Background: In Japan, the westernization of lifestyle, especially dietary habits, has progressed remarkably since1950 and is presumably directly related to the increasing incidence of colorectal cancer (CRC). The aim of thisepidemiology note was to summarize the most recent trends in CRC incidence and predictions until 2020 for suggestingthe preventive strategies in Japanese.
Methods: Using the newest published data in Japan, the most recent trends inCRC incidence and the predicted numbers of incident cases of CRC until 2020 were summarized.
Results: Dietaryintake of milk, meat, eggs and fat/oil demonstrated remarkable increment through 1950 to 1970, and since then hasremained relatively constant. Compared with values for 1975, age-adjusted incidence rates for colon and rectalcancers were estimated to be 3.7 and 1.9 times higher among men and 2.9 and 1.3 times higher among women by1995 or 2000, respectively, and then to plateau. Considering progression of aging of the society, numbers of incidentcases for colon cancer among men and women have been predicted to increase 9.5 and 7.5 times by 2005 and 12.3 and10.5 times by 2020, respectively, from the 1975 baseline. Likewise, the figures for rectal cancer have been predictedto increase.
Conclusion: The increment of CRC incidence is assumed to coincide with such changes in dietary intakeafter approximately 20-years lag. Concrete programs for lifestyle modification and more emphasis of early cancerscreening are now needed for prevention purposes.