Abstract PD06-01: A Single Treatment with Targeted Intraoperative Radiotherapy (TARGIT) Is Similar to Several Weeks of External Beam Radiotherapy (EBRT) with Respect to Efficacy and Safety, and Has Obvious Advantages to the Patient and the Economy

Abstract

Abstract Background: After breast-conserving surgery, 90% of local recurrences occur within the index quadrant despite the presence of multicentric cancers elsewhere in the breast. Thus, restriction of radiation therapy to the tumour bed during surgery might be adequate for selected patients. Materials and methods: Having safely piloted the new technique of single-dose targeted intraoperative radiotherapy (TARGIT) with Intrabeam, we launched the TARGIT-A trial on March 24, 2000. In this prospective, randomised, non-inferiority trial, women aged 45 years or older with invasive ductal breast carcinoma undergoing breast-conserving surgery were enrolled to compare TARGIT with whole breast external beam radiotherapy (EBRT). The primary outcome was local recurrence in the conserved breast with a predefined absolute non-inferiority margin of 2-5%. Analysis was by intention-to-treat. Results: 1113 patients were randomly allocated to TARGIT and 1119 were allocated to EBRT. The Kaplan-Meier estimate of local recurrence in the conserved breast at 4 years was 1-20% (95% CI 0-53-2-71) in the TARGIT and 0-95% (0.39-2-31) in the EBRT group (difference between groups 0.25%, −1.04 to 1.54; p=0.41). The frequency of any complications and major toxicity (TARGIT 3.3% vs. EBRT 3.9% p=0·44) was similar. Radiotherapy toxicity was lower in the TARGIT group (0.5% vs. 2.1%, p=0.002). 14% of patients who received TARGIT also received EBRT as per the protocol, i.e., the remaining 86% patients could safely avoid 3-6 weeks of daily radiotherapy treatments and its obvious associated costs in economic and human terms. Discussion: For selected patients with early breast cancer, a single-dose targeted intraoperative radiotherapy should be considered as an alternative to whole breast EBRT delivered over several weeks. It could save time, effort, and money for the patient and the healthcare system, which is particularly relevant in the present times of healthcare reform. NB the main trial results have been presented in ASCO 2010 and published in the Lancet Online First. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr PD06-01.