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Risk Factors for Male Breast Cancer
While only approximately 1% of all breast cancer cases occur in men, several risk
factors have been identified that make some men more likely to develop breast cancer than
others. These risk factors include:
Advancing age: The average age of men diagnosed with breast cancer is between 60
and 70 years old.
Family history: Approximately 20% of men with breast cancer have close female
relatives who have (or have had) breast cancer.
Radiation exposure: Prior exposure to radiation (usually for treatment of a
cancer inside the chest such as Hodgkin's or non-Hodgkin's lymphoma) is a risk factor for
male breast cancer.
Liver disease: The liver helps with hormone metabolism by binding proteins that
carry hormones in the blood. Men with severe liver diseases such as cirrhosis tend to have
lower levels of androgens (male hormones) and higher estrogen levels (female hormones),
which puts them at an increased risk of developing gynecomastia (non-cancerous tissue
growth) and breast cancer. According to the American Cancer Society, in certain Middle
Eastern and African countries, severe liver disease due to infection with certain
parasites is common. Men in these countries may have a significantly higher risk of breast
cancer than men in the United States.
Treatment with estrogen: Estrogen may feed some types of cancerous breast
tumors, and therefore, men who have been treated with estrogen may be at an increased risk
for breast cancer. However, according to the American Cancer Society, the risk of breast
cancer due to estrogen treatment appears to be small. The benefit of slowing the growth of
prostate cancer with estrogen, for example, often outweighs the risk of developing breast
cancer. Also, men who take high doses of estrogen as part of a gender-changing procedure
may be at a higher risk for breast cancer.
BRCA2 gene mutations:
When functioning normally, the breast cancer
gene 2 (BRCA2) helps repair damage to DNA (a process that also
prevents tumor development). However, some men and women have genetic
mutations of the BRCA2 gene, which can lead to an increased risk of breast
cancer. BRCA1
(breast cancer gene 1) mutations also increase the risk for breast cancer in women. Men
who carry mutations of the BRCA1 gene may pass the gene along to their daughters, who
would be at an increased risk of developing breast cancer.
Klinefelter's syndrome: Normally, men are born with one X chromosome and one Y
chromosome (the chromosomes which determine gender). Klinefelter's syndrome is a
genetic condition that occurs when a man is born with two or more X (female) chromosomes.
Approximately 1 in 850 men have Klinefelter's syndrome. Symptoms of
Klinefelter's syndrome include longer legs, a higher voice, a thinner beard than
average men, smaller than normal testicles, and the inability to produce sperm
(infertility). Men with Klinefelter's syndrome also have lower levels of androgens
(male hormones) and higher levels of estrogen (female hormones). Therefore, men with
Klinefelter's syndrome are at a higher risk of developing gynecomastia (non-cancerous
tissue growth) and breast cancer.
Diagnosing Male Breast Cancer
A breast lump or abnormality will usually first be
investigated with a physician-performed clinical breast exam and complete
physical (to check for enlarged lymph nodes,
liver problems, etc.). The physician will also assess the patient's personal and
family history, since male breast cancer tends to occur more frequently when one or more
female relatives also has (or has had) breast cancer. Because men have significantly less
breast tissue than most women, a breast lump or other abnormality is usually much easier
to detect with physical examination on a man than on a woman. However, male breast cancer
tends to affect the skin and muscles underneath the breast more quickly than female breast
cancer. While male breast cancer tends to be smaller when found, it is more likely to have
spread past the breast than female breast cancer.
If a physician is concerned about his or her
findings during a clinical breast exam, he or she may order a mammogram to further investigate the breast
abnormality. Diagnostic mammography
involves taking x-ray images of the breast. In some cases, special
mammography views such as spot compression
or magnification are needed. Additional
tests such as ultrasound or a nipple discharge examination may also be ordered. If
testing reveals the possibility of cancer, a breast
biopsy may be performed (although the mammographic signs of some
benign conditions such as gynecomastia can be quite characteristic and
biopsy may not be needed in some cases). A biopsy involves taking samples
of breast tissue for pathological examination under a microscope. A biopsy
is the only definitive way to determine whether breast cancer is present.
Click here
to learn about the different methods of breast biopsy.
Treating Male Breast Cancer
Depending on the type and stage
of breast cancer, one of the following treatment will most likely be used:
Surgery: usually a modified radical mastectomy is performed to remove the breast, the lining over
the chest muscles, and part of the chest wall muscles. Some or all of the
axillary (underarm) lymph nodes
may also be removed and sent to the laboratory for pathological examination to determine
whether breast cancer has spread past the breast.
Radiation therapy: involves using
high-energy rays to stop cancer cells from growing and dividing.
Chemotherapy: treatment with anticancer
drugs.
Hormone therapy: often
used if the breast cancer cells have estrogen receptors or progesterone receptors. Over 80%
of male breast cancers have estrogen receptors. Hormone therapies used to
treat male breast cancer include drugs tamoxifen
(brand name Nolvadex) and megace (brand name, Megestrol). Tamoxifen is an antiestrogen and
works by blocking estrogen in the breast, thereby slowing the growth and reproduction of
breast cancer cells that depend on estrogen for survival. Megace is an anti-androgen and
blocks the effect of androgen (a male hormone) on breast cancer cells. Researchers are not
certain why blocking androgen in the breast helps treat male breast cancer.
Survival Rates for Male Breast Cancer
In the past, it was believed that the prognosis (expected outcome) for male breast
cancer was worse than for female breast cancer. Today, it is widely accepted that the
survival rates are similar when treatment of the tumor begins at the same stage. However,
male breast cancer tends to be diagnosed in later stages than female breast cancer.
The five-year survival rates for male breast
cancer are based on the stage of the breast cancer. Staging is the process physicians use to assess the
size and location of a patient’s cancer. Identifying the cancer stage is
one of the most important factors in selecting treatment options. Breast
cancer stages range from Stage 0 (the earliest stage) to Stage IV (advanced breast cancer). The stage of the
breast cancer is determined by the tumor size, lymph node involvement, and
the extent to which the cancer has spread (metastasis). Click here
to learn more about the stages of breast cancer.
The following chart is an approximate survival rate for each stage of breast cancer.
The percentages are only averages. The chances of survival will differ for each man
depending on his own medical situation and several other factors, including new treatment
options, how he responds to treatment, etc.
|
Stage of Male Breast Cancer |
5-year Relative
Survival Rate |
|
0
I
II
III
IV
|
100%
96%
84%
52%
24%
|
Source: American Cancer Society
Additional Resources and References
The American Cancer Society provides
information on male breast cancer at
http://www.cancer.org/
The National Cancer Institute provides
information on male breast cancer at
http://www.cancer.gov/
The University of Pennsylvania's Oncolink document, "NCI/PDQ Physician
Statement: Male Breast Cancer," is available at
http://cancer.med.upenn.edu/
Updated: January 29, 2008
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