Hyperthermia combined with radiation in treatment of locally advanced prostate cancer is associated with a favourable toxicity profile

Purpose: Hyperthermia is used to treat several pelvic tumours. An important step in establishing a broader role for hyperthermia in treatment of prostate cancer is verification of an acceptable toxicity profile. In this report, short- and long-term toxicity profiles of a completed phase II trial of transrectal ultrasound hyperthermia combined with radiation in treatment of locally advanced prostate cancer are presented. Methods and materials: Thirty-seven patients enrolled on a phase II study of external beam radiation +/- androgen suppression with two transrectal ultrasound hyperthermia treatments were assessed for short- and long-term toxicity. Prostatic and anterior rectal wall temperatures were monitored. Rectal wall temperatures were limited to 40 degrees C (19 patients), 41 degrees C (three patients) and 42 degrees C (15 patients). Univariate logistic regression was used to estimate the log hazard of developing NCI CTC Grade 2 toxicity based on temperature parameters. Hazard ratios, 95% confidence intervals, p-values for statistical significance of each parameter and proportion of variability explained for each of the parameters were calculated. Results: Median follow-up was 42 months. Both short- and long-term GI toxicity were limited to grade 2 or less. Acute grade 2 proctitis was greater for patients with allowable rectal wall temperature of >40 degrees C. Eleven of 18 patients in this group had acute grade 2 proctitis vs three of 19 patients with rectal wall temperatures limited to 40 degrees C (p = 0.004). Long-term grade 2 GI and GU toxicity occurred in 5% and 19% of patients. No late grade 3 or greater toxicity occurred. Late GI and GU toxicity were not associated with the allowable rectal wall temperature. Conclusion: Transrectal ultrasound hyperthermia combined with radiation for treatment of advanced clinically localized prostate cancer is safe and well tolerated.