Impact of Screening Program on Incidence of Colorectal Cancer: A Cohort Study in Italy

Abstract

Objectives: Colorectal cancer (CRC) screening using the fecal occult blood test (FOBT) has been shown to be effective in reducing cause-specific mortality. However, although it detects pre-cancerous adenomas, it is uncertain whether FOBT reduces the incidence of invasive cancer. The objective is to evaluate the impact of screening with immunochemical FOBT (FIT) on CRC incidence and mortality.

Methods: An organized screening program was implemented in 2005 in the province of Reggio Emilia (Northern Italy). The program invites the resident population aged 50-69 for FIT every 2 years. Subjects who test positive are referred for colonoscopy. Incidence was studied through cancer registry. Person-times of people aged 50-74 from 1997 to 2012 were classified for exposure to screening according to age and period. Furthermore, two open cohorts-one never screened (aged 50-69 in 1997) and one invited for screening (aged 50-69 in 2005)-were followed up for 8 years.

Results: A total of 171,785 people have been invited, and approximately 70% have undergone FIT at least once (272,197 tests). The rate of colonoscopy participation has been about 90%, and 2896 cancers have been recorded (1237 in the screening period). The age-adjusted and sex-adjusted incidence rate ratios as compared with pre-screening were 1.60 (95% confidence interval (CI), 1.43-1.79), 0.86 (95% CI, 0.78-0.94), and 0.59 (95% CI, 0.50-0.69) for the first round, subsequent rounds, and post screening, respectively. Cumulative incidence and incidence-based mortality decreased by 10% (95% CI, 3-17%) and 27% (95% CI, 15-37%), respectively.

Conclusions: FIT screening leads to a decrease in the incidence of CRC and in its mortality.