Researchers: Lior Katz^1,2, Ronit Calderon Margalit^1,2, Zohar Levi^3,4

Background: Colorectal cancer (CRC) is the second leading cause of cancer-associated mortality in Israel. Screening reduces CRC-associated mortality. We assume that most cases of CRC-related mortality are associated with failures during the screening process.

Objectives: To determine the association between participation and adherence to CRC cancer screening program and CRC-related mortality, and discover different failure types in the screening process.

Method: This is a case-control study, including all Clalit Health Services members, died from CRC during 2012-2019 at the age of more than 55 years. We measured the rate of participation and adherence to CRC screening 10 years before CRC diagnosis. Data was compared by a ratio of 1:3 to a matched control group. Specific clinical endoscopic and histologic data were collected from a subgroup of patients from Dan-Petach-Tikvah district and South District. Differences in proportions of screening failure types were analyzed in the case and control groups.

Findings: Of 1366 CRC deaths, 76.8% (n = 1026) occurred in patients who were not up to date in screening. Of 6648 cancer-free patients, 77% were up to date in their screening. Patients who were not up to date in their screening had a higher risk of CRC death (odds ratio, 3.01; 95% confidence interval, 2.41-3.68). Failure to screen at appropriate intervals, occurred in a 54.48% of patients who died of CRC vs 28.43% of cancer-free patients. CRC death was associated with higher odds of failure to screen or failure to screen at appropriate intervals or failure to follow-up on abnormal results (odds ratio, 4.56; 95% confidence interval, 3.98-5.22).

Conclusions: Being up to date on screening substantially decreases the risk of CRC death. Even though there are high rates of screening, most people who died of CRC had failures in the screening process that could be rectified, such as failure to screen at intervals and to ever screen; these significantly increased the risk for CRC death.

Recommendations: Our conclusions can help policy makers in Israel to plan a specific intervention for reducing failures in the CRC screening process and to identify populations at risk for non-compliance in the screening program.

Research end date: 05/2024