Clinical Outcomes and Prognostic Significance of PSA90 in Patients With Prostate Cancer and Initial PSA >1,000 ng/ml at Diagnosis.

Background/Aim: Prostate cancer (PCa) patients with an initial prostate-specific antigen (PSA) level >1,000 ng/ml at diagnosis represent a rare and high-risk subgroup for which prognostic factors remain poorly defined. Therefore, we investigated the clinical features of this population and identified predictors of overall survival (OS). Patients and Methods: The present study retrospectively analyzed 35 patients diagnosed with PCa and initial PSA >1,000 ng/ml at our institution between August 2013 and December 2024. Clinical characteristics, treatment courses, PSA responses, and survival outcomes were collected. A nadir PSA level ≤0.2 ng/ml and a 90% decline in PSA from baseline (PSA90) were evaluated. OS was estimated using the Kaplan-Meier method, and the impact of clinical variables on OS was assessed using univariate and multivariate Cox proportional hazards regression models. Results: Median age was 74 years, and median initial PSA was 3,027 ng/ml. The median time to castration-resistant prostate cancer was 18.25 months, and median OS was 55.0 months. Univariate analyses revealed that PSA90 achievement correlated with longer OS, whereas age ≥75 years, an Eastern Cooperative Oncology Group performance status ≥1, elevated lactate dehydrogenase, and elevated C-reactive protein correlated with shorter OS. Multivariate analyses identified PSA90 achievement as the only independent predictor of prolonged OS (hazard ratio=0.13). Conclusion: These results suggest the potential of PSA90 as a simple and valuable early biomarker for prognostic stratification in patients with PCa and initial PSA >1,000 ng/ml.