Safety and Efficacy of IMPT or IMRT for Breast Cancer

Acute radiation-induced toxicities will be assessed and recorded from the start of radiotherapy to six months after its completion. Evaluations will occur weekly during treatment, and at 2 weeks, 4 weeks, 3 months, and 6 months post-treatment. The assessment will utilize the Radiation Therapy Oncology Group (RTOG)/European Organization for Research and Treatment of Cancer (EORTC) Late Radiation Morbidity Scoring Schema and the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.

From six months after the completion of radiotherapy to five years post-treatment, any late radiation-induced toxicity will be assessed and recorded every six months during the first two years, and annually thereafter. Assessments will utilize the Radiation Therapy Oncology Group (RTOG) /European Organization for Research on Treatment of Cancer (EORTC) Late Radiation Morbidity Scoring Schema and CTCAE 5.0

Any first recurrence confirmed by histology or cytology within the ipsilateral breast or chest wall and/or regional nodes area (including supraclavicular, infraclavicular, axillary, or internal mammary lymph nodes)

The duration from the date of enrollment to the occurrence of any breast tumor recurrence at distant sites, death from any cause, or the last follow-up.

The duration from the date of enrollment to the occurrence of the first invasive breast tumor recurrence, death from any cause, or the last follow-up.

The duration from the date of enrollment to the date of death from any cause or the last follow-up.

The percentage of patients who achieve ypT0/is and ypN0 (no invasive residual in the breast or lymph nodes) after preoperative radiotherapy.

The duration from the initiation of definitive radiotherapy to the earliest occurrence of any of the following events:

Disease Progression: As determined by the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1.

Death: From any cause. Last Follow-Up: If neither progression nor death occurs during the study period.

The percentage of patients who achieve a complete response (CR) or partial response (PR) to definitive radiotherapy, as assessed by the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1.

The percentage of patients who achieve a complete response (CR), partial response (PR), or stable disease (SD) to definitive radiotherapy, as assessed by the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1.

The time from the date of enrollment to 5 years after completion of radiotherapy, Quality of life will be assessed before radiotherapy, every 6 months during the first 2 years and annually thereafter using self-administered questionnaire EORTC QLQ-C30

The duration from the date of enrollment to five years after the completion of radiotherapy will be assessed for cosmetic outcomes. Evaluations will occur before radiotherapy, every 6 months during the first two years, and annually thereafter. Cosmetic outcomes will be assessed using the Allegheny General Modification of the Harvard/National Surgical Adjuvant Breast and Bowel Project (NSABP)/RTOG scoring scale, which classifies patients into the following four categories:

Excellent: Minimal or no difference in size or shape of the treated breast compared to the untreated breast.

Good: Slight difference in size or shape of the treated breast. Fair: Obvious difference in size or shape of the treated breast. Poor: Marked change in size or shape of the treated breast.

PRO are measures that capture patients' perceptions of their health status, symptoms, and quality of life directly from the patients, without interpretation by healthcare providers. In this study, PROs will be assessed at baseline before the initiation of radiotherapy, then every 6 months during the first 2 years, and annually thereafter.