Breast, androgens

Glucocorticoids have inhibitory (apoptotic) effects on lymphocyte proliferation and are used to treat leukemias and lymphomas. Estrogens (fosfestrol) are used to block the effect of androgens in prostate cancer. Progestogens (megestrol, medroxyprogesteroneacetate) have been useful for treating endometrial carcinoma, renal tumors, and breast cancer. 

Hormone antagonists (tamoxifen and toremifen bind to the estradiol receptor, flutamide binds to the androgen receptor) are used for treating breast and prostate cancer. 

In men, administration of an androgen may result in breast enlargement (gynecomastia), testicular atrophy, inhibition of testicular function, impotence, enlargement of the penis, nausea, jaundice, headache, anxiety, male pattern baldness, acne, and depression. Fluid and electrolyte imbalances, which include sodium, water, chloride, potassium, calcium, and phosphate retention, may also be seen. 

In women receiving an androgen preparation for breast carcinoma, the most common adverse reactions are amenorrhea, other menstrual irregularities, and virilization (acquisition of male sexual characteristics by a woman). Virilization produces facial hair, a deepening of the voice, and enlargement of the clitoris. Male pattern baldness and acne may also be seen. 

Exemestane is an irreversible aromatase inactivator that binds to the aromatase enzyme to block the production of estrogen from androgens. Exemestane is absorbed rapidly after oral administration, with a terminal half-life of 24 hours. The drug is eliminated primarily by the liver and feces, with less than 1% of the dose excreted unchanged in the urine. Exemestane is indicated for the treatment of advanced breast cancer in postmenopausal women who have had disease progression following tamoxifen therapy. Side effects include hot flashes, fatigue, osteoporosis/bone fractures, and flulike symptoms. 

Letrozole is another selective aromatase that inhibits the conversion of androgens to estrogen. Maximum plasma concentrations occur 1 hour after oral dosing concomitant food has not been shown to have an effect on the extent of absorption of letrazole. The terminal half-life is approximately 2 days. Letrozole is used in the treatment of postmenopausal women with hormone-receptor-positive or unknown advanced breast cancer. Side effects include bone pain, hot flushes, back pain, nausea, arthralgia, osteoporosis/bone fractures, and dyspnea. 

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