Residential radon exposure linked to ovarian cancer

Women residing in homes with high radon levels may be at increased risk of ovarian cancer, as suggested in a study.

A total of 127,547 women (mean age 63.1 years) from the Women’s Health Initiative were included in the analysis and were followed up for up to 31 years. Radon measurements were obtained from the 1993 US Geological Survey and linked with the geocoded home addresses of participants at baseline. Exposure levels were classified into low (<2 pCi/L), medium (2–4 pCi/L), and high zones (>4 pCi/L).

Over a median follow-up of 17.7 years, ovarian cancer occurred in 1,645 women, of which 1,048 died from the disease.

In Cox proportional hazards regression analysis, women living in the high radon zone had a 31-percent higher risk of ovarian cancer compared with those living in the low zone (hazard ratio [HR], 1.31, 95 percent confidence interval [CI], 1.11–1.54). The risk was not significantly different between women living in the medium radon zone and those living in the low zone (HR, 1.13, 95 percent CI, 1.00–1.29).

Results were consistent for serious ovarian cancer, the most common histologic type. A risk increase was observed among women living in the high vs low radon zone (HR, 1.38, 95 percent CI, 1.09–1.74) but not among those living in the medium vs low radon zone (HR, 1.06, 95 percent CI, 0.88–1.27).

Additionally, women living in the high radon zone had a significantly higher risk of ovarian cancer mortality compared with those living in the low radon zone (HR, 1.31, 95 percent CI, 1.07–1.60).

Similar results were obtained in sensitivity analyses using three alternate radon measures.