Tamoxifen as a therapeutic agent in acromegaly.
OBJECTIVE
Administration of high doses of estrogens to patients with acromegaly has been shown to improve symptomatology of acromegaly and glucose tolerance more than 50 years ago. Selective estrogen receptor modulators (SERMs) mimic the effects of estrogen in bone, liver and the cardiovascular system, but function as an anti-estrogen in endometrial and breast tissue. In this study, we evaluated hormonal effects of a SERM, tamoxifen, in active acromegalic patients with particular emphasis on its use in males.


METHODS
We studied 15 men and 2 post-menopausal women with biochemically-active acromegaly despite the fact that other modalities were ineffective in normalizing their insulin-like growth factor-1 (IGF-1) levels. All patients were treated with tamoxifen 20-40 mg daily for 2-11 months (median of 4 months).


METHODS
IGF-1 and growth hormone (GH) levels were assessed immediately before the beginning of treatment and at 2-4 monthly intervals thereafter. Baseline and treatment levels of total and bioavailable testosterone were measured in men.


RESULTS
Tamoxifen did not affect basal GH secretion, but it decreased circulating IGF-I in 14 patients (82%) by an average of 90 ± 4 mcg/L, (p = 0.005), and normalized plasma IGF-I in 8 patients (47%). Total and bioavailable testosterone levels increased in all evaluable men (n = 8). Tamoxifen was well tolerated.


CONCLUSIONS
Tamoxifen might be useful in the treatment of patients with biochemically-mild active acromegaly, but longer term studies are warranted.
Division of Metabolism, Endocrinology and Diabetes, University of Michigan, 24 Frank Lloyd Wright Drive, G-1500, Ann Arbor, MI, 48106, USA.
Irida
I
Balili
Ariel
A
Barkan
D000172:Acromegaly / Q000188:drug therapy*; D000328:Adult; D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D005260:Female; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D013629:Tamoxifen / Q000627:therapeutic use*; D013739:Testosterone / Q000097:blood; D016896:Treatment Outcome; D055815:Young Adult
D018931:Antineoplastic Agents, Hormonal; D013629:Tamoxifen; D019382:Human Growth Hormone; D013739:Testosterone; D007334:Insulin-Like Growth Factor I