Lung cancer in women and type of dwelling in relation to radon exposure.

A case-control study based on interviews with 210 incident female lung cancer patients, 209 age-matched population controls, and 191 hospital controls was carried out in Stockholm county, Sweden. Radon measurements made in a sample of 303 dwellings, in which the study subjects had lived, showed that dwellings with ground contact had an average concentration of approximately 160 Bqm-3, twice the average concentration of other dwellings. A cumulated radon exposure index was calculated for each subject based on data from the interviews and the measurements. For the total group of lung cancer a relative risk (RR), adjusted for smoking, age, and degree of urbanization, of 1.8 (95% confidence interval: 1.2-2.9) and 1.7 (0.9-3.3) associated with "intermediate" and "high" exposure to radon was found. There was also a significant trend to a positive dose-response relationship (Ptrend = 0.03). For small cell cancer the corresponding figures for RRs were 1.9 (0.6-4.5) and 4.7 (1.5-14.2), respectively (Ptrend = 0.01). There seemed to be a positive interaction between radon exposure and smoking in relation to lung cancer. The findings indicate that domestic radon may be of importance for the induction of lung cancer, particularly for some histological types.