Lipids in breast carcinogenesis.

Excess dietary fat has been identified as a risk factor in the development of human breast carcinoma. However, the quality of fat may be more important than the overall quantity. We have studied the growth of human MCF7 breast carcinoma xenografts in athymic mice treated with dietary supplements of N-6 and N-3 series essential fatty acids given as natural preparations of evening primrose oil and fish oil. Olive oil and normal laboratory diet lacking the essential fatty acids served as controls. Animals treated with essential fatty acids developed tumours which were significantly smaller than both control groups (Mann-Whitney U test, P less than 0.001). Median tumour weights according to diet were: evening primrose oil, 133 mg; fish oil, 70 mg; olive oil, 212 mg; and control, 270 mg. Nutritional intervention to increase the proportion of essential fatty acids in the diet may have a role in the management of breast carcinoma.