Interstitial microwave hyperthermia combined with iridium-192 radiotherapy for recurrent tumors.

From 1985 through 1987, 44 tumors in 39 patients with recurrent cancer were treated with interstitial microwave hyperthermia (HT) combined with interstitial 192Ir radiotherapy (RT). All patients had unresectable and previously treated tumors (mean RT dose 57.6 Gy). Diagnoses were squamous cell carcinoma in 27 (62%), adenocarcinoma in 11 (25%), melanoma in 5 (11%), and soft tissue sarcoma in 1 (2%) site. Interstitial RT dose was from 25 to 50 Gy (mean 38.3 Gy). The first HT session was scheduled immediately before the loading of 192Ir, and the second was scheduled following its removal. Each session lasted 45-60 min at therapeutic temperature (42.5 degrees C). Complete response (CR) was obtained in 28 (64%) sites and partial response (PR) in 15 (34%) sites. None of the CR patients had local recurrence. Tumor volume was the most important factor influencing CR (p less than 0.001). The treated site, radiation dose, and thermal dose were not significant factors for CR (p = 0.03). The overall median survival was 39 weeks, with a 2-year survival of 22%. The treatment was well tolerated, with two patients developing focal skin necrosis.