ESHO 1-85. Hyperthermia as an adjuvant to radiation therapy in the treatment of locally advanced breast carcinoma. A randomized multicenter study by the European Society for Hyperthermic Oncology.

Background: The ESHO protocol 1-85 is a multicenter randomized trial initiated by the European Society for Hyperthermic Oncology with the aim to investigate the value of hyperthermia (HT) as an adjuvant to radiotherapy (RT) in treatment of locally advanced breast carcinoma. The trial is one of the largest studies of hyperthermia in radiotherapy but has not been previously published.

Patients And Methods: Between February 1987 and November 1993, 155 tumors in 151 patients were included. Tumors were stratified according to institution and size (T2-3/T4) and randomly assigned to receive radiotherapy alone (2 Gy/fx, 5 fx/wk) to a total dose of 65-70 Gy, incl. boost, or the same radiotherapy followed once weekly by hyperthermia (aimed for 43 °C for 60 min). Radiation was given with high voltage photons or electrons. The primary endpoint was persistent complete response (local control) in the treated area.

Results: A total of 146 tumors in 142 patients were evaluable, with a median observation time of 19 (range 1-134) months. Seventy tumors were randomized to RT alone and 76 to RT + HT. Size was T4 in 92, and T2-3 in 54 tumors, respectively. The compliance to RT was good with all but 4 patients fulfilling the planned RT treatment. The tolerance to HT was fair, but associated with moderate to severe pain and discomfort in 15 % of the treatments. In 84 % of the heated patients a least one heat treatment achieved the target temperature, but the temperature variation was large. Addition of heat did not significantly increase the acute nor late radiation reactions. Overall, the 5-year actuarial local failure rate was 57 %. Univariate analysis showed a significant influence of hyperthermia (RT alone 68 % versus RT + HT 50 %, p = 0.04, and T-size (T4 75 % versus T2-3 36 %, p < 0.01). A Cox multivariate analysis showed the same factors to be the only significant prognostic parameters: hyperthermia (HR: 0.61 [0.38-0.98], and small tumor strata (HR: 0.46 [0.26-0.92]. Consequentially, more patients given RT + HT (36 %) survived without disease (DFS), than after RT alone (19 %), p = 0.021) CONCLUSION: A randomized multicenter trial investigating the addition of a weekly hyperthermia treatment to radiotherapy of patients with locally advanced breast cancer significantly enhanced the 5-year tumor control and yielded more patients surviving free from cancer. The results substantiate the potential clinical benefit of hyperthermic oncology.