3005 - Preoperative Single Fraction Radiosurgery for Early Stage Breast Cancer: Preliminary Results
Presenter(s)
A. Prisco1, G. Facondo1, C. Reverberi1, T. Ceschia2, Y. Beorchia3, D. Marfisi4, E. Moretti5, L. Seriau6, S. Bertozzi6, C. Cedolini7, M. Bonotto8, S. Buriolla8, E. Pegolo9, M. Orsaria9, C. Di Loreto9, and M. Trovo1; 1Department of Radiation Oncology, ASUFC "Santa Maria della Misericordia", Udine, Italy, 2ASUFC, Udine, Friuli-Ven, Italy, 3Department of Epidemiology, ASUFC, Udine, Italy, 4Department of Medical Physics, ASUFC, Udine, Italy, 5Azienda Sanitaria-Universitaria Friuli Centrale, Udine, Italy, 6Breast Unit, Department of Surgery, DAME, University Hospital of "Santa Maria della Misericordia", Udine, Italy, 7Breast Surgery, Department of Medicine (DAME), University Hospital of Udine, Udine, Italy, 8Department of Medical Oncology, ASUFC, Udine, Udine, Italy, 9Institute of Anatomic Pathology, ASUFC "Santa Maria della Misericordia", Udine, Italy
Purpose/Objective(s):
We are conducting a phase II clinical trial to investigate the safety and feasibility of pre-operative single-fraction Stereotactic Partial Breast Irradiation (S-PBI) for early-stage breast cancer using the GammaPod system. This novel technology is designed to deliver a highly focused dose to the breast under stereotactic localization. The first stage of the study has been completed with the treatment of 40 patients. Here, we report the toxicity results.Materials/Methods:
The study was designed using the 2-stage Simon method. In the first stage, 40 patients were enrolled. If more than 7% of Grade = 2 acute toxicity events were observed, the study would be closed due to excess toxicity; otherwise, accrual would continue until reaching a total of 148 participants. Eligibility criteria included postmenopausal patients, over the age of 50, with early-stage (cT1-T2 cN0), luminal type, any grade, unifocal breast cancer suitable for conservative surgery. For this study the CTV is equal to the GTV. The PTV is defined as CTV plus a 3 mm margin. A single dose of 30-36 Gy was delivered to the 95% of the PTV using the GammaPod system, with imaging, planning and dose delivery mostly completed within a 1 hour session. Surgery was performed within 6 months after S-PBI. Toxicity including pain, erythema, hyperpigmentation and fibrosis, was graded according to the CTCAE v4.0 one month after S-PBI and at 3, 6, 12 and 24 months after surgery.Results:
The median age was 69 years (range, 50-87 years). Thirty-eight (95%) patients had a clinical stage T1N0, and 24 (60%) had a Ki-67 value < 14%, no patient had Grade 3 disease. The mean PTV volume was 4 cc (range, 2-33 cc). The mean PTV dose was 34 Gy. No Grade = 2 acute toxicity events were observed 1 month after S-PBI. Breast-conserving surgery was performed at a median of 15 weeks (range, 8-28 weeks) after S-PBI. With a median follow-up of 29 months (range, 19-35 months), no cases of Grade = 3 late toxicity events were documented. Grade 2 toxicity at 3 months after surgery was reported in 4 patients (10%), at 6 months in 2 cases (5%) and in 1 patient at 1 year. Table 1 displays the recorded toxicity events. No patient experienced local or distant relapse.Conclusion:
The highly focused dose distribution with sharp fall-off, combined with a minimal PTV margin enabled by stereotactic localization allowed the safe delivery of a single dose of 30-36 Gy with a negligible toxicity profile in the pre-operative setting. To confirm these results, we will continue accrual up to 148 patients and extend the follow-up to assess long-term toxicity and local-regional control. Abstract 3005 - Table 1: Toxicity reported outcome| Pre Surgery | Post Surgery | ||||||||
| 1 months (Nr of events) | 3 months (Nr of events) | 6 months (Nr of events) | 1 year (Nr of events) | ||||||
| Toxicity | Grade 1 | Grade 2 | Grade 1 | Grade 2 | Grade 1 | Grade 2 | Grade 1 | Grade 2 | |
| Pain Dermatitis Hyperpigmentation Fibrosis Skin Atrophy | 4 6 0 1 0 | 0 0 0 0 0 | 7 0 10 17 1 | 0 0 1 3 0 | 6 0 5 12 1 | 0 0 0 2 0 | 3 0 3 9 1 | 1 0 0 0 0 | |