Several factors are known to increase the risk that a man will develop breast cancer. But it’s important to know that many men who develop breast cancer do not have any of these risk factors.
Factors that can increase a man’s breast cancer risk include:
The risk of male breast cancer increases as you age. The average age of men diagnosed with breast cancer, about 67. But breast cancer can occur in young men, too.
Family history of breast cancer:
A man’s risk for breast cancer is higher if any of his close relatives have had breast cancer, and especially if any male relatives have had the disease.
Men who inherit certain genetic mutations from their mothers or fathers have a higher risk of developing breast cancer. A man who inherits a BRCA1 mutation has about a 1% risk of developing breast cancer in his lifetime, compared to a risk of 0.1% (about one in 1,000) for the average man. A man who inherits a BRCA2 mutation has a 7% to 8% risk.
Mutations in the ATM, CHEK2, PALB2, and other genes are also linked to breast cancer in men, but more research is needed to understand those risks.
High estrogen levels:
You may think of testosterone as a male hormone and estrogen as a female hormone. The truth is, both men and women have different levels of testosterone and estrogen in their bodies. Men have less estrogen than women, but all men have some estrogen in their bodies.
Higher levels of estrogen can increase the risk of male breast cancer. Men (and people assigned male at birth) can have high estrogen levels as a result of:
– Hormone therapy for prostate cancer (androgen suppression therapy).
– Hormone therapy taken by transgender women (as part of male-to-female transition; also called feminizing hormone therapy or gender affirming hormone replacement therapy).
– Being overweight or obese.
– Being a heavy drinker or having liver disease (like cirrhosis), both of which can limit the liver’s ability to balance hormone levels in the blood.
– Having an undescended testicle.
– Surgery to remove one or both testicles (orchiectomy).
– Swelling or injury of the testicles.
Men usually have one X and one Y chromosome in their cells. But men born with Klinefelter syndrome — a rare genetic condition that happens when a male is born with more than one X chromosome in their cells — may increase their risk of breast cancer.
Kinefelter syndrome may cause the testicles to develop abnormally. This can result in lower levels of androgens (usually higher in males) and higher levels of estrogen.
Men with Klinefelter’s syndrome may have an increased risk of developing gynecomastia (breast tissue growth that is not cancer) and male breast cancer.
If a man has received radiation therapy to the chest, such as for the treatment of Hodgkin lymphoma, he has an increased risk of developing breast cancer.