PIP: Benign breast disease (BBD), of which fibrocystic disease (FCD) is the most common, results from an imbalance in estrogen-progestogen ratios or inappropriate target gland response to changing tides of hormonal stimulation. Histologically, FCD may present as simple cystic glandular hyperplasia, adenosis, chronic cystic mastitis with apocrine metaplasia, and ductal papillomatosis. Fibroadenoma, a pseudoencapsulated tumor, is another variant. Experimental animal data yield some clues as to the etiology of FCD, but extrapolation to the human may be inappropriate. The anovulatory female rarely develops severe FCD, as manifested by marked pain and lumpiness. Oral contraceptives (OCs) reduce the incidence of FCD and the frequency of mammary cancer in comparison with controls. The administration of methyltestosterone, and at times testosterone, to males has resulted in multiple soreness and gynecomastia. Cancer of the breast has occurred in 2 male transvestites who had been on estrogens. The development of mammary cancer in men on stilbestrol therapy for prostatic cancer has recently been challenged. 1 in 11 women in the U.S. will develop breast cancer in her lifetime. Warren has claimed that malignancy was 4.5 times greater in women who had been biopsied for FCD than in normal female population. Cole and MacMahon reviewed the world literature and found the presence of FCD increased the risk of cancer by 2.64 times. FCD is an exaggeration of the normal tissue response of the breast resulting from the ebb and flow of ovarian hormones. FCD is characterized by pain and tenderness, most marked in the premenstrual period but later may continue throughout the cycle. The lumpiness or nodularity may be localized or generalized, unilateral or bilateral. Reported surveys showing that oral contraceptives (OCs) lessen the incidence of FCD suggest that hormonal manipulation can effectively reduce the frequency of this disease, and, possibly in turn, the incidence of mammary cancer. Cystic masses should be aspirated and the contents examined for cytologic atypia. It is important to find those women who are at greater risk of developing mammary cancer because of florid fibrocystic disease. FCD should be medically managed unless a dominant lump develops, in which case a biopsy should be performed. The use of a newsteroidal agent, danazol, on a 3-6 month trial of 100-400 mg/day will eliminate pain and nodosities in some 69% of women and in another 30% the signs and symptoms will be diminished.