Genetics may determine whether men get male breast cancer—or not.

There have been approximately 2,030 cases of breast cancer in men this year and 450 deaths, according to the National Cancer Institute, a small number compared to the more than 170,000 cases, and growing, in women each year. The cancer usually strikes men who are in their 60s or 70s, but can affect men of all ages.

Early signs, much like those in female breast cancer, include a lump on a man’s breast. Once a man notices this, they should go through all the normal breast examinations as a woman would, including a breast exam by a physician, a mammogram and, if advanced, an ultrasound or biopsy.

Dr. Larissa Korde, Division of Cancer Epidemiology and Genetics at the National Cancer Institute, said that because breast cancer in men is so rare, a routine screening is not recommended. However, if men have a strong family history of breast cancer, or a BRCA mutation, a consultation with a health care professional who specializes in genetics may be necessary to screen since there may be an increased risk of other cancers.

Men with BRCA1 or BRCA2 mutations, which associated with a 50 to 85 percent of lifetime breast cancer risks in women, also contribute to an increase in the risk of breast cancer in men, according to Korde.

“Men with BRCA2 mutations have about a 6 percent lifetime risk of breast cancer,” she said. “Those with BRCA1 mutations also have an increased risk. BRCA mutations may also increase the risk of prostate cancer in male family members carrying these mutations, so screening for prostate cancer is recommended in this population.”

Korde said that other risk factors include increased levels of estrogen, or Klinefelter syndrome, obesity, excessive alcohol use and cirrhosis of the liver. A history of radiation therapy on the chest may also increase risk.

Internationally, there is also variation of risk in male breast cancer. For example, there is a higher rate of the cancer in African countries like Uganda and Zambia, according to Korde and lower rates in some Asian regions. In the U.S., the risk of breast cancer is slightly higher in black men than it is in white men.

Major Misconceptions

One major misconception is that gynecomastia, a condition in which men have an increased amount of breast tissue, increases the risk of breast cancer in men, said Korde. However, there has been no data supporting this, but the condition is usually a result of increased estrogen levels, which can increase risk of breast cancer.

The misconceptions and small numbers make it hard to pinpoint specific reasons for risk in men. “The incidence of breast cancer in men has been increasing slowly but steadily in recent years, but because the numbers are so small, it is difficult to pinpoint reasons behind this increase,” said Korde.

Korde said that more work needs to be done in male breast cancer research as well as a more appropriate treatment. “Because this is a rare disease, information on treatment for male breast cancer generally comes from either small, single institution retrospective studies, or from extrapolation of data from studies in women,” she said. “The rarity of this disease makes it impractical for any single institution to perform clinical trials to determine the most effective treatments. I think the best way to gain a better understanding of this disease is through multinational collaborations and consortial studies.”

The chance of survival is almost equivalent to chances for women with breast cancer and is determined by factors such as size and grade or tumor.

“Mastectomy is generally the surgical treatment of choice, with lymph node evaluation by either sentinel node biopsy or full axillary lymph node dissection,” said Korde. “The large majority of male breast cancers, about 90 percent, do express hormone receptors, so treatment with tamoxifen is generally also recommended. Chemotherapy may also be recommended depending on the size, lymph node status, and characteristics of the tumor.”