Abstract P3-12-11: One-year follow-up results of a multi-center trial of intra-operative radiation therapy using electronic brachytherapy at the time of breast conservation surgery for early stage breast cancer

Abstract

Objectives: To describe observations of one-year follow-up of subjects treated on a multi-center, non-randomized study with a single fraction of intra-operative radiation therapy (IORT) using the Xoft® Axxent® Electronic Brachytherapy System® (eBx®) immediately following surgical resection of early stage breast cancer. Methods: Two-hundred forty three (243) subjects were treated at seventeen (17) US hospitals. Upon meeting the inclusion/exclusion criteria, patients underwent partial mastectomy, placement of a balloon applicator suitable to the surgical bed in the lumpectomy cavity and inflated with saline (30 – 75 cc). The skin was temporarily closed over the balloon and ultrasound examination performed to confirm that the balloon surface-to-skin distance was > 1.0 cm. A single fraction of intra-operative radiation therapy was delivered to the lumpectomy cavity using the Xoft System. The prescribed dose was 20 Gy at the balloon applicator surface, and the mean treatment time was 10.2 minutes. After treatment, the balloon was deflated and removed, and skin sutured. Results: Two-hundred forty two (242) subjects received the prescribed dose of 20 Gy; one subject received 21 Gy. Eighteen (18) subjects were removed from the primary analysis post-IORT due to positive surgical margins (N=2), positive sentinel lymph nodes (N=13), or balloon surface-to-skin distance < 1 cm (N=3). However, these eighteen subjects will continue to be followed for the duration of this 10-year study. The mean follow-up for the two-hundred twenty five evaluable subjects is 494 days (range 300-465 days). The mean patient age was 65 years (41-89). Forty-nine subjects (21.8%) had ductal carcinoma in situ, one-hundred seventy one (76%) had invasive ductal carcinoma, and five (2.2%) had unknown histology. The DCIS nuclear grade was evenly distributed between high (N=18) and low/intermediate (N=23); 5 were unknown. Invasive cancer was Grade 1-2 in 142/171 cases. Two-hundred twelve subjects (94.2%) had T1 lesions, eight (3.6%) had T2 lesions, and five (2.2%) were unknown. The mean tumor size was 10.6 mm ± 6.4 mm. At the time of the last subject visit, 49/318 reported adverse events were Grade 2 or higher, and only 1/100 had serious side effects, i.e. infection. One patient died of aortic aneurism and two developed secondary malignancies, i.e. ovarian cancer and chronic lymphocytic leukemia. The most frequent side effects were seroma (12.5%), erythema (9.1%), and induration (7.5%). Cosmesis was excellent to good in 95% of cases. Conclusions: IORT using the Xoft System as part of the conservative treatment of breast cancer is safe, with low morbidity. Early results from this multi-center trial demonstrate this short, convenient course of radiation therapy for select patients with early stage breast cancer has excellent-to-good cosmetic results and a low rate of low-grade adverse events. Citation Format: Syed AMN, Chang H, Schwartzberg BS, Bremner AK, Lopez-Penalver C, Coomer C, Boylan S, Chakravarthy A, Vito CA, Bhatnagar A, Proulx GM, Dooley WC, Davis M, Golder SL, Ivanov O, Fernandez K, Rahman S. One-year follow-up results of a multi-center trial of intra-operative radiation therapy using electronic brachytherapy at the time of breast conservation surgery for early stage breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-12-11.

Eficacia, efectividad y seguridad de la radioterapia intraoperatoria en carcinoma de mama

“…Figura 1. Diagrama de flujo para la identificación y selección de estudios sobre RIO Los resultados estéticos son evaluados por 6 estudios 35,38,[50][51][52][53] y la calidad de vida percibida por las mujeres en uno de los estudios seleccionados 50 . La seguridad del personal sanitario es abordada en uno de los estudios seleccionados 54 , y la evaluación económica de la RIO por tres 6,55,56 .…”

“…Dos de los seis estudios seleccionados que comparan RIO con EBRT, obtienen los siguientes resultados estéticos: uno muestra resultados con diferencias estadísticamente significativas 53 y el otro, al establecer el umbral de significación en p = 0,01, ofrece resultados sin significación estadística 50 . Los estudios restantes no ofrecen resultados comparados con un grupo control 35,38,51,52 (ver tabla 4).…”

“…Describen, con un mínimo de tiempo transcurrido desde la intervención y RIO de 7 meses, que el 92,5% (185/200) de las mujeres presentaron resultados estéticos excelentes o buenos 35 . Otro estudio sobre 242 mujeres informa de unos resultados estéticos excelentes o buenos al año, del 95%, sin que especifiquen quienes realizaron la valoración 38 .…”

“…Se han seleccionado 21 estudios para la descripción y análisis de la seguridad de la RIO 10,11,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] , uno específico sobre la aparición de cicatrices hipertróficas 42 , otro sobre seguridad cardíaca 43 , dos estudios que abordan el correcto posicionamiento del emisor de radiaciones 46,47 y dos estudios que debaten la aparición de segundas neoplasias 44,45 .…”

“…El resto de estudios se realizan sin grupo control 27,31,33,38 , con un número reducido de pacientes 39 o un periodo de seguimiento inferior a las 6 semanas 33,39 .…”