Breast cancer is when the cells under one or both breasts grow out of control.

If you have breast cancer, you may wonder how fast the cancer is growing and how fast it will continue to grow.

With breast cancer, your focus will be on getting the right treatment. You'll also wonder about your chances of surviving.

Under 7% of all breast cancer cases happen in women under 40. But it can happen at any age.

Breast cancer can have different symptoms for different people. Most don’t notice any signs at all.

Breast cancer doesn’t always have signs you can see or feel. There are also less-common signs that can be helpful to know.

 If you notice symptoms of breast cancer, it’s important to see your doctor as soon as possible.

The cause of breast cancer is unclear, but we know the main risks: being older and having breast cancer in your family.

You notice that something is different with your breast, and you find a lump. Get it checked by a doctor, but don't panic.

Chances are, your breast cancer isn't caused by a faulty gene. But in about 5% to 10% of cases, the cause is hereditary.

Some lifestyle factors may raise your chances for breast cancer. Having these traits doesn’t mean you’ll get the disease.

A breast biopsy is a procedure in which your doctor takes out cells or a small piece of tissue from part of your breast.

The FISH (fluorescence in situ hybridization) test checks the DNA of cancer cells for extra copies of the HER2/neu gene.

The Oncotype DX analyzes a sample of cancer tumor to see the activity of certain genes that affect the cancer's outcome.

The immunohistochemistry (IHC) test can tell your oncologist whether you have certain types of breast cancer.

About 80% of all breast cancers are “ER-positive.” About 65% of these are also “PR-positive.”

Inflammatory breast cancer is a rare, aggressive form of breast cancer that often appears as a rash or skin irritation.

Invasive and metastatic both refer to cancer that has spread from the site in the breast where it first started.

Invasive lobular carcinoma is breast cancer that begins in one of the milk glands and spreads to other parts of the breast.