PURPOSE: Examine whether baseline colonoscopy findings are associated with non-Colorectal Cancer (CRC) mortality in a Veteran screening population.
BACKGROUND: Although screening colonoscopy findings are associated with future risk of CRC mortality, whether these findings are also associated with non- CRC mortality remains unknown.
METHODS: The Cooperative Studies Program (CSP) #380 cohort is comprised of 3,121 Veterans age 50-75 who underwent screening colonoscopy from 1994-97. Veterans were followed for 10 years or death, as verified in electronic medical records. Those who died from CRC-specific causes were excluded from this analysis (n=18, 0.6%). Hazard ratios (HR) for risk factors on non-CRC mortality were calculated by Cox Proportional Hazard model, adjusting for demographics, baseline comorbidities, and lifestyle factors. Information on comorbidities, family history, diet, physical activity, and medications were obtained from self-reported questionnaires at baseline.
RESULTS: Of the included 3,103 Veterans, most were male (n=3,021, 96.8%), white (n=2,609, 83.6%), with a mean age of 62.9. During the 10-year follow-up period, 837 (27.0%) Veterans died from non-CRC causes. The risk of non-CRC mortality was higher in Veterans with ≥3 small adenomas (HR 1.45, p=0.02), advanced adenomas (HR 1.34, p=0.04), or CRC (HR 3.00, =0.05) on baseline colonoscopy when compared to Veterans without neoplasia. Additionally, increasing age (HR 1.07, <0.001), modified Charlson score (HR 1.57 for 3-4 points, <0.001, compared to 0-2 points) and current smoking (HR 2.09, <0.001, compared to former and non-smokers) were associated with higher non-CRC mortality. On the other hand, increasing physical activity (HR 0.88, <0.001), family history of CRC (HR 0.75, =0.02), and increased BMI (HR 0.73-0.75, <0.01) were associated with reduced non-CRC mortality. Neither race, NSAID use (including aspirin), or dietary factors impacted non-CRC mortality.
CONCLUSIONS: In a Veteran CRC screening population, we found that high-risk adenomas or CRC on baseline colonoscopy were independently associated with increased non-CRC mortality within 10 years. Future work will examine the cause-specific factors associated with non-CRC mortality in these groups to 1) identify potential high-yield strategies for tailored non-CRC mortality risk reduction during CRC screening, and 2) better determine when competing risks of non-CRC mortality outweigh the benefit of follow up colonoscopy.