The role of 7, 12 DMBA and three hormones in 7, 12 DMBA-induced rat mammary cancer: three hypotheses.

The investigation of the role of hormones in the development of hormone-dependent cancers is an interesting and important area of cancer research. A popular mode of examining this area is through experiments with rat or mouse mammary cancer induced by the potent carcinogen, 7, 12 dimethyl (alpha) benzanthracene (7, 12 DMBA). This paper looks at the action of three specific hormones--estrogen, progesterone and prolactin--in the 7, 12 DMBA-induced mammary cancers. Three hypothesis for their action are examined: 1) the hormone as a carcinogen, 2) the hormone as a regulator or neoplasia, and 3) the hormone as both an initiator and a regulator of neoplasia. Although the third hypothesis is probably the least popular among researchers, it will be suggested that it is the most comprehensive and the most complete in that it accounts for evidence giving rise to the first two hypotheses by incorporating both of them. The base of this third hypothesis as presented here is the structural homologies between steric hormones and 7, 12 DMBA. It is suggested that these homologies allow 7, 12 DMBA to interfere with normal hormonal action, and that this interference results in the development of these rat mammary tumors.