Cells in the body normally divide (reproduce) only when new cells are needed. Sometimes, cells in a part of the body grow and divide out of control, which creates a mass of tissue called a tumor. If the cells that are growing out of control are normal cells, the tumor is called benign (not cancerous). If, however, the cells that are growing out of control are abnormal and don't function like the body's normal cells, the tumor is called malignant (cancerous).
Cancers are named after the part of the body from which they originate. Breast cancer originates in the breast tissue. Like other cancers, breast cancer can invade and grow into the tissue surrounding the breast. It can also travel to other parts of the body and form new tumors, a process called metastasis.
Breast cancer is the most common cancer among women other than skin cancer. Increasing age is the most common risk factor for developing breast cancer, with 66 perccent of breast cancer patients being diagnosed after the age of 55.
In the US, breast cancer is the second-leading cause of cancer death in women after lung cancer, and it's the leading cause of cancer death among women ages 35 to 54. Only 5 to 10 percent of breast cancers occur in women with a clearly defined genetic predisposition for the disease. The majority of breast cancer cases are "sporadic”, meaning there is no definitive gene mutation.
Benign breast conditions rarely increase your risk of breast cancer. Some women have biopsies that show a condition called hyperplasia (excessive cell growth). This condition increases your risk only slightly.
When the biopsy shows hyperplasia and abnormal cells, which is a condition called atypical hyperplasia, your risk of breast cancer increases somewhat more. Atypical hyperplasia occurs in about 5 percent of benign breast biopsies.
The most common types of breast cancer are:
Cancers can also form in other parts of the breast but are less common. These include:
There are two different staging systems for breast cancer. One is called “anatomic staging” while the other is “prognostic staging”. The anatomic staging is defined by the areas of the body where the breast cancer is found and helps to define appropriate treatment. The prognostic staging helps medical professionals communicate how likely a patient is to be cured of the cancer assuming that all appropriate treatment is given.
The anatomic staging system is as follows:
Stage 0 breast disease is when the disease is localized to the milk ducts (ductal carcinoma in situ).
Stage I breast cancer: The cancer is smaller than 2 cm across and hasn't spread anywhere, including no involvement in the lymph nodes.
Stage II breast cancer is one of the following:
Stage III breast cancer is also called "locally advanced breast cancer." The tumor is any size with cancerous lymph nodes that adhere to one another or to surrounding tissue (IIIA). Stage IIIB breast cancer is a tumor of any size that has spread to the skin, chest wall, or internal mammary lymph nodes (located beneath the breast and inside the chest).
Stage IV breast cancer is defined as a tumor, regardless of size, that has spread to areas away from the breast, such as bones, lungs, liver or brain.
We do not know what causes breast cancer, although we do know that certain risk factors may put you at higher risk of developing it. A woman's age, genetic factors, family history, personal health history, and diet all contribute to breast cancer risk.
Like many conditions, risk factors for breast cancer fall into the categories of things you can control and things that you cannot control. Risk factors affect your chances of getting a disease, but having a risk factor does not mean that you are guaranteed to get a certain disease.
Controllable risk factors for breast cancer
Non-controllable risk factors for breast cancer
These changes may be found when performing monthly breast self-exams. By performing breast self-exams, you can become familiar with the normal monthly changes in your breasts.
Breast self-examination should be performed at the same time each month, three to five days after your menstrual period ends. If you have stopped menstruating, perform the exam on the same day of each month.
During your regular physical examination, your doctor will take a thorough personal and family medical history. He or she will also perform and/or order one or more of the following:
Based on the results of these tests, your doctor may or may not request a biopsy to get a sample of the breast mass cells or tissue. Biopsies are performed using surgery or needles.
After the sample is removed, it is sent to a lab for testing. A pathologist -- a doctor who specializes in diagnosing abnormal tissue changes -- views the sample under a microscope and looks for abnormal cell shapes or growth patterns. When cancer is present, the pathologist can tell what kind of cancer it is (ductal or lobular carcinoma) and whether it has spread beyond the ducts or lobules (invasive).
Laboratory tests, such as hormone receptor tests (estrogen and progesterone) and human epidermal growth factor receptor (HER2/neu), can show whether hormones or growth factors are helping the cancer grow. If the test results show that they are (a positive test), the cancer is likely to respond to hormonal treatment or antibody treatment. These therapies deprive the cancer of the estrogen hormone or use a monoclonal antibody known as herceptin to treat the cancer.
Breast cancer diagnosis and treatment are best accomplished by a team of experts working together with the patient. Each patient needs to evaluate the advantages and limitations of each type of treatment and work with her team of physicians to develop the best approach.
Other methods being investigated include:
If the tests find cancer, you and your doctor will develop a treatment plan to eradicate the breast cancer, to reduce the chance of cancer returning in the breast, as well as to reduce the chance of the cancer traveling to a location outside of the breast. Treatment generally follows within a few weeks after the diagnosis.
The type of treatment recommended will depend on the size and location of the tumor in the breast, the results of lab tests done on the cancer cells, and the stage, or extent, of the disease. Your doctor will usually consider your age and general health as well as your feelings about the treatment options.
Breast cancer treatments are local or systemic. Local treatments are used to remove, destroy, or control the cancer cells in a specific area, such as the breast. Surgery and radiation treatment are local treatments. Systemic treatments are used to destroy or control cancer cells all over the body. Chemotherapy and hormone therapy are systemic treatments. A patient may have just one form of treatment or a combination, depending on her individual diagnosis.
Surgery: Breast conservation surgery involves removing the cancerous portion of the breast and an area of normal tissue surrounding the cancer, while striving to preserve the normal appearance of the breast. This procedure has often been called a lumpectomy, also referred to as a partial mastectomy. Typically, some of the lymph nodes, either in the breast and/or under the arm are also removed for evaluation. Usually, six weeks of radiation therapy is then used to treat the remaining breast tissue. Most women who have a small, early-stage tumor are excellent candidates for this approach.
Mastectomy (removal of the entire breast) is another option. The mastectomy procedures performed today are not the same as the older, radical mastectomies. Radical mastectomies were extensive procedures that involved removing the breast tissue, skin, and chest-wall muscles. Today, mastectomy procedures do not ordinarily remove muscles and, for many women, mastectomies are accompanied by either immediate or delayed breast reconstruction.
Following local breast cancer treatment, the treatment team will determine the likelihood that the cancer will recur outside the breast. This team usually includes a medical oncologist, a specialist trained in using medicines to treat breast cancer. The medical oncologist, who works with the surgeon, may advise the use of the drugs like tamoxifen or anastrozole (ARIMIDEX®) or possibly chemotherapy. These treatments are used in addition to, but not in place of, local breast cancer treatment with surgery and/or radiation therapy.
Follow these three steps for early detection:
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition. This document was last reviewed on: 12/31/2018