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Invasive Breast Cancer: Symptoms, Treatments, Prognosis

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Cancer can happen to anyone. It is not bound by age, gender, or ethnic group. Even so, among women, breastcancer is the most common form of the disease.

Women in the U.S. have a one in eight chance of developing invasive breast cancer during their lifetime. 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.

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

The two most common types of invasive breast cancer include:

  • Invasive ductal 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.
  • 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.

There are mixed types of IDC and ILC and other less common types of invasive breast cancer.

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