Feasibility of Intraoperative Radiotherapy Tumor Bed Boost in Patients with Breast Cancer after Neoadjuvant Chemotherapy

• Published in: Yonsei medical journal 2024, 65(3), , pp.129-136
• Main Authors: Yang, Gowoon, Kim, Jun Won, Lee, Ik Jae, Jeong, Joon, Ahn, Sung Gwe, Bae, Soong June, Kim, Jee Hung, Cho, Yeona
• Format: Article
• Language: English
• Subjects: Breast Neoplasms - drug therapy; Breast Neoplasms - radiotherapy; Breast Neoplasms - surgery; Combined Modality Therapy; Feasibility Studies; Female; Humans; Mastectomy, Segmental; Neoadjuvant Therapy; Neoplasm Recurrence, Local - pathology; Neoplasm Staging; Original; Radiotherapy Dosage; 의학일반
• ISSN: 0513-5796; 1976-2437
• DOI: 10.3349/ymj.2023.0229

This study aimed to assess the feasibility and safety of administering intraoperative radiotherapy (IORT) as a boost during breast-conserving surgery (BCS) following neoadjuvant chemotherapy for patients at high risk of breast cancer recurrence. Patients who underwent neoadjuvant chemotherapy received a single 20-Gy dose of IORT during BCS, followed by external beam radiotherapy 4-6 weeks after surgery. The median follow-up duration was 31.0 months (range, 18.0-59.0 months). Initial tumor sizes had a median of 2.6 cm (range: 0.8-5.3 cm), reducing to 0.3 cm (range: 0-4.0 cm) after neoadjuvant chemotherapy. The most common neoadjuvant chemotherapy regimen was doxorubicin and cyclophosphamide, followed by paclitaxel (n=42, 73.7%). Among 57 patients who received neoadjuvant chemotherapy before BCS and IORT, 2 patients (3.5%) required secondary surgery to achieve negative resection margins due to initially positive margins. Regional lymph node irradiation was performed in 37 (64.9%) patients. There was no grade 3 or higher adverse events, with 4 patients (7.0%) experiencing grade 2 acute radiation dermatitis and 3 (5.3%) having less than grade 2 breast edema. Binary correlation analysis did not reveal statistically significant associations between applicator size or radiation therapy modality and the risk of treatment-related toxicity. Furthermore, chi-square analysis showed that the grade of treatment-related toxicity was not associated with the fractionated regimen ( =0.375). Most patients successfully received IORT as a tumor bed boost after neoadjuvant chemotherapy. Thus, IORT may be a safe and feasible option for patients with advanced-stage breast cancer receiving neoadjuvant chemotherapy.