Regional hyperthermia and moderately dose-escalated salvage radiotherapy for recurrent prostate cancer. Protocol of a phase II trial

BACKGROUND: Current studies on salvage radiotherapy (sRT) investigate timing, dose-escalation and anti-hormonal treatment (ADT) for recurrent prostate cancer. These approaches could either be limited by radiation-related susceptibility of the anastomosis or by suspected side-effects of long-term ADT. A phase II protocol was developed to investigate the benefit and tolerability of regional hyperthermia with moderately dose-escalated radiotherapy. METHODS: The study hypothesis is that radio-thermotherapy is a safe and feasible salvage treatment modality. The primary endpoint is safety measured by frequency of grade 3+ genitourinary (GU) and gastrointestinal (GI) adverse events (AE) according to Common Toxicity Criteria (CTC) version 4. Feasibility is defined by number of hyperthermia treatments (n ≥ 7) and feasibility of radiotherapy according to protocol. Target volume delineation is performed according to the EORTC guidelines. Radiation treatment is administered with single doses of 2 Gy 5×/week to a total dose of 70 Gy. Regional hyperthermia is given 2×/week to a total of 10 treatments. RESULTS: European centres participate in the phase II trial using intensity modulated RT (IMRT) or volumetric modulated arc technique (VMAT). The initiating centres were participants of the SAKK 09/10 study, where the same patient criteria and target volume definition (mandatory successful performed dummy run) were applied insuring a high standardisation of the study procedures. CONCLUSIONS: The introduced phase II study implements highly precise image-guided radiotherapy and regional hyperthermia. If the phase II study is found to be safe and feasible, a multicenter phase III study is planned to test whether the addition of regional hyperthermia to dose-intensified sRT improves biochemical control.