The effectiveness of colorectal cancer screening for cancer survivors.

Abstract

e16091 Background: Colorectal cancer (CRC) is one of the highest-incident neoplasms in many countries. Although the incidence of CRC is increasing gradually, the mortality rate has not increased due to early detection and multidisciplinary treatment. CRC screening programs, including colonoscopy and fecal occult blood tests, have been reducing CRC-related mortality worldwide. In Taiwan, the CRC screening program uses a biennial fecal immunochemical test (FIT) as the initial screening tool. FIT-positive participants receive a colonoscopy as a CRC confirmation examination. Cancer survivors have a higher incidence of secondary primary malignancies. Methods: We conducted a nationwide population-based study in Taiwan. The cancer survivors with FIT in the Nationwide Colorectal Cancer Screening (NCCS) Program between January 2010 and September 2014 were enrolled as the study group. The patients aged under 50, diagnosed with CRC before the FIT were excluded. The screening participants without a cancer history were served as the comparison group. The primary endpoint was CRC diagnosis within six months after a FIT. The cancer diagnosis was identified by using Taiwan Cancer Registry. The ratios of positive FIT, confirmatory colonoscopy, and CRC diagnosis in the cancer survivors and the comparison cohort were calculated and compared. Analyses were adjusted for participants’ characteristics by using multilevel logistic regression models. Results: We identified 288,919 cancer survivors who participated in the NCCS Program. Of them, 41.1% were male and the median age was 59 (interquartile ranges 54–64). There were 417,907 FITs performed in the study cohort. The FIT positive rates were 11.3% and 7.4% in the study and comparison groups, respectively (OR 1.59 95% CI 1.57–1.60). Of the FIT positive participants, 50.5% and 52.3% received confirmatory colonoscopy or the related examinations within six months, respectively (OR 0.93 95% CI 0.91–0.95). Then 3.0% and 4.4% of those receiving confirmatory colonoscopy were diagnosed with CRC in the study and comparison groups, respectively (OR 0.68 95% CI 0.63–0.74). After adjustment for age, sex, income, a family history of CRC, and comorbidities, the cancer survivors in this screening program had a similar rate of CRC diagnosis compared with those without antecedent malignancies (adjusted OR: 0.97, 95% CI 0.87–1.08). Conclusions: Although the cancer survivors had a higher rate of positive FIT, the CRC diagnosed by the screening did not increase. We further identified the risk factors associated with CRC in the cancer survivors.