Antioxidant micronutrients and the risk of renal cell carcinoma in the Women's Health Initiative cohort

Prospective cohort analysis within the Women's Health Initiative (WHI). 96,196 postmenopausal women aged 50–79 at enrollment (1993–1998) from clinical trials and an observational study; excluded those with a history of any cancer other than nonmelanoma skin cancer at baseline and those with implausible energy intake; follow-up through July 2013; RCC cases centrally adjudicated. Baseline dietary micronutrient intake assessed by semi-quantitative FFQ; supplement use recorded via inventory; Cox proportional hazards models to estimate RCC risk across nutrient quartiles, adjusting for demographic, lifestyle, and health covariates.

Lycopene intake was inversely associated with RCC risk. Highest quartile vs lowest quartile showed a 39% lower risk (HR 0.61; 95% CI 0.39–0.97; P-trend = .015) after multivariable adjustment. Similar results in sensitivity analyses (HR 0.58; 95% CI 0.36–0.95; time-varying analyses HR 0.64; 95% CI 0.42–0.98). No significant associations for other micronutrients (β-carotene, α-carotene, β-cryptoxanthin, lutein + zeaxanthin, vitamin C, vitamin E), whether dietary or supplemental. Conclusion: Increased lycopene intake among postmenopausal WHI participants was associated with a lower RCC risk; findings support potential protective effect of lycopene but cannot prove causality due to observational design; further research on mechanism is warranted.

Baseline micronutrient intake rather than plasma levels; did not account for changes in intake over time; RCC subtypes data were insufficient for analysis; observational design limits causal inference; limited power for smoking-status subgroup analyses (only 7% current smokers; 21 cases among smokers).