Dynamic dose-feedback prostate brachytherapy in patients with large prostates and/or planned transurethral surgery before implantation.

ABSTRACT

OBJECTIVE: To compare the quality of permanent prostate brachytherapy (PPB) implants, dosimetric outcomes and urinary morbidity between patients with large (>50 mL) and those with smaller prostates, treated with a dynamic dose-feedback technique as monotherapy for localized prostate cancer. PATIENTS AND METHODS: The series included patients with pre-existing bladder outlet obstruction managed with planned transurethral resection or incision of the prostate; 155 consecutive men had PPB implants as monotherapy for localized prostate cancer using a dynamic dose-feedback approach. Dosimetric variables assessed included the implant volume, the minimum dose to 90% of the prostate (D90), and the volumes of prostate receiving 100% and 150% of the prescribed dose as a percentage of the total volume (V100 and V150), during and after implantation. Urinary morbidity was recorded in terms of acute urinary retention (AUR), the need for surgical intervention after implantation and the American Urologic Association (AUA) symptom score at baseline, 1.5, 3, 6, 9, 12 and 18 months. RESULTS: In all, 38 patients had prostate volumes of >or=50 mL; prostate volume had no influence on any dosimetric variable assessed. Two patients with large prostates (>or=50 mL) had AUR and required delayed surgery. Three patients with small prostates (<50 mL) had transient retention; the differences were not statistically significant (Fisher's exact test). AUA symptom scores peaked at 6 weeks and returned to baseline within a year; there were no statistically significant differences between the groups. Eight patients had planned transurethral surgery at >or=4 months before implantation; they all had D90s of >130 Gy and had no incontinence. CONCLUSION: Using the dynamic feedback technique, there was no adverse dosimetric and urinary morbidity in men having PPB and with prostates of >50 mL. Likewise, there were no impediments, e.g. pubic arch interference, which precluded a favourable dosimetric implant in men with a large prostate. Large prostates should not be a contraindication to PPB and require no hormonal cytoreduction. Patients with obstructive lower urinary tract symptoms can be managed with planned transurethral prostatic surgery before implantation, without compromising implant quality or morbidity.