Cost-effectiveness of lung cancer screening in Japan.

BACKGROUND Because the mortality rate from lung cancer is increasing sharply in Japan, lung cancer screening is being performed actively to assure early diagnosis and early treatment. However, its effectiveness is not clear, because it is extremely difficult to diagnose early microcarcinoma of the lungs (< 1 cm in greatest dimension) with the indirect X-rays that are used in mass screening. Therefore, the authors compared differences in the study population by gender and by age and economic class with the present method for mass screening of lung cancer as well as with computed tomography (CT) screening from the standpoint of cost-effectiveness. METHODS The cost-effectiveness of lung cancer screening was analyzed using the deterministic mathematical model developed by T. Iinuma. The total cost for one life saved (Y/N) and the total cost for the mean life expectancy of a patient saved (Y/NT) were compared for each three cases: mass screening of the type used in 1983, mass screening of the present type, and mass screening using CT in 1993. RESULTS For the present mass screening method, the results show that costs are reduced when patients are males age - 55 years and females age > or = 65 years. There was almost no difference between 1983 and 1993, and the percentage increased slightly with the introduction of CT. The cost-effectiveness was observed using two values, Y/N and Y/NT. The cost of screening in 1993 for females age < or = 50 years was lower than that in 1983, but there was no major difference in males from the other age groups. The Y/NT value became even lower when CT was introduced. CONCLUSIONS The results show that the present method used in lung cancer screening is cheaper, but its effectiveness is also low; and, although the cost of screening by CT is higher than that of the present screening method, it is much more effective. Lung cancer screening by CT should become the most appropriate screening method with respect to cost-effectiveness.