Masataka Sawaki1, Takeshi Miyamoto2, Tomomi Fujisawa2, Yoshiyuki Itoh3, Takeshi Ebara4, Hiroyuki Tachibana5, Takeshi Kodaira5, Toyone Kikumori6, Yasuhiro Yanagita2, Hiroji Iwata7. 1. Department of Breast Oncology, Aichi Cancer Center Hospital, Nagoya, Japan. m-sawaki@aichi-cc.jp. 2. Department of Breast Oncology, Gunma Prefectural Cancer Center, Ota, Gunma, Japan. 3. Department of Radiology, Nagoya University Graduate School of Medicine, Nagoya, Japan. 4. Department of Radiation Oncology, Gunma Prefectural Cancer Center, Ota, Gunma, Japan. 5. Department of Radiation Oncology, Aichi Cancer Center Hopsital, Nagoya, Japan. 6. Department of Breast and Endocrine Surgery, Nagoya University School of Medicine, Nagoya, Japan. 7. Department of Breast Oncology, Aichi Cancer Center Hospital, Nagoya, Japan.
Abstract
BACKGROUND: We performed a multicenter phase II study on the efficacy and safety of intraoperative radiotherapy (IORT) as partial breast irradiation using multiple devices. METHODS: The primary endpoint was ipsilateral breast tumor recurrence (IBTR). Key inclusion criteria were T < 2.5 cm, age > 50 years, surgical margin > 1 cm, intraoperative pathologically free margins, and sentinel node negative. After resection of the tumor, radiation at 21 Gy was delivered directly to the mammary gland employing an electron linear accelerator in the operating room, otherwise the patient was transported from the surgical suite to the radiation room. RESULTS: Overall, 142 patients were enrolled in this study and 129 underwent IORT. Stage 0: n = 4 (3.1%); stage I: n = 98 (76.0%); and stage IIA: n = 27 (20.9%). Luminal type: n = 116 (89.9%); triple-negative: n = 9 (7.0%); and human epidermal growth factor receptor 2: n = 4 (3.1%). Median follow-up time was 59.5 months (range 27.5-99.0), and the rate of IBTR was 3.1% (95% confidence interval 0.9-7.8). The toxicities included fibrosis in deep-connective tissue: grade 1, 78.1%; wound infection: grade 3, 1.6% and grade 2, 1.6%; and soft tissue necrosis: grade 3, 0.8% and grade 2, 0.8%. Recurrence in the breast occurred in four cases; the site of recurrence was just under the skin near the primary tumor site, with similar histology and subtype. CONCLUSIONS: In this multicenter phase II study, the rate of IBTR was low and IORT at 21 Gy was feasible in properly selected patients. It is important to use a careful surgical technique to reduce local recurrence because the skin is not included in the radiation field of IORT.
BACKGROUND: We performed a multicenter phase II study on the efficacy and safety of intraoperative radiotherapy (IORT) as partial breast irradiation using multiple devices. METHODS: The primary endpoint was ipsilateral breast tumor recurrence (IBTR). Key inclusion criteria were T < 2.5 cm, age > 50 years, surgical margin > 1 cm, intraoperative pathologically free margins, and sentinel node negative. After resection of the tumor, radiation at 21 Gy was delivered directly to the mammary gland employing an electron linear accelerator in the operating room, otherwise the patient was transported from the surgical suite to the radiation room. RESULTS: Overall, 142 patients were enrolled in this study and 129 underwent IORT. Stage 0: n = 4 (3.1%); stage I: n = 98 (76.0%); and stage IIA: n = 27 (20.9%). Luminal type: n = 116 (89.9%); triple-negative: n = 9 (7.0%); and humanepidermal growth factor receptor 2: n = 4 (3.1%). Median follow-up time was 59.5 months (range 27.5-99.0), and the rate of IBTR was 3.1% (95% confidence interval 0.9-7.8). The toxicities included fibrosis in deep-connective tissue: grade 1, 78.1%; wound infection: grade 3, 1.6% and grade 2, 1.6%; and soft tissue necrosis: grade 3, 0.8% and grade 2, 0.8%. Recurrence in the breast occurred in four cases; the site of recurrence was just under the skin near the primary tumor site, with similar histology and subtype. CONCLUSIONS: In this multicenter phase II study, the rate of IBTR was low and IORT at 21 Gy was feasible in properly selected patients. It is important to use a careful surgical technique to reduce local recurrence because the skin is not included in the radiation field of IORT.