Breast cancer is the most common cancer in American women regardless of race or ethnicity. It begins in the breast tissue that is made up of glands for milk production, called lobules, and the ducts that connect the lobules to the nipple. The remainder of the breast is made up of fatty, connective, and lymphatic tissues.
While all breasts are made up of three main parts—glands, ducts, and connective tissues—the size and shape vary from woman to woman. The way breasts look and feel can be affected by age, weight or medications. Most women say their breasts feel lumpy or uneven, but a lot of the time, it’s only when an unusual lump is found that notice is taken.
When breast cancer has spread outside the ducts or lobes into normal breast tissue, it is said to be invasive.
The main types of invasive breast cancer are:
- Ductal carcinoma, which is cancer that begins in the ducts of the breast. This is the most common type of breast cancer.
- Lobular carcinoma, which is cancer that begins in the lobes of the breast. This is the second most common type.
Some breast cancer is a mixture of both ductal and lobular carcinoma.
There are also some less common types of invasive breast cancer, such as inflammatory breast cancer and male breast cancer.
When abnormal cells in the lining of a duct or lobe of the breast haven't spread, they are said to be noninvasive, or "in situ" (say "in-SY-too"). The main types of noninvasive cancer are:
- Younger age during first menstrual period
- Starting menopause at a later age
- Being older at birth of first child, never giving birth
- Not breastfeeding
- Long-term use of hormone replacement therapy
- Changes in the breast cancer-related genes BRCA1 or BRCA2
- Personal history
- Family history
- New lump in breast or underarm
- Thickening/swelling of part of breast
- Irritation/dimpling of breast skin
- Redness/flaky skin in nipple area or breast
- Pulling in of the nipple or pain in nipple area
- Nipple discharge other than breast milk, including blood
- Any change in size/shape of breast
- Pain in any area of breast
The type and frequency of breast cancer screening that is best for you changes as you age.
- Ages 20 to 39: Some experts recommend that women have a clinical breast exam every 3 years, starting at age 20. Talk with your doctor about how often you should have a breast exam. If you have a high risk for developing breast cancer, talk to your doctor about when to begin having routine mammograms and other screening tests, such as magnetic resonance imaging (MRI).
- Ages 40 and older: It is important for you to discuss with your doctor the medical evidence about mammograms before you decide when to start having mammograms and how often to have them. For woman at average risk:
- The U.S. Preventive Services Task Force recommends a screening mammogram every 2 years for women ages 50 to 74. For women ages 40 to 49, the balance of benefits and harms isn't as clear. Your doctor can help you understand the balance in your specific case. The Task Force says that the decision to start regular screening before age 50 should be an individual one. It should be based on a woman's values, her health history, and what she prefers.
- The American Cancer Society recommends that women start screening at age 45 with a mammogram every year until age 54. At age 55, women should switch to having a mammogram every 2 years. This can continue as long as their health is good and they are expected to live 10 or more years. The Society also states that women should have another option based on their values and preferences. This option is annual screening for women ages 40 to 44 and women ages 55 and older.
- The risk of breast cancer increases with age, and the age at which testing no longer helps reduce death from breast cancer is not known. If you are 75 or older, talk to your doctor about mammography as a regular part of your health care plan.
You can find out your personal risk level at www.cancer.gov/bcrisktool.
Early detection is an important factor in the success of breast cancer treatment. The earlier breast cancer is found, the more easily and successfully it can be treated. Tests used for screening include:
- Mammogram. A mammogram is an X-ray of the breast that can often find tumors that are too small for you or your doctor to feel. Standard mammograms use film to record images of the breast, but most mammograms done now are digital mammograms. Digital mammograms record images of the breast in an electronic file.
- Digital breast tomosynthesis (3-D mammogram). This test uses X-rays to create a three-dimensional image of the breast. This is a newer test that may be used alone or with a digital mammogram.
- Clinical breast exam (CBE). During a clinical breast exam, your doctor will carefully feel your breasts and under your arms to check for lumps or other unusual changes. Talk to your doctor about whether to have a clinical breast exam.
Make sure you know what your breasts normally look and feel like. When you know what is normal for you, you are better able to notice changes. Tell your doctor right away if you notice any changes in your breasts.
Magnetic resonance imaging (MRI) of the breast may be used as a screening test for women who have a high risk of breast cancer. This includes women who test positive for the BRCA1 or BRCA2 gene, or have two or more close family members who have had breast cancer before age 50. MRI may also be useful for women who have breast implants or for women whose breast tissue is very dense.
Your breast density can affect how clearly your breast tissue can be seen on a mammogram. Still, if you have dense breasts and if nothing else increases your risk for breast cancer, a mammogram is the recommended test for you.
For more information, see the topic Breast Cancer.
Stages 0-IV tell whether cancer is limited to one area in breast, or has spread to healthy tissues inside breast or other parts of body based on these characteristics: Size, invasive or non-invasive, in lymph nodes or not, and spreading to other body parts.
- Hormonal therapy
- Biologic therapy
Most often, more than one kind of treatment is used.