[Modifying effect of darkness on the growth of mammary cancer and on the efficacy of experimental hormone therapy].

A study was made of the effect of different light regimen on the changes in the reactive properties, and also of the efficacy of hormone therapy of the transplantable rat mammary carcinoma (RMC-1). In darkness the percentage of the take of the carcinoma proved to be less, and also the growth of the RMC-1 was delayed; there was also a marked increase in the efficacy of estrogen-therapy of mammary carcinoma. It is supposed that more effective treatment of the RMC-1 in darkness was associated with the change in functional activity of the hypothalamo-hypophyseal system.