[High-risk group--breast cancer].

Amongst the various elements regarded as risk factors of breast cancer, such as family history of breast cancer, past history of mammary diseases, unmarried status, sterility and first birth at a late age, the most critical is weight and height increase due to a high fat/high protein diet. Only twenty years ago, Japan was one of the countries with the lowest mortality rate due to breast cancer, and the rapid rise seen since then is presumably because of the westernization of food. Our present investigation has proved that breast cancer patients are larger in weight and height in comparison with normal women. The second cause of this increase in breast cancer patients in Japan is the longer period for which women menstruate, due to early menarche and late menopause. This tendency has lately become conspicuous and is considered to have a strong influence on the increase of breast cancer. It has also been noted that the age of occurrence of breast cancer in Japan is gradually advancing, so that the range is shifting from middle-aged patients to those in old age, as in Western countries.