Higher Radon Levels Connected to Increased Risk of Ovarian Cancer in Postmenopausal Women

Key Takeaways:

• Higher radon levels are associated with an increased risk of ovarian cancer: Ovarian cancer had a higher occurrence among women living in high-level radon zones as opposed to medium- or low-level zones.
• Ovarian cancers in high radon zones have higher hazard ratios (HRs): Among all ovarian cancers in this study, those in high-level radon zones had substantially higher HRs than cancers in medium or low radon zones.
• These findings suggest radon as a potential risk factor for ovarian cancer: Targeting home radon levels could help mitigate the risk of ovarian cancer.

Despite ovarian cancer being the fifth leading cause of cancer-related deaths in the US, its etiology is not well understood by clinicians. Ionizing radiation has emerged as a possible risk factor for ovarian cancer, the largest source of which is radon gas. This study sought to observe whether higher radon levels are associated with an increase in ovarian cancer incidence and mortality.

This study used data from an observational study of postmenopausal women established by the Women’s Health Initiative. Participants were enrolled between 1993 and 1998 across 40 clinical centers with a follow-up of 31 years.

The Connection Between Radon Levels and Ovarian Cancer

Researchers assessed the possible impact of radon levels on a sample of 127 547 postmenopausal women. Radon levels were categorized into 3 zones, measured by picocuries per liter of air: low (<2 pCi/L), medium (2-4 pCi/L), and high (>4 pCi/L).

Out of the 127 547 patients, 28 225 (22.1%) lived in high radon zones, 48 145 (37.7%) lived in medium radon zones, and 51 177 (40.1%) lived in low radon zones.

This study recorded 1645 ovarian cancer incidences and 1048 ovarian cancer deaths. Incidence and mortality were higher among women living in higher radon zones: in high zones, there were 14.5 incident ovarian cancers per 1000 women; in medium zones, there were 13.0 incident ovarian cancers per 1000 women; and low zones had 11.9 incident ovarian cancers per 1000 women.

The HRs for ovarian cancer were higher in higher radon zones compared to medium and low radon zones. However, there was not a significant difference in HR between medium and low radon zones.

Implications for Clinicians

This study is one of the first to evaluate the association between radon and ovarian cancer, so future research is required to validate its findings.

These findings suggest radon as a potential risk factor for ovarian cancer. The risk of ovarian cancer appears to increase with radon exposure, as women living in higher radon zones had higher incidence and mortality of ovarian cancer.

The authors said, “Because serous ovarian cancer is highly fatal, and because radon levels in homes can be reduced, our findings could have large implications for ovarian cancer prevention.”

Reference

Williamson MR, Whitsel EA, Smith RL, et al. Residential radon levels and ovarian cancer among postmenopausal women. JAMA Netw Open. 2026;9(4):e268641. doi:10.1001/jamanetworkopen.2026.8641