Epidemiologists in Japan have been performing calculations to estimate nationwide cancer incidence rates as well as 5-year survival rates using population-based cancer registry data. There have been remarkable changes in cancer incidence and/or mortality in cancers of the lung, liver and stomach, which were thought to be attributed to the changing impact of exposure to cigarette smoking, chronic hepatitis C virus infection and Helicobacter pylori infection, respectively. In systematic reviews providing evidence in risk/protective factors for cancer sites using case-control and cohort studies of the Japanese population, there were associations between cancer sites (esophagus, stomach, colo-rectum, liver, pancreas, lung and breast) and various lifestyle factors. In the past 10 years, a hospital-based case-control study at Aichi Cancer Center provided valuable evidence of gene-environment interaction on the development of cancer [i.e., the effects of aldehyde dehydrogenase-2 (ALDH2) polymorphism and heavy alcohol drinking on esophageal cancer, ALDH2 polymorphism and smoking on lung cancer, methylenetetrahydrofolate reductase polymorphism and heavy alcohol drinking on pancreatic cancer]. The database with stored DNA was also used and identified seven loci containing significant but low-penetrance polymorphisms associated with the development of breast cancer. These findings together with established risk factors are likely to be useful to predict personalized breast cancer risk in East Asian women. In 2005, the Japan Multi-Institution Collaborative Cohort (J-MICC) study was launched to elucidate gene-environment interactions as well as to confirm preclinical diagnostic biomarkers of cancer. J-MICC, which has recruited 92,000 healthy individuals by the end of 2012, will follow the individuals until 2025.Over the past five decades, research on cancer epidemiology in Japan has been developing at a rapid pace. In descriptive epidemiology, Dr. Mitsuo Segi (well-known for "Segi's world population") started a population-based cancer registry in Miyagi prefecture in 1959. The population-based cancer registry expanded to cover the whole country of Japan in 2012, together with improving the quality of the data. These population-based data have been efficiently used in cancer control planning conducted by the Japanese Government since 2007. In analytical epidemiology, a "Large-Scale Census-Based Cohort Study" of cancer, and other major causes of death, was conducted by Dr. Takeshi Hirayama in 1965, recruiting 265,118 adults aged 40 years and over. From this cohort study, Dr. Hirayama first reported that passive smoking increased the risk of lung cancer in 1981.1 In 1991, the Japan Epidemiological Association (JEA) was established to promote epidemiological research. The recent trend in cancer epidemiology is focusing on molecular epidemiology, elucidating gene-environment interaction, as well as international collaboration of combining cohort data. This paper presents recent results in cancer epidemiology studies in Japan. Som...