What exactly does it mean when you have breast cancer in three different areas?

See below: Do you mean 3 areas in the same breast? Then that is considered multi focal breast cancer and may need mastectomy if the areas are far apart, and depends on if invasive or in situ breast cancer. If it is in other areas then it may be metastatic such as to lymph nodes or other sites. Your oncologist would be able to be much more specific for your situation.

Multicenteric: Breast cancer may be present in more than one area in the breast being called multifocal or multicenteric. Usually a mastectomy is recommend for surgical treatment.

Not sure what u mean: If the cancer is in multiple areas of the same breast, it is called multifocal, and is treated by total mastectomy, and possibly follow up chemotherapy. If however, you mean several different areas of the body, beyond the breast then that is stage IV disease, or metastatic cancer, and is treated primarily with chemotherapy, .