Radiation dose-event relationship after intraoperative radiotherapy as a boost in patients with breast cancer

Yeona Cho; Jun Won Kim; Jee Suk Chang; Ji Young Kim; Sung Gwe Ahn; Soong June Bae; Joon Jeong; Ik Jae Lee

doi:10.3389/fonc.2023.1182820

Radiation dose-event relationship after intraoperative radiotherapy as a boost in patients with breast cancer

Front Oncol. 2023 May 5:13:1182820. doi: 10.3389/fonc.2023.1182820. eCollection 2023.

Authors

Yeona Cho¹, Jun Won Kim¹, Jee Suk Chang¹, Ji Young Kim¹, Sung Gwe Ahn², Soong June Bae², Joon Jeong², Ik Jae Lee³

Affiliations

¹ Department of Radiation Oncology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea.
² Department of Surgery, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea.
³ Department of Radiation Oncology, Yonsei Cancer Center, Heavy Ion Therapy Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea.

Abstract

Purpose: Intraoperative radiotherapy (IORT) can be used as a boost in combination with external whole breast irradiation. This study reports the clinical and dosimetric factors associated with IORT-related adverse events (AE).

Methods and materials: Between 2014 and 2021, 654 patients underwent IORT. A single fraction of 20 Gy was prescribed to the surface of the tumour cavity using the mobile 50-kV X-ray source. For skin dose measurement, at least four optically stimulated luminescent dosimeter (OSLD) chips were annealed and attached to the skin edge in the superior, inferior, medial, and lateral locations during IORT. Logistic regression analyses were conducted to identify factors associated with IORT-related AE.

Results: With a median follow-up period of 42 months, 7 patients experienced local recurrence, resulting in a 4-year local failure-free survival rate of 97.9%. The median skin dose measured by OSLD was 3.85 Gy (range, 0.67-10.89 Gy), and a skin dose of > 6 Gy was observed in 38 patients (2%). The most common AE was seroma (90 patients, 13.8%). We also found that 25 patients (3.9%) experienced fat necrosis during follow-up, and among them, 8 patients underwent biopsy or excision to exclude local recurrence. IORT-related late skin injury occurred in 14 patients, and a skin dose > 6 Gy was significantly associated with IORT-induced skin injury (odds ratio 4.942, 95% confidence interval 1.294-18.871, p = 0.019).

Conclusions: IORT was safely administered as a boost to various populations of patients with breast cancer. However, several patients may experience severe skin injuries, and for older patients with diabetes, IORT should be performed with caution.

Keywords: boost radiotherapy; breast cancer; intraoperative radiation therapy (IORT); radiation toxicites; radiotherapy.

Grants and funding

This research was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI19C1330). This study was also supported by the National Research Foundation of Korea Grant funded by the Korean Government (No. NRF-2021R1A2C1007191). All data were prospectively collected in a phase II study (NCT02213991) and conducted as the Conditional Approval System of Health Technology approved by the Ministry of Health and Welfare of Korea (CAS-2017-4-1) since 2017.