Risk factors for renal cell cancer in a Japanese population.

The incidence of renal cell cancer has been increasing worldwide. Although the incidence of renal cell cancer in Japan is lower than the rates in the other industrialized countries, there is no doubt that it is increasing. In this paper, we would like to introduce the result of our studies, which evaluate the risk factors for renal cell cancer in Japan. Hypertension, diabetes mellitus, kidney diseases, fondness for fatty food and black tea showed an increased risk of renal cell carcinoma while an intake of starchy roots such as taro, sweet potato and potato reduced the risk of renal cell carcinoma. In Japan, however, drinking black tea may be a surrogate for westernized dietary habits while eating starchy roots may be a surrogate for traditional Japanese dietary habits. Further studies may be needed to evaluate risk factors for renal cell cancer because the number of renal cancer cases was small in our studies in spite of a large population-based cohort study.