Present status of thermoradiotherapy for recurrent breast cancer. Multi-institutional retrospective analysis by the JASTRO Hyperthermia Study Group

To evaluate the role of combined hyperthermia (HT) and radiotherapy (RT) in the management of loco-regional recurrent breast cancer, a multi-institutional retrospective analysis was undertaken by the JASTRO Hyperthermia Study Group. Clinical records of recurrent breast cancer treated with thermoradiotherapy in six Japanese institutions were reviewed. In total, 128 fields in 118 patients were enrolled in this study. Thirty-four fields (27%) were recurrence in previously irradiated areas. Hyperthermia was given within 30 min after RT for most tumors, once-a-week (70 fields) or twice-a-week (58 fields). Average total RT dose was 51.2±11.6 Gy. In total, 764 HT sessions were administered for the 128 fields, and invasive measurements of tumor temperature were performed in 531 HT sessions (70%). Effective HT sessions (tumor temperatures of >42degC for >20 min) were achieved in 311 HT sessions (59%). Response rates 1 month after the combined treatment were: complete response (CR) 46%, partial response (PR) 38%, and no change (NC) 15%. At 6 months following the treatment, 60% of the tumors were locally controlled. Mean tumor depth and tumor volume of CR responders were significantly smaller than those of PR responders. In terms of thermal parameters, the number of effective HT sessions of CR responders were significantly higher than those of NC responders, and the mean percentage of intratumor points of >41degC in CR responders was significantly higher than that in PR responders. Thus, some correlation between thermal parameters and tumor response was obtained. Complications associated with thermoradiotherapy were not serious. The present analysis will aid in the design of subsequent phase III trials of thermoradiotherapy for the local-regional recurrent breast cancer. (author)