This study is exploring different ways to give proton radiation therapy for breast cancer treatment. Proton radiation therapy uses powerful beams of tiny particles called protons to target cancer cells. This study compares a shorter treatment schedule of 3 weeks (hypofractionated) with a traditional 5-week schedule (conventionally fractionated). The focus is on women who need radiation to the breast/chest wall and nearby lymph nodes.

• **Study Duration**: The study involves either a 3-week or 5-week treatment plan.
• **Eligibility**: Only women with specific types of breast cancer, who haven't had metastasis, are eligible.
• **Compensation**: There is no mention of compensation in the study details.

This research aims to find out if the shorter treatment has similar side effects to the longer one. Participants need to start radiation within 12 weeks after surgery or chemotherapy. Some conditions, like having a prior breast cancer history or being pregnant, will exclude you from the study. If you're eligible and interested, consider discussing with your doctor to see if it's right for you.