Results of international correlation and migrant studies suggest that
dietary fat promotes
carcinogenesis in
hormone-sensitive sites, but this is disputed. In the present study, we used a Noble rat model of
sex hormone-induced
cancers to examine the effect of a high-fat diet on the incidence and latency of prostate and
mammary cancer in male (n 139) and female (n 72) animals respectively. We also measured
alpha-tocopherol levels in female breast tissue to determine whether a high intake of
polyunsaturated fatty acids depletes
antioxidant defence in target tissues, providing a possible potentiating mechanism for
carcinogenesis. Results showed a very high incidence of
hormone-induced
adenocarcinomas of prostate and mammary gland, irrespective of diet. There was no difference in the pattern of
carcinogenesis in different prostatic locations, weight of the prostate, or
weight gain between male rats on the high-fat diet compared with the control (standard,
low-fat) diet. In female rats, the incidence of
mammary cancer and the
body-weight gain were the same in both dietary groups, and breast
alpha-tocopherol was also unaffected by
dietary fat intake. Our present results are supportive of recent cohort studies that reported no significant association between intake of fat and the development of human prostate and
breast cancer, and do not support a role for
dietary fat in promoting
sex hormone-induced prostate and mammary
carcinogenesis.