Mechanisms by which dietary fat may stimulate mammary carcinogenesis in experimental animals.

Evidence drawn from epidemiological and experimental studies suggests that dietary fat is an important determinant of breast cancer risk and, in addition, that dietary fat acts as a modulator rather than an initiator of breast carcinogenesis. At present, however, it is not known how dietary fat exerts its tumor-promoting effects. A variety of mechanisms, some involving direct action by fat at the target organ and others involving host-mediated responses, have been proposed. The present status of one of these, namely, a mechanism based on mediation by the endocrine system, and the hormone prolactin in particular, is described. Further studies in laboratory animals are required to determine the precise cellular and molecular events which underlie the fat effect.