Genetic mutations, hormonal imbalances, and environmental factors can trigger the uncontrolled growth of breast cells in males.

Male breast cancer is a rare but serious condition that is often underrecognized due to its significantly lower incidence compared to female breast cancer.

While women have a lifetime breast cancer risk of about 1 in 8, men have a risk of about 1 in 726.

Despite this, understanding the causes and risk factors of male breast cancer is essential for early detection and prevention.

Male breast cancer develops when genetic mutations cause normal breast cells to grow uncontrollably. Although males have much less breast tissue than females, they still have a small amount of glandular tissue where breast cancer can develop.

As the mutated cells divide uncontrollably, they form a tumor, which may spread to nearby tissue or other parts of the body. Most male breast cancers are estrogen receptor-positive, meaning estrogen fuels their growth.

This is why hormonal therapies like tamoxifen, a selective estrogen receptor modulator (SERM), are often effective in treating the disease. Tamoxifen selectively binds to estrogen receptors, exerting both estrogenic (estrogen-like) and anti-estrogenic (estrogen-blocking) effects depending on the tissue, making it a patient-specific treatment.

Key underlying causes include:

  • Genetic mutations: Mutations in genes like BRCA1 or BRCA2, especially BRCA2, disrupt regular DNA repair, allowing harmful mutations to accumulate and lead to cancer. Other genetic changes, such as mutations in the p53 or PTEN genes, can also play a role.
  • Hormonal imbalances: High levels of estrogen (due to conditions like Klinefelter syndrome, obesity, or hormone therapy) stimulate breast tissue growth, increasing the chance of malignant changes.
  • Radiation damage: Exposure to therapeutic or diagnostic radiation can damage DNA in breast cells, increasing the risk of malignancy years later.

BRCA2 mutation carriers and individuals with Klinefelter syndrome (KS) account for up to 15% of cases of male breast cancer.

The main risk factors for male breast cancer include the following:

  • Family History: About 1 out of 5 males with breast cancer have a close family member, either male or female, who also has the disease.
  • Age: Most cases happen in males over 60 years old.
  • Liver disease: This includes cirrhosis or other liver problems that increase estrogen levels.
  • Obesity: Extra body fat raises estrogen levels.
  • Chemical exposure: Examples include long-term work around high heat or chemicals in steel or petroleum industries.
  • Testicular problems: This includes undescended testicles, testicular injury, or inflammation (orchitis).
  • Alcohol use: Drinking too much alcohol raises the risk.

While male breast cancer cannot be entirely prevented, certain steps may reduce the risk:

  • Maintaining a healthy weight: Obesity is linked to higher estrogen levels, increasing breast cancer risk.
  • Staying physically active: Regular exercise lowers the risk of several cancers, including breast cancer, by 10% to 20%. For those with breast cancer, increased physical activity can reduce overall and cancer-specific mortality by up to 40% to 50%.
  • Minimizing alcohol use: Alcohol is a known human carcinogen, with higher consumption linked to an increased risk of several cancers, including breast cancer. The more alcohol a person drinks regularly, the higher their risk. Even light drinking slightly raises the chance of developing cancer.
  • Avoiding radiation exposure: Minimize unnecessary exposure to therapeutic or diagnostic radiation, especially to the chest area.
  • Getting regular medical checkups: Early detection through self-awareness and periodic medical evaluations can improve outcomes.
  • Addressing hormonal imbalances: Seek medical advice if you experience symptoms like gynecomastia or other hormonal changes.
  • Undergoing genetic testing: For individuals with a strong family history, testing for BRCA1/2 mutations can help determine preventive steps, like more frequent screenings or preventive surgeries.

Male breast cancer is a rare but serious condition with several known causes and risk factors, including genetic mutations like BRCA2, hormonal imbalances, and medical conditions such as Klinefelter syndrome.

Although the number of cases is much lower compared with female breast cancer, male breast cancer should not be overlooked. Early detection is important, and understanding individual risk factors can help identify those at higher risk.