Effects of danazol on incidence of progesterone and oestrogen receptors in benign breast disease.

Results from a continuing clinical trial in benign breast disease indicate that danazol may induce progesterone receptors and that this effect persists after treatment. In women given danazol the number of biopsy specimens that were positive for progesterone receptors rose from 14 out of 31 before treatment to 23 out of 30 at the end of six months' treatment and remained raised at 21 out of 31 six months later. The number of biopsy specimens that were positive for oestrogen receptors rose transiently from eight out of 31 to 12 out of 30 and then fell to six out of 31. A satisfactory clinical response was achieved in 26 of the 31 patients but was maintained in only 11 six months or more after the end of treatment. It was only in this group that a significant and long-standing increase in progesterone receptors was observed. These findings suggest that in some women with benign breast disease who have been treated with danazol changes occur that may have long term benefit.