Lung Cancer Incidence in Counties at Low and High Risk of Radon Exposure: A Population-Based SEER Analysis (1975-2022)

Background Lung cancer is the leading cause of cancer-related mortality in the United States. While smoking cigarettes remains the dominant risk factor, declining smoking rates have drawn attention to Radon. Despite the known risks from individual exposure to radon, less is known about long-term trends in Radon-related lung cancer at the population-level. Methods Using SEER-8 cancer registry data from Connecticut, Iowa, New Mexico, and Utah, we compared lung cancer incidence between counties classified by the EPA as low-risk and high-risk (>4.0 pCi/L) for radon exposure. Constructing a random effects Generalized Least Squares regression, which adjusted for county-level smoking prevalence, we quantified the excess lung cancer rate attributable to radon risk across decade, sex, and histologic subtype. Results Compared to low-risk counties, counties at high risk of radon exposure had a significantly higher overall lung cancer incidence: 13.5+ cases per 100,000 person-years (95% CI: 10.0, 17.1). This gap between low and high-risk counties was largest for Adenocarcinoma and small cell carcinoma, and larger in males than females. However, only in females did we observe the gap in lung cancer incidence between low- and high-risk counties grow decade after decade. Conclusions This study illustrates how county-level radon data can be leveraged to enhance cancer surveillance and guide prevention and control strategies. Further research is needed to evaluate the impact and cost-effectiveness of radon prevention or mitigation policies, especially in females. We argue that public health systems, over the next fifty years, must prioritize eliminating the two main drivers of America’s deadliest cancer. Key Messages Radon is the second leading cause of lung cancer, and the primary cause among non-smokers. High-risk Radon counties had higher incidence of lung cancer over a nearly 50-year period. In females only, the gap between low and high-risk Radon counties grew decade after decade.