Why does breast cancer come back after being treated with radiation?

 Radiation can reduce the risk of breast cancer recurrence by about 70%. It is a highly targeted, highly effective way to destroy cancer cells in the breast that may stick around after surgery.

However, recurrence can happen when tumor cells, which were missed by radiation or even surgery, remain in the original site and over time, grow to a measurable mass.

There is no guarantee that each and every cancer cell will be removed during surgery or destroyed during chemotherapy or radiation therapy.

Maryann