Extending colorectal cancer screening to persons aged 40 to 49 years with immunochemical fecal occult blood test a prospective cohort study of 513,283 individuals

Goals: To assess the association between the initial immunochemical fecal occult blood tests (FIT) and subsequent colorectal cancer, and to explore the ability of FIT to identify individuals age 40 to 49 years with a higher cancer risk. Background: The number of cancer cases in this age group is increasing globally and the cancers found in younger age tend to be more advanced than in older age. Methods: A total of 513,283 individuals had FIT as part of their selfpaying medical screening program between 1994 and 2008. The initial FIT test was used. When matched with the Taiwan cancer registry, the cohort identified 2138 colorectal cancer cases. The number needed to screen (NNS) to identify 1 cancer was calculated from the reciprocal of cancer incidence cases during the study period. Results: One in 7 colorectal cancers above age 40 years occurred in the age group of 40 to 49 years. Individuals 40 to 49 years old with positive FIT (≥100 ng/mL) had a 3 times larger cancer risk than those 50 to 59 years old and without FIT, or double the cancer risk as those 50 to 69 years old and without FIT, with NNS at 42, 135, and 95, respectively. A similar relationship existed for the cancer incidence rate. The HR for ages 40 to 44 years or 45 to 49 years with a positive FIT was 2.3 or 5.7 times larger than the HR for ages 50 to 54 years. There was a dose-response relationship between increasing FIT values and the cancer risk for each age group, including ages 40 to 49 years. Conclusions: Offering FIT to individuals 40 to 49 years of age could identify higher-risk individuals earlier for follow-up colonoscopy, and could, in turn, reduce cancer mortality.