Prostate brachytherapy in men with gland volume of 100cc or greater: Technique, cancer control, and morbidity

Purpose: To determine the outcomes of prostate seed implantation in men with prostate volume (PV) of 100. cc or greater (PV100). Methods: A total of 2051 men with localized prostate cancer were treated with permanent prostate brachytherapy of whom 34 (1.7%) had PV100 (mean, 126.2; range, 100-205cc). The PV100 patients were older (mean, 69 vs. 66 years; p=0.031), had higher initial prostate-specific antigen level (20.4 vs. 9.6 ng/mL, p<0.001), and received a lower dose (182 vs. 194Gy₂ biologic equivalent dose, p=0.032). There were no differences in clinical stage, Gleason score, and baseline International Prostate Symptom Score. The mean followup time was 6.7 years (range, 2-18). Biochemical freedom from failure (bFFF) was defined using the Phoenix definition. Results: The BFFF at 10 years was no different between PV100 and smaller glands (82.4% vs. 84.5%, p=. 0.71). At last followup, mean International Prostate Symptom Score for PV100 increased from 8.5 to 9.1 against 7.4 to 9.2 for smaller glands (. p=. 0.935). Urinary retention rates were higher for PV100 (6/34, 17.6% vs. 148/2017, 7.3%; odds ratio, 2.71; 95% confidence interval, 1.1-6.6; p=. 0.038). Postimplant transurethral resection of the prostate was performed in none of the 34 patients with PV100 against 66 of the 2017 patients (3.3%, p<. 0.001). Long-term radiation proctitis for PV100 were 1 of 34 (2.9%) against 82 of 2017 (4.1%, p=. 0.741). Rectourethral fistula occurred in 4 patients (0.19%), that is, 1 of 34 (2.9%) in PV100 group and 3 of 2017 (0.1%, p<. 0.001). Conclusion: This study demonstrates the feasibility of implanting patients with PV100. Very large PV does not influence bFFF. Although urinary retention rates were higher, the long-term urinary symptoms were no different between the two groups. Requirement for transurethral resection of the prostate was no higher in patients with PV100. Radiation proctitis rates were similar for both.