Prospective Cohort for Tumor Bed Boost Radiotherapy in HER2 Positive Breast Cancer

The purpose of this study is to analyze treatment outcomes related to tumor bed boost of postoperative radiation therapy in patient with HER2+ breast cancer who underwent breast conserving surgery. The main questions it aims to answer are: * 7-year ipsilateral breast tumor recurrence * 7-year disease-free survival * 7-year locoregional recurrence * 7-year overall survival * Adverse events of radiation therapy Participants will be assessed by multi-dimensional methods after radiation therapy: * Assessment for the disease status (disease-free or recurrence) including physical and radiologic examination * Assessment for the adverse events according to CTCAE version 5.0

NCT Number	NCT05893966
Lead Sponsor	Samsung Medical Center
Conditions	Breast Cancer
Enrollment	400 participants
Start Date	2022-11-29
Primary Completion	2030-11-29 (estimated)
Study Completion	2032-11-29 (estimated)
Updated on ClinicalTrials.gov	2026-08-10