Rocky Mountain Cancer Centers

According to the American Cancer Society, more than 200,000 women will be diagnosed with invasive breast cancer this year. While breast cancer primarily strikes women, men can be affected as well. In women, approximately 90 percent of breast cancer starts in the mammary ducts of the breast while 10 percent originates in the lobules, the glands that make breast milk.

Noninvasive breast cancer, ductal carcinoma in situ, is used to describe breast cancer in its early stages before it has spread outside the duct into the surrounding tissue or to other organs of the body. In this stage, the cancer remains where it started, in the mammary ducts, and has not spread. Noninvasive cancer increases a woman’s risk of developing invasive breast cancer.

The two most common types of invasive breast cancer are infiltrating ductal carcinoma (IDC) and infiltrating lobular carcinoma (ILC).

IDC is the most common type of invasive breast cancer, accounting for 90 percent of all cases. IDC begins in the milk ducts and invades the tissues of the breast by breaking through the walls of the milk duct. Once in the breast’s fatty tissues, IDC can spread to the armpit lymph nodes or to other organs of the body, namely the bones, lungs or liver.

ILC accounts for nearly 10 percent of all invasive breast cancers. ILC starts in the lobules (milk glands) and invades the tissues of the breast by breaking through the walls of the milk glands. ILC can also spread to the armpit lymph nodes and to other organs of the body.