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Background. Cancer of the male breast (MBC) is rare, accounting for less than 1% of cancer in males and representing less than 1% of all breast cancers. Reports of abnormalities in the expression of the tumor suppressor gene p53 in MBC have been few. Methods. To assess the expression and mutations of the p53 gene, 35 patients with 36 MBC (one patient with bilateral breast carcinoma) were examined using immunohistochemical methods, polymerase chain reaction (PCR)‐single strand conformation polymorphism and DNA sequencing. Results. Thirty‐one of the 36 carcinomas were studied by immunohistochemistry and by the PCR‐based approach. Five patients were studied by immunohistochemistry only. Twelve patients (41.4%) of the 29 studied by molecular analysis presented an altered pattern in the single strand conformation polymorphism gel and point mutations were confirmed in all by direct DNA sequencing. Thirty‐six tumors were studied by immunohistochemistry and 2 (5.5%) patients showed overexpression of the p53 protein. There were no statistically significant differences in p53 status with respect to: age, stage, estrogen receptors, progesterone receptors, tumor type. Patients with normal p53 showed a predisposition, although not statistically significant, for a longer disease free survival (5.6 years versus 4.2 years) and overall survival (5.9 years versus 4.8 years) than did patients with genetically altered p53. Conclusions. The incidence of male patients detected with p53 mutations (41.4%) in this series is concordant with the incidence of p53 mutations in female breast cancer, supporting the idea that cancer of the male breast is similar to the female counterpart.

Background. Although an uncommon disease, male breast cancer (MBC) will be responsible for 300 deaths in 1993 in the United States. Because of the high rate of estrogen receptor positivity in males, adjuvant hormonal therapy with tamoxifen in the adjuvant setting has been used widely. Little is known about the side effects of this estrogen receptor blocker in males. Methods. The authors evaluated the side effects of adjuvant tamoxifen treatment in 24 patients (19 of whom were estrogen receptor positive) treated at the authors' institution between 1990 and 1993. Results. Fifteen (62.5%) patients reported at least one side effect. The most common side effect was a decrease in libido, which occurred in 7 (29.2%) patients; followed by weight gain, which occurred in 6 (25%) patients; hot flashes, which occurred in (5 20.8%); mood alterations, which occurred in 5 (20.8%); depression, which occurred in 4 (16.6%); insomnia, which occurred in 3 (12.5%); and deep venous thrombosis, which occurred in 1 (4.2%). Five (20.8%) patients terminated treatment with tamoxifen in less than 1 year because of these side effects. Two of these patients had decreased libido, two had hot flashes, and one suffered deep venous thrombosis. Conclusions. In contrast to female breast cancer patients, who have a 4% attrition rate to adjuvant tamoxifen treatment, MBC patients have a 20.8% attrition rate related to side effects of tamoxifen treatment.

An overall response rate of 83.5% was obtained, including 15.1% complete pathological responses. The regimen was well tolerated with 17.7% grade 2/3 nausea and 12.8% grade 3/4 leukopenia. There was a statistically significant correlation between response and expression of p53. Of the 25 patients who obtained a complete clinical response, two were classified as positive (P = 0.004, chi-square). Of 11 patients who obtained a complete pathological remission, one was positive (P = 0.099, chi-square). Discussion The combination is highly effective in locally advanced breast cancer. A negative expression of p53 indicates a higher chance of responding to this regimen. The p53 status may be used as a biological marker to identify those patients who would benefit from more aggressive treatments.

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