Breast Cancer

Breast cancer begins when healthy cells in the breast change (mutate) and multiply rapidly. As the cells grow, a tumor may be felt or seen on imaging. Breast cancer is the most common cancer in American women.¹⁵ About 1 of 8 women in the U.S. (about 13 percent) will develop invasive breast cancer. Your treatment plan will be tailored based on the results of all of your testing. You may see many specialists, including your surgeon, a reconstructive surgeon, medical oncologist, radiation oncologist, nurses, and therapists. For more information on testing, go to Preoperative Tests and Imaging.

Noninvasive breast cancer, is also called in-situ breast cancer. This means that the cancer cells are located within the lining of the lobule or duct. Noninvasive cancer may never spread to become an invasive cancer. One cannot predict which cases may spread, so nearly all cases are treated.

Invasive breast cancer has spread outside of the lining of the ducts or lobules. This means that is has spread into your breast tissue. It can continue to invade the blood, lymph system, and other organs of your body.

Cancers are either invasive or noninvasive. They are named by the area where the tumor first develops.

Ductal carcinoma starts in the milk ducts of your breast.

Lobular carcinoma begins in the milk lobules.

Most breast cancers begin in the lobules or ducts.³