Cancer occurs when there are mutations in genes that regulate cell growth. The mutations let the cells divide and multiply in an uncontrolled, chaotic way. The cells keep multiplying, producing progressively more abnormal copies rather than reverting towards being healthy cells. This eventually forms a tumor in most cases.
Breast cancer is cancer that develops in breast cells. Usually, the cancer forms in the lobules or ducts of the breast. These are the glands that produce milk and the pathways that help bring the milk from the glands to the nipple. Cancer can also occur in fatty and fibrous breast tissue. This is known as stromal tissue.
The uncontrolled cancer cells start to invade healthy breast tissue and can travel to the lymph nodes under the arms. The lymph nodes are a primary pathway that helps the cancer cells move to other parts of the body.
How Common Is Breast Cancer?
According to the American Cancer Society, approximately 232,240 new cases of invasive breast cancer were expected to be diagnosed in 2013. More than 64,000 non-invasive breast cancer diagnoses (carcinoma in situ) were also expected. More than 39,000 women were expected to die from the disease. Breast cancer can also be diagnosed in men, and it was estimated that in 2013, more than 2,000 men were diagnosed.
What Are the Types?
Several types of breast cancer exist. The type you have determines your treatment options, as well as your prognosis.
The most common types of breast cancer include:
Ductal carcinoma in situ. Ductal carcinoma in situ (DCIS) is a non-invasive precursor for cancer. If you have DCIS, the cells that line the ducts in your breast have changed and now look cancerous. Unlike cancerous cells, however, DCIS cells haven’t invaded the surrounding breast tissue.
Lobular carcinoma in situ. Lobular carcinoma in situ (LCIS) is cancer that grows in the milk-producing glands of your breast. However, the cancer cells haven’t yet invaded the surrounding tissue.
Invasive ductal carcinoma. Invasive ductal carcinoma (IDC) is the most common type of breast cancer. This type of breast cancer begins in your breast’s milk ducts and then invades nearby tissue in the breast. Once the breast cancer has spread to the tissue outside your milk ducts, it can begin to spread to other nearby organs and tissue.
Invasive lobular carcinoma. Invasive lobular carcinoma (ILC) first develops in your breast’s lobules, or milk-producing glands. If breast cancer is diagnosed as ILC, it has already spread to nearby tissue and organs.
Other types of breast cancer are less common. These include:
Inflammatory breast cancer. Inflammatory breast cancer (IBC) is an uncommon type. In IBC, cells block the lymph nodes, so the breast can’t properly drain. However, instead of creating a tumor, IBC causes your breast to swell, look red, and feel very warm. A cancerous breast may appear pitted and thick, like an orange peel. IBC makes up only slightly more than one percent of all breast cancer cases.
Triple-negative breast cancer. To be diagnosed as triple negative breast cancer, a tumor must have all three of the following characteristics:
- It must lack estrogen receptors.
- It must lack progesterone receptors.
- It must not have additional HER2 proteins on its surface. HER2 is a protein that fuels breast cancer growth.
If a tumor meets these three criteria, it’s labeled a triple-negative breast cancer. This type of breast cancer has a tendency to grow and spread more quickly than other types of breast cancer. Triple-negative breast cancers are also difficult to treat because traditional breast cancer treatments are not effective.
Paget disease of the nipple. This type of breast cancer begins in the breasts’ ducts, but as it grows, it begins to affect the skin and areola of your nipple. Paget disease may occur with other types of breast cancer, such as DCIS or IDC.
Phyllodes tumor. This very rare type of breast cancer grows in the connective tissue of the breast.
Angiosarcoma. Cancer that grows on the blood vessels or lymph vessels in your breast is called angiosarcoma.
Who Is at Risk for Developing Breast Cancer?
There are several risk factors that can increase your chances of getting breast cancer. However, having any of these doesn’t mean you will definitely develop the disease.
Some risk factors can’t be avoided, like family history. Other risk factors, like smoking, you can change. You can take steps to help protect your health and get regular screening, which helps catch the disease at an earlier stage.
Risk factors include:
Age. Your risk for developing breast cancer increases as you age. Roughly 12 percent of invasive breast cancer occurs in women under age 45, but 66 percent of invasive breast cancers are found in women over age 55.
Drinking alcohol. Excessive alcohol consumption can increase your risk.
Dense breast tissue. Dense breast tissue makes mammograms hard to read. It also increases your risk for breast cancer.
Gender. Women are 100 times more likely to develop breast cancer than men.
Genes. Women who have the BRCA1 and BRCA2 gene mutations are more likely to develop breast cancer than women who don’t. Other gene mutations may affect your risk, too.
Early menstruation. If you had your first period before age 12, you have an increased risk for breast cancer.
Giving birth at an older age. Women who don’t have their first child until after age 35 have an increased risk of breast cancer.
Hormone therapy. Women who took or are taking postmenopausal estrogen and progesterone medications to reduce their signs of menopause have a higher risk of breast cancer.
Inherited risk. If a close female relative has had breast cancer, you have an increased risk for developing it. This includes your mother, grandmother, sister, or daughter. If you don’t have a family history of breast cancer, you can still develop breast cancer. In fact, the majority of women who develop it have no family history of the disease.
Late menopause start. Women who do not start menopause until after age 55 are more likely to develop breast cancer.
Never being pregnant. Women who never became pregnant and carried a pregnancy to full-term are more likely to develop breast cancer.
Previous breast cancer. If you have had breast cancer in one breast, you have a 3- to 4-fold increased risk of developing breast cancer in your other breast or in a different area of the previously affected breast. The second series on this article is coming soon. Stay tuned.
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