Male breast cancer is relatively rare, accounting for less than 1 percent of all cases of cancer in men. An estimated 1,500 new cases were diagnosed in 2002, and approximately 400 deaths were attributed to the disease. The median age at diagnosis is 68 years, and the age range is five to 93 years. Giordano and associates reviewed the literature on breast cancer in men.

Risk factors (see accompanying table) for breast cancer in men suggest a hormonal imbalance, and up to 20 percent of male breast cancer cases have been associated with Klinefelter's syndrome. A family history of breast cancer, especially in first-degree relatives, is an important predisposing factor. Men with mutations of the breast cancer susceptibility gene BRCA2 have a higher risk of breast cancer. Gynecomastia is not a risk factor for breast cancer in men.

The most common clinical presentation is a painless subareolar mass. Other common presenting signs include nipple retraction, local pain, nipple ulceration, bleeding, and discharge. Unilateral disease is most common. Mammography is useful to identify malignant conditions. A biopsy is the definitive diagnostic test and should include tumor grade and hormone-receptor status.

The histology of breast cancer in men is similar to that in women, with more than 80 percent of all breast tumors in men being invasive, infiltrating ductal carcinomas. The rate of hormone-receptor (either estrogen or progesterone) positivity is higher in men than in women with matched tumors. Prognostic factors include axillary lymph node involvement, tumor size, histologic grade, and hormone-receptor status. Clinical outcomes in men with breast cancer are similar to those in women. Disease staging can be used to estimate five-year survival rates.

The recommended treatment for localized disease is modified radical mastectomy with axillary dissection. The role of radiation after surgery is unclear. Although some retrospective studies have shown improved survival rates in patients treated with tamoxifen, no randomized studies have been performed to confirm these findings. The authors recommend five years of treatment with tamoxifen in men with hormone-receptorpositive tumors. Adjuvant chemotherapy may be useful in men with a high risk for recurrence, including patients with node-positive disease or primary tumors that are larger than 1 cm in diameter. Systemic chemotherapy is a potential second-line treatment and can be useful in patients in whom hormone therapy has failed or in those with hormone-receptor–negative disease.

The authors conclude that breast cancer in men is similar to breast cancer in women in terms of staging and treatments, but it has different genetic and pathologic attributes.