The prognostic effect of prostate-specific antigen half-life at the first follow-up visit in newly diagnosed metastatic prostate cancer

Abstract

PURPOSE: Several prostate-specific antigen (PSA) kinetics parameters such as nadir PSA level and time to nadir PSA level are used commonly as predictive prognostic factors for patients with metastatic prostate cancer (mPCa) who have undergone androgen deprivation therapy. However, based on the limitations of these factors, earlier and more clinically available prognostic factors are needed. Therefore, we examined the PSA half-life (PSAHL) estimated at the first follow-up visit as a prognostic factor of newly diagnosed mPCa. METHODS: We performed a retrospective review of 309 patients with newly diagnosed mPCa who had undergone androgen deprivation therapy. After categorizing the included patients to short and long PSAHL groups, based on the median PSAHL value, Cox regression analyses were performed to identify independent prognostic factors of newly diagnosed mPCa. The Kaplan-Meier method was used for detecting differences in survival between both the groups. RESULTS: The median follow-up period was 44 months, and the prostate cancer-specific mortality (PCSM)-free survival length was 65 months in all included patients. Long PSAHL group (hazard ratio [HR] = 2.383, P<0.001), nadir PSA level (HR = 1.004, P<0.001), time to nadir PSA level (HR = 0.856; P<0.001), and Gleason score 8 to 10 relative to 6 to 7 (HR = 2.025; P = 0.008) were found to be independent predictors of the PCSM. By the Kaplan-Meier method, the median PCSM-free survival of the short PSAHL group was 73.7 (95% CI: 54.8-92.6) and of the long PSAHL group was 52.5 months (95% CI: 33.4-71.6). This difference between both the groups was found to be statistically significant (P = 0.014, log rank test). CONCLUSIONS: PSAHL estimated at the first follow-up visit is an independent prognostic factor for newly diagnosed mPCa. If the prospective validation test is performed on a large scale, it may demonstrate that PSAHL is an early surrogate prognostic factor of newly diagnosed mPCa.