Invasive breast cancer occurs when cancer cells from inside the milk ducts or lobules break out into nearby breast tissue.

Cancer cells can travel from the breast to other parts of the body through the blood stream or the lymphatic system. They may travel early in the process when a tumor is small or later when a tumor is large.

If breast cancer spreads, the lymph nodes in the underarm area (the axillary lymph nodes) are the first place it’s likely to go.

Learn about treatment for invasive breast cancer.

Metastatic breast cancer

Metastatic breast cancer (also called stage IV or advanced breast cancer) is invasive breast cancer that has spread beyond the breast and axillary lymph nodes to other parts of the body (most often the bones, lungs, liver or brain).

Metastatic breast cancer is not a specific type of breast cancer, but rather the most advanced stage of breast cancer.

Learn about treatment for metastatic breast cancer.  

Most common invasive breast cancers

• Invasive ductal carcinoma (also called infiltrating ductal carcinoma) begins in the milk ducts and is the most common invasive breast cancer.
• Invasive lobular carcinoma begins in the lobules and is the second most common invasive breast cancer.

Less common invasive breast cancers

• Inflammatory breast cancer is an aggressive form of locally advanced breast cancer. It’s called inflammatory breast cancer because the main warning signs are swelling (inflammation) and redness in the breast.

  With inflammatory breast cancer, warning signs tend to arise within weeks or months. With other breast cancers, warning signs may not occur for years.

• Paget disease of the breast (Paget disease of the nipple) is a cancer in the skin of the nipple or in the skin closely surrounding the nipple. It’s usually found with an underlying breast cancer.
• Metaplastic breast cancers tend to be larger and have a higher tumor grade than more common breast cancers. Metaplastic breast cancers can be hard to diagnose because the tumor cells can look very different from the tumor cells of more common breast cancers.

Prognosis for invasive breast cancer

The prognosis (chances for survival) after invasive breast cancer depend on each person’s diagnosis and treatment.

For example, people diagnosed with early breast cancers have a better prognosis than those diagnosed with more advanced breast cancers.

Learn more about factors that affect prognosis.

Treatment for invasive breast cancer

Treatment for invasive breast cancer usually involves some combination of surgery, radiation therapy, chemotherapy, hormone therapy and/or HER2-targeted therapy.

The order of therapies and the specific treatments depend on the cancer stage and the characteristics of the tumor (such as hormone receptor status).  

Learn more about treatment.

Learn more about breast cancer stage.

Learn more about factors that affect breast cancer treatment.