The influence of isotope and prostate volume on urinary morbidity after prostate brachytherapy.

PURPOSE: To evaluate the influence of isotope and prostate size on International Prostate Symptom Score (IPSS) normalization, catheter dependency, and the need for surgical intervention secondary to bladder outlet obstruction after prostate brachytherapy.

METHODS AND MATERIALS: Between January 1998 and June 2003, 976 consecutive patients underwent brachytherapy for clinical stage T1b-T3a (2002 American Joint Committee on Cancer) prostate cancer. Seven hundred eighty-nine (80.8%) were implanted with 103Pd and 187 (19.2%) with 125I. The median follow-up was 41.2 months. Patients were stratified into size cohorts < or = 25 cm3, 25.1-35 cm3, 35.1-45 cm3, and >45 cm3. Four hundred eighteen patients (42.8%) received androgen deprivation therapy (ADT). Four hundred eighty-six patients (49.7%) received supplemental external-beam radiation therapy (XRT). In all patients, an alpha blocker was initiated before implantation and continued at least until the IPSS returned to baseline. IPSS resolution was defined as a return to within one point of baseline. The median number of IPSS determinations per patient was 21. Clinical, treatment, and dosimetric parameters evaluated included patient age, pretreatment PSA, Gleason score, clinical T stage, percent positive biopsies, preimplant IPSS, ultrasound volume, planning volume, isotope, V(100/150/200), D(90), urethral dose (average and maximum), supplemental XRT, ADT, and the duration of ADT (< or = 6 months vs. >6 months). Catheter dependency and the need for postsurgical intervention were also evaluated.

RESULTS: For both isotopes and all prostate size cohorts, IPSS peaked 1 month after implantation and returned to baseline at a mean of 1.9 months. Stratification of prostate size cohorts by isotope demonstrated no significant differences in prolonged catheter dependency (> or = 5 days), IPSS resolution, or postimplant surgical intervention. In Cox regression analysis, IPSS normalization was best predicted by preimplant IPSS, XRT, and any need for a catheter after brachytherapy. Catheter dependency correlated with prostate size and ADT, whereas the need for surgical intervention was most closely related to any catheter dependency, maximum urethral dose, ADT, and maximum IPSS increase.

CONCLUSIONS: Regardless of prostate size, isotope did not impact IPSS resolution, catheter dependency, or the need for postbrachytherapy surgical intervention. Although prostate size did predict for short-term (<5 days) catheter dependency, it did not influence IPSS resolution or the need for surgical intervention.