Clinical Pearls & Morning Reports
Published February 26, 2020
Data from the International Male Breast Cancer Program (IMBCP) show that 85 to 90% of men with breast cancer have ductal tumors, whereas only 1 to 1.5% have lobular tumors. More than 99% of men with breast cancer have estrogen-receptor–positive tumors, and only 9% have HER2-positive tumors. In contrast, 15 to 20% of women with breast cancer have HER2-positive tumors. Read the NEJM Case Records of the Massachusetts General Hospital here.
Q: How common is breast cancer in men?
A: Breast cancer in men represents approximately 1% of all breast cancers and will account for an estimated 2620 cases and 520 deaths in the United States in 2020, as compared with over 276,000 cases of breast cancer in women. The median age at diagnosis in men is 68 years, which is 5 to 10 years older than the median age in women.
Q: Mutations in what genes, in addition to BRCA1/2, may be associated with breast cancer in men?
A: Although both BRCA1 and BRCA2 mutations are associated with breast cancer in men, the association is much stronger for BRCA2 mutations, which account for approximately 4 to 14% of all cases, than for BRCA1 mutations, which account for approximately 1%. The other genetic alterations that are now detected in multigene panel testing — particularly mutations in PTEN, TP53, CHEK2, and PALB2, as well as the Lynch syndrome — may also be associated with breast cancer in men, but evidence is limited at this time. Most men with breast cancer, however, have no identifiable risk factors.
A: Mastectomy has historically been the most common procedure for men with breast cancer; in the IMBCP cohort, mastectomy was performed in 96% of men. Studies to determine the outcome of nipple-sparing mastectomies, which are now offered to many women, have not been formally done for men, but some experts suggest that this option should be considered more frequently. However, approximately 50% of breast cancers in men occur under the nipple–areolar complex, and therefore, nipple-sparing techniques may not be ideal in many men. In the IMBCP cohort, breast-conserving surgery was reported in 4% of patients during the 20-year period, but the use of this approach has been increasing over time and has been shown to be safe, with good long-term outcomes in limited studies. Sentinel-node biopsy is an accurate diagnostic procedure in men with breast cancer and is considered to be a standard part of the surgical evaluation.
A: National Comprehensive Cancer Network guidelines recommend that men with a known genetic risk perform breast self-examination as well as undergo annual clinical breast examination beginning at 35 years of age. Imaging-based breast screening in men who are at high risk for breast cancer is not routinely recommended. In male carriers of BRCA2 mutations, the lifetime risk of the development of prostate cancer is as high as 25%, and the tumors often are aggressive and occur at a young age. For BRCA2 carriers, prostate cancer screening should be started at 45 years of age.