Abstract P5-14-10: Adjuvant intra-operative electron-beam therapy for early invasive breast carcinoma using non-dedicated linear accelerator: Toxicity, efficacy, and aesthetic satisfaction
Authors: Hanna SA , Carvalho HA , Andrade FEM , Bevilacqua JLB , Piato JRM , Docema MFL , Barros ASCD 
Published: August 2014

INTRODUCTION: In May 2004 we started a prospective trial on adjuvant intraoperative electron-beam therapy (IORT) in early invasive breast cancer, but instead of a dedicated machine, we used a non-dedicated linear accelerator (NDLA).

OBJECTIVES: To analyze early and late complications, cosmetic satisfaction of patients, and recurrence rates.

METHODS: Patients with the following characteristics were included: invasive breast ductal carcinoma, local staging with mammogram, ultrasound and magnetic resonance imaging showing uni-central and uni-focal tumor, age≥40 years, T1N0. The procedure is done according to the following steps on table 1:

PROTOCOL STEPS1Surgery performed in an operative room close to linear accelerator suite2Wide local excision with frozen sections of surgical margins and sentinel lymph node biopsy3If positive margins, they are expanded until negativity. If sentinel node positive, or multicentric/multifocal tumor, IORT is aborted4With both margins and sentinel lymph node free, the parenchyma round the surgical cavity is detached from skin and pectoralis major muscle. A shield (lead/aluminum/silicone disc) is placed underneath the breast parenchyma to avoid foward radiation5The breast parenchyma is sutured above the shield surface6The parenchyma thickness is measured for selection of the suitable electron energy7A collimator (cilindrical radiation applicator) is chosen for entire coverage of parenchyma8The patient is transferred from operative room to linear accelerator room and the collimator is attached to the machine9A portal-film (6MV photon-beam) is taken to check the alignment between the shield and applicator10If portal-film shows unfavorable positioning, the shield is realigned and a new portal-film is taken. Upon satisfactory condition, a single dose of 21Gy is delivered at 90% isodosis11After IORT completion the surgical procedure is ended

RESULTS: Initially 194 patients were included, but due to intraoperative exclusion criteria (positive sentinel lymph nodes or margins), 159 were analyzed. The median age was 57.9 (40 to 85.4) years and the median follow-up was 56.6 (1 to 103.2) months. Seven patients recurred (4 local and 3 regional). The average estimates for overall and event-free survival were respectively 95.4 (CI 95% 93.1-97.6) months and 90.1 (CI 95% 85.8-94.5) months. The crude incidences for acute (up to one month after surgery) and late (after one month) toxicities were respectively 8.2% and 26.2%. Excellent, good, fair and bad cosmetic outcomes (Harvard/NSABP/RT OG scale) were observed in 70.9%, 14.2%, 3.7% and 3.0%, respectively. Collimator sizes were 4cm in 18.7%, 5cm in 80.6%, and 7cm in 0.7% of cases. The electron energy chosen for treatment was 6MeV in 7.4%, 9MeV in 52.2%, 12MeV in 35.8%, 15MeV in 3.7% and 18MeV in 0.7%. The alignment between the shield and the collimator was appropriate in 72.4% (27.6% of patients required repositioning). No infection cases were related to peri-hospitalar time.

CONCLUSIONS: IORT using NDLA has shown low toxicity profile, high favorable aesthetics outcomes, and good oncologic efficacy. The use of NDLA may be usefull in settings without dedicated equipment for breast IORT.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-14-10.