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Invasive Breast Cancer: Symptoms, Treatments, Prognosis

Breast cancer can happen to anyone. It is not bound by age, gender, or ethnic group. But among women, breast cancer is the most common form of cancer.

Women in the U.S. have a one in eight chance of developing invasive breast cancer. And the American Cancer Society estimates that more than 1 million women in the U.S. have breast cancer and don't know it.

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There are effective treatments for invasive breast cancer. It's important to recognize the signs of invasive breast cancer and to work closely with your doctor. Here's information you can use to help you have the best outcome with invasive breast cancer.

How does the anatomy of the breast relate to breast cancer?

The female breast consists of:

fat
fibrous or connective tissue
glands
15 to 20 lobes and smaller lobules
tiny ducts

After a pregnancy, milk is produced in tiny glands and then flows through miniscule tubes or ducts to the nipple.

The breast also contains lymph vessels and lymph nodes. The lymph nodes serve to keep the body well. They do that by trapping cancer cells, bacteria, and other harmful substances.

Some breast cancers begin in the glands. Most breast cancers, though, begin in the breast ducts or tubes that connect the lobules to the nipple. Other cancers start in the breast tissues.

What is invasive breast cancer?

Invasive breast cancer is cancer that spreads outside the membrane of the lobule or duct into the breast tissue. The cancer can then spread into the lymph nodes in the armpit or beyond to the brain, bones, liver, or lungs.

When breast cancer cells are found in other parts of the body, the cancer is called metastatic breast cancer.

There are several types of invasive breast cancer, including:

Invasiveductal carcinoma (IDC). With IDC, cancer cells start in a milk duct, break through the duct walls, and then invade fatty breast tissue. IDC can remain localized, which means it stays near the site where the tumor originated. Or the cancer cells may enter the bloodstream or lymphatic system and metastasize -- spread -- anywhere in the body. Invasive ductal carcinoma is the most common type of invasive breast cancer. It accounts for 80% of invasive cancers.
Ductal carcinoma in situ (DCIS). This cancer is ductal carcinoma in its earliest stage -- stage 0. In situ means the breast cancer hasn't spread beyond its point of origin. That means the cancer is confined to the milk ducts and has not invaded nearby breast tissue. If it is left untreated, though, it can become invasive cancer.
Infiltrating (invasive) lobular carcinoma (ILC). This cancer accounts for about 10% to 15% of invasive breast cancers. ILC starts in the lobules or milk glands. It then spreads in a way similar to IDC. With ILC, most women feel a mass or thickening instead of a breast lump.