Abstract
Few cohort studies have used multiple surveys of screening attendance to simultaneously evaluate the effectiveness of fecal occult blood test (FOBT) and colonoscopy. We analyzed data of 30,381 middle-aged Japanese adults from a population-based prospective cohort study. Information on FOBT and colonoscopy was obtained from three questionnaire surveys (every 5 years). We classified the subjects into three groups: the FOBT (15,649 subjects), screening colonoscopy (2,407 subjects), and unscreened (12,325 subjects) groups. We used the unscreened group as the reference group to compare the mortality and incidence of colorectal cancer (CRC). During the 14-year follow-up, 64, 12, and 104 CRC deaths were identified in the FOBT, screening colonoscopy, and unscreened groups, respectively. The risk of CRC death reduced with increasing the number of FOBTs (P for trend = 0.02) and was reduced by 44% in the subjects screened twice or thrice using FOBT (hazard ratio [HR] 0.56; 95% confidence interval [CI], 0.33-0.94). Significant decreases were seen for the incidence of CRC but not seen for the incidence of non-advanced CRC in the FOBT group. Concerning the screening colonoscopy, subjects screened at the start of follow-up showed a 69% reduced risk of CRC death (HR 0.31; 95% CI, 0.10-0.9996). Significant decreases were also seen for the incidence of CRC and non-advanced CRC in the subjects screened at the start of follow-up. FOBT, depending on the number of FOBTs, and colonoscopy, depending on recency, reduced the risk of death due to CRC and the incidence of CRC.
Highlights
Colorectal cancer (CRC) was the second leading cause of cancerrelated death and the third most common cancer worldwide in 2018.1 Cancer screening is a way to decrease the number of deaths due to CRC
Cohort studies regarding the effectiveness of cancer screening often use information on onetime exposure, such as the previous Japan Public Health Centerbased prospective study (JPHC) on the efficacy of fecal occult blood test (FOBT),[6] or divide the exposure into two
The subjects screened at the start of follow-up showed a 69% reduced risk of death due to CRC compared with unscreened subjects (HR 0.31; 95% confidence intervals (CIs), 0.10–0.9996), but there was no reduction among the subjects screened 10 years before the start of follow-up and 5 years before the start of follow-up
Summary
Colorectal cancer (CRC) was the second leading cause of cancerrelated death and the third most common cancer worldwide in 2018.1 Cancer screening is a way to decrease the number of deaths due to CRC. The United States Preventive Services Task Force and the American Cancer Society have recently recommended guaiac-based fecal occult blood testing and fecal immunochemical testing every year, flexible sigmoidoscopy every 5 years, and colonoscopy every 10 years for CRC screening.[2,3] In Japan, screening programs using annual fecal immunochemical tests (FITs) have been implemented nationwide since 1992.4 According to the 2005 guidelines for CRC screening, the fecal occult blood test (FOBT) is recommended for organized and opportunistic (grade A) screenings, and colonoscopy is recommended only for opportunistic (grade C) screening.[5]. Few cohort studies have used multiple surveys of screening attendance to simultaneously evaluate the effectiveness of fecal occult blood test (FOBT) and colonoscopy
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