Interval colorectal cancer rates after Hemoccult Sensa and survival by detection mode for individuals diagnosed with colorectal cancer in Winnipeg, Manitoba.

Abstract

ObjectiveTo assess the performance of the Sensa fecal occult blood test (FOBT) in a population-based screening program.SettingManitoba, Canada.MethodsThis historical cohort study included individuals 52 to 74 years of age diagnosed with colorectal cancer (CRC) from 2008 to 2013. CRCs were categorized by detection following a screening program FOBT (Sensa), non-program FOBT (non-Sensa), or no FOBT. Screening program CRCs were classified as program-detected, interval program, or non-compliant. Logistic regression was used to compare characteristics by detection mode. Cox regression adjusted for lead-time was used to examine the effect of detection mode on survival.Results1,498 individuals were diagnosed with CRC; 132 (8.8%) had a screening program FOBT, 626 (41.8%) had a non-program FOBT, and 740 (49.4%) had no FOBT. Of the screening program FOBT CRCs, 72 were program-detected (54.5%), 42 were interval program (31.8%), and 18 were non-compliant (13.6%). Sensa interval cancer rate was 37.4% and sensitivity was 63.1% (95% Confidence Interval (CI): 54.3%-72.0%). The risk of death for individuals that had a non-program (Hazard ratio (HR) = 0.57, 95% CI:0.44–0.75) or a screening program FOBT (HR = 0.55, 95% CI:0.31–0.97) was lower than no FOBT. There was no significant difference in the risk of death for interval, non-compliant, and non-program CRCs compared to program-detected CRCs. Adjusting for lead time bias, sex, income quintile, tumour location, and age at diagnosis did not appreciably change the risk estimates.ConclusionMore than one-third of CRCs may not be detected by Sensa. There may be no difference in survival between CRC detected by Sensa and non-Sensa FOBTs.