Breast Cancer: An Overview
What is Breast Cancer?
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.
What Causes Breast Cancer?
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.
Who gets Breast Cancer?
Breast cancer is the most common cancer among women other than skin cancer.
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% 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 direct family history of the disease. Increasing age is another risk factor for developing breast cancer.
What are the warning signs of breast cancer?
- A lump or thickening in or near the breast or in the underarm that persists through the menstrual cycle
- A mass or lump, which may feel as small as a pea
- A change in the size, shape, or contour of the breast
- A blood-stained or clear fluid discharge from the nipple
- A change in the look or feel of the skin on the breast or nipple (dimpled, puckered, scaly, or inflamed)
- Redness of the skin on the breast or nipple
- An area that is distinctly different from any other area on either breast
- A marble-like hardened area under the skin
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.
What are the types of breast cancer?
The most common types of breast cancer are:
- Infiltrating (invasive) ductal carcinoma. This cancer starts in the milk ducts of the breast. It then breaks through the wall of the duct and invades the surrounding tissue in the breast. This is the most common form of breast cancer, accounting for 80% of cases.
- Ductal carcinoma in situ is ductal carcinoma in its earliest stage (stage 0). In situ refers to the fact that the cancer hasn't spread beyond its point of origin. In this case, the disease is confined to the milk ducts and has not invaded nearby breast tissue. If untreated, ductal carcinoma in situ may become invasive cancer. It is almost always curable.
- Infiltrating (invasive) lobular carcinoma. This cancer begins in the lobules of the breast where breast milk is produced, but has spread to surrounding tissues or the rest of the body. It accounts for 10% to 15% of breast cancers. This cancer can be more difficult to diagnose with mammograms.
- Lobular carcinoma in situ is a marker for cancer that is only in the lobules of the breast. It isn't a true cancer, but serves as a marker for the increased risk of developing breast cancer later, possibly in both or either breasts. Thus, it is important for women with lobular carcinoma in situ to have regular clinical breast exams and mammograms.
Cancers can also form in other parts of the breast but are less common.
What are the stages of breast cancer?
- Stage 0 breast cancer is when the disease is localized to the milk ducts (carcinoma in situ).
- Stage I breast cancer: The cancer is smaller than 1-inch across and hasn't spread anywhere.
- Stage II breast cancer is one of the following:
- The tumor is less than an inch across but has spread to the underarm lymph nodes (IIA); or
- The tumor is between 1 and 2 inches (with or without spread to the lymph nodes); or
- The tumor is larger than 2 inches and has not spread to the lymph nodes under the arm (both IIB).
Advanced breast cancer (metastatic) results after cancer cells spread to the lymph nodes and to other parts of the body.
- Stage III breast cancer is also called "locally advanced breast cancer." The tumor is larger than 2 inches and has spread to the lymph nodes under the arm, or a tumor that 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, or liver.
How is breast cancer diagnosed?
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:
- Breast examination: During the breast exam, the doctor will carefully feel the lump and the tissue around it. Breast cancer usually feels different (in size, texture, and movement) than benign lumps.
- Mammography: An X-ray test of the breast can give important information about a breast lump.
- Digital mammography: A technique in which an X-ray image of the breast is digitally recorded into a computer rather than on a film. This may be better for women with dense breasts.
- Ultrasonography: This test uses sound waves to detect the character of a breast lump -- whether it is a fluid-filled cyst (not cancerous) or a solid mass (which may or may not be cancerous). This may be performed along with the mammogram.
Based on the results of these tests, your doctor may or may not request a biopsy test 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 diagnostic tests
Other methods being investigated include:
- Scintimammography: A technique in which radioactive contrast agents are injected into a vein in the arm. An image of the breast is taken with a special camera, which detects the radiation (gamma rays) emitted by the dye. Tumor cells, which contain more blood vessels than benign tissue, collect more of the dye and project a brighter image.
- Positron emission tomography (PET) scanning: A technique that measures a signal from injected radioactive tracers that migrate to the rapidly dividing cancer cells. The PET scanner picks up the signal and creates an image.
- Magnetic resonance imaging (MRI): A test that produces very clear pictures, or images, of the human body without the use of X-rays. MRI uses a large magnet, radio waves, and a computer to produce these images.
- Scientists are also exploring ways to detect breast cancer or markers of cancer in the blood, urine, and in fluid taken from the nipple.
- Breast cancer vaccines are under development.
How is breast cancer treated?
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 needs.
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, which is a partial mastectomy. Some of the lymph nodes under the arm are also removed. 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.
What happens after treatment?
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.
Does a benign breast condition mean that I have a higher risk of getting breast cancer?
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% of benign breast biopsies.
How can I protect myself from dying from breast cancer?
Follow these three steps for early detection:
- Get a mammogram. The American Cancer Society recommends mammography. Mammograms are an important part of your health history. Annual mammograms start at age 45 and are personalized. Some women can wait until age 50 to begin screening mammograms and have them done every two years. High risk women need more intensive screening. Talk to your physician about what time interval is best for you.
- Breast self-exam. Examine your breasts each month after age 20. You will become familiar with the contours and feel of your breasts and will be more alert to changes.
- Clinical breast exams. Have your breast examined by a healthcare provider at least once every three years after age 20, and every year after age 40. Clinical breast exams can detect lumps that may not be detected by mammogram.