Abstract 1582: Catechol-O-methyltransferase (COMT) genotypes modify the effects of beta-carotene supplementation on cancer incidence in a controlled trial: findings from the ATBC Study

Abstract

Abstract Large cancer prevention trials of vitamin supplementation have yielded mixed results over the past three decades. Whether and how genetic variation that influences oxidative stress or vitamin absorption, transport, and metabolism can modify responses to supplementation remains to be elucidated. Catechol-O-methyltransferase (COMT) genotypes have been shown to impact the effects of vitamin E (i.e., alpha-tocopherol) supplementation on cancer, and the present pharmacogenetic analysis examines interactions among COMT, beta-carotene supplements, and risk of cancer. In a case-control study nested within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study of 29,133 Finnish men, we examined overall cancer risk based on the randomized assignment to beta-carotene supplementation (BC; 20 mg daily for 5-8 years) and two common genetic variants in COMT, rs4680 and rs4818 (genotyped by Illumina scans). Based on 2396 cases and 2235 non-cases, Cox proportional hazards models that adjusted for age, smoking intensity and duration, and randomized assignment to the trial vitamin E supplement were conducted to estimate overall cancer risk for the trial and 10-year post-trial periods combined. For rs4680, BC supplementation (versus no BC) was associated with higher cancer risk only in men with the AA (met/met) genotype (HR 1.29, 95% CI 1.08-1.53, P=0.004) as compared with the AG (met/val) and GG (val/val) genotypes (respectively, HR 1.04, 95% CI 0.93-1.16, P=0.52; and, HR 0.99, 95% CI 0.86-1.15, P=0.94). We observed a somewhat similar pattern for rs4818, with the BC supplement being associated with higher cancer risk in men with the GG and GC genotypes (respectively, HR 1.21, 95% CI 0.94-1.55, P=0.14; and, HR 1.15, 95% CI 1.01-1.30, P=0.03), but not the CC genotype (HR 0.99, 95% CI 0.88-1.11, P=0.80). Our findings indicate that the AA (met/met) genotype of COMT rs4680 and the G allele of rs4818 potentiate the increased cancer risk resulting from BC supplementation. Citation Format: Stephanie J. Weinstein, Jiaqi Huang, Kathryn Tayo Hall, Howard D. Sesso, Demetrius Albanes. Catechol-O-methyltransferase (COMT) genotypes modify the effects of beta-carotene supplementation on cancer incidence in a controlled trial: findings from the ATBC Study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1582.