Spatial Needle Placement Strategies and Pathological Concordance in Prostate Biopsy: A National Multicenter Retrospective Cohort Study

Prostate cancer is a major malignancy in men, and prostate biopsy determines both cancer detection and risk stratification. Biopsy strategies vary substantially across centers in approach (transperineal vs. transrectal), use of multiparametric MRI (mpMRI), targeted versus systematic sampling, and the spatial distribution of cores; however, most prior databases record only the total number of cores and cannot reconstruct the spatial location of individual cores. This national multicenter, retrospective, non-interventional observational cohort study, led by Guangxi Medical University and involving more than 20 hospitals across more than 10 provinces in China, will establish a layered database linking patients, MRI lesions, biopsy events, actual needle passes/specimen jars/cores, and radical prostatectomy pathology, and will convert historical needle-placement strategies into unified, auditable spatial variables. The study aims to compare the detection rate and per-core detection efficiency of ISUP Grade Group (GG) \>=2 prostate cancer across different spatial needle-placement strategies, to estimate the absolute missed-cancer cost and core-saving benefit of candidate reduced templates through within-patient reconstruction, and to evaluate the concordance, upgrading, and downgrading between biopsy and radical prostatectomy GG. The study adds no tests, biopsies, treatment, or follow-up, and the main risks are privacy breach and data misuse. Target enrollment is at least 30,000 cases.

Inclusion Criteria: 1. Age \>=18 years at the time of biopsy. 2. Underwent transperineal or transrectal prostate biopsy within the time window specified by the participating center. 3. Interpretable biopsy pathology results available, uniquely matchable to the patient and the biopsy event. 4. At minimum, the center, a de-identified within-center patient number, the biopsy date or orderable time information, and interpretable biopsy pathology are available. Missing biopsy approach, total needle passes, specimen jars, or core counts does not prevent entry into the patient-level detection cohort but determines eligibility for strategy, per-core efficiency, or spatial analyses. 5. Meets the additional data requirements of the corresponding analysis cohort; lack of MRI or radical prostatectomy data does not affect entry into the full biopsy cohort. Exclusion Criteria: 1. Only a consultation summary or conclusion is available, without confirmation that the biopsy was actually performed or without matchable pathology. 2. All specimens from the entire biopsy event are indeterminate lesions with no subsequent evidence confirming cancer or non-cancer, so the patient-level outcome cannot be determined. (If only individual cores are indeterminate while other cores have definite cancer or non-cancer evidence, the patient is retained and the core is separately marked as unclassifiable.) 3. Conflicts in key identity or dates prevent de-duplication or determination of biopsy sequence. 4. Biopsy performed after radical treatment for prostate cancer, or other sampling not fitting the prespecified clinical scenario. 5. The center cannot provide minimum data-quality certification, or ethics/data-use authorization does not cover the research use. 6. Cross-center visits may cause the same patient to appear more than once; centers de-duplicate locally, and the lead center does not receive direct identifiers. If ethics- and data-security-approved, irreversible salted hashing or a trusted third party may be used for cross-center suspected-duplicate checks; otherwise this is treated as a limitation with sensitivity analyses.