Continuous Positive Airway Pressure (CPAP) Assisted Radiotherapy in Breast Cancer

This study is testing whether using CPAP (a continuous positive airway pressure device, similar to sleep apnea therapy) during radiation treatment for breast cancer can help protect the heart from radiation exposure by shifting the chest position. **You may be eligible if...** - You are a woman between 40 and 80 years old - You have had breast-conserving surgery (lumpectomy) for breast cancer - You have been recommended to receive radiation therapy to the breast or lymph nodes - Prior chemotherapy, immunotherapy, or hormonal therapy is allowed **You may NOT be eligible if...** - You have certain lung conditions such as bullous lung disease or a collapsed lung that are contraindications to CPAP - You have had major head trauma or a CSF leak (also contraindications to CPAP use) - You are pregnant or planning to become pregnant - You are a male breast cancer patient - You have had a full mastectomy rather than breast-conserving surgery Talk to your doctor to see if this trial is right for you.