Circulating antioxidants play no protective role in breast, ovarian cancers

Genetically predicted circulating antioxidants do not appear to have a protective effect on the risk of breast cancer, ovarian cancer, or their histotypes, according to the results of a two-sample Mendelian randomization (MR) study.

Researchers used several published data to obtain instrumental variables as proxies of genetic liability to circulating antioxidants. Meanwhile, they utilized genome-wide association study (GWAS) conducted by the Breast (122,977 patients and 105,974 controls) and the Ovarian (25,509 patients and 40,941 controls) Cancer Association Consortiums to obtain summary-level data of breast and ovarian cancer.

Results of inverse variance–weighted tests showed no evidence supporting that breast cancer and its histotypes had a causal association with absolute levels of genetically predicted circulating antioxidants, such as β-carotenoid (odds ratio [OR], 0.98, 95 percent confidence interval [CI], 0.92–1.05; p=0.627), lycopene (OR, 0.99, 95 percent CI, 0.95–1.03; p=0.532), retinol (OR, 0.87, 95 percent CI, 0.49–1.55; p=0.645), ascorbate (OR, 1.00, 95 percent CI, 0.99–1.00; p=0.123), and metabolites α-tocopherol (OR, 0.88, 95 percent CI, 0.65–1.19; p=0.394), γ-tocopherol (OR, 1.00, 95 percent CI, 0.87–1.16; p=0.978), retinol (OR, 1.02, 95 percent CI, 1.00–1.04; p=0.070), and ascorbate (OR, 0.99, 95 percent CI, 0.91–1.06; p=0.703).

Likewise, genetic determinants of circulating antioxidants had no beneficial effect on ovarian cancer and its histotypes.

While the present data suggest that single antioxidants may not play a significant role in breast or ovarian cancer prevention, it is still possible that high intake of antioxidant-rich foods, which also contains many other potentially beneficial components, may be helpful.