Results of a phase I regional hyperthermia device evaluation: microwave annular array versus radiofrequency induction...

The safety and efficacy of two devices in producing elevated temperatures in bulky deep tumours was evaluated in 11 patients with 12 tumours. Nine of 11 patients had pelvic tumours. Each patient was given a separate trial heating with the microwave annular phased microwave array system (APAS) and the radiofrequency concentric magnetic induction coil (MI), and evaluation was based upon paired comparison of power-limiting patient tolerance endpoints as well as intratumoural temperatures achieved. Toxicity was minimal with either device. On average, 66 per cent of intra-tumoural (IT) temperatures reached greater than 41 degrees C with the APAS, and 12 per cent of IT temperatures reached greater than 41 degrees C with the MI (P less than 0.001). Thirty-two per cent of IT temperatures were greater than 42 degrees C with the APAS, compared to 7 per cent with MI (P less than 0.001). Although the annular microwave array is more complex to use, it has a significantly higher likelihood of achieving temperatures in the therapeutic range near 42 degrees C in deep pelvic tumours than does the magnetic induction coil.