Prediction and stratification of the biochemical recurrence in patients with high-risk prostate cancer after low dose rate permanent seed implantation.
Treatment of high-risk prostate cancer (PCa) remains challenging for urologists. The present study was undertaken to identify risk factors for the biochemical recurrence (BCR) in patients with high-risk PCa who underwent low dose rate permanent seed implantation brachytherapy with iodine-125 (LDR).
Medical records of 335 patients with high-risk PCa identified by NCCN risk stratification treated with LDR during the period of 2004-2015 at our institution have been reviewed. All patients received extra beam radiation therapy after LDR. Possible risk factors assessed for the future BCR included age, PSA, prostate volume, histological findings of biopsy specimens, neoadjuvant hormone therapy and local extent of disease evaluated by pelvic MRI. BCR free survival rates were constructed using the Kaplan-Meier method. Risk factors for BCR were evaluated by the log-rank test and multivariate Cox proportional hazard model with a stepwise selection procedure.
The Kaplan-Meier analysis showed that the 5- or 10-year BCR free survival rates were 86.7%, and 78.8%, respectively. Multivariate analysis demonstrated that grade group 5 (Hazard ratio; HR 3.75, p<0.01), cT3 (HR 2.03, p<0.04), PSA >20ng/ml (HR 2.45, p<0.05) and no neoadjuvant hormone therapy (HR 2.16, p<0.05) were significant prognostic factors. The patients were stratified into a good-risk group (0 or 1 risk factor), intermediate-risk group (2 risk factors), and poor-risk group (3 risk factors). There were significant differences in the BCR free survival among the groups; p<0.01 for low- vs. intermediate-risk group, and p<0.01 for intermediate- vs. high-risk group. The 5- or 10-year BCR free survivals rates were 92.4%, 83.1%, and 75.3%, 72.5%, and 26.7%, 26.7% in good-, intermediate-, and poor-risk patients, respectively.</p>
These results indicate that grade group 5, cT3, PSA >20ng/ml and no neoadjuvant hormone therapy were independent risk factors for the BCR in patients with high-risk PCa treated with LDR. The combination of these factors may be helpful to identify candidates for additional treatments to control disease progression.