Prospective cohort study of the association of residential radon levels with ovarian cancer risk among postmenopausal women

Women exposed tot ionizing radiation from atomic bombs during World War II experienced an increased risk of ovarian cancer. Today, the largest source of ionizing radiation in radon gas in the home. A prospective cohort study including postmenopausal participants from the Women’s Health Initiative, from 40 clinical centers across the US followed up for 31 years (1993-2024), investigated the association between home radon level and risk of ovarian cancer. Radon measurements from the 1993 US Geological Survey were classified into low (<2 pCi/L), median (2-4 pCi/L) and high zones (> 4 pCI/L) and linked to geocoded home addresses of participants at baseline (1993-1988). Among 127,547 women with available radon zone values, 1648 incident ovarian cancers and 1048 ovarian cancer deaths were observed over a mean follow-up of 17.7 ± 8.4 years. After adjustment for covariates, the HR for all ovarian cancers for women living in a median radon zone was nog significantly higher compared with women in a low radon zone (1.13; 95% CI 1.00-1.29); however the HR was significantly higher for women in a high radon zone compared with those living in a low radon zone (1.31; 1.11-1.54). Similar findings were observed for the most common histologic type, serous ovarian cancer. Ovarian cancer mortality also was significantly higher in the high compared with the low radon zone (HR 1.31; 95% CI 1.07-1.60). The authors conclude that the risks of ovarian cancer incidence and mortality were significantly higher for postmenopausal women living in high radon zones compared to low radon zones.