Although very rare, approximately 1% of all breast cancer is diagnosed in men.  It is estimated (in 2015) that about 2350 men in the US, approximately 200 men in Canada, 400 men in Australia and 125 men in the UK are diagnosed annually  with male breast cancer (MBC).  As a result, approximately 450 men in the US, about 45 men in Canada, approximately 80 men in Australia and about 25 men in the UK will die from this disease each year.  When diagnosed with the same type and grade of tumor at the same stage, the prognosis and treatment options for men are similar to that for women.  Unfortunately, the overall prognosis for men is not as good as for women because more often than not, male breast cancer is diagnosed at a later, more advanced stage.  Consequently, the survival rate for men diagnosed with breast cancer is about 74% compared to about 83% for women1.  This is in part due to the fact that many men are unaware that breast cancer is a disease that can affect them and also because men, in generally, are reluctant to seek medical advice, especially about a breast issue.


What is Cancer

Cancer is a general term used to describe a multifaceted group of different types of cancers that can develop in almost every organ in the human body.

Cancer Development

Cells are the human building blocks that can divide and multiply as required by the body.  However, the continued reproduction of cells when not required can result in a growth or mass commonly referred to as a tumor.  Tumors are classified as benign (non-cancerous) or malignant (cancerous).  Benign tumors do not spread throughout the body do not usually present any health risks, and are often surgically removed from the body without major complications. Conversely, malignant cells are cancerous and have the potential to spread (metastasize) to other organs throughout the body.

What Causes Breast Cancer 

DNA is inherited from our parents and it is responsible for providing the instructional codes for how our cells function.  Mutations or changes that can speed up or slow down cell division in our DNA can be responsible for causing normal breast cells to become cancerous.  The inherited tumor suppressor genes, BRCA1 and BRCA2 can also increase the risk of developing breast cancer.  If the BRCA1 or BRCA2 genes demonstrate a mutation, it can be passed down to offspring.  The mutations will then no longer allow for the genes to suppress abnormal cell growth, leading to an increased risk of developing breast cancer.       

        There are still many risk factors associated with the development of breast cancer.  The exact relationship as to why and how these risk factors cause cancerous cells to develop remains unanswered.  Hormones are now recognized as playing a significant part in the complex role in the development of many cases of breast cancer, especially in breast cancer tumors that exhibit estrogen/progesterone positive receptors.

        Although estrogen is usually classified as a hormone found in women, it is also found at significantly lower levels in men.  In approximately 90% of breast cancer diagnosed in men, the surface cells of the tumors exhibit hormone receptors that are estrogen/progesterone positive that can usually be successfully treated with hormone therapy.  On the other hand, however, estrogen/progesterone negative tumors do not respond to hormone therapy.

What Is Male Breast Cancer

 Male breast cancer (MBC) involves a malignant tumor or group of cancer cells in the breast that may invade the surrounding breast tissue or metastasize to other parts of the body.  It is very rare in men, approximately 1% of all breast cancer is diagnosed in men. 

 Prepubescent males and females (ages 13-14) normally demonstrate a small amount of breast tissue that is made up of minimal breast ducts located beneath the nipple and the surrounding areola.  Once puberty occurs in females, hormones are produced in the ovaries, allowing for the breast ducts to grow and develop.  In males, the hormones that develop in the testicles are responsible for preventing further growth of breast tissue.  The male breast has a minimal amount of breast ducts and like all cells of the human body, cancerous changes can occur within these cells.

Types of MBC

Benign Breast Tumors

Benign breast tumors are non life threatening and do not metastasize throughout the body.  These types of tumors are commonly found in women and are very rarely found in men.


Gynecomastia is the most common disorder of the male breast.  The benign lesion usually presents as a disk-shaped, palpable mass found beneath the nipple and/or areola. Occasionally, the mass can be seen.  Because non-cancerous and cancerous lesions can both originate under the nipple, it is very important to have any suspicious lump examined by a physician.

Gynecomastia is mostly found in adolescent males as a result of hormone changes during puberty.  It may also be found in older men, as hormone levels change with age.

Under rare circumstances, gynecomastia can develop as a result of certain endocrine tumors. These types of tumors are hormone producing, which means that they can alter the amount of estrogen produced in the male body.  Diseases of the liver and obesity can also affect hormone levels in men that could result in gynecomastia. 

Medications used to treat ulcers, heartburn, high blood pressure, and heart failure can cause side affects that may lead to gynecomastia.  Men that have gynecomastia should always consult a physician.

Klinefelter Syndrome

Klinefelter syndrome, a rare medical condition in men, is the most prominent risk factor. Klinefelter patients have lower levels of testosterone and increased levels of estrogen (i.e. an additional X chromosome, XXY).  Those with Klinefelter’s Syndrome have a 14-50 times higher risk in developing male breast cancer.

Breast Cancer Terminology


Carcinoma is a type of cancer that forms within the epithelial cells (the cell lining of the organs).  The majority of breast cancers are categorized as either ductal carcinoma or as lobular carcinoma.


Adenocacrinoma is a type of cancer that forms within glandular tissue (cells that produce and secrete material).

Carcinoma in situ

Carcinoma in situ, also known as non-invasive breast cancer, refers to the preliminary stages of cancer, i.e. where the cancer cells are confined to the cell layer from which they first developed.  In situ refers to breast cancer cells confined to either the ducts (Ductal carcinoma in situ-DCIS) or to the lobules (Lobular carcinoma in situ- LCIS).  At this preliminary stage, the cancer cells have not penetrated further in to the breast tissue, which means that they have not spread throughout the body.  

Invasive (infiltrating) carcinoma

Invasive carcinoma, are cancer cells that have penetrated through the primary cell layer.  At this stage, the cancer cells can spread throughout the breast tissue and to other organs of the body.  The majority of invasive breast cancers are classified as invasive ductal carcinoma or as invasive lobular carcinoma.

Types of Male Breast Cancer

Ductal carcinoma in situ (DCIS)

DCIS accounts for approximately 1 in 10 male breast cancer cases.  Because the cancer cells are confined to the ducts, surgery alone will almost always cure it.

Infiltrating (or invasive) ductal carcinoma (IDC)

Alone or in conjunction with other types of breast cancers, IDC accounts for approximately 8 out of 10 reported male breast cancer cases.  The cancer cells penetrate through the walls of the breast ducts and they infiltrate into the surrounding fatty breast tissue.  Due to the fact that men usually have a minimal amount of breast tissue, the majority of male breast cancer cases develop near the nipple and therefore metastasis to the nipple is common.

Infiltrating (or invasive) lobular carcinoma (ILC)

ILC and LCIS are very rarely diagnosed in men, accounting for approximately 2% of all reported male breast cancer cases.  The cancer cells penetrate through the lobules in to the surrounding fatty breast tissue.  When this occurs, the cancer cells can metastasize to other organs of the body.

Lobular carcinoma in situ (LCIS)

Because men do not usually have multiple breast lobules, LCIS is rarely diagnosed in men.  The cancer cells form and remain within the lobules.  Although LCIS is classified as a non-invasive disease, many breast oncologists suggest that LCIS may be a pre-cancerous condition

Paget disease of the nipple

Because most male breast cancer cases originate close to the nipple, Paget’s disease of the nipple is more commonly found in men than in women.  The cancer cells develop in the ducts of the breast and they spread to the nipple and or/areola.  Advanced stages of this disease can cause the nipple to appear red and crusted with areas of itching and burning. The nipple can also display oozing and bloody discharge.  Paget’s disease of the nipple is thought to be associated with DCIS or IDC.