Abstract 1909: Pre-diagnostic vitamin D in association with colorectal cancer- and all-cause mortality: a prospective study among a non-Hispanic Black cohort

Abstract Purpose: Evidence from RCTs suggests vitamin D supplementation may improve colorectal cancer (CRC) outcomes after diagnosis. However, most trials did not include large numbers of Black patients, who typically have lower vitamin D levels. We evaluated associations between vitamin D with all-cause and CRC-specific mortality after CRC diagnosis. Methods: Data arose from 220 participants of the Southern Community Cohort Study diagnosed with incident CRC. Eligible patients were ages 40-79 at enrollment, non-Hispanic Black, English-speaking, and provided a blood sample at enrollment for biomarker measurement. Patients provided information on lifestyle factors, demographics, and personal medical history, primarily via in-person interviews. Concentration of 25-hydroxyvitamin D was measured from blood samples taken at enrollment and were categorized by the Institute of Medicine’s categories of deficient (<12ng/mL), inadequate (12-19.9ng/mL), or adequate (≥20ng/mL). Vital status was obtained through linkages with the National Death Index through December 31, 2020. Cox proportional hazards were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between 25-hydroxyvitamin D concentration and mortality. Statistical models adjusted for the following covariates: age at diagnosis, race, sex, cancer stage, education, income, alcohol intake, smoking history, screening history, obesity, insurance coverage, and physical activity. Results: Circulating 25-hydroxyvitamin D concentration was inversely associated with CRC-specific and all-cause mortality. Specifically, patients with pre-diagnosis 25-hydroxyvitamin D concentration categorized as adequate had reduced all-cause mortality in comparison to participants with deficient vitamin D concentration with a HR of 0.58 (95%CI: 0.35, 0.97). Stronger associations between 25-hydroxyvitamin D concentration and all-cause mortality were observed among participants where blood draw occurred three-five years before diagnosis. Associations were strongest among current smokers where the HR for each per-standard deviation increase of 25-hydroxyvitamin D concentration with all-cause mortality was 0.58 (95%CI: 0.36,0.92), and among obese participants the HR for a per-standard deviation increase of 25-hydroxyvitamin D with all-cause mortality was 0.45 (95%CI: 0.27,0.75). An inverse association was also observed with CRC-specific mortality, although the association was attenuated (HR for per-standard deviation increase of 25-hydroxyvitamin D=0.83; 95%CI: 0.63,1.08). Conclusions: Our findings suggest that pre-diagnosis vitamin D concentration is inversely associated with mortality after a CRC diagnosis among Black individuals. Correcting vitamin D deficiency may be warranted among Black CRC patients, particularly for those who smoke or are obese. Citation Format: Shaneda Warren Andersen, Thomas Lawler, Nikhil K. Khankari, Xiao-Ou Shu, Mark D. Steinwandel, Qiuyin Cai, Peter W. Peter W Jurutka, Wei Zheng. Pre-diagnostic vitamin D in association with colorectal cancer- and all-cause mortality: a prospective study among a non-Hispanic Black cohort [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1909.