Why is radiation therapy necessary after a lumpectomy?
Radiation therapy is given to most patients who have lumpectomy for breast cancer to kill cancer cells that may remain after the lumpectomy or to prevent them from reproducing or spreading. Radiation damages both cancer cells and healthy cells, but unlike normal healthy cells, cancer cells cannot repair themselves after exposure to radiation. As a result, cancer cells exposed to sufficient levels of radiation are killed. This reduces the risk of recurrence of the cancer in the breast.