Breast cancer is the second most common type of cancer in women. It occurs when abnormal cells grow out of control in one or both breasts. These cancer cells can spread (metastasize) to nearby tissues and form a mass, called a tumor. The cells can spread within the breast, to nearby lymph nodes and other tissues, and to other parts of the body.
The most common type of breast cancer begins in the ducts of the breast. It is called ductal carcinoma.
How can you prevent breast cancer?
At this time, there is no sure way to prevent breast cancer. But you can make healthy choices that help lower your risk. These choices include:
- Staying at a healthy weight.
- Eating a healthy diet with plenty of fruits, vegetables, and whole grains.
- Getting plenty of physical activity.
- If you drink alcohol, limiting how much you drink. Any amount of alcohol may increase your risk for some types of cancer.
If you're at high risk for breast cancer, your doctor may talk to you about ways to lower your risk. Based on your risk, your doctor will recommend a screening schedule for you. Your doctor may also talk with you about genetic testing.
What are the symptoms of breast cancer?
The first sign of breast cancer is often a painless lump. But early breast cancer is often found on a mammogram before a lump can be felt.
Other symptoms of breast cancer may not appear until the cancer is more advanced. These include:
- A thickening in the breast or armpit.
- A change in the size or shape of the breast.
- Changes in the skin of the breast, such as a dimple or skin that looks like an orange peel.
- A change in the nipple, such as scaling of the skin or a nipple that turns in.
- A green or bloody fluid that comes from the nipple.
- A change in the color or feel of the skin around the nipple (areola).
Symptoms such as changes in the skin of the breast or the nipple may be a sign of inflammatory breast cancer.
How is breast cancer diagnosed?
Depending on your age and risk factors, the doctor may recommend that you have a mammogram. A mammogram can often find a lump that is too small to feel.
During a regular physical exam, your doctor can check your breasts for lumps or changes. You also may find a lump during a breast self-exam.
If there are concerns, the doctor will check to see if there is cancer by examining a sample of cells (biopsy). The results of the biopsy help your doctor know if you have cancer and what type of cancer it is.
You may have other tests to find out the stage of the cancer. The stage is a way for doctors to describe how far the cancer has spread.
What are the types of breast cancer?
Breast cancer is the abnormal growth of the cells that line the ducts and lobes of the breast. 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:
Ductal carcinoma in situ (DCIS).
This is a precancer that may progress to breast cancer. The abnormal cells are only in the ducts of the breast.
Lobular carcinoma in situ (LCIS).
This is a precancer that rarely spreads. Having LCIS increases the risk of getting an invasive breast cancer later in life.
Other factors
Some breast cancer cells have:
Hormone receptors for estrogen and progesterone.
Some breast cancers need the hormones estrogen or progesterone (or both) to grow. These cancer cells have "receptors" on their surfaces. Receptors are like doorways to let hormones in. These types of cancer are called estrogen-receptor-positive (ER+) and progesterone-receptor-positive (PR+) breast cancer.
Large amounts of a protein called HER-2.
And some breast cancers also have a large amount of a protein called human epidermal growth factor receptor 2 (HER-2 or HER-2/neu). These breast cancers tend to grow faster and spread more quickly than breast cancers without as much HER-2. So, HER-2 positive (HER-2+) breast cancers are usually treated with a targeted medicine (such as trastuzumab) and chemotherapy.
If the breast cancer cells don't have estrogen receptors, progesterone receptors, or large amounts of HER-2 protein, they are said to be triple-negative. Triple-negative breast cancer is a less common type of breast cancer. It tends to grow faster and spread more quickly and is harder to treat than breast cancers that have hormone receptors. Medicines that target hormone receptors or HER-2 won't help with triple-negative cancer, but chemotherapy can help.
How is breast cancer treated?
Several types of treatments may be used for breast cancer. They include:
- Surgery to remove the cancer. This may be done by removing just the part of the breast that contains the breast cancer (lumpectomy). Or the surgeon may remove the whole breast (mastectomy). Some of the lymph nodes under the arm may also be removed.
- Radiation therapy. This uses high-dose X-rays to destroy cancer cells and shrink tumors.
- Chemotherapy. It uses medicine to destroy cancer cells.
- Hormone therapy with tamoxifen or an aromatase inhibitor. This changes the way hormones in the body cause cancer growth.
- Targeted therapy. It uses medicines that go directly to the cancer cells.
Your and your doctor's decisions about treatment will depend on many things, such as your age and health, the type of breast cancer you have, how likely it is to spread, and your feelings about keeping your breast.