Comparing Male and Female Breast Cancer
All individuals are born with certain breast cells and tissue. Even though men do not have milk-producing breasts, they can still get cancer. Nonetheless, breast cancer is 100x less common among men then it is among women. The American Cancer Society estimates for breast cancer in the United States for 2017 is:
- Over 250,000 new cases for women
- Just less than 2,500 new cases for men
For women, the lifetime risk of developing breast cancer is around 1 in 8. For men, on the other hand, the lifetime risk of developing breast cancer is around 1 in 1,000. For this reason, the number of cases of male breast cancer was fairly constant over the last few decades.
Characteristics of breast cancer are different for men and women
Findings presented at the European Breast Cancer Conference in 2016 found that characteristics of male breast cancer were different from those in female breast cancer. The study looked at 1,203 samples from men with breast cancer. Researchers looked at different characteristics such as grade, subtype, breast density, and tumor-infiltrating lymphocyte levels.
The researchers found that low amounts of tumor-infiltrating lymphocyte and high amounts of fibrous tissue in male breasts were associated with worsening results in male breast cancer as opposed to female breast cancer. Moreover, male breast cancer tends to have various subtypes in comparison to female breast cancer.
“However, this sub-typing of breast tumors does not seem to result in an optimal risk classification for male breast cancer patients. Additional tests that are well established in women, including gene-expression profiling, may result in the identification of more accurate prognostic and predictive markers. These could enable us to take better treatment choices, individualized for each patient, particularly in regard to the use of chemotherapy and new targeted agents” said Carolien van Deurzen, MD.
A future clinical trial?
The researchers hope to conduct a clinical trial very soon, putting into use a new medication that hinders the act of the androgen receptor – a protein normally seen in male breast cancer. “This will only be possible with a worldwide collaboration, but it is also important that male breast cancer patients should take part in general breast cancer trials, since trials for them alone are difficult to run due to the rarity of the disease. In the past, male patients have been persistently excluded, with no scientific rationale for doing so. It is also essential to find independent sources of funding to study male breast cancer; once again, it is its rarity that makes this difficult.” added Dr. van Deurzen.
Breast cancer in men is typically identified as a hard lump under the nipple and areola. Therefore, men have a higher mortality rate than women do because they are less likely to become aware of a lump in the breast – leading to delay in seeking treatment. What’s more, it can be rather difficult to perform research and clinical trials in order to fully comprehend the biology behind breast cancer in men due to its rarity. However, there is plenty of information available regarding risk factors, how breast cancer in men develops, as well as the molecular genetics of breast cancer in men.
The most common symptoms of breast cancer include the following:
- A thick lump
- Swelling of the entire breast or a part of the breast
- Nipple discharge
- Peeling or flaking of the skin around the breast
- Inverted nipple
- Changes in the appearance, shape, or size of the breast
The most common risk factors for breast cancer include the following:
- Age
- Gender
- Genes
- A family history of breast cancer
- A personal history of breast cancer
- Dense breast tissue
- Obesity
- Hormone replacement therapy
- Chronic alcohol consumption
Some risk factors, such as family history of the disease and age, cannot be avoided. Other risk factors, such as excessive alcohol drinking, can be altered. The general risk factors for breast cancer in men and women are similar, with one main difference. Age is a common risk factor among both ends; however, the average age of breast cancer in men is 66 years old, as opposed to women at 61 years old – confirmed a new study in the 2011 Breast Cancer Symposium in San Francisco, Calfornia. “Men are diagnosed with breast cancer at an older age and more frequently have lymph node involvement at diagnosis compared to women” said lead author Siva K. Talluri, MD.
Notable male breast cancer risk factors
One of the greatest risk factors for developing male breast cancer is Klinefelter syndrome, also known as XXY karyotype. Klinefelter syndrome is a genetic disorder that is triggered when a boy is born with one or more additional X chromosomes, making him more susceptible to unusual physical traits. Klinefelter syndrome occurs in 1 in 500-1000 male infants.
Some of the reasons why men develop larger cancers and why they are diagnosed at a more advanced stage is due to irregular mammography screening. In women, a majority of breast cancers is detected through such screening, whereas for most men, it does not occur to them that they could develop breast cancer and so they do not undergo regular screening tests. The more advanced disease in men “may be related possibly to the lack of awareness among patients as well as primary care physicians and absence of screening routinely done in women” said Dr. Talluri. Unfortunately, lack of awareness usually leads to delayed diagnosis at a more advanced stage.
Dr. Talluri and colleagues performed a study involving information gathered from 2475 men and 393,259 women with breast cancer. “We updated the information on survival and predictors of male breast cancer by analyzing more recent data from 1990-2007.There is a paucity of epidemiologic data on male breast cancer because it so rare; therefore any information garnered from such large datasets as SEER is valuable” said Dr. Talluri. Furthermore, the percentage of breast tissue in breast cancer is much smaller in men than it is in women.
Another recent study found:
- The average tumor size in men was 2.3 centimeters, as opposed to 1.7 centimeters in women
- Stage 1 breast cancer was seen in 22% of men and 60% of women
- Estrogen receptor positive breast cancers were seen in 97% of men and 83% of women
In men, there is a higher frequency of inherited genetic mutations in the predisposition of breast cancer genes. Carriers of mutations, such as BRCA, have a higher risk of developing breast cancer – 65 fold higher. A recent study involving the participation of 715 men with breast cancer found that 11% had BRCA2 mutations (compared to 2% in women with breast cancer).
Any individual who develops breast cancer should perform a comprehensive assessment of family history of cancer in 1st and 2nd degree relatives, as well as the ages at which they developed the cancer. Men who have developed breast cancer should look more closely into undergoing a genetics test, for possible indication of high incidence of CHEK2 and PALB2 genetic mutations. To date, it remains unknown why breast cancer in men is so rare, why men are carriers of BRCA2 genes or why they have higher rates of BRCA2 related cancers. Since most clinical trials have looked at womens’ perspective on breast cancer diagnosis and have been shaped on breast cancer treatment for women, further research needs to be performed to learn the best way to treat male breast cancer and catch it at an earlier stage.
References
http://www.nationalbreastcancer.org/male-breast-cancer
https://www.cancer.org/cancer/breast-cancer-in-men/about/key-statistics.html
http://www.breastcancer.org/research-news/male-bc-differs-biologically-from-female
http://www.medscape.com/viewarticle/749792
https://www.webmd.com/men/tc/klinefelter-syndrome-topic-overview
