A SUGGESTED MECHANISM FOR EFFECTS OF DIET ON MAMMARY-CANCER

The adipose tissue of the mammary gland appears to have a marked influence on growth and development of the glandular epithelial parenchyma. This glandular tissue can be transplanted to other fat pads but develops only within the boundaries of the fat pads. A high-fat diet favours the deposition of fat in body tissues and our recent experiments have indicated that this is reflected in the fat content of the mammary gland more rapidly than on body weight as a whole. An expansion of the adipose tissue intimately associated with the mammary parenchyma may promote mammary carcinogenesis by increasing the amounts of estrogens, eicosanoids, diacylglycerols or other growth factors that stimulate cellular proliferation. On the other hand, caloric restriction or increased exercise may inhibit mammary carcinogenesis by decreasing the amount of adipose tissue in the mammary gland. Dietary palm oil does not promote mammary carcinogenesis like other vegetable oils and this may be related to a protective effect of palm oil tocotrienols deposited in mammary adipose tissue.