A novel “early warning” system for biochemical recurrence in prostate cancer: development and validation of the SII-HALP combined score

Traditional clinicopathological features often inadequately reflect systemic host-tumor dynamics, compromising the predictive accuracy of biochemical recurrence (BCR) in prostate cancer, particularly with respect to early oncological failure. This study sought to evaluate the SII-HALP combined score—integrating the Systemic Immune-Inflammation Index (SII) and Hemoglobin, Albumin, Lymphocyte, and Platelet (HALP) score—and assess its time-dependent prognostic value in patients undergoing radical prostatectomy. Clinicopathological data from patients with localized prostate cancer were retrospectively analyzed. Maximally selected rank statistics identified optimal threshold values for SII and HALP. A prognostic nomogram incorporating the combined score was then constructed. Model performance was assessed using time-dependent receiver operating characteristic (ROC) curves, calibration plots, and decision curve analysis (DCA). The incremental predictive value was quantified via integrated discrimination improvement (IDI) and net reclassification improvement (NRI). Multivariable Cox regression established the SII-HALP combined score as an independent predictor of BCR. The nomogram exhibited an improved predictive performance for 1-year recurrence (AUC 0.866 vs. 0.821 in the base model; P = 0.002). This incremental gain was confirmed by an IDI of 0.067 ( P < 0.001) and an NRI of 0.532 ( P = 0.040). While the incremental benefit diminished at exploratory 3- and 5-year timepoints as anatomical factors became predominant, DCA indicated a superior net benefit at 1 year across most threshold probabilities, and tentatively at higher thresholds (> 50%) for exploratory long-term projections. Based on internal validation, the preliminary SII-HALP combined score may serve as an exploratory, low-cost prognostic tool that contributes to optimizing risk stratification for 1-year biochemical recurrence. Reflecting a possible host-tumor biological interaction, it offers a conceptual pathway for individualized risk triage, pending further robust external validation and extended longitudinal follow-up.