While radiation has been a standard treatment for breast cancer patients since the early 20th century, a new study shows that it does not significantly improve survival for women with early-stage cancer at medium level of risk. A late-stage international trial looked at survival rates over a decade for more than 1,600 breast cancer patients who had undergone mastectomy, lymph-node surgery, and systemic therapy including chemotherapy. Researchers found that participants with “intermediate risk”