While still rare, rates of male breast cancer have been increasing along with rates of obesity and exposure to endocrine disruptors (from packaged foods and personal care products, as well as from various industrial and environmental sources). The biology of most male breast cancer appears to resemble that of hormone receptor positive (ER+/PR+) female breast cancer. Since such cancer is estrogen sensitive, we have some ability to reduce the risk of breast cancer in our sons.
There are some male breast cancer risk factors, such as BRCA mutations, an undescended testicle, Klinefelter syndrome, CHEK2 mutation, and Cowden syndrome, that are not primarily hormonally derived. The breast cancer risk in men with BRCA2 mutations is 7.1% by age 70 and 8.4% by age 80 years, according to one study. Men with BRCA1 mutations also have a higher risk of breast cancer than the general population. Use of the heart medication digoxin (digitalis) has been found to increase risk of breast cancer in men.
Male breast cancer characteristics
Male breast cancer is most often invasive ductal carcinoma and hormone receptor positive, a profile that is not among the most aggressive. However, since men are not normally screened for breast cancer, their tumors are often large when found and may have nipple or skin involvement. At this stage, they are less treatable than they would have been if found early. Age at diagnosis tends to be higher in men than women (median 67 years of age for men compared to 61 years for women in one large U.S. study) and men are more likely to have positive lymph nodes. The most common presentation of male breast cancer is a palpable breast mass. However, men are more likely to present with nipple discharge than women. This symptom should lead to thorough evaluation for breast cancer in a man who experiences it, whether or not the discharge is bloody.
Male breast cancer treatment
Most men with breast cancer are treated with a mastectomy, followed by systemic treatment such as chemotherapy and/or anti-estrogen treatment (typically tamoxifen. The most common serious side effects of tamoxifen in men are weight gain, sexual dysfunction and the development of blood clots. radiation treatment are increasingly being used for men under appropriate circumstances.
A study of 939 Veterans Administration male breast cancer cases is described in the study entitled Male breast cancer in veteran population: Retrospective analysis of VACCR database under the Selected breast cancer studies heading at the end of this article. Note that the information given with respect to treatment in the study should not be considered a guide. From our point of view, the treatment statistics describe a remarkable degree of undertreatment which neither the age of the patients nor their stage of disease could justify.
Male breast cancer prognosis
While there are biological differences between men and women with hormone receptor positive ER+/PR+ disease, men with ER+/PR+ breast cancer tend to have similar or better survival as women given comparable tumor characteristics. Like women, men with hormone receptor negative tumors (most of which are triple negative (ER-/PR-/HER2-)) have a worse prognosis than men with other breast cancer subtypes. In addition, men with triple negative disease have been found to have worse outcomes than women with triple negative disease.
Weight gain is common during treatment, including chemotherapy and tamoxifen. However, weight gain during treatment has been found to be associated with less favorable prognosis in women, even among those who are not initially overweight, and is to be avoided.
Although one study has reported that smoking is not a risk factor for male breast cancer, cigarette smoking tends to worsen prognosis. One 2015 study reported that men who continued to smoke after diagnosis had poorer survival — the more smoking, the worse the outcomes. A previous history of smoking also tended to worsen survival compared to never smoking.
One large U.S. study reported that men with breast cancer survive for a median of nine years. The five-year survival rate was 63% and 10-year survival was 43% (mortality was often from causes other than cancer given the age of the men at diagnosis). Higher age at diagnosis, large tumor size, positive lymph node status, ER- status and poorly differentiated grade each were independently associated with decreased survival. African-American men experienced shorter survival (median 7.08 years) after diagnosis than Caucasian men (9.2 years). Another study reported that for men initially diagnosed with stage II, median cancer-specific survival was 12.9 years; for stage III it was 7.2 years, and for stage IV it was 0.8 years. A small 2016 study reported that male breast cancer patients with harmful BRCA mutations had less favorable long-term survival rates than men without such mutations.
We have elected not to try to summarize the statistics concerning risk of recurrence for male breast cancer here because it varies greatly depending on numerous factors. Specific data concerning relapse and survival can be found in the studies below.