Radiotherapy with 8-MHz radiofrequency-capacitive regional hyperthermia for stage III non-small-cell lung cancer: the radiofrequency-output power correlates with the intraesophageal temperature and clinical outcomes.

PURPOSE: To assess the efficacy of radiotherapy (RT) combined with regional hyperthermia (HT) guided by radiofrequency (RF)-output power and intraesophageal temperature and evaluate the potential contribution of HT to clinical outcomes in patients with Stage III non-small-cell lung cancer (NSCLC). METHODS AND MATERIALS: Thirty-five patients with Stage III NSCLC treated with RT plus regional HT were retrospectively analyzed. Twenty-two of the 35 patients underwent intraesophageal temperature measurements. Patients with subcutaneous fat of 2.5 cm or greater, older age, or other serious complications did not undergo this therapy. The 8-MHz RF-capacitive heating device was applied, and in all patients, both the upper and lower electrodes were 30 cm in diameter, placed on opposite sides of the whole thoracic region, and treatment posture was the prone position. The HT was applied within 15 minutes after RT once or twice a week. RESULTS: All thermal parameters, minimum, maximum, and mean of the four intraesophageal temperature measurements at the end of each session and the proportion of the time during which at least one of the four intraesophageal measurements was 41 degrees C or higher in the total period of each session of HT, of the intraesophageal temperature significantly correlated with median RF-output power. Median RF-output power (>/=1,200 W) was a statistically significant prognostic factor for overall, local recurrence-free, and distant metastasis-free survival. CONCLUSIONS: The RT combined with regional HT using a higher RF-output power could contribute to better clinical outcomes in patients with Stage III NSCLC. The RF-output power thus may be used as a promising parameter to assess the treatment of deep regional HT if deep heating using this device is performed with the same size electrodes and in the same body posture.