• Jayant S Vaidya, Michael Baum, Jeffrey S Tobias, Frederik Wenz, Samuele Massarut, Mohammed Keshtgar, Basil Hilaris, Christobel Saunders, Norman R Williams, Chris Brew-Graves, Tammy Corica, Mario Roncadin, Uta Kraus-Tiefenbacher, Marc Sütterlin, Max Bulsara, and David Joseph.
• Research Department of Surgery, Division of Surgery and Interventional Science, University College London, London, UK. jayant.vaidya@ucl.ac.uk
• Int. J. Radiat. Oncol. Biol. Phys. 2011 Nov 15;81(4):1091-7.

PurposeWe have previously shown that delivering targeted radiotherapy to the tumour bed intraoperatively is feasible and desirable. In this study, we report on the feasibility, safety, and long-term efficacy of TARGeted Intraoperative radioTherapy (Targit), using the Intrabeam system.Methods And MaterialsA total of 300 cancers in 299 unselected patients underwent breast-conserving surgery and Targit as a boost to the tumor bed. After lumpectomy, a single dose of 20 Gy was delivered intraoperatively. Postoperative external beam whole-breast radiotherapy excluded the usual boost. We also performed a novel individualized case control (ICC) analysis that computed the expected recurrences for the cohort by estimating the risk of recurrence for each patient using their characteristics and follow-up period.ResultsThe treatment was well tolerated. The median follow up was 60.5 months (range, 10-122 months). Eight patients have had ipsilateral recurrence: 5-year Kaplan Meier estimate for ipsilateral recurrence is 1.73% (SE 0.77), which compares well with that seen in the boosted patients in the European Organization for Research and Treatment of Cancer study (4.3%) and the UK STAndardisation of breast RadioTherapy study (2.8%). In a novel ICC analysis of 242 of the patients, we estimated that there should be 11.4 recurrences; in this group, only 6 recurrences were observed.ConclusionsLumpectomy and Targit boost combined with external beam radiotherapy results in a low local recurrence rate in a standard risk patient population. Accurate localization and the immediacy of the treatment that has a favorable effect on tumour microenvironment may contribute to this effect. These long-term data establish the long-term safety and efficacy of the Targit technique and generate the hypothesis that Targit boost might be superior to an external beam boost in its efficacy and justifies a randomized trial.Copyright © 2011 Elsevier Inc. All rights reserved.

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