Breast cancer definition
Breast cancer is a malignant tumor (a collection of cancer cells) arising from the cells of the breast. Although breast cancer predominantly occurs in women, it can also affect men. This article deals with breast cancer in women.
What are the statistics on male breast cancer?
Breast cancer is rare in men (approximately 2,400 new cases diagnosed per year in the U.S.) but typically has a significantly worse outcome. This is partially related to the often late diagnosis of male breast cancer, when the cancer has already spread.
Symptoms are similar to the symptoms in women, with the most common symptom being a lump or change in skin of the breast tissue or nipple discharge. Although it can occur at any age, male breast cancer usually occurs in men over 60 years of age.
What are the different types of breast cancer? Where does breast cancer come from?
- Ductal carcinoma in situ: The most common type of noninvasive breast cancer is ductal carcinoma in situ (DCIS). This type of cancer has not spread and therefore usually has a very high cure rate.
- Invasive ductal carcinoma: This cancer starts in a duct of the breast and grows into the surrounding tissue. It is the most common form of breast cancer. About 80% of invasive breast cancers are invasive ductal carcinoma.
- Invasive lobular carcinoma: This breast cancer starts in the glands of the breast that produce milk. Approximately 10% of invasive breast cancers are invasive lobular carcinoma.
- The remainder of breast cancers are much less common and include the following:
- Mucinous carcinoma are formed from mucus-producing cancer cells. Mixed tumors contain a variety of cell types.
- Medullary carcinoma is an infiltrating breast cancer that presents with well-defined boundaries between the cancerous and noncancerous tissue.
- Inflammatory breast cancer: This cancer makes the skin of the breast appear red and feel warm (giving it the appearance of an infection). These changes are due to the blockage of lymph vessels by cancer cells.
- Triple-negative breast cancers: This is a subtype of invasive cancer with cells that lack estrogen and progesterone receptors and have no excess of a specific protein (HER2) on their surface. It tends to appear more often in younger women and African-American women.
- Paget’s disease of the nipple: This cancer starts in the ducts of the breast and spreads to the nipple and the area surrounding the nipple. It usually presents with crusting and redness around the nipple.
- Adenoid cystic carcinoma: These cancers have both glandular and cystic features. They tend not to spread aggressively and have a good prognosis.
- Lobular carcinoma in situ: This is not a cancer but an area of abnormal cell growth that can lead to invasive breast cancer later in life.
The following are other uncommon types of breast cancer:
- Papillary carcinoma
- Phyllodes tumor
- Tubular carcinoma
What causes breast cancer?
There are many risk factors that increase the chance of developing breast cancer. Although we know some of these risk factors, we don’t know the cause of breast cancer or how these factors cause the development of a cancer cell.
We know that normal breast cells become cancerous because of mutations in the DNA, and although some of these are inherited, most DNA changes related to breast cells are acquired during one’s life.
Proto-oncogenes help cells grow. If these cells mutate, they can increase growth of cells without any control. Such mutations are referred to as oncogenes. Such uncontrolled cell growth can lead to cancer.
What are breast cancer risk factors? How do you get breast cancer?
Some of the breast cancer risk factors can be modified (such as alcohol use) while others cannot be influenced (such as age). It is important to discuss these risks with a health-care provider anytime new therapies are started (for example, postmenopausal hormone therapy).
Several risk factors are inconclusive (such as deodorants), while in other areas, the risk is being even more clearly defined (such as alcohol use).
The following are risk factors for breast cancer:
- Age: The chances of breast cancer increase as one gets older.
- Family history: The risk of breast cancer is higher among women who have relatives with the disease. Having a close relative with the disease (sister, mother, daughter) doubles a woman’s risk.
- Personal history: Having been diagnosed with breast cancer in one breast increases the risk of cancer in the other breast or the chance of an additional cancer in the original breast.
- Women diagnosed with certain benign breast conditions have an increased risk of breast cancer. These include atypical hyperplasia, a condition in which there is abnormal proliferation of breast cells but no cancer has developed.
- Menstruation: Women who started their menstrual cycle at a younger age (before 12) or went through menopause later (after 55) have a slightly increased risk.
- Breast tissue: Women with dense breast tissue (as documented by mammogram) have a higher risk of breast cancer.
- Race: White women have a higher risk of developing breast cancer, but African-American women tend to have more aggressive tumors when they do develop breast cancer.
- Exposure to previous chest radiation or use of diethylstilbestrol increases therisk of breast cancer.
- Having no children or the first child after age 30 increases the risk of breast cancer.
- Breastfeeding for one and a half to two years might slightly lower the risk of breast cancer.
- Being overweight or obese increases the risk of breast cancer both in pre- and postmenopausal women but at different rates.
- Use of oral contraceptives in the last 10 years increases the risk of breast cancer slightly.
- Using combined hormone therapy after menopause increases the risk of breast cancer.
- Alcohol use increases the risk of breast cancer, and this seems to be proportional to the amount of alcohol used. A recent study reviewing the research on alcohol use and breast cancer concluded that all levels of alcohol use are associated with an increased risk for breast cancer. This includes even light drinking.