Your gift is 100% tax deductible
Causes, Risk Factors, and Prevention of Breast Cancer in Men
Although breast cancer is much more common in women, men can get it too. Understanding the causes and risk factors, such as genetics, hormone levels, and certain medical conditions, can help you take steps to lower your risk of breast cancer.
Risk factors for breast cancer in men
A risk factor is anything that increases your chances of getting a disease, such as breast cancer.
But having a risk factor, or even many, does not mean that you are sure to get the disease. Many men with one or more breast cancer risk factors never develop the disease, while some men with breast cancer have no apparent risk factors.
Although the overall risk of breast cancer in men is low, several factors can increase a man’s risk of getting breast cancer.
The risk of breast cancer goes up as a man ages. On average, most men with breast cancer are in their 60s or 70s when they are diagnosed.
A man’s risk of breast cancer is higher if other blood-related family members have had breast cancer.
Inheriting certain gene changes (mutations) from a parent can increase breast cancer risk in men, although the overall risk is generally still low. For example:
BRCA1 and BRCA2: The most common causes of hereditary breast cancer are inherited mutations in the BRCA1 or BRCA2 gene. In normal cells, these genes help make proteins that repair damaged DNA. Mutated versions of these genes cause abnormal cell growth, which can lead to certain types of cancer. Men with one of these gene changes have an increased risk of breast, prostate, and pancreas cancer.
The lifetime risk of breast cancer is higher in men with an inherited BRCA2 mutation (about 7 in 100) than with a BRCA1 mutation (about 1 in 100).
Other genes: Other inherited gene mutations can also lead to a higher risk of breast cancer in men. These gene mutations are less common, and most of them don’t raise the risk of breast cancer as much as the BRCA genes.
- The PALB2 gene makes a protein that interacts with the protein made by the BRCA2 gene.
- The TP53 gene helps stop the growth of cells with damaged DNA. Inherited mutations of this gene cause Li-Fraumeni syndrome. People with this syndrome have an increased risk of other cancers (such as leukemia, brain tumors, and sarcomas) as well as breast cancer.
- The CHEK2 gene also normally helps with DNA repair.
- The PTEN gene normally helps regulate cell growth. Inherited mutations in this gene can cause PTEN hamartoma tumor syndromes, including Cowden syndrome, a rare disorder that puts people at higher risk for both cancer and benign (non-cancer) tumors in the breasts and some other organs.
If you have been diagnosed with breast cancer
Consider genetic testing to see if you have inherited one of these gene changes. While most men will not have an inherited gene change that led to their cancer, finding out that you do might be helpful in several ways:
- Men who have an inherited gene mutation might also be at risk for other cancers, such as prostate and pancreas cancer. Knowing this might lead to testing for and finding such cancers earlier.
- Having one of these inherited gene changes might affect a man’s close family members’ chances of getting certain cancers.
- Having one of these changes might affect a man’s treatment options in some situations.
Klinefelter syndrome is a congenital (present at birth) condition that affects about 1 in 1,000 men. Normally, the cells in men's bodies have one X chromosome and one Y chromosome, while women's cells have two X chromosomes. Men with Klinefelter syndrome have cells with a Y chromosome plus at least two X chromosomes.
Compared with other men, men with Klinefelter syndrome have a higher ratio of female hormones to male hormones. For this reason, they often develop gynecomastia (benign male breast growth). Men with Klinefelter syndrome are also more likely to get breast cancer than other men.
Heavy drinking may increase the risk of breast cancer in men. This might be related to the effects of alcohol on the liver.
The liver plays an important role in balancing the levels of sex hormones in the body. In some severe liver diseases, such as cirrhosis, the liver does not work well and the hormone levels become uneven, leading to a higher ratio of female hormones to male hormones.
Men with liver disease have a higher chance of developing gynecomastia, as well as breast cancer.
Estrogen-related drugs are occasionally used in hormone therapy for men with prostate cancer. This treatment may slightly increase breast cancer risk.
Some research has suggested that transgender people who take high doses of estrogen as part of gender-affirming hormone treatment could also have a higher breast cancer risk, especially after a few decades. Research on breast cancer risk in transgender people is still fairly new.
Studies have shown that men's breast cancer risk is increased by excess body weight. Fat cells can convert male hormones into female hormones, so men with excess body weight often have higher levels of female hormones in their body.
Certain conditions, such as having an undescended testicle or having one or both testicles surgically removed (orchiectomy), may increase male breast cancer risk.
What causes breast cancer in men?
Although certain risk factors can increase a man's chances of developing breast cancer, the exact cause of many breast cancers in men is unknown. Here is what we do know about what causes breast cancer in men.
Higher levels of female hormones
Breast cells normally grow and divide in response to female hormones such as estrogen. Higher levels of these hormones cause them to divide more often. The more cells divide, the more chances there are for mistakes to be made when they are copying their DNA. These DNA changes can eventually lead to cancer (see below).
This is why having an imbalance in the levels of female and male hormones can affect breast cancer risk.
Gene changes (mutations) linked to breast cancer in men
Genes are pieces of DNA inside each cell that carry instructions for how the cell works. Certain genes help control when our cells grow, divide to make new cells, or repair mistakes in DNA. They also cause cells to die when they’re supposed to. If these genes aren’t working properly, it can lead to cells growing out of control.
Cancer develops when changes (mutations) in certain genes lead to abnormal cell growth. To learn more, see Gene Changes and Cancer.
Some gene changes linked to male breast cancer are inherited from a parent, but most are acquired during life. The cause of most acquired mutations is not clear. Mutations may:
- Result from radiation to the chest area, which is a factor in a small number of breast cancers in men.
- Develop after exposure to cancer-causing chemicals in our environment or diet, though no specific chemicals have been clearly linked to male breast cancer.
- Occur randomly inside cells, without an outside cause. These gene changes can build up over time, which may help explain why breast cancer risk increases with age.
Can breast cancer in men be prevented?
Since the cause of most breast cancers is not known, there is no way to prevent them completely. But there are some things you can do to lower your risk.
Get to and stay at a healthy weight
Excess body weight is linked with a higher risk of breast cancer in men, as well as several other cancers. The American Cancer Society recommends you stay at a healthy weight throughout your life and avoid excess weight gain by balancing your food intake with physical activity.
Avoid or limit alcohol
Alcohol use may increase the risk of breast cancer in men, as well as several other cancers. It is best not to drink alcohol. For men who do drink, they should have no more than 2 alcoholic drinks a day.
Be physically active
Many studies have shown that moderate to vigorous physical activity is linked with lower breast cancer risk in women, as well as many other types of cancer. While it’s not yet clear if the same holds true in men, it can have many health benefits, including lowering the risk of some other types of cancer.
The American Cancer Society recommends that adults get at least 150 to 300 minutes of moderate intensity or 75 to 150 minutes of vigorous intensity activity each week (or a combination of these), preferably spread throughout the week. Getting to or going over the upper limit of 300 minutes is ideal.
Learn more: American Cancer Society Guideline for Diet and Physical Activity for Cancer Prevention
- Written by
- References
Developed by the American Cancer Society medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).
Brinton LA, Cook MB, McCormack V, et al. Anthropometric and hormonal risk factors for male breast cancer: Male breast cancer pooling project results. J Natl Cancer Inst 2014;106: djt465.
de Blok CJM, Wiepjes CM, Nota NM, et al. Breast cancer risk in transgender people receiving hormone treatment: Nationwide cohort study in the Netherlands. BMJ. 2019 May 14;365:l1652.
Gradishar WJ, Ruddy KJ. Breast cancer in men. UpToDate. 2025. Accessed at https://www.uptodate.com/contents/breast-cancer-in-men on July 16, 2025.
National Cancer Institute. Genetics of Breast and Gynecologic Cancers (PDQ?)–Health Professional Version. 2025. Accessed at http://www.cancer.gov/cancertopics/pdq/genetics/breast-and-ovarian/HealthProfessional on July 21, 2025.
National Cancer Institute. Male Breast Cancer Treatment (PDQ?)–Health Professional Version. 2024. Accessed at https://www.cancer.gov/types/breast/hp/male-breast-treatment-pdq on July 16, 2025.
Rock CL, Thomson C, Gansler T, et al. American Cancer Society guideline for diet and physical activity for cancer prevention. CA: A Cancer Journal for Clinicians. 2020;70(4).
Tai YC, Domchek S, Parmigiani G, Chen S. Breast cancer risk among male BRCA1 and BRCA2 mutation carriers. J Natl Cancer Inst. 2007;99:1811-1814.
Last Revised: October 15, 2025
American Cancer Society medical information is copyrighted material. For reprint requests, please see our Content Usage Policy.
American Cancer Society Emails
Sign up to stay up-to-date with news, valuable information, and ways to get involved with the American Cancer Society.