Combined radiation and hyperthermia: comparison of two treatment schedules based on data from a registry established by the Radiation Therapy Oncology Group (RTOG).

A registry established by the Radiation Therapy Oncology Group provides data for assessing the impact of clinical heating in a set of non-randomized patients treated with hyperthermia in participating member institutions from 1/77 to 6/81. This analysis focuses on tumor response when localized hyperthermia is produced by microwave and applied pursuant to two distinctly different treatment schedules. Hyperthermia treatments were biweekly and combined with daily radiation treatments in one patient group, and combined with biweekly radiation treatment in another. Sample X consists of 65 patients who received a course of therapy using combined hyperthermia and radiation in consecutive treatment sessions each separated by at least 48 hours, but no more than 96 hours. Sample Y consists of 34 patients who received further radiation after the start of a course of combined therapy--either between or at the end of a series of combined treatment sessions. The average length of heat treatment was 72 minutes for Sample X and 32 minutes for Sample Y patients. None of the patients received concurrent chemotherapy; all received between 3 and 13 hyperthermia treatments; all had superficial, measurable tumors. On the average, Sample X patients received 704 total minutes of heat compared to Sample Y patients who received 233 total minutes of heat. Total tumor radiation doses ranged from 17.0 Gy to 44.0 Gy among Sample X patients with 92.3% receiving radiation at either 3 Gy or 4 Gy per fraction. In Sample Y the range for total tumor dose was 16.0 Gy to 70.2 Gy with 73.4% of the patients receiving radiation at 2.5 Gy or less per fraction. Generally, the two treatment schedules achieved similar levels of tumor response. Among treated tumors in Sample X and Sample Y, complete regression rates were 52.4 and 61.8%, respectively, and partial regression rates were 16.9 and 14.7%. Adenocarcinoma and squamous cell carcinoma in both samples responded well to these combined treatments. Only in Sample X was there a statistically significant trend of decreasing complete regression rate when the treated tumor sizes increased. Best responses to treatment generally occurred between 28 and 84 days after completion of the combined therapy course. There were no differences between the two samples with respect to median days to best response or response duration. Blister, ulcer or wet desquamation were reported in 47.7% of Sample X as the maximum skin reaction. In contrast, only 20.6% of Sample Y had these complications.(ABSTRACT TRUNCATED AT 400 WORDS)