HYPERTHERMIA AND RADIATION-THERAPY FOR INOPERABLE OR RECURRENT PAROTID CARCINOMA - A PHASE I II STUDY/

Background. The treatment of advanced, inoperable, or recurrent paroti d tumors represents a clinical challenge. The results obtained with co nventional radiotherapy are disappointing. To improve the early respon se and local control of parotid tumors, local microwave hyperthermia w as used in combination with ionizing radiation in a biinstitutional Ph ase I/II study, Methods. From 1984 to 1991, 13 patients (20 lesions) w ith advanced (10 lesions) or recurrent (10 lesions) parotid tumors (15 primaries and the remaining 5 nodal metastases), were treated with 30 0-915 MHz of external hyperthermia after external irradiation. Heat wa s applied twice weekly at a minimum desired temperature of 42.0 degree s C for 30 minutes at steady state. Ionizing radiation was delivered u sing photon, electron, or mixed electron-photon beams; the prescribed total dose was 70 Gy and 30 Gy for untreated and previously treated le sions, respectively; the median computed total dose was 66 Gy for prev iously untreated patients (range, 56-70 Gy) and 30 Gy for previously i rradiated patients (range, 28-32 Gy). Results. Acute side effects were limited. Major acute toxicities included three patients (15%) with su perficial necrosis, two of three who healed spontaneously in 4 and 6 m onths. Clinical response evaluated during the third month after the co mpletion of therapy found that 16/20 patients (80%) had a complete res ponse (CR), and 4 (20%) had a partial response. Four out of 16 patient s who had CRs (20%) had a local recurrence, resulting in an actuarial local control at 5 years of 62.3 +/- 13.2%. Conclusions. The combined treatment of local microwave hyperthermia and ionizing radiation prove d to be feasible and moderately toxic for patients with advanced, inop erable, or recurrent parotid tumors. Even if clinical result evaluatio n was not the study endpoint, early response, and 5-year local control rates were encouraging.