Yonsei Med J.  2024 Mar;65(3):129-136. 10.3349/ymj.2023.0229.

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

• Yang G
• Kim JW
• Lee IJ
• Jeong J
• Ahn SG
• Bae SJ
• Kim JH
• Cho Y

• KMID: 2553353
• DOI: http://doi.org/10.3349/ymj.2023.0229

Abstract

Purpose
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.
Materials and Methods
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.
Results
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 (p=0.375).
Conclusion
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.

Keyword

Breast neoplasms; intraoperative; neoadjuvant therapy; radiotherapy; safety