Role of 10-Gy boost radiation after breast-conserving surgery for stage I-II breast cancer with a 5-mm negative margin.

Background: According to the Guidelines for breast-conserving therapy of the Japanese Breast Cancer Society, the surgical margin is "negative" when the minimum distance between the tumor edge and the margin of the resected specimen is more than 5 mm. The value of boost radiation for early breast cancer with a 5-mm negative margin remains unclear.

Methods: A total of 137 patients with stage I-II breast cancer underwent breast-conserving surgery between July 1987 and August 2002.