Background: Adjuvant radiation therapy is proven to reduce local recurrence in patients with early stage breast cancer. To reduce toxicity, improve geographic accuracy, and reduce treatment time, IOERT can be utilized as an alternative to external beam radiation therapy. The study’s objective was to determine the short term toxicity and cosmesis profile of single fraction IOERT given as definitive treatment in a community setting. Materials and Methods: From Mar 2012 to Jul 2014, 84 patients (3 bilateral), ages 45-91 y.o. with stage 0-II were treated with IOERT (Mobetron, IntraOp Medical, Sunnyvale, CA). A single 21 Gy fraction was administered to the tumor bed after resection. IOERT was delivered using 4.5 – 6 cm applicators with electron energies from 6-12 MeV. At 2w, 6mo and 12mo, toxicity was assessed according to CTCAE Version 4.0 (range 0-4) and cosmesis based on a scale derived for national trials. Results: The median pathologic tumor size was 13 mm (4 tumors > 25mm) with 34 tumors being IDC, 4 ILC, 20 DCIS, and 29 mixed histologies. After the initial resection with IOERT, 85 breasts had a negative margin. Two required re-excision due to positive margins. 65 SLN biopsies were completed, 61 were negative, 4 positive (1 completion ALND). Median follow up was 57.1 weeks.
Toxicity (Grade at 2 weeks, 6 months, and 12 months in %):
0: 49, 69, 62
1: 44, 29, 35
2: 7, 2, 3
Cosmesis(Appearance at 2 weeks, 6 months, 12 months in %):
Excellent: 71, 86, 79
Good: 28, 14, 21
Fair: 1, 0, 0
*No patients had a toxicity of 3 or 4; or a cosmesis of poor.
Conclusion: Single fraction IOERT was well tolerated by all patients with no grade 3+ toxicity up to 12 months. At one year, 97% of patients had 0-1 grade toxicity and 100% of patients had excellent or good cosmesis. This treatment, consistent with current reports, meets critical criteria for incorporation into practice and reduces treatment by 3-6 weeks.
Hanna, Monica; Ash, Robert; Babaran, Wesley; Carpenter, Michele M.; Forouzannia, Afshin; Harness, Jay K.; Kaltenecker, Brian; Maddula, Snehith; Williams, Venita; and Wagman, Lawrence, "Toxicity and Cosmesis Outcomes for Single Fraction Intra-Operative Electron Radiotherapy (IOERT) for Breast Cancer" (2014). Student Research Day Abstracts and Posters. 75.