Information & Support
Exploring hormones and their risk and impact on male breast cancer
Male Breast Cancer Hormones
Hormones, especially a higher level of estrogen (found in women and men), can increase the risk of developing breast cancer. Below is a list of how or why one might have a higher level.
Taking hormonal medicines
Being overweight, which increases the production of estrogen
Having been exposed to estrogens in the environment (such as estrogen and other hormones fed to fatten up beef cattle or the breakdown products of the pesticide DDT, which can mimic the effects of estrogen in the body)
Being heavy users of alcohol which can limit the liver's ability to regulate blood estrogen levels
Having liver disease usually leads to lower levels of androgens (male hormones) and higher levels of estrogen (female hormones). This increases the risk of developing gynecomastia (breast tissue growth that is non-cancerous) as well as breast cancer.
Hormones can play a large part in the development and growth of breast cancer. When a biopsy is performed, part of the diagnosis will include whether the cancer is Estrogen and/or Progesterone dominant or negative. Depending on the findings, the information will partly determine the course of action needed following any surgical procedures.
Approximately 9 out of 10 breast cancers in men are diagnosed as hormone receptor-positive. This can include either estrogen receptor (ER) positive and/or progesterone receptor (PR) positive. This is helpful as then men can be treated with hormone therapy
Currently, Tamoxifen is the preferred hormone treatment as it is the best-studied hormone drug for breast cancer in men. Tamoxifen (Nolvadex) works to prevent estrogen from binding to its receptor on breast cancer cells. The treatment regimen is to remain on Tamoxifen from 5-10 years post surgery for the best results and is taken in pill form one daily.
Other Hormone therapy drugs include Aromatase Inhibitors
This group of drugs includes anastrozole (Arimidex®), letrozole (Femara®), and exemestane (Aromasin®). They work by blocking an enzyme (aromatase) in fat tissue that converts male hormones from the adrenal glands into estrogen. Aromatase inhibitors are taken daily as pills. They have been very effective in treating breast cancer in women, but they have not been well-studied in men and are used if Tamoxifen stops working.
Fulvestrant is a drug that also acts on the estrogen receptor, but instead of blocking it, this drug eliminates it. In postmenopausal women, this drug is often effective even if the breast cancer is no longer responding to tamoxifen. In one small study of men with advanced breast cancer who had previously been treated with at least one other hormone drug, some of the men saw their tumors shrink with fulvestrant. It is given by injection every 2 weeks for a month, then monthly.
Luteinizing hormone-releasing hormone (LHRH) analogs and anti-androgens
LHRH analogs such as leuprolide (Lupron®) and goserelin (Zoladex®) affect the pituitary gland. In men they turn off production of the male hormone testosterone by the testicles, leading to lower testosterone levels. They are given as shots either monthly or every few months. These drugs may be used by themselves, or combined with aromatase inhibitors or anti-androgens to treat advanced breast cancer in men.
Anti-androgens such as flutamide and bicalutamide work by blocking the effect of male hormones on breast cancer cells. These drugs are taken daily as pills.
Megestrol is a progesterone-like drug. It is unclear how it stops cancer cells from growing, but it appears to compete for hormone receptor sites in the cells. This is an older drug that is usually reserved for men who are no longer responding to other forms of hormone therapy. Megestrol may increase the risk for blood clots and frequently causes weight gain by increasing appetite.
Surgical removal of the testicles greatly lowers the levels of testosterone and other androgens (male hormones). Most male breast cancers have androgen receptors that may cause the cells to grow. Androgens can also be converted into estrogens in the body. Orchiectomy shrinks most male breast cancers, and may help make other treatments like tamoxifen more likely to work. This treatment was once quite common, but it is now used less often because of new non-surgical approaches to lowering androgen levels, such as the LHRH analogs discussed previously.
Possible side effects of hormone therapy
Although some of these drugs have unique side effects (see descriptions above), in general they can cause loss of sexual desire, trouble having an erection, weight gain, hot flashes, and mood swings. Be sure to discuss any such side effects with your cancer care team because there may be ways to treat them.
Source: American Cancer Society