Male Breast Cancer

What is male breast cancer?

Breast cancer is commonly believed to be a disease affecting women alone, but men can also get this cancer. In men however, the cancer is much rarer than in women with only one in every 100,000 men affected.

The normal male breast

The normal male or female breast has:

  • lobules (milk-producing glands)
  • ducts (tiny tubes that carry the milk from the lobules to the nipple)
  • stroma (fatty tissue and connective tissue surrounding the ducts and lobules
  • tiny blood vessels, and lymphatic vessels
Male breast structure
Lymphatic system of the male breast.

Until puberty, young boys and girls have a small amount of breast tissue consisting of a few ducts located under the nipple and areola (dark area around the nipple). At puberty, the female hormones in girls cause the breast ducts to grow, lobules to form at the ends of ducts, and the amount of stroma to increase.

In boys, male hormones made by the testicles keep breast tissue from growing as much as females. Men's breast tissue has ducts, but only a few if any lobules.

Causes of breast cancer

Certain risk factors predispose to developing male breast cancer. The most important of these is age as most cases develop after 70 years of age. Those who are alcoholic or obese are also at a greater risk. The risk is high among patients who have a family member (male or female) with breast cancer.

Also, men with a rare genetic condition called Klinefelter's syndrome are 20 to 50 times more likely to get breast cancer than normal men. Men with Klinefelter's syndrome have an extra, female, X chromosome, making them XXY, and often have slightly more breast tissue than normal.

The highest risk factors include radiation to the chest when young and exposure to hormonal therapy for other disease conditions. Men with high blood levels of female hormone estrogen are at risk of breast cancer.

How many people does male breast cancer affect?

In the UK around 300 new cases of breast cancer in men are diagnosed annually with majority patients over 60 to 70 years of age. In the United States 2,190 men are expected to be diagnosed, and 410 are expected to die from the disease in 2012.

Rates of breast cancer are slightly higher in Jewish men. This could due to genetic associations between breast cancer and some inherited genes.

Worldwide there are highest rates in Zambia. This could be due to common endemic liver infections there that lead to increased production of estrogen in men. Japan has a lower incidence of breast cancer for both men and women.

Symptoms of male breast cancer

The most common symptom of male breast cancer is development of a hard, painless lump over one of the breasts or clear or bloody discharge from one of the nipples. The shape of the affected breast and the nipple may differ from the other. If the cancer has spread to the lymph nodes in the respective armpit, the glands there may be swollen as well.

Male and female breast cancer comparison

Similarities and differences in male and female breast cancer:

  • Most of the risk factors for breast cancer in men are also seen in women.
  • The signs and symptoms of the disease are the same in both sexes and the responses to treatment are similar. 
  • Survival from breast cancer is similar in men and women
  • The same types of tumors seen in women are also seen in men
  • The average age of diagnosis however is five to ten years later for men than for women.
  • The number of estrogen receptor containing breast tumors (estrogen receptor positive tumors) in men is higher than in women

Treatment of male breast cancer

Male breast cancer is treated primarily with surgery to remove a section of the breast. Thereafter chemotherapy and/or radiation therapy may be used to kill the residual cancer cells.

Chemotherapy and radiation therapy may be used alone if the cancer is advanced and spread to other organs as well. Hormonal therapy with tamoxifen that helps to block the effects of hormones on breast tissue that are known to stimulate the growth of cancerous cells may be used to prevent the cancer recurrence.

Outlook for male breast cancer

The outcome of therapy in male breast cancer is less favourable than for breast cancer in women. This is mainly because the cancer is often detected at a later stage and there is a lack of awareness of the condition.

However, those diagnosed at stage 1 have a 75-100% rate of survival 5 years after diagnosis, those diagnosed in stages 2 or 3 have a 50-80% rate of five year survival and those diagnosed in stage 4 or advanced stages have a 30-60% rate of five year survival.

Causes of male breast cancer

Normal cells have a tightly regulated system that guides when they would grow, reproduce and eventually die. Cancer occurs in normal cells when this regulation fails and cells grow uncontrollably. There are defects in the coding information in cells, which is present in the deoxyribonucleic acid (DNA) that is found in the nucleus of cells in all human cells.

A change in the code is called a mutation and can alter the instructions that control cell growth leading to cancer. These deranged cells grow in an uncontrollable manner and produce a lump of tissue that is known as a tumor.

Once the cancer is formed it can quickly grow and spread to other parts of the body. Breast cancer may spread directly into the surrounding muscle and skin and may also spread via blood or lymphatic system to different organs of the body like the lungs, brain and liver. The spread first occurs to the nearby lymph nodes that may appear swollen.

Breast cancer is rare among men compared to its incidence in women. There are several risk factors that raise the chance of men getting breast cancer. These include increasing age, inheritance, exposure to female hormone estrogen and so forth.

Increasing age and risk of male breast cancer

Increasing age is the common risk factor. Most cases occur after 60 to 70 years of age.

Genetics and inherited breast cancer

A genetic mutation may be inherited from family members. Those with a family member (both male or female) have a higher risk of breast cancer. The most significant mutation identified to date is known as the BRAC2 mutation.

One study that was carried out in the UK found that 1 in 20 men with breast cancer have the BRAC2 mutation. In addition at least 1 in 5 men who develop breast cancer, have a first-degree relative (a parent or a sibling) who also has a history of breast cancer.

Exposure to female hormone estrogen

Long term exposure to estrogen can increase the risks of breast cancer in men. Normally men have a low level of this hormone but levels may rise in certain conditions in men like:

  • those undergoing hormonal therapy (those with prostate cancer and transsexuals who are undergoing a male to female sex change)
  • obese men
  • a genetic condition called Klinefelter's syndrome

Klinefelter's syndrome is a major risk factor for breast cancer in men. Men who have the condition are 20 times more likely to develop breast cancer than the male population at large.

Boys with Klinefelter's syndrome are born with much higher levels of oestrogen than normal. They have an extra X chromosome (XXY) compared to normal males who have XY chromosomes. It is estimated that 1 in every 1,000 people are affected by Klinefelter's syndrome.
Exposure to environmental factors

Men who work in hot environments are twice as likely to develop breast cancer compared with men who work in cooler environments. In includes blast furnace workers, steel workers, those working at car manufacturing plants and steel works. It is speculated that excess heat may damage the testicles causing a decline in male hormones and rise in female hormones like estrogen.

In addition, exposure to certain chemicals may increase the risk of developing breast cancer in men. Those men working with perfumes and soaps are seven times more likely to develop breast cancer than the male population at large. Those exposed to Polycyclic aromatic hydrocarbons (as in petrol and exhaust fumes) are also at a raised risk.

Exposure to radiation

Men who have been exposed to radiation of the chest are at a higher risk.

Chronic liver disease

Chronic liver disease also leads to high levels of female hormones estrogen and increases the risk of male breast cancer. This is seen in men with chronic alcoholism.

Pituitary tumors

Those with pituitary tumors or Pituitary adenomas leading to increased levels of the hormone prolactin in blood are at a higher risk of developing breast cancer in both breasts.

Gynecomastia

Gynecomastia or enlargement of male breasts is not a risk factor for male breast cancer.

Symptoms of male breast cancer

The male breast is structurally and functionally different from female breast due to the hormones that guide its growth and maturity.

Anatomy of the breast

The normal male or female breast has:

  • Lobules (milk-producing glands)
  • Ducts (tiny tubes that carry the milk from the lobules to the nipple)
  • Stroma (fatty tissue and connective tissue surrounding the ducts and lobules
  • tiny blood vessels, and lymphatic vessels
  • The nipple where the ducts come together and a darkened area around it called the areola

Breast during puberty

Until puberty, young boys and girls have a small amount of breast tissue consisting of a few ducts located under the nipple and areola (dark area around the nipple).

At puberty, the female hormones in girls cause the breast ducts to grow, lobules to form at the ends of ducts, and the amount of stroma to increase.

In boys, male hormones made by the testicles keep breast tissue from growing as much as females. Men's breast tissue has ducts, but only a few if any lobules.

Most common symptom of male breast cancer

The most common symptom of male breast cancer is development of a hard, painless lump over one of the breasts or clear or bloody discharge from one of the nipples. The shape of the affected breast and the nipple may differ from the other.

Symptoms of male breast cancer

Symptoms of male breast cancer may be outlined as:

  • Firm mass underneath the nipple
  • The nipple may appear retracted to one side or underneath or depressed and there may be a discharge that is clear or bloody at the tip of the nipple
  • There may be pain or itching at the nipple.
  • There may be redness or scaling of the nipple or breast skin
  • The mass itself is painless and may appear hard on touch
  • The mass may be fixed to the underlying tissues, muscles and the ribcage or may be freely mobile on touch, slipping beneath the fingers.
  • There may be dimpling or puckering of the skin if the mass is attached to the skin over the breast.
  • Sometimes a breast cancer can spread to lymph nodes under the arm or around the collar bone and cause a lump or swelling there. This may occur even before the original tumor in the breast is large enough to be felt
  • Very rarely gynaecomastia or enlargement of male breast may be seen. In patients with gynaecomastia the warning signs of breast cancer are swelling in one breast, hard or irregular breast tissue, rapid growth and recent onset, fixed mass and nipple or skin changes, pain, size over 5 cm in diameter and swelling of the lymph nodes in the armpits.
  • General symptoms include weakness, fatigue, unexplained weight loss, anemia etc.
  • In advanced cancers that have spread to other parts, other features include bone pain, shortness of breath, nausea, jaundice (if liver is involved) etc.

Male and female breast cancer compared

The male breast cancer is similar and different from female breast cancer in numerous ways.

Similarities and differences in male and female breast cancer include:

  • Most of the risk factors for breast cancer in men are also seen in women.
  • The signs and symptoms of the disease are the same in both sexes and the responses to treatment are similar. 
  • Survival from breast cancer is similar in men and women
  • The same types of tumors seen in women are also seen in men
  • The average age of diagnosis however is five to ten years later for men than for women.
  • The number of estrogen receptor containing breast tumors (estrogen receptor positive tumors) in men is higher than in women