Prognostic assessment of lung cancer risk under combined action of radon and smoking using an additive-multiplicative risk model

An application of geometric mixed additive-multiplicative models for lung cancer risk modeling under combined action of radon and smoking is justified in this paper. The geometric mixed model allows: 1) to reduce the discrepancies between estimates of the lung cancer risk for males and females, 2) to predict the population risk under condition of the varying smoking prevalence and changing average indoor radon concentration level. Using the geometric mixed model, the calculation of the lung cancer risks for the Russian Federation population was carried out for different percentages of smokers among the population, an increase in life expectancy, and a change in the average radon concentration level in residential buildings. Assuming that currently rounded average indoor radon concentration in Russia is 50 Bq/m3, the contribution of radon to total mortality in 2009 was 0.46% and 0.20% for male and female, respectively. Modeling has shown that the effect of lung cancer mortality reducing due to the predicted decrease in the proportion of smoking population will partly be offset by an increase in the realization of lung cancer risk with the life expectancy increase. For a hypothetical situation, when the entire population maintain a healthy lifestyle and mortality from cardiovascular, oncological, infectious diseases, diseases of the respiratory tract and from external causes has significantly decreased, the contribution of radon exposure to total mortality will increase to about 0.8%. If the average level of radon in buildings will increase due to energy-efficient technologies widespread implementation in building construction, the contribution of radon to total mortality will be even more noticeable.