Initial results of phase I/II interstitial thermoradiotherapy for primary advanced and local recurrent tumors

Since January 1986 in a phase I/II study, 45 lesions (30 head and neck, 11 pelvic, and 4 other lesions) in 44 patients (24 men, 20 women; age 18-81 years) received a combination of interstitial Ir-192 radiotherapy (IRT) and interstitial 915 MHz MW hyperthermia (IHT) supplemented by external radiation (ERT). In June 1989, evaluation was performed for lesions with minimum follow-up (FU) of 6 months and FU periods between 6 and 39 months (mean: 16 months, SD +/- 9). The tumors comprised 21 advanced primary (AP) lesions without prior ERT, 18 local recurrent (LR) and 6 local metastatic (LM) lesions with variable prior treatment modes; 24 lesions had received prior ERT between 40 and 70 Gy, 23 chemotherapy and 30 prior surgery. The mean dimensions of 42 lesions were 4.5 X 4.0 X 3.0 (cm3) with tumor volumes ranging from 12 to 135 cm3 (mean: 54 cm3, SD +/- 35); 3 lesions had extensive tumor volumes greater than 225 cm3. IHT was applied immediately prior to and/or after low-dose Ir-192 IRT (20-30 Gy) for 60 min at temperatures between 41 and 44 degrees C. ERT (40-50 Gy) was always given for AP and LM lesions, but variably applied for previously irradiated LR lesions, thereby avoiding the cumulative radiation dose exceeding 110 Gy per site. IRT doses ranged from 17-48 Gy (mean: 26.8 Gy, SD +/- 8) at a dose rate of 25-70 cGy/h (mean: 42 cGy/h, SD +/- 12). Thirty-three lesions received additional ERT of 30-56 Gy (mean: 46.5 Gy, SD +/- 9). Total radiation dose (IRT + ERT dose) ranged from 31 to 82 Gy (mean: 61 Gy, SD +/- 18). The hyperthermia systems of Lund/Buchler 4010 and Clini-Therm Mark VI/IX with thermistor or fiber-optic thermometry devices were employed. Initial response at 3 months FU showed 31 (69%) lesions complete response (CR), 10 (22%) partial response (PR), and 4 (9%) no change (NC). Long-term response of 30 lesions at 12 months FU revealed a total of 27 (90%) with local control (LC) and 3 (10%) in-field recurrences. Six patients died prior to 12 months FU, three with LC and three with progressive disease. So far 10 (22%) patients have developed distant metastases. Acute side-effects occurred in 15 lesions (33%) resulting in 12 (27%) long-term complications with 3 lesions (7%) requiring surgery.(ABSTRACT TRUNCATED AT 400 WORDS)