Cyberknife Concomitant With Neoadjuvant Chemotherapy For Breast Tumour Phase I

e11032 Background: Robotic stereotactic radioablation (RSR) by CyberKnife has never been used for breast tumors and may have a real potential. We conducted a phase I study, including neoadjuvant chemotherapy, with a 4-level dose-escalation study (19.5 Gy, 22.5 Gy, 25.5 Gy, 28.5 Gy in 3 fractions) using RSR, and breast-conserving surgery followed by conventional radiotherapy. Neoadjuvant chemotherapy consist of anthracyclines plus taxanes sequential (NACT). We propose this protocol if tumor/breast ratio does not allow a conservative treatment. Major objective: defines the maximal tolerated dose to find recommended dose. Minor objectives: results of RT-CT on the number of sterilized histological exams, evaluation of the quality of surgical resection, evaluation of quality of life. Methods: For each patient, we performed 4 clinical dermatologic examinations by two independent observers; before the neoadjuvant chemotherapy treatment onset, after RSR irradiation, after 3 cures of neoadjuvant chemotherapy, and prior to surgery. Surgery was performed 4 to 8 weeks after the last chemotherapy session, the evaluation of surgery quality is made by 3 different surgeons. A pathologic examination was also performed. Complication are noticed. Quality of life is made with QLQ C30 B33. Results: 14 patients have been included is this study. We noticed one grade III skin toxicity at level IV (28.5 Gy in 3 fractions). The conservative surgery rate is 93%, the clinical complete response rate is 85% and the complete histological response rate is 35%. Maximum tolerable dose was not reached. All patients tolerated RSR with no fatigue, postoperative irradiation (50 Gy) has been delivered without toxicity. Conclusions: The study showed the feasibility of irradiation with RSR combined with chemotherapy and surgery for breast tumors. We noticed one grade III skin toxicity at a dose of 28.5 Gy delivered in 3 fractions combined with chemotherapy. The surgical morbidity was not increased. Pathologic response was acceptable. Patient enrolment is currently underway for further escalation of the neoadjuvant RSR irradiation dose. No significant financial relationships to disclose.