Time to Disease Recurrence Is a Predictor of Metastasis and Mortality in Patients with High-risk Prostate Cancer Who Achieved Undetectable Prostate-specific Antigen Following Robot-assisted Radical Prostatectomy

Background: Robot-assisted radical prostatectomy (RARP) is a feasible treatment option for high-risk prostate cancer (PCa). While patients may achieve undetectable prostate-specific antigen (PSA) levels after RARP, the risk of disease progression is relatively high. We investigated metastasis-free survival, cancer-specific survival (CSS), and overall survival (OS) outcomes and prognosticators in such patients. Methods: In a single-center cohort of 342 patients with high-risk PCa (clinical stage ${\geq}T3$, biopsy Gleason score ${\geq}8$, and/or PSA levels ${\geq}20ng/mL$) treated with RARP and pelvic lymph node dissection between August 2005 and June 2011, we identified 251 (73.4%) patients (median age, 66.5 years; interquartile range [IQR], 63.0-71.0 years) who achieved undetectable PSA levels (< 0.01 ng/mL) postoperatively. Survival outcomes were evaluated for the entire study sample and in groups stratified according to the time to biochemical recurrence dichotomized at 60 months. Results: During the median follow-up of 75.9 months (IQR, 59.4-85.8 months), metastasis occurred in 38 (15.1%) patients, most often to the bones, followed by the lymph nodes, lungs, and liver. The 5-year metastasis-free, cancer-specific, and OS rates were 87.1%, 94.8%, and 94.3%, respectively. Multivariate Cox-regression analysis revealed time to recurrence as an independent predictor of metastasis (P < 0.001). Time to metastasis was an independent predictor of OS (P = 0.003). Metastasis-free and CSS rates were significantly lower among patients with recurrence within 60 months of RARP (log-rank P < 0.001). Conclusion: RARP confers acceptable oncological outcomes for high-risk PCa. Close monitoring beyond 5 years is warranted for early detection of disease progression and for timely adjuvant therapy.