[Epidemiology of lung cancer and prevention strategy in Japan]

The incidence of and mortality from lung cancer have been increasing rapidly during recent decades in Japan, and in 1993 lung cancer became the leading cause of death from cancer in males. This increasing tendency is most striking for older age groups, especially those above 70 years of age. The incidence of multiple cancers related to lung cancer has been also increasing. Of the major risk factors for lung cancer, direct smoking has the greatest influence. When divided by histologic type, above 90% of cases of squamous cell carcinoma and small cell carcinoma can be explained by direct smoking, while this is true for only about 40% of adenocarcinomas. Although the efficacy of lung cancer screening is still controversial, its role in lung cancer control strategy appears to be limited. Therefore, a multi-disciplinary control program, including anti-smoking activity, chemoprevention and early detection by new techniques should be developed.