Background: In Japan, the westernization of lifestyle, especially dietary habits, has progressed remarkably since 1950 and is presumably directly related to the increasing incidence of colorectal cancer (CRC). The aim of this epidemiology note was to summarize the most recent trends in CRC incidence and predictions until 2020 for suggesting the preventive strategies in Japanese.
Methods: Using the newest published data in Japan, the most recent trends in CRC incidence and the predicted numbers of incident cases of CRC until 2020 were summarized.
Results: Dietary intake of milk, meat, eggs and fat/oil demonstrated remarkable increment through 1950 to 1970, and since then has remained relatively constant. Compared with values for 1975, age-adjusted incidence rates for colon and rectal cancers were estimated to be 3.7 and 1.9 times higher among men and 2.9 and 1.3 times higher among women by 1995 or 2000, respectively, and then to plateau. Considering progression of aging of the society, numbers of incident cases for colon cancer among men and women have been predicted to increase 9.5 and 7.5 times by 2005 and 12.3 and 10.5 times by 2020, respectively, from the 1975 baseline. Likewise, the figures for rectal cancer have been predicted to increase.
Conclusion: The increment of CRC incidence is assumed to coincide with such changes in dietary intake after approximately 20-years lag. Concrete programs for lifestyle modification and more emphasis of early cancer screening are now needed for prevention purposes.