TARGIT-E(lderly)—Prospective phase II study of intraoperative radiotherapy (IORT) in elderly patients with small breast cancer

Background Patients ≥ 70 years with small, low-risk breast cancer who are operated but not irradiated how local relapse rates around 4% after 4 years. With adjuvant whole breast radiotherapy (WBRT) the local relapse rate drops to 1% after 4 years under Tamoxifen. It has been demonstrated that the efficacy of radiotherapy of the tumor bed only in a selected group can be non-inferior to WBRT. Methods/Design This prospective, multicentric single arm phase II study is based on the protocol of the international TARGIT-A study. The TARGIT-E study should confirm the efficacy of a single dose of intraoperative radiotherapy (IORT) in a well selected group of elderly patients with small breast cancer and absence of risk factors. Patients will receive IORT (20 Gy with Intrabeam system/Carl Zeiss) during breast conserving surgery. In presence of risk factors postoperative WBRT will be added to complete the radiotherapeutic treatment according to international guidelines. Endpoints are the local relapse rate (within 2 cm of the tumor bed), ipsilateral in breast relapse, cancer-specific and overall survival and contralateral breast cancer as well as documentation of quality of life and cosmetic outcome. The expected local relapse rates are 0.5/1/1.5% after 2.5/5/7.5 years, respectively. Discontinuation of the trial is scheduled if rates of local relapse rates rise to 3/4/6% after 2.5/5/7.5 years. Power calculations result in 540 patients with a calculated dropout rate of 20% and loss to follow-up of 20%, an alpha of 0.01 and a beta 0.05. There will be a pre- and a post-pathology stratum (n = 270 each). Discussion It is a pragmatic trial in which each participating centre has the option to modify entry criteria and criteria for WBRT according to this core protocol after consultation with the steering committee and local ethics committee (e.g. size, free margins). Only centers with access to the Intrabeam system (Carl Zeiss) can recruit patients into the trial. Its aim is to confirm the efficacy and toxicity of IORT in a well selected collective of elderly patients with breast cancer. Trail registration NCT01299987