Invasive Breast Cancer: Symptoms, Treatments, Prognosis Women in the U.S. have a 1 in 8 chance of developing an invasive form of breast cancer during their lifetime. When breast cancer is invasive, it starts in the breast ducts or glands but grows into breast tissue. It can then spread into the nearby lymph nodes and beyond.

There are effective treatments. Your own treatment will depend on what type you have and how much and where your cancer has spread. You’ll work together with your doctor to come up with a plan that's best for you.

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Types of Invasive Breast Cancer

Two types account for about 95% of invasive breast cancer.

• Invasive ductal carcinoma (IDC). This is the most common type, making up about 80%. With IDC, cancer cells start in a milk duct, break through the walls, and invade breast tissue. It can remain localized, which means it stays near the site where the tumor started. Or cancer cells may spread anywhere in the body.
• Invasive lobular carcinoma (ILC). This type accounts for about 10% of invasive breast cancers. ILC starts in the lobules or milk glands and then spreads. With ILC, most women feel a thickening instead of a lump in their breast.

Some women may have a combination of both.

What are the signs of invasive breast cancer?

Breast cancer may have no signs or symptoms, especially during the early stages. As the cancer grows, you may notice one or more of the following:

• A lump or thickening in or near the breast or in the underarm that continues after your monthly menstrual cycle
• A mass or lump, which may feel as small as a pea
• A change in the size, shape, or contour of the breast
• A blood-stained or clear fluid from the nipple
• A change in the feel or appearance of the skin on the breast or nipple -- dimpled, puckered, scaly, or inflamed
• Redness of the skin on the breast or nipple
• A change in shape or position of the nipple
• An area that is distinctly different from any other area on either breast
• A marble-like hardened area under the skin

You may notice changes when you do a monthly breast self-exam. By doing a regular self-check of your breast, you can become familiar with the normal changes in your breasts.