Radon Risk May Extend Beyond Lung Cancer

Emerging data from the Women’s Health Initiative (WHI) reveal that increased ovarian cancer incidence and mortality amongst postmenopausal women have a strong association with residential radon exposure. Women who lived in high-radon zones (> 4 pCi/L) were found to have a greater risk for developing ovarian cancer compared with women who resided in low-exposure zones (< 2 pCi/L). These data imply that the established environmental carcinogen, radon, has ties to the development of ovarian cancer beyond its association with developing lung cancer.¹

What Radon Is and Why it Matters

Radon is a naturally occurring radioactive gas that lacks color, smell, or taste and is produced by the decay of uranium in soil and rock. Radon can accumulate indoors and be inhaled over time. This leads to radon breaking down or decaying inside the body and releasing alpha radiation that can directly damage cellular DNA and promote carcinogenesis, leading to a higher risk of cancer.² In the United States, radon exposure is the second-highest leading cause of lung cancer, and is designated a preventable environmental health risk by the US Environmental Protection Agency.³ While there are insufficient data on radon’s ties with nonpulmonary cancers, a biologically plausible mechanism exists for systemic radiation-related effects.

Study Overview

The WHI prospective cohort followed 127,547 postmenopausal women who participated in this research between 1993 and 1998 and were followed for up to 31 years. The estimated radon exposure was determined by the US Geological Survey (USGS), and addresses were categorized as low (< 2 pCi/L), medium (2-4 pCi/L), or high (> 4 pCi/L).¹ The data gathered from participants revealed 1645 incident ovarian cancers and 1048 ovarian cancer deaths. The data analysis also took alternative factors into consideration, including smoking, age, reproductive history, and hormone therapy use, to further understand radon exposure’s role in ovarian cancer risk.¹

Key Findings: Association Between Radon and Ovarian Cancer

After adjusting for other risk factors, the data revealed that women residing in high radon exposure zones had a significant increase in risk for ovarian cancer compared with women who resided in low radon exposure zones (HR, 1.31; 95% CI, 1.11-1.54). However, there was no statistically significant increase in ovarian cancer risk for women in medium radon exposure areas.¹ The data show that high radon exposure is associated with a higher risk of developing serous ovarian cancer, the most common and aggressive type of ovarian cancer. These findings remained consistent across multiple analytical models, which supports the reliability of the association.¹

Biological Plausibility and Interpretation

When radon decays, it produces ionizing alpha particles that emit alpha radiation. These particles are highly energetic and damaging to cells. This damage includes double-strand DNA breaks and chromosomal instability, both of which are central mechanisms in carcinogenesis.² Breathing radon into the lungs is the primary source of exposure; however, radon is soluble in blood, raising the possibility of it traveling beyond the lungs and raising exposure to internal organs, including ovarian tissue. This is consistent with data regarding atomic bomb survivors that linked the significant increase in risk of cancer, including ovarian cancer, to high-dose ionizing radiation exposure.² These data also suggest that even chronic low-dose environmental exposure is associated with increased risk in the general population.

Implication for Pharmacists

Pharmacists play a crucial role in preventive health care, oncology care, and environmental risk counseling. It is vital to keep patients informed about lifestyle risks, including environmental risks such as radon, and to provide counseling on potential risk-reduction strategies, such as encouraging home testing. Pharmacists are well positioned to recommend cancer screenings; perform point-of-care testing; refer patients to the appropriate physicians if abnormalities are detected; and identify potential drug interactions between medications and treatments. Pushing for home testing is especially crucial for patients in geographic regions with known elevated radon levels. For patients with elevated baseline cancer risk, such as those with BRCA mutations or significant family history, pharmacists may incorporate environmental exposures into broader risk assessment discussions. Addressing environmental carcinogens during counseling aligns with the expanding role of pharmacists in cancer prevention and population health.

REFERENCES

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

2. National Research Council. Biological Effects of Ionizing Radiation (BEIR VI): The Health Effects of Exposure to Indoor Radon. National Academies Press; 1999.

3. Radon and health. US Environmental Protection Agency. Accessed April 2026. https://www.epa.gov/radon