Abstract P3-13-04: Use of an absorbable implant to mark the lumpectomy cavity: Initial report of 300 patients in a multi-center registry database

Abstract

Abstract Objective: Increased use of oncoplastic procedures makes it difficult to distinguish the lumpectomy margins from seroma fluid. Many side effects of radiation therapy are due to overestimated treatment volumes due to seroma based planning. A novel 3-dimensional (3D) absorbable device sutured to the lumpectomy tumor bed allows greater precision in targeting of the margins while avoiding normal tissues. A multi-center clinical registry was established to assess use of this device over time. This initial report of the first 300 patients provides insight into patient selection, tumor characteristics, method of implantation and initial outcomes. Methods: A bioabsorbable 3D implantable marker with a fixed array of 6 titanium clips was sutured to the site of the excised breast cancer during lumpectomy with or without oncoplastic closure techniques. The framework of the implant resorbs slowly over time, while the clips remain permanently. The marker was utilized for boost or partial breast irradiation (PBI) planning or treatment targeting. To date the registry has accrued 300 patients from 12 centers. Data includes patient demographics, breast size, tumor characteristics, surgical and radiotherapy techniques, cosmesis and follow-up. Results: Data on 300 patients with median follow-up 10.4 months was analyzed. Median age was 64.4 years, 83% of women were postmenopausal and 10% had comorbidities. Breast size was evenly distributed between cup size B, C and >D. Cancer histology was in-situ (20%), invasive ductal (62%), invasive lobular (9%) and others (10%) measuring T1 (80%) and T2 (20%). Laterality and tumor location within the breast were typical. Most patients had oncoplastic rearrangement (74%) at the time of lumpectomy. Re-excision (including mastectomy for extensive disease) occurred in 14% of patients. Infections occurred in 2% of patients and in one patient the device was removed during surgical debridement of the postoperative infection. No devices have been removed during follow-up due to misplacement or patient-generated concerns. No cancer recurrences have been reported. In most cases, size of the device reflected size of the tumor with the 2X2cm (47%) and 2X3cm (32%) devices used most often. The device was utilized by radiation oncologists for boost or PBI planning and treatment. Data on ease of setup and boost planning is being collected. Early reports regarding cosmetic appearance show a trend for excellent or good cosmesis as judged separately by both physicians and patients (93% and 92%). Conclusions: A novel 3-dimensional absorbable device sutured into the tumor bed provides clarity in radiation targeting of tissues at greatest risk while sparing adjacent normal tissues mobilized during surgery. This initial report of a multi-center clinical registry on over 300 patients characterizes patient selection, treatment methods and follow-up. Ongoing collection of additional data, regarding radiation regimen, cosmesis and patient satisfaction, have been accumulated and provide insight regarding clinical attributes of this implantable marker. Citation Format: Kaufman CS, Cross MJ, Goyal S, Barone J, Devisetty K, Dekhne NS, Edmonson D, Gass JS, Graham CL, Hong RL, Patton BJ, Phillips RF, Schonholz SM, Smith LA, Tafra L, Smith AB, Dilworth J. Use of an absorbable implant to mark the lumpectomy cavity: Initial report of 300 patients in a multi-center registry database [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-13-04.