Indoor Radon and Lung Cancer Risk. A Pooling Study on the Second Risk Factor for Lung Cancer

Abstract

Background. Residential radon is the second risk factor of lung cancer following tobacco consumption, according to WHO (World Health Organization) and United States EPA statements. It is recognized as the first cause of lung cancer in never-smokers by both organizations. Nevertheless, case-control studies performed in radon prone areas are still scarce and with limited sample sizes. We aim to know the relationship between residential radon and lung cancer risk in a study performed in a radon-prone area, and where inhabitants live for a long time in the same dwelling.

Method. We have pooled results from 5 different case-control studies performed in the same geographical area to assess the relationship between indoor radon and lung cancer. One of these studies was focused specifically in never smokers and other in Small Cell Lung Cancer. All cases and controls were older than 30 and cases had a confirmed diagnosis of lung cancer. Controls were selected for attending hospital for trivial surgery. Controls were selected through a frequency-based sampling based on age and gender distribution of cases. The information and questionnaires collected was the same in all studies, with special focus on tobacco consumption. Radon devices of an alpha track type were placed at the participants’ homes for at least three months. Odds Ratios of lung cancer due to radon exposure have been calculated adjusted by age, gender, and tobacco consumption.

Result. We included 1691 cases and 1698 controls. Median age was 63 and 67, respectively, and females comprised 33% of both cases and controls. Adenocarcinoma was the most frequent histology (43%) and participants lived a median of 30 years in the same dwelling. The table show the risk of lung cancer due to radon exposure.

Conclusion. Residential radon is a relevant risk factor for lung cancer, even below concentrations established as safe by USEPA and WHO.