
Analysis code, the frozen pre-operative logistic-regression model (coefficients and PSA restricted-cubic-spline knots), and aggregate result files underlying a study developing and externally validating a model for clinically significant ISUP grade upgrading (radical-prostatectomy ISUP grade group >= 3 among favorable-risk biopsy ISUP grade group 1-2 prostate cancer). The model was developed in a Polish cohort and externally validated in a de-identified United States cohort. No patient-level data are included; individual-participant data are under controlled access. The model is shared for transparency and reproducibility and is not externally established or deployment-ready.
