Safety and Efficacy of IMPT or IMRT for Breast Cancer

Inclusion Criteria * Aged ≥18 years old * Karnofsky Performance Status (KPS) score ≥70 * Histologically confirmed breast cancer with indications for preoperative radiotherapy, postoperative radiotherapy, or definitive radiotherapy as determined by the treating physician. * ER (estrogen-receptor), PR (progesterone-receptor), HER2 (human epidermal growth factor receptor 2), and Ki67 testing must be performed on the primary breast tumor. * Women of child-bearing potential must agree to use adequate contraception starting 1 month before study treatment and throughout the duration of study participation. * Ability to understand and willingness to participate in the research and sign the informed consent form. Exclusion Criteria * Pregnant or lactating women. * Severe non-neoplastic medical comorbidities that may interfere with treatment or study participation. * Active collagen vascular disease or other autoimmune disorders that could significantly increase the risk of radiation toxicity. * Patients with contraindications to undergoing IMPT or IMRT, such as severe claustrophobia that cannot be managed or inability to remain immobilized during treatment.