Hypo Versus Conventional Fractionation in Reconstructed-Breast Cancer Mastectomy Patients

This study is a multicenter, randomized, phase 3 clinical trial. For breast cancer patients who underwent breast reconstruction after mastectomy, the hypofractionation radiotherapy group (experimental group) and the conventional fractionation radiotherapy group (control group) were divided 1:1 and compared to reveal the non-inferiority with hypofractionation in terms of major complication rate.

I. Primary Objective

• To show the non-inferiority of major complication rate in reconstructed-breast between the hypofractionation radiotherapy group (experimental group) and the conventional fractionation radiotherapy group (control group) at 2 years after radiation therapy.
• The main complications are defined at those requiring hospitalization or surgery among complications.

II. Secondary Objective:

• Comparison of other side effects between the two groups.
• Comparison of complication rate stratified by reconstruction timing and type of reconstruction

• Immediate implant-based reconstruction
• Immediate autologous reconstruction
• Delayed-immediate implant reconstruction (2-stage)
• Comparison of quality of life between the two groups.
• Comparison of local and regional control rates between the two groups.

III. Tertiary Objective:

• Comparison of cosmetic evaluations between the two groups.
• Dosimetry analysis for correlation between the occurrence of complications and the dose profile.

Inclusion criteria

• Female patient who underwent mastectomy for invasive breast cancer
• Patients who have undergone breast reconstruction after mastectomy or who have inserted a tissue expander
• (y)p patients with stage IIIA or lower (excluding T4 and N3 patients) who need adjuvant radiation therapy
• Eastern Cooperative Oncology Group Performance ≤ 2
• Age ≥ 19 years
• Patients who agreed to participate in the study

Exclusion criteria

• Patients who already had implants at the time of diagnosis of breast cancer or who have already undergone reconstructive surgery
• Patients who underwent reconstruction after partial resection or breast conserving surgery rather than mastectomy
• Patients who are using or planning to use an air expander
• Patients receiving radiation therapy for salvage or palliative purposes
• Patients with distant metastases at the time of diagnosis
• Patients who are scheduled to undergo concurrent chemoradiation therapy
• Patients with bilateral breast cancer
• Male breast cancer patients
• Patients who have previously received radiation therapy for the ipsilateral breast or supraclavicular area
• Patients with history of cancers other than thyroid cancer, intraepithelial cancer of the cervix, or skin cancer
• Patients diagnosed with ductal breast carcinoma in situ, lobular carcinoma in situ, phyllodes, metaplastic cancer, or other benign tumors based on histological diagnosis