First Experience in Korea of Stereotactic Partial Breast Irradiation for Low-Risk Early-Stage Breast Cancer

Won Hee Lee; Jee Suk Chang; Min Jung Kim; Vivian Youngjean Park; Jung Hyun Yoon; Se Young Kim; Jee Ye Kim; Hyung Seok Park; Seung Il Kim; Young Up Cho; Byeong Woo Park; Yong Bae Kim

doi:10.3389/fonc.2020.00672

First Experience in Korea of Stereotactic Partial Breast Irradiation for Low-Risk Early-Stage Breast Cancer

Front Oncol. 2020 Apr 29:10:672. doi: 10.3389/fonc.2020.00672. eCollection 2020.

Authors

Affiliations

¹ Department of Radiation Oncology, Breast Cancer Center, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea.
² Department of Radiology, Breast Cancer Center, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea.
³ Department of Surgery, Breast Cancer Center, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea.

Abstract

Purpose: Accelerated partial breast irradiation (A-PBI) in Korean women has been considered impracticable, owing to small breast volume and lack of high-precision radiotherapy experience. We present the first experience of stereotactic-PBI (S-PBI) with CyberKnife M6 to investigate feasibility of use and early toxicities in Korean women with early breast cancers. Materials and Methods: A total of 104 breasts receiving S-PBI at our institution between September 2017 and October 2018 were reviewed. Patients were selected based on the American Society for Radiation Oncology (ASTRO), American Brachytherapy Society, American Society of Breast Surgeons, and Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology guidelines. A dose of 30 Gy in 5 fractions (NCT01162200) was used. Gold fiducials were routinely inserted near the tumor bed for tracking. Constraints regarding organs-at-risk followed the NSABP-B39/RTOG 0413 protocol. Results: Median follow-up was for 13 months. Patients were categorized as "suitable" (71.2%) or "cautionary" (28.8%) according to 2017 the ASTRO guidelines. No tracking failure of inserted gold fiducials occurred. Median planning target volume (PTV) and PTV-to-whole breast volume ratio was 73.6 mL (interquartile range, 58.8-103.9 mL) and 17.0% (13.3-19.1%), respectively. Median PTV V_95%, PTV D_max, and ipsilateral breast V_50% were 97.8% (96.2-98.8%), 105.3% (104.2-106.4%), and 35.5% (28.3-39.8%), respectively. No immediate post-S-PBI toxicity ≥ grade 2 was reported, except grade 2 induration in three breasts. All patients remain disease-free to date. Conclusion: The first use of S-PBI in Korean women was feasible and safe for selected early breast cancer. Based on these results, we have initiated a prospective study (NCT03568981) to test S-PBI in whole-breast irradiation for low-risk early breast cancer.

Keywords: Korean; accelerated partial breast irradiation; breast cancer; dosimetric outcomes; early toxicity; feasibility studies; stereotactic partial breast irradiation.