Learning About Invasive Ductal Carcinoma

Invasive ductal carcinoma (IDC) is a type of breast cancer that starts in the ducts of the breast. Invasive means cancer has spread from the ducts into nearby breast tissue.

IDC is the most common type of invasive breast cancer. In some cases, the cancer can spread to nearby lymph nodes and other tissues and to other parts of the body.

Doctors don’t know exactly what causes IDC. But some things are known to increase the chance that you will get it, such as your age, your health history and family history, being female, and having breast changes.

Normal breast tissue is made of healthy cells. They divide to make new cells that look and work the same. Sometimes breast cells change or become abnormal. These changes sometimes become IDC.

Breast changes include:

• Hyperplasia. This is an increase in the number of cells in the breast. The cells appear normal under a microscope. They are not cancer. But they may become cancer.
• Atypical ductal hyperplasia (ADH). This means that there are extra cells in the ducts that are not normal. ADH is not cancer. But having it increases the risk of breast cancer.
• Ductal carcinoma in situ (DCIS). This is the growth of abnormal cells in the ducts. It’s an early form of noninvasive breast cancer. Noninvasive means that the cells haven’t spread. Some cases of DCIS will become invasive breast cancer, but there is no way to know which ones.

Most of the time IDC doesn’t cause symptoms. In some cases, symptoms can include a painless lump or thickening in the breast or underarm. But early IDC is often found on a mammogram before a lump can be felt. The size, shape, or appearance of the breast may also change. Or the nipple may turn in or leak fluid.

IDC is usually first seen on a mammogram. To diagnose IDC, your doctor will remove a sample of breast tissue and look at it under a microscope. This is called a breast biopsy. The results of the biopsy help your doctor know if you have IDC.

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.

Cancer cells are checked for certain traits, including estrogen receptors, progesterone receptors, and large amounts of a protein called HER2. This information helps your doctor plan your treatment.

If the cancer cells don't have these three traits, they are called "triple negative." Triple-negative breast cancer is a less common type of invasive breast cancer.

Treatment is based on the stage of the cancer, the traits of the cancer cells, and other things, such as your overall health.

Surgery may be used to remove the cancer. The types of surgery are:

• Breast-conserving surgery. This removes just the cancer and a border of healthy tissue around it. This may also be called a lumpectomy.
• Mastectomy. This removes the breast.

During breast surgery, your doctor may remove one or more nearby lymph nodes to check them for cancer.

Other treatments may include:

• Radiation therapy. This uses high-dose X-rays to destroy cancer cells and shrink tumors. It may be given after surgery.
• Chemotherapy. These medicines kill fast-growing cells, including cancer cells and some normal cells. It may be used before or after surgery.
• Hormone therapy. These medicines block the natural hormones that cause certain cancers to grow. Tests can show if you have this type of cancer and which medicines to use.
• Targeted therapy. These medicines target cancer cells and may cause less harm to normal cells.
• Immunotherapy. This treatment helps your immune system fight cancer.

Some people choose to have breast reconstruction after cancer surgery. Your doctor will talk to you about your options and then make a treatment plan.