A Phase III, randomised clinical study called the TARGIT A trial was a prospective trial comparing IORT with EBRT in a group of women over 45 years old who had unifocal invasive ductal carcinoma and who were suitable for wide local excision. A 50-kV x-ray source was housed within a tumour bed applicator and that supplied 20 Gy at the applicator surface, was able to deliver a therapeutic dose, isotropically, to breast tissue 1 cm beyond the surgical margins. Where pathological examination of the excised lesion subsequently revealed unfavourable features, EBRT was delivered to the whole breast, but without any further local boost. This proved necessary in 239 out of the 1571 patients (15.2%) allocated to IORT, and was well tolerated.
The Targit A trial demonstrated in the pre-pathology arm that recurrence of breast cancer following IORT was non-inferior to EBRT (2.1% vs. 1.1% at 5-years). The likelihood of breast cancer returning was not statistically different between the two groups.
A smaller series of similar patients has shown that an alternative 50-kV source method of delivering SD-IORT™ produces similar dosimetry to the operative cavity walls but the radiation delivery time is only between 8 and 12 minutes (giving an overall operation time of 1 hour 39 minutes). Cosmetic results were excellent in 10 of the 11 patients studied.
Recent one-year follow-up results of a multi-centre non-randomised study of single dose IORT using the Xoft® Axxent system at the time of breast conservation surgery for early stage breast cancer has been shown to be safe, with low moribidity. Early results from this multi-center trial of two hundred forty three (243) subjects treated at seventeen (17) US hospitals demonstrate this short, convenient course of radiation therapy for select patients with early stage breast cancer has excellent-to-good cosmetic results and a low rate of low-grade adverse events.
All SD-IORT patients are consented to be enrolled into ORL’s national anonymised registry, data collected is identical to that collected in the START trial. Level III observational data collected on patients using this anonymised registry will extend the data on SD-IORT already published.
The Hoag IORT series is currently the largest single facility IORT series in the United States and included 702 patients as of January 2016. This data has been submitted for publication in a 2016 edition of The Breast Journal. This poster was presented at the recent University of Florida Multidisciplinary Symposium on Breast Disease and was awarded the first place 2016 Breast Journal award. A link to the poster can be found HERE
One-year follow-up results of a multi-center trial of intra-operative radiation therapy using electronic brachytherapy at the time of breast conservation surgery for early stage breast cancer can be found HERE