Male breast cancer is a rare type of cancer that occurs in the male breast. Though breast cancer affects women much more commonly, it can also occur in men.
Causes, diagnosis, and treatment of male breast cancer are generally similar to that in females. However, breast cancer in men is rare in comparison with female breast cancer.
Male breast cancer accounts for less than 1% of all breast cancers. The lifetime risk of developing breast cancer for U.S. men is about 1 in 1,000.
It is most common in older men, though it can occur at any age.
Because of the rarity of the disease, it is generally diagnosed at a later or advanced stage. This results in proportionately higher mortality as compared to female breast cancer. However, if adjusted for age at diagnosis and the stage of the disease, the outcomes for both male and female breast cancer are similar.
Normal Breast Tissue in Males
All boys and men have a small amount of breast tissue behind their nipples.
Until puberty, both boys and girls have the same, small amount of breast tissue behind the nipple and areola. It is composed of few ducts surrounded by fatty tissue and connective tissue (blood vessels, lymphatic vessels and nerves).
At puberty, a girl’s ovaries begin to produce the hormone estrogen. This hormone leads to the development of breast tissue by causing the breast ducts to grow and lobules to form at the ends of ducts.
Boys also produce the hormone estrogen at puberty, although in low amounts. The hormone testosterone is produced in a much greater quantity in males which acts against the effects of estrogen.
In some boys, the low level of estrogen produced at puberty causes swelling of the breast but this is usually temporary. The male breast tissue doesn’t develop like the female breast. An adult male’s breast tissue consists of mainly ducts and few if any, lobules.
In some men, the balance between the hormones estrogen and testosterone changes either due to some disease process (such as cirrhosis, disorders of testes, hyperthyroidism, etc) or due to the side effect of some drugs (eg., digoxin, isoniazid, spironolactone, etc). This can cause swelling of the breast tissue which is called gynecomastia. Gynecomastia is not breast cancer, neither does it increase the chance of breast cancer in the future.
Image Credit: verywellhealth.com
Risk Factors for Breast Cancer in Men
These are similar to risk factors associated with female breast cancers, especially high estrogen levels and genetic factors. High estrogen levels in men are also related to obesity, liver disease, and thyroid dysfunction.
The incidence of breast cancer increases with age. Majority of the breast cancers occur in men who are 50 years or above in age. It is rare in young men.
Family history of breast cancer
The risk of breast cancer is increased in men who have single or multiple first-degree relatives (whether male or female) diagnosed with breast cancer.
This increased risk is due to the inherited mutation in one of two genes, BRCA1 and BRCA2.
Inherited gene mutations
Men with a genetic mutation in the BRCA genes have an increased risk of breast cancer. The lifetime risk with BRCA2 mutations is slightly more than with BRCA1 mutations. BRCA gene mutations account for about 5% to 10% of all breast cancers.
BRCA mutations are commonly found in members of families in which multiple family members may have breast and/or ovarian cancer. However, these genetic effects are also found in some male breast cancer patients who do not have a family history of breast cancers.
Read more about BRCA Gene Mutation and Testing
Mutations in some other genes like PTEN, CHEK2, and PALB2 may also be responsible for some male breast cancers.
Klinefelter syndrome is a congenital condition (present since birth). Men with Klinefelter syndrome have more than one X chromosomes along with a Y chromosome in their cells. Normal men have one X and one Y chromosome in their cells while normal females have two X chromosomes and no Y chromosome in their cells. This condition affects about 1 in 1,000 men.
Men with Klinefelter syndrome have lower levels of androgens and higher levels of estrogens as compared to normal males. Due to this reason, they have an increased risk of having breast cancer that equals that of females. The risk is about 20-60 times more than normal men.
These men also commonly develop gynecomastia (benign male breast growth).
Increased weight or obesity is a risk factor for male breast cancer. This is because the fat present in the body converts male hormones (androgens) into female hormones (estrogens). Thus obese men have increased levels of the hormone estrogen.
Regular and heavy alcohol consumption increases the risk of male breast cancer.
The liver plays an important role in balancing the levels of sex hormones. In cases of severe liver disease, such as cirrhosis, the liver does not function well causing reduced levels of androgens and increased levels of estrogen. Higher estrogen levels increase the risk of breast cancer.
Liver disease or cirrhosis also increases the chance of developing gynecomastia (benign growth of the male breast).
Exposure to radiation (in case of treatment of cancer in the chest, like lymphoma) increases the risk of developing breast cancer.
Estrogen therapy used to treat prostate cancer or loss of bone density may slightly increase breast cancer risk.
Conditions affecting the testes, such as an undescended testicle or surgical removal of both testes (bilateral orchiectomy) may increase the risk of male breast cancer.
Signs and Symptoms
- A lump in the breast.
In the majority of cases, the lump is a hard and fixed nodule in the subareolar region. It is usually painless.
Nipple involvement is more common than in women. Because the male breast is much smaller than the female breast, all male breast cancers start relatively close to the nipple, so they are more likely to spread to the nipple.
Often, the disease is not detected until it is advanced. It may also be confused with gynecomastia which is a benign enlargement of the male breast and is much more common than male breast cancer.
Other presentations include:
- Change in the skin over the breast, such as dimpling or redness or scaling and crusting of the skin of the breast.
- Change in the size, shape or appearance of a breast.
- A newly inverted nipple, change in the shape or appearance of the nipple.
- Discharge from the nipple which could be bloody.
Types of Male Breast Cancer
Most of the breast cancers are carcinomas. Since they arise from the breast glandular tissue they are known as adenocarcinoma.
The majority of the male breast cancers arise from the epithelium lining the ducts of the breast (Ductal carcinoma)
- When the cancer cells are confined to the ducts but do not invade the surrounding tissue, it is known as Ductal Carcinoma in situ (DCIS)
- On the other hand, when the cancer cells do not remain confined to the ducts and start spreading to the surrounding tissue, it is called Infiltrating or Invasive Ductal Carcinoma.
Once cancer has spread to the tissue outside the breast ducts or lobules, it can start spreading to other nearby organs and tissue.
Breast cancer that originates from the breast lobules is called Lobular carcinoma in situ (LCIS) or invasive lobular carcinoma depending upon whether the cancer cells are confined to the lobules or have spread to the surrounding tissue.
In men, lobular breast carcinoma is extremely rare because lobules are not usually found in the normal male breast. However, lobules may be seen rarely in the male breast. Lobular carcinoma in situ is even rarer.
Other types of invasive breast carcinomas include:
- Tubular carcinoma
- Cribriform carcinoma
- Mucinous carcinoma
- Medullary carcinoma
- Invasive micropapillary carcinoma
- Invasive papillary carcinoma
- Metaplastic carcinoma
- Spindle cell carcinoma
- Carcinoma with neuroendocrine features
- Secretory carcinoma
- Inflammatory breast carcinoma
Other, still rarer types of breast cancers include sarcomas, phyllodes tumor, Paget’s disease, liposarcoma, angiosarcoma, etc which originate from the connective tissue (muscle, fat, fibrous tissue, etc) present around the breast ducts.
Diagnosis of Male Breast Cancer
Mammography uses low dose x-rays to examine the breasts. The breasts are exposed to a small amount of ionizing radiation and pictures of the inside of the breasts from different angles are obtained. It is the most effective non-invasive test to detect breast cancer. Mammography is more accurate in men than women since the breast tissue in men is not as dense as in women. Also the male breast does not undergo changes like lactational or hormonal changes which may interfere with the interpretation.
Ultrasound uses high-frequency sound waves to obtain pictures of the inside of the breasts. It is non-invasive and free of harmful radiation. It can capture images of areas of the breast that are difficult to see with mammography. It can distinguish between fluid-filled (cystic) and solid breast lumps.
Breast MRI (Magnetic Resonance Imaging)
MRI uses a powerful magnetic field, radiofrequency pulses and a computer to produce images of the inside of the breasts. A contrast material is injected through a vein into the body before obtaining the images. MRI can be used to diagnose breast lumps in select high-risk patients, in cases of dense breast tissue or when findings of mammogram and ultrasound are not conclusive.
Nipple discharge cytology
The discharge from the nipple can be smeared on a glass slide and examined under a microscope to look for the presence of cancer cells.
In this procedure, a fine needle is inserted into the lump and some material is aspirated. This material is then spread on a glass slide, stained with appropriate stains and examined under a microscope. The procedure may be performed under the guidance of ultrasound.
It is a quick, relatively painless, non-invasive, outdoor procedure to diagnose breast cancer.
It is a small surgical procedure carried out under local anesthesia. A small piece of the breast lump is removed (and after a series of steps including processing, fixation, and staining) it is examined under a microscope. It is the best method to confirm whether cancer is present or not. However, the processing and other steps involved make it a lengthy procedure. The results are available in about 3-4 days.
A breast biopsy can be of various types:
Core needle biopsy: A needle larger than that used for FNAC and having a special tip is used to remove a tiny sample of breast tissue.
Stereotactic biopsy: Mammography is used to precisely identify the suspicious area and then that area is biopsied.
Vacuum-assisted biopsy: A probe with a vacuum is inserted through a small incision in the skin and a sample of breast tissue is removed. It is performed under imaging guidance (ultrasound or mammogram or MRI).
Surgical biopsy: A small cut is made in the skin and part or whole of the lump is removed.
- Incisional biopsy: Only a part of the lump is removed.
- Excisional biopsy: The entire lump is removed. It is also called a lumpectomy.
Once breast cancer has been diagnosed, additional testing may be carried out to determine the stage or extent of the disease. This helps to determine the prognosis and the best treatment options available. However complete information about the stage of cancer becomes available only after breast cancer surgery.
- Blood tests, such as a complete blood count
- Mammogram of the other breast to look for signs of cancer
- Bone scan
- Computerized tomography (CT) scan
- Positron emission tomography (PET) scan
- Tumor markers such as receptors for estrogen (ER), progesterone (PR) and HER2 along with proliferation factors.
If cancer is confirmed, the biopsy material is subjected to further testing to see if the cancer cells have hormone receptors (estrogen and progesterone receptors) or if they are producing increased amounts of the HER2 protein (HER2-positive breast cancer). Most of the male breast cancers are positive for estrogen and progesterone receptors. If both estrogen and progesterone receptors are absent and HER2 protein is not being produced excessively, the cancer is labeled as triple-negative breast cancer.
Treatment for both male and female breast cancer is generally the same. It depends on the type of breast cancer and the stage of the disease (meaning the extent to which it has spread within the body).
The various treatment modalities available to treat breast cancer can be grouped as follows.
The tumor and some surrounding healthy tissue are removed during an operation. The axillary lymph nodes, which are under the arm are also usually removed. This surgical procedure is called Modified Radical Mastectomy.
In certain cases, lumpectomy or breast-conserving surgery (removing only the cancerous breast lump) may be carried out.
Image Credit: https://visualsonline.cancer.gov/
Special medicines are given to the patient which helps to shrink or kill the cancer cells in the body. These drugs can be either given orally or injected through the veins.
It may be given before surgery to shrink a large tumor, so as to make surgery easier and reduce the risk of recurrence (called neoadjuvant chemotherapy).
It may also be given after surgery to reduce the risk of recurrence (adjuvant chemotherapy)
Usually, a combination of drugs is given in a specific number of cycles over a set period of time. Common drugs include Capecitabine (Xeloda), Carboplatin, Cisplatin, Cyclophosphamide, Docetaxel, Doxorubicin, etc.
High-energy rays are delivered to the affected part of the body to kill the cancer cells. The most common type of radiation treatment is external-beam radiation therapy which is given from a machine outside the body.
It is usually given after surgery to lower the risk of recurrence in the breast. If there is cancer in the axillary lymph nodes, radiation therapy may be given to the same side of the neck or underarm near the breast or chest wall.
If the cancer is extensive or inoperable or has metastasized, radiation therapy may be the main treatment.
Read more about Metastasis or Metastatic Disease
Tumors that have receptors on their surface for certain hormones can be treated using hormonal therapy. Certain hormones stimulate the growth of cancer. In these patients, medications can prevent the tumor from getting the hormone or stop the body from making the hormone.
The anti-estrogenic drug tamoxifen is the standard hormone therapy for male breast cancer.
Aromatase inhibitors (such as anastrozole) decrease the body’s estrogen by blocking the enzyme aromatase from converting androgen into estrogen. Luteinizing hormone-releasing hormone (LHRH) agonist (such as Leuprolide) acts on the pituitary gland which directs the testicles to produce less testosterone.
In addition, removal of the testes reduces the amount of certain male hormones in the system. Men with breast cancer should never take testosterone because it causes breast cancer cells to grow.
HER2-positive male breast cancer patients can be given trastuzumab (Herceptin), a drug that stops the HER-2 protein from making the cancer cells grow.
Biological therapy or Immunotherapy
This includes drugs that stimulate the body’s immune system to fight cancer cells. It can also be used to reduce the side effects of other cancer treatments. An example is the drug atezolizumab (Tecentriq) which blocks a protein called PD-L1. The expression of the PD-L1 protein on the tumor cell surface helps the tumor cells to escape immunosuppression.
Outlook and Long-term monitoring
Male breast cancer has a poor prognosis in comparison with female breast cancer mainly because it is usually diagnosed at an advanced stage. If adjusted for age at diagnosis and the stage of the disease, the outcomes for both male and female breast cancer are similar.
Men who have had breast cancer are at increased risk for second breast cancer (either in the same breast or opposite breast). Thus, regular screening of both breasts is advised in male breast cancer patients.