Men are not immune to breast cancer.

Like women, men have breast tissue where cancer can develop. However, cases are rare. Male breast cancer accounts for fewer than 1% of all cases in Canada and Quebec. It affects 1 in 1,000 men (compared to 1 in 8 women). This means approximately 200 men who get sick and 55 men who die from breast cancer every year in Canada.

Male breast cancer is similar to female breast cancer, and it develops in the same way in men as in women. Therefore, most of the information available on this site, including on development and progression, screening, diagnosis and treatment, applies to all affected people regardless of sex.

Although this cancer can develop in adults of any age, breast cancer usually strikes men between 60 and 70. The most common male breast cancer is ductal carcinoma, which forms in the mammary ducts.

Due to the lack of screening programs, men are often diagnosed at a later age and stage of the cancer than women are, resulting in a lower overall survival rate. However, the survival rates for men and women are similar when the same stages of the disease are compared. Over the years, as with female breast cancer, the survival rate has improved greatly.
Male breast cancer is under-researched. Clinical studies rarely include men, and the findings from studies with women are extrapolated to men. Studies are underway to better characterize male breast cancer and understand its biology to optimize treatment options. Male breast cancer is similar to female breast cancer, but it has several distinct characteristics due to hormonal differences.

Most common signs
Some of the symptoms of breast cancer men may notice are:

  • A non-painful mass (nodule) in the breast
  • Light discharge or bleeding from the nipple or retraction (nipple turned inward)
  • Skin ulcers
  • Swollen lymph nodes

These signs may be related to an issue that is completely different than breast cancer and easily treatable. In fact, most breast-related health problems are not cancerous. If you are a man having one or more of these symptoms, you should nonetheless see a doctor. Only a medical examination by a healthcare professional can determine the problem and the
appropriate treatment.

Risk factors

The main risk factors for male breast cancer are:

  • Family history of breast cancer
  • Carrying a genetic mutation, such as BRCA1, BRCA2, CHEK2 or PALB2
  • Exposure to radiation
  • Low levels of androgen (male hormone) or high levels of estrogen (female hormone)
  • A disease or condition associated with gynecomastia (excessive development of the mammary glands in men), Klinefelter syndrome (two X chromosomes instead of one), obesity, testicular abnormalities or cirrhosis (chronic liver disease)
  • Age (the risk increases with age)
  • Race (black men have higher rates)

Note that these are risk factors—not certainties—of developing the disease. So you might have one or more of these factors and never develop breast cancer. However, other men might get breast cancer without having any of these risk factors.

Subtypes

The vast majority of human breast cancers express the ER and AR androgen hormone receptors.
The cancer cell mutations in men are not the same as those in women. In men, mutations are more often found in the genes involved in DNA repair, while women have more mutations in the 16q, PI3KCA and TP53 genes.
The most commonly diagnosed type of male breast cancer is invasive ductal carcinoma since ductal carcinoma in situ is not palpable. Lobular carcinomas are rare (12%) because men generally do not have lobules (breast glands that make milk). Rarer breast cancers include papillary (34%) and mucinous (12%).

Treatments

Surgery is recommended. Total mastectomy is performed more often in men than lumpectomy. However, observational studies show that lumpectomy is as effective as mastectomy, and has the advantage of being more aesthetic and functional.
For men, studies suggest that radiation therapy is underutilized and that greater consideration of this treatment option would be beneficial. As with women, chemotherapy and HER2-targeted therapies should be used in men as neoadjuvant or adjuvant treatments.
Hormone therapy is often used, but the approach is different in men because of their different mechanisms of hormone production. Men generally receive Tamoxifen for 5 to 10 years, depending on their risk of recurrence and side effects.

The side effects of Tamoxifen for men include:

  • Venous thrombosis
  • Cataracts
  • Sexual dysfunction
  • Mood swings
  • Hot flashes
  • Leg cramps


Aromatase inhibitors are less effective at lowering estrogen levels in men than in women. However, they can be taken with gonadotropin-releasing hormone analogues. More studies are needed to confirm the effectiveness of this combination.

Ongoing studies
Several studies are being conducted to improve male breast cancer treatments:

  • The International Male Breast Cancer Program is studying samples from 1,400 men with breast cancer to better understand the disease.
  • Another study is examining Seviteronel, an inhibitor of the CYP17A1 enzyme involved in estrogen and androgen synthesis.
  • A third study is assessing the efficacy of combining a GnRH analogue with Tamoxifen or an aromatase inhibitor.

A growing number of breast cancer clinical studies are now recruiting men.
Some useful links:

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