Targeted Intraoperative Radiotherapy (Targit) Boost after Breast Conserving Surgery Results in a Remarkably Low Recurrence Rate in a Standard Risk Population: 5 Year Results.
Authors: Vaidya J. , Baum M. , Tobias J. , Massarut S. , Wenz F. , Hilaris B. , Corica T. , Roncadin M. , Kraus-Tiefenbacher U. , Keshtgar M. , Williams N. , Brew-Graves C. , Bulsara M. , Saunders C. , Joseph D. 
Published: December 2010

Background: In 1998 we started a phase II study of TARGeted Intraoperative radioTherapy (Targit) using the Intrabeam™ system. We present the updated results of this first group of breast cancer patients treated with breast conserving surgery where Targit was used as a boost to the tumour bed.Patients and Method: We treated 300 cancers in 299 patients undergoing breast-conserving surgery with no other selection criteria. 32% of the patients were younger than 51 years, 57% of cancers were between 1 to 2cm, (21% &gt; 2cm), 29% had a grade 3 tumour and 29% were node positive. After lumpectomy, a single dose of 20Gy was delivered intraoperatively using 50 kV X-rays –calculated at the surface of the tumour bed1. In all except 9 patients Targit was delivered at the time of the lumpectomy. Postoperative external beam radiotherapy excluded the usual boost. We analyzed recurrences according to their position within the ipsilateral breast.Results: The treatment was well tolerated. The median follow up is 60.5 months (range 10-120 months). 8 patients have had ipsilateral recurrence: 5- year Kaplan Meier estimate for ipsilateral recurrence 1.74% (SE 0.77). 5 of these 8 patients had recurrence in the tumor bed: 5-year Kaplan Meier recurrence rate is 1.04% (SE 0.59). Additionally, 7 patients developed a contralateral breast cancer. Our results appear superior to those seen in the boosted patients in the EORTC study (4.3%) and the START-B study (2.8%) despite a higher node positivity in our series (29%), compared with 21% in the EORTC and 24% in the START-B trial and a larger proportion of younger women (&lt;50 were 32% in Targit, 37% in EORTC and 21% in START-B).Conclusion: Lumpectomy and Targit boost combined with external beam radiotherapy results in an exceptionally low tumor bed recurrence rate in an unselected patient population. This could be attributed to both accurate localisation and timeliness of the treatment that could have a favorable effect on tumour micro-environment2. When used as a boost Targit is likely to be superior to conventional external boost. These data establish the long-term safety and efficacy of the Targit technique, which is being used in the soon to be completed randomised TARGIT trial of partial breast irradiation vs conventional external beam whole breast radiotherapy.1. Vaidya JS, Baum M, Tobias JS, Morgan S, D'Souza D. The novel technique of delivering targeted intraoperative radiotherapy (Targit) for early breast cancer. Eur J Surg Oncol 2002;28(4):447-54.2. Belletti B, Vaidya JS, D'Andrea S, Entschladen F, Roncadin M, Lovat F, et al. Targeted Intraoperative radiotherapy (TARGIT) impairs surgical wound-stimulated breast cancer cell proliferation and invasion Clin.Cancer Res. 2008;14(5):1325-32.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4104.