Acute urinary toxicity following transperineal prostate brachytherapy using a modified Quimby loading method

Purpose: To examine the acute urinary toxicity following transperineal pros tate implant using a modified Quimby loading method with regard to time cou rse, severity, and factors that may be associated with a higher incidence o f morbidity. Methods and Materials: One hundred thirty-nine patients with prostate adeno carcinoma treated with brachytherapy from 1997 through 1999 had follow-up r ecords available for review. Patients considered for definitive brachythera py alone included those with prostate specific antigen (PSA) less than or e qual to 6, Gleason score (GS) less than or equal to 6, clinical stage < T2b , and prostate volumes generally less than 40 cc. Patients with larger pros tate volumes were given neoadjuvant antiandrogen therapy. Those with GS > 6 , PSA > 6, or Stage > T2a were treated with external beam radiation therapy followed by brachytherapy boost. Sources were loaded according to a modifi ed Quimby method. At each follow-up, toxicity was graded based on a modifie d RTOG urinary toxicity scale. Results: Acute urinary toxicity occurred in 88%. Grade I toxicity was repor ted in 23%, grade II in 45%, and grade III in 20%,with 14% requiring prolon ged (greater than 1 week) intermittent or indwelling catheterization, Overa ll median duration of symptoms was 12 months. There was no difference in du ration of symptoms between patients treated with I-125 or Pd-103 sources (p = 0.71). After adjusting for GS and PSA, multivariate logistic regression analysis showed higher incidence of grade 3 toxicity in patients with large r prostate volumes (p 0.002), and those with more seeds implanted (p < 0.00 1). Higher incidence of prolonged catheterization was found in patients rec eiving brachytherapy alone (p = 0.01), with larger prostate volumes (p = 0. 01), and those with more seeds implanted (p < 0.001). Conclusion: Interstitial brachytherapy for prostate cancer leads to a high incidence of acute urinary toxicity, most of which is mild to moderate in s everity. A prolonged need for catheterization can occur in some patients. P atients receiving brachytherapy alone, those with prostate volumes greater than 30 cc, and those implanted with a greater number of seeds have the hig hest incidence of significant toxicity. (C) 2001 Elsevier Science Inc.