 0.524 ( P < 0.001) in men, and 0.774 ( P = NS), 0.841 ( P = NS), 0.598 ( P < 0.001), and 0.605 ( P < 0.001) in women, respectively. Interestingly, when confined to patients with metabolic syndrome in their 40s, HRs for CRC in the colonoscopy cohort were statistically significantly lowered to 0.372 in early 40’s and 0.386 in men of late 40s, respectively, but not in women of 40s. Conclusions: The CRC prevention effect of colonoscopy is expected from late 40s in men and early 50s in women. Furthermore, in cases with metabolic syndrome, the preventive effect of colonoscopy is expected in men of early forties.