While breast cancer overwhelmingly affects women, men also have breast tissue and are at risk of developing breast cancer.
What’s more, because breast cancer is primarily seen as a “woman’s disease,” men may ignore symptoms—resulting in later-stage diagnoses and potentially worse outcomes. Although overall survival for male breast cancer patients has improved over time, the prognosis for men with the disease hasn’t advanced as much as it has for women.
Men need to not only know that they can and do get breast cancer—but also that they must be proactive about reporting any lumps, inflammation, or otherwise unusual changes to their doctors. Here, we highlight male breast cancer statistics, what we know about causes of the disease in this group, and why research is critical.
Similar to previous years, in 2023, about 2,800 men will be diagnosed with breast cancer and approximately 530 will die from the disease, according to the American Cancer Society. In comparison, about 297,790 women will be diagnosed in 2023 and 43,170 will die, based on the same statistics. Male breast cancer accounts for less than one percent of all breast cancer diagnoses.
About one in 726 men will develop breast cancer in their lifetime. While that statistic may not sound as daunting as the equivalent for women—one in eight will be diagnosed in their lifetime—the fact that male breast cancer is so rare makes it uniquely challenging.
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Because of a lack of research and awareness among men and clinicians, some disparities in breast cancer outcomes in men compared to women have been noted in recent studies. One 2019 study from Vanderbilt University researchers based on mortality data from 1.8 million women and 16,025 men who had breast cancer found that male breast cancer patients have a 19 percent higher mortality rate than women. In a 2023 study published in the Journal of the National Cancer Institute, several BCRF investigators and others found that, unlike breast cancer in women, survival rates for male breast cancer have not significantly improved in the last 30 years.
While men who carry a mutation in the BRCA2 gene have in increased risk of developing breast cancer, most breast cancers in men are not caused by inherited factors. Nevertheless, knowing a man’s family history can be informative and help guide decisions regarding the need for genetic testing. Exposure to radiation treatment to the chest, as well as conditions that increase levels of estrogen—such as obesity—are also factors that influence the risk of breast cancer in men.
Most breast cancers in men are estrogen receptor (ER)–positive invasive ductal carcinoma. This is also the most common breast cancer in women. Most oncologists will rarely see and treat a man with breast cancer. Even when a man sees his primary care physician with unusual chest symptoms, neither the doctor nor the patient expects breast cancer—and so it often goes undiagnosed until it is more advanced.
Signs and symptoms of male breast cancer can include:
Unfortunately, there has been little research in male breast cancer, especially in how best to treat it, in part because of the disease’s rarity and lack of surveillance. Men are often excluded from—or at least not actively recruited to—breast cancer clinical trials. As a result, treatment in men is much the same as treatment in women, with anti-hormone drugs such as tamoxifen and chemotherapy. While this trend is changing and more clinical trial protocols are including men, the sheer lack of men with breast cancer also makes the disease difficult to study.
Pioneering work by Dr. Fatima Cardoso and the BCRF-supported International Male Breast Cancer Program suggests that men are frequently undertreated for breast cancer. Her 2018 study of 1,482 men with breast cancer reported that men were less likely to get breast-conserving surgery for early-stage breast cancers or receive endocrine therapy for ER-positive disease compared to women with similar breast cancers.
In studies, Dr. Cardoso and her colleagues have also reported that male breast cancers are biologically and molecularly different compared to female breast cancers—underscoring the need for more research.
In 2019, researchers at the Mayo Clinic analyzed data from more than 10,000 men in the National Cancer Database. Their study found that factors such as a higher age at diagnosis, being African American, having a high grade/stage tumor at diagnosis, and receiving total mastectomy all negatively affected breast cancer outcomes. Those men with a higher economic status, a progesterone receptor–positive breast cancer, and who received radiation, chemotherapy, and endocrine therapy had better outcomes.
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In the final phase of the International Breast Cancer Program, Dr. Cardoso hopes to initiate a clinical trial to test a combination hormone therapy in men with breast cancer. Her team continues to conduct molecular profiling on the more than 500 tumor samples from the retrospective component of the study.
With BCRF support, Dr. Jose Pablo Leone, BCRF researcher and director of Dana-Farber Cancer Institute’s Program for Breast Cancer in Men, is launching a study in men with breast cancer to test multiple therapeutic strategies used to treat women, including hormone-targeting drugs and CDK4/6 inhibitors. The study will open at Dana-Farber and then expand to multiple sites throughout the Translational Breast Cancer Research Consortium, a BCRF-supported collective of leading breast cancer sites across the U.S.
Through research, we’ll gain greater insight into the clinical and biological characteristics of breast cancer in men, and we will be able to provide male patients with better treatments and ultimately improve outcomes.
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