Ductal Carcinoma In Situ (DCIS)
In DCIS (also known as intraductal carcinoma), cancer cells form in the breast ducts but do not invade through the walls of the ducts into the fatty tissue of the breast or spread outside the breast. DCIS accounts for about 1 in 10 cases of breast cancer in men. It is almost always curable with surgery.
Infiltrating (or invasive) Ductal Carcinoma (IDC)
This type of breast cancer breaks through the wall of the duct and invades the fatty tissue of the breast. At this point, it can spread (metastasize) to other parts of the body. IDC (alone or mixed with other types of invasive or in situ breast cancer) accounts for at least 8 out of 10 male breast cancers. Because the male breast is much smaller than the female breast, all male breast cancers start relatively close to the nipple, so spread to the nipple is more likely. This is different from Paget disease as described below.
Infiltrating (or invasive) Lobular Carcinoma (ILC)
This type of breast cancer starts in the breast lobules (collections of cells that, in women, produce breast milk) and invades the fatty tissue of the breast. ILC is very rare in men, accounting for only about 2% of breast cancers. This is because men do not usually have much lobular tissue.
Lobular Carcinoma In Situ (LCIS)
In LCIS, abnormal cells form in the lobules, but they do not invade into the fatty tissue of the breast or spread outside the breast. Although LCIS is sometimes classified as a type of non-invasive breast cancer, most breast specialists think it is a pre-cancerous condition rather than a true non-invasive cancer. As with invasive lobular carcinoma, LCIS is very rare in men.
Paget Disease of the Nipple
This type of breast cancer starts in the breast ducts and spreads to the nipple. It may also spread to the areola (the dark circle around the nipple). The skin of the nipple usually appears crusted, scaly, and red, with areas of itching, oozing, burning, or bleeding. Using the fingertips, a lump may be detected within the breast.
Paget disease may be associated with DCIS or with infiltrating ductal carcinoma. It accounts for about 1% of female breast cancers and a higher percentage of male breast cancers.
Risk Factors for Breast Cancer in Men
The National Cancer Institute (NCI) Surveillance, Epidemiology, and End Results
(SEER) Program have shown that the number of cases of breast cancer in men (Nahley and Girnius et al 2006) went up by 26% from 1973 to 1998 . Rates of breast cancer in men vary widely globally. For example in central Africa (Uganda and Namibia), there is a significantly higher number of male breast cancer cases of between 6–15%. One reason for this global variation is thought to be the variation in occurrence of infectious diseases, which then leads to liver damage whose linkage has been previously described because it leads to high levels of estrogen (hyperestrogenism).
While just 1% of all breast cancer cases occur in men, there are several risk factors that have been identified as making some men more likely to develop breast cancer than others. These male breast cancer risk factors include:
Research shows that age when combined with other risk factors such as a family history of breast cancer could mean a significantly higher risk than the normal population of male breast cancer. The average age of men diagnosed with breast cancer is between 60 and 70 years.
BRCA2 gene mutations: The normal function and role of the breast cancer gene 2 (BRCA2) is to help repair damage to DNA (Yoshida and Miki, 2004). BRCA2 protein binds to and regulates the protein produced by the RAD51 gene to fix breaks in DNA caused by natural, medical radiation or other environmental exposures. This process 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 (Duncan et al, 1998). 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: Generally speaking, men have one X chromosome and one Y chromosome (the chromosomes which determine gender) at birth. Klinefelter’s syndrome is a genetic condition that is characterized by the addition of at least one X chromosome to the normal XY (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, testicular dysgenesis (smaller than normal testicles), and the inability to produce sperm (infertility). Men with Klinefelter’s syndrome also exhibit much lower levels of androgens (male hormones) and higher levels of estrogen (female hormones). As a result of these, men with Klinefelter’s syndrome are categorized as having a higher risk of developing gynecomastia, or breast cancer.
Family history: Approximately 1 in 5 men with breast cancer have close female relatives who have (or have had) breast cancer.
Another risk factor for breast cancer in men is obesity, and this is thought to act by affecting estrogen levels produced by the body through a process known as peripheral aromatization of androgens, that is, male hormones androstenedione changing to estrone and testosterone to estradiol thus leading to increased production rates of estrogens.
Treatment with estrogen: Men who have had some form of estrogen may be at an increased risk for breast cancer, this is because estrogen is thought to feed some types of cancerous breast tumors. According to the American Cancer Society, the risk of breast cancer in men due to estrogen therapy for prostate cancer or transgender application is considered small.
Some studies have shown an higher risk of developing breast cancer in men who are employed in workplaces with chronic heat , exhaust emissions, radiation exposure (maybe through the treatment of a cancer inside the chest such as Hodgkin’s or non-Hodgkin’s lymphoma), electromagnetic fields or environments that can suppress testicular function.
Other studies show that men with testicular damage, or those who have had mumps orchitis, or undescended testes have an increased risk of breast cancer due to androgen deficiency or excess estrogen.
Liver disease: Severe liver disease due to infection and subsequent cirrhosis causes men to have lower levels of androgens (male hormones) and higher estrogen levels (female hormones), this puts them at an elevated risk of developing gynecomastia (benign breast tissue growth) or breast cancer.