Urinary morbidity following ultrasound-guided transperineal prostate seed implantation

Abstract

Purpose: To assess the urinary morbidity experienced by patients undergoing ultrasound-guided, permanent transperineal seed implantation for adenocarcinoma of the prostate.

Methods and materials: Between September 1992 and September 1997, 693 consecutive patients presented with a diagnosis of clinically localized adenocarcinoma of the prostate, and were treated with ultrasound-guided transperineal interstitial permanent brachytherapy (TPIPB). Ninety-three patients are excluded from this review, having received neoadjuvant antiandrogen therapy. TPIPB was performed with 125I in 165 patients and with 103Pd in 435 patients. Patients treated with implant alone received 160 Gy with 125I (pre TG43) or 120 Gy with 103Pd. One hundred two patients received preimplant, pelvic external beam radiation (XRT) to a dose of either 41.4 or 45 Gy because of high-risk features including PSA > or = 10 and/or Gleason score > or = 7. Combined modality patients received 120 Gy and 90 Gy, respectively for 125I or 103Pd. All patients underwent postimplant cystoscopy and placement of an indwelling Foley catheter for 24-48 h. Follow-up was at 5 weeks after implant, every 3 months for the first 2 years, and then every 6 months for subsequent years. Patients completed AUA urinary symptom scoring questionnaires at initial consultation and at each follow-up visit. Urinary toxicity was classified by the RTOG toxicity scale with the following adaptations; grade 1 urinary toxicity was symptomatic nocturia or frequency requiring none or minimal medical intervention such as phenazopyridine; grade 2 urinary toxicity was early obstructive symptomatology requiring alpha-blocker therapy; and grade 3 toxicity was considered that requiring indwelling catheters or posttreatment transurethral resection of the prostate for symptom relief. Log-rank analysis and Chi-square testing was performed to assess AUA score, prostate size, isotope selection, and the addition of XRT as possible prognosticators of postimplant urinary toxicity. The prostate volume receiving 150% of the prescribed dose (V150) was studied in patients to assess its correlation with urinary toxicity.

Results: Median follow-up was 37 months (range 6-68). Within the first 60 days, 37.3% of the patients reported grade 1 urinary toxicity, 41% had grade 2, and 2.2% had grade 3 urinary toxicity. By 6 months, 21.4% still reported grade 1 urinary toxicity, whereas 12.8% and 3% complained of grade 2 and 3 urinary difficulties, respectively. Patients with a preimplant AUA score < or = 7 had significantly less grade II toxicity at 60 days compared to those with an AUA score of >7 (32% vs. 59.2%, respectively, p = 0.001). Similarly, prostatic volumes < or = 35 cc had a significantly lower incidence of grade II urinary toxicity (p = 0.001). There was no difference in toxicity regarding the isotope used (p = 0.138 at 60 days, p = 0.45 at 6 months) or the addition of preimplant XRT (p = 0.069 at 60 days, p = 0.84 at 6 months). Twenty-eight patients (4.7%) underwent TURP after 3 isotope half-lives for protracted obstructive symptoms. Five of these men (17%) developed stress incontinence following TURP, but all patients experienced relief of their obstructive symptoms without morbidity at last follow-up. The percent of the prostate receiving 150% of the prescribed dose (V150) did not predict urinary toxicity.

Conclusions: TPIPB is well tolerated but associated with mild to moderate urinary morbidity. Pretreatment prostatic volume and AUA scoring were shown to significantly predict for grade 2 toxicity while the use of preimplant, pelvic XRT and isotope selection did not. Patients undergoing TURP for protracted symptoms following TPIPB did well with a 17% risk of developing stress incontinence. V150 did not help identify patients at risk for urinary morbidity. As transperineal prostate implantation is used more frequently the associated toxicities and the definition of possible pretreatment prognostic factors is necessary to