Study of 3-Day Partial Breast Radiation Therapy in Women With Breast Cancer

This study is testing a new shorter radiation approach for early-stage breast cancer — delivering partial breast radiation in just 3 days instead of several weeks. The radiation targets only the area where the tumor was removed, rather than the whole breast. **You may be eligible if...** - You are a woman aged 45 or older (some women 40–44 may also qualify) - You have been diagnosed with early-stage invasive breast cancer or DCIS (a non-invasive form), with the tumor measuring less than 3 cm - You had a lumpectomy with clear margins (no cancer cells at the edge of the removed tissue) - You are not pregnant **You may NOT be eligible if...** - The cancer has spread to other parts of your body - You are pregnant or breastfeeding - You have cancer in multiple areas of the breast or in both breasts - You had previous radiation to the chest or breast - You have been tested and found to carry a BRCA gene mutation - You have had breast implants in the breast being treated - You have conditions like lupus or scleroderma that make radiation risky Talk to your doctor to see if this trial is right for you.