Gynaecomastia complicating the treatment of myeloma.

The hormonal mechanisms involved in the development of gynaecomastia accompanying the treatment of multiple myeloma in adult men have been investigated by studying levels of circulating testosterone (T), oestrone (EI), oestradiol (E2), sex-hormone binding globulin (SHBG), prolactin (PRL) and the gonadotrophins LH and FSH, before, during and after development of gynaecomastia in 4 men. These have been compared with 5 closely matched men who did not develop gynaecomastia during similar treatment for myeloma. Levels of circulating T fell, and levels of E1 and E2 rose during treatment periods in all subjects, and the changes were statistically significant in subjects developing gynaecomastia, which resolved as levels of sex steroid returned towards normal following cessation of treatment. We conclude that treatment of adult men for myeloma results in testicular dysfunction with a reduction in circulating T and a rise in circulating oestrogens. These changes are most marked in subjects developing gynaecomastia in whom the normal breast tissue is stimulated by a subtle, transient oestrogen:androgen imbalance in favour of oestrogens.