Darby

Researchers are evaluating a treatment approach for early-stage hormone-sensitive, HER-2 negative breast cancer with an Oncotype recurrence score of 18 or less. This Phase III trial compares breast conservation surgery with endocrine therapy alone against breast conservation surgery with both radiation and endocrine therapy. The goal is to see if skipping radiation after lumpectomy is not worse in preventing cancer recurrence in the same breast. Participants will be randomly assigned to one of two groups. One group will receive radiation therapy to the breast plus at least five years of endocrine therapy with drugs such as Tamoxifen, Anastrozole, Letrozole, or Exemestane. The other group will receive endocrine therapy only for at least five years without radiation. Radiation must start within 12 weeks of surgery if assigned. Endocrine therapy dosing and schedule are determined by the treating doctor. During the study, participants will have regular follow-ups up to five years to monitor cancer recurrence in the breast and elsewhere, survival, and breast preservation. Assessments will include clinical exams, imaging like mammograms or MRI, and pathology reviews. The main outcome is time to invasive or noninvasive breast tumor recurrence within five years. Some measures will continue through an average of 15 years, including breast conservation rates. Safety and overall health will be monitored throughout and after treatment.