Male breast cancer is a rare but serious condition that accounts for about 1% of all breast cancers, with an estimated 2,500 new cases diagnosed in men in the United States in 2018. While sharing similarities with female breast cancer, male breast cancer has distinct biological features, including being overwhelmingly hormone-receptor positive (99% estrogen-receptor positive) and presenting at a later average age (67 years). Treatment approaches are largely extrapolated from women's studies due to limited male-specific research, but recent advances in genetic understanding and genomic testing are helping tailor care for male patients.
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Understanding Male Breast Cancer: A Comprehensive Guide for Patients
Table of Contents
- Epidemiology and Risk Factors
- Clinical Presentation and Evaluation
- Pathological Characteristics
- Prognosis and Survival Rates
- Treatment Approaches
- Genetic Testing and Counseling
- Study Limitations
- Patient Recommendations
- Source Information
Epidemiology and Risk Factors
Male breast cancer is relatively rare, accounting for approximately 1% of all breast cancers diagnosed. In 2018, researchers estimated that about 2,500 new cases would be diagnosed in American men, with approximately 500 men expected to die from the disease. The incidence rate has increased significantly over time, rising from 0.85 cases per 100,000 men in 1975 to 1.43 cases per 100,000 men in 2011.
The lifetime risk of breast cancer for men is approximately 1 in 1,000, compared to 1 in 8 for women. Men are typically diagnosed at an older age than women, with an average age of 67 years at diagnosis compared to 62 years for women. Black men appear to be at greater risk than non-Hispanic white men, and having a first-degree relative with breast cancer doubles a man's risk.
Several specific risk factors have been identified for male breast cancer:
- Genetic mutations: BRCA2 mutations (4-16% of cases), BRCA1 mutations (0-4% of cases)
- Moderate risk genes: CHEK2, PALB2, and others
- Radiation exposure: Particularly from atomic bomb studies showing a clear dose-response relationship
- Hormonal factors: Elevated estrogen levels (men in highest quartile had 2.47 times higher risk)
- Medical conditions: Klinefelter's syndrome (47,XXY karyotype, 50 times higher risk), liver disease, testicular abnormalities, obesity, and gynecomastia
Clinical Presentation and Evaluation
Most men with breast cancer first notice a painless lump behind the nipple (retroareolar mass). Other warning signs can include nipple retraction, bleeding from the nipple, skin ulceration, or swollen lymph nodes in the armpit area. The most common condition that can be mistaken for breast cancer is gynecomastia, which is a benign enlargement of breast tissue.
If cancer is suspected, doctors recommend specific imaging tests based on age. For men under 25, ultrasound is typically the first test. For men 25 and older, mammography is recommended first, with ultrasound used if results are unclear. On mammograms, male breast cancers often appear as irregular, spiculated masses located behind the nipple.
Due to low public awareness and no routine screening programs, men often present with more advanced disease than women. Men typically have larger tumors (average 20 mm vs. 15 mm in women) and more frequent lymph node involvement (42% vs. 33% in women). Any suspicious finding should be confirmed with a core biopsy for diagnosis.
Pathological Characteristics
Without routine mammographic screening, only about 10% of male breast cancers are detected as ductal carcinoma in situ (DCIS), the earliest form of breast cancer. The vast majority (90%) are invasive carcinomas, with invasive ductal carcinoma being the most common type.
Male breast cancers have distinct biological characteristics compared to female breast cancers:
- 99% are estrogen-receptor positive (vs. 83% in women)
- 97% are androgen-receptor positive (vs. 61% in women)
- Only 9% are HER2-positive (vs. 17% in women)
- Only 1-2% are invasive lobular carcinoma (vs. 12% in women)
- Less than 1% are triple-negative (negative for all three receptors)
Genetic studies have revealed that male breast cancers have different mutation patterns than female breast cancers. They're more likely to have DNA-repair gene mutations and less likely to have specific mutations in PIK3CA and TP53 genes that are common in women's breast cancers.
Prognosis and Survival Rates
Overall, men with breast cancer have slightly lower survival rates than women, but this difference largely disappears when accounting for age and stage at diagnosis. Men are typically older when diagnosed and may have other age-related health conditions that affect survival.
The 5-year survival rates for men with breast cancer by stage are:
- Stage I: 87% survival
- Stage II: 74% survival
- Stage III: 57% survival
- Stage IV: 16% survival
Black men tend to have worse outcomes than white men, though this difference diminishes when considering insurance coverage and income levels. Survival has improved over time for both men and women, but the improvement has been slower for men.
Men with breast cancer also face an increased risk of developing second cancers, including:
- Second breast cancer (just under 2% risk)
- Melanoma
- Cancers of the small intestine, rectum, pancreas, and prostate
- Lymphohematopoietic system cancers
Treatment Approaches
Since no randomized clinical trials have focused specifically on treating male breast cancer, treatment approaches are adapted from studies involving women. The most common surgical approach is mastectomy (breast removal), with only 18% of men with early-stage tumors undergoing breast-conserving surgery. However, studies show that breast-conserving therapy with radiation offers equivalent survival outcomes with potentially better cosmetic results.
Radiation therapy is often underused in men, with only 42% of men with stage I cancer receiving radiotherapy after breast-conserving surgery. For node-positive cancer, radiation after mastectomy appears beneficial based on observational studies.
Chemotherapy and targeted therapies should be offered to men at high risk of recurrence, similar to treatment guidelines for women. One small study of 31 men with stage II node-positive cancer showed promising long-term results with chemotherapy: 80% survival at 5 years, 65% at 10 years, and 42% at 20 years.
Genomic testing like Oncotype DX (a 21-gene test that predicts recurrence risk) appears valid for men though with some important differences:
- 12% of men had high recurrence scores (≥31) vs. 7% of women
- 34% of men had low scores (<11) vs. 22% of women
- 5-year survival for men with high scores was 81% vs. 94.9% for women
Genetic Testing and Counseling
Given the strong genetic component of male breast cancer, all men diagnosed should consider genetic counseling and testing. BRCA2 mutations are found in 4-16% of men with breast cancer, while BRCA1 mutations are found in 0-4%. The lifetime risk of breast cancer for male BRCA2 mutation carriers is 6.8% by age 70, and for BRCA1 carriers it's 1.2%.
The National Comprehensive Cancer Network recommends that men with BRCA mutations receive:
- Breast self-examination training starting at age 35
- Yearly clinical breast examinations
- Consideration of prostate cancer screening (especially for BRCA2 carriers starting at age 45)
Other genes that moderately increase risk include CHEK2 (10 times higher risk with specific mutation) and PALB2 (1-2% of cases). Genetic counseling can help determine appropriate screening and risk management strategies.
Study Limitations
This review highlights several important limitations in our current understanding of male breast cancer. The most significant limitation is the lack of prospective studies and clinical trials specifically designed for men with breast cancer. Most treatment recommendations are extrapolated from studies involving women, which may not account for biological differences between male and female breast cancers.
The rarity of the disease means that most studies have small sample sizes or rely on retrospective data from single institutions. This makes it difficult to draw firm conclusions about optimal treatment approaches. Additionally, long-term outcome data is limited, particularly for newer treatments and genomic testing approaches.
Many studies also lack diversity in their patient populations, which may limit how applicable the findings are to all racial and ethnic groups. The underrepresentation of men in breast cancer research has created significant gaps in our knowledge that need to be addressed through dedicated research efforts.
Patient Recommendations
Based on the current evidence, men should be aware of their breast health and report any changes to their healthcare providers. Specifically, we recommend:
- Be aware of changes: Report any lumps, nipple changes, or breast pain to your doctor promptly
- Know your risk: Discuss family history and genetic testing options with your doctor if you have a personal or family history of breast cancer
- Seek specialized care: Consider treatment at centers experienced with male breast cancer
- Discuss all options: Talk with your doctors about surgical choices (including breast conservation when appropriate), radiation, chemotherapy, and endocrine therapy
- Consider genetic testing: All men with breast cancer should discuss genetic counseling to inform family risk assessment
- Ask about genomic testing: Inquire about recurrence score testing to help guide chemotherapy decisions
- Follow-up care: Maintain regular follow-up for monitoring recurrence and second cancers
Remember that while male breast cancer is rare, it is treatable—especially when detected early. Being proactive about your health and seeking appropriate medical care can significantly impact outcomes.
Source Information
Original Article Title: Breast Cancer in Men
Author: Sharon H. Giordano, M.D., M.P.H.
Publication: The New England Journal of Medicine, June 14, 2018
DOI: 10.1056/NEJMra1707939
This patient-friendly article is based on peer-reviewed research from The New England Journal of Medicine. It maintains all original data, statistics, and findings while making the information accessible to patients and caregivers.