Main Session
Sep
29
QP 25 - Clinical Potpourri: Navigating Early-Stage RT, N1mi Disease, and Risk Mitigation in Triple Negative and HER2+ Breast Cancer
LBA 29 - TARGIT US: A Prospective Registry Trial of Risk Adapted Intraoperative Radiation +/- Whole Breast Radiation after Breast Conserving Therapy
Presenter(s)
William Small, MD, FASTRO - Loyola University Medical Center, Maywood, IL
W. Small Jr1, M. K. Bulsara2, S. Grobmyer3, E. E. R. Harris4, D. R. Holmes5, D. Pavord6, M. Choi7, and M. D. Alvarado8; 1Department of Radiation Oncology, Stritch School of Medicine, Cardinal Bernardin Cancer Center, Loyola University Chicago, Maywood, IL, 2University of Notre Dame, Fremantle, Perth, Australia, 3Cleveland Clinic Abu Dhabi, Oncology Institute, Abu Dhabi, United Arab Emirates, 4St. Luke's University Health Network, Easton, PA, 5XpediteMD, Inc., Burbank, CA, 6Drexel University College of Medicine, Philadelphia, PA, 7University of California San Francisco, Department of Surgery, San Francisco, CA, 8University of California, San Francisco, Department of Surgery, San Francisco, CA
Purpose/Objective(s):
Partial breast radiation after lumpectomy in breast cancer can be delivered using brachytherapy, external beam radiation (EBRT) or Intraoperative Radiation (IORT). TARGIT A was a randomized trial that suggested a risk adapted IORT approach offers similar outcomes to whole breast irradiation (WBI). We hypothesize that the 5-year recurrence rate in the US population will be similar to the randomized trial results. TARGIT US is a prospective US based multi-institutional single arm registry trial to systematically collect and assess toxicity and outcomes in a large cohort of US patients. The primary objective was ipsilateral in breast recurrence rate (IBTR) at 5-years.Materials/Methods:
Eligible patients included woman 45 years and older, unifocal T1 or T2 lesions < 3.5 cm N0 M0, pathologically confirmed invasive ductal cancer suitable for breast conservation and who had undergone a diagnostic mammogram. All patients were to receive a single fraction of 20 Gy prescribed to the surface of a spherical applicator at the time of the initial lumpectomy. If the final pathology revealed lobular cancer or extensive intraductal component, WBI was to be delivered, and IORT used as a boost. For a positive margin, a re-excision was to be performed followed by WBI. Other factors, i.e., LVSI or positive sentinel node, could be utilized per facility to select for WBI +/- nodal treatments. The trial was designed for a 90% power to detect a reduction in the 5 year IBTR from a background rate of 4.5% to 2.0%.Results:
A total of 774 patients were accrued between 5/2012 and 9/2017. 34 patients withdrew consent after surgery. The median age was 66 with 162 (22%) < 60, 301 (41%) < 65 and 493 (67%) < 70. 580 (78%) were white. Median tumor size was 11 mm with 178 (24%) > 15 mm. All patients were ER +, 73 were PR- and 27 Her2neu +. 298 (40%) grade 1, 390 grade 2 (53%) and 52 (7%) grade 3. 71 patients were node positive and 124 (17%) received EBRT. The median follow-up was 5.1 years with 452 (61%) patients with > 5 years follow-up and 600 (81%) with at least 4 yr follow-up. 30-day complications included 26 (3.5%) patients needing aspiration for seroma and 18 (2.4 %) delayed wound healing. 88 (12 %) received chemotherapy and all were recommended to receive hormonal therapy. 13 patients (1.7%) experienced IBTR, 2 (0.27%) axillary recurrence and 5 (0.67%) distant recurrences. There were 17 (2.3 %) deaths, 2 (0.27%) due to breast cancer. The Kaplan-Meir (KM) estimates for 5 year IBTR was 1.6 % and overall survival 97.6 %. For the patients treated with IORT alone the 5-year KM estimates for 5 year IBTR was also 1.6 %.Conclusion:
TARGIT US is a prospective multi-institutional registry trial of risk adapted IORT. The results note an excellent ipsilateral breast tumor recurrence and survival consistent with TARGIT A. This trial confirms risk adapted IORT as an evidence-based treatment for early-stage ER + invasive ductal cancer.