A clinical study of curative partial breast irradiation for stage I breast cancer using carbon ion radiotherapy

Abstract

Background and purpose: Our institute initiated carbon ion radiotherapy research for patients with stage I breast cancer in April 2013. The purpose of this article is to evaluate the treatment outcome of cases treated outside clinical trial up to May 2020.Materials and methods: Eligibility criteria of the patients were having untreated stage I breast cancer and being unsuitable for operation for physical or mental reasons. The irradiated volume was defined as the gross tumor including intraductal components. The dose escalation study was initially conducted four times a week for a total of 52.8 Gy ([Relative Biological Efficacy (RBE)]). After confirming that adverse effects were within acceptable range, the total dose was increased to 60.0 Gy (RBE). Results: Between April 2013 and November 2015, 14 cases were treated. The median follow up period was 61 months. No adverse toxicities were observed except for grade 1 acute skin reaction in 10 cases. The time required from carbon-ion radiotherapy to tumor disappearance was 3 months in 1 case, 6 months in 3 cases, 12 months in 4 cases, and 24 months in 5 cases. The third case developed local recurrence 6 months after radiotherapy. Twelve patients with luminal subtype received 5-year endocrine therapy. Thirteen of 14 tumors have been maintaining complete response with excellent cosmetic results.Conclusions: The time from carbon ion radiotherapy to tumor disappearance was longer than expected, but complete tumor disappearance was observed except for one high-grade case. With careful patient selection, carbon-ion radiotherapy in patients with stage I breast cancer is deemed effective and safe, and further research is recommended.

Combining Carbon-Ion Irradiation and PARP Inhibitor, Olaparib Efficiently Kills BRCA1-Mutated Triple-Negative Breast Cancer Cells

“…17 We have also shown the merit of C-ion radiotherapy (RT) for BC in a phase-I clinical trial that was initiated in 2013. 18,19 However, some malignant tumors exhibit resistance to RT, and hence, candidates for use as radiosensitizers have been investigated in many studies. 20 DNA repair in cancer cells constitutes a major factor responsible for tumor resistance to RT.…”

Stereotactic Partial Breast Irradiation

“…Thus, stereotactic partial breast irradiation (SPBI) has inspired novel delivery methods, including Cyberknife(Accuray), Gammapod (Xcision), and heavy ion therapy. [23][24][25] In seminal dose-finding studies, dose escalation with SPBI was achieved with acceptable tumor control and cosmetic outcomes (Table 1). [26][27][28][29][30][31][32][33][34] Doses up to 40 Gy in 5 fractions and 30 Gy in a single fraction were achieved without significant acute or late toxicity, unlike the accelerated hypofractionated WBRT experience from UK FAST-Forward.…”

“…As a result of improved precision of radiation delivery to submillimeter levels by incorporating stereotactic localization and advanced image guidance, ablative doses of radiation can be achieved. Thus, stereotactic partial breast irradiation (SPBI) has inspired novel delivery methods, including Cyberknife(Accuray), Gammapod(Xcision), and heavy ion therapy 23–25. In seminal dose-finding studies, dose escalation with SPBI was achieved with acceptable tumor control and cosmetic outcomes (Table 1).…”