Intratumoral Microbiota and Immune Microenvironment in Prostate Cancer

Prostate cancer is a common malignancy in men, with rising incidence worldwide. Current clinical risk assessment tools-including PSA, Gleason score/ISUP grade, pathological stage, margin status, perineural invasion, and postoperative PSA kinetics-cannot fully explain the marked heterogeneity in disease progression, recurrence, and treatment response, highlighting the need for novel microenvironment-based biomarkers. Emerging evidence has identified intratumoral microbiota as a component of the tumor microenvironment in various solid tumors (e.g., breast, lung, ovarian, pancreatic, and melanoma), where microbial signals correlate with immune infiltration, inflammation, drug metabolism, and patient outcomes. However, the composition, spatial distribution, and immune-related roles of intratumoral microbiota in prostate cancer remain poorly characterized. Given that prostatic tissue resides at the urogenital junction and is continuously exposed to urine, prostatic fluid, and local inflammation, it is plausible that microbial components influence local immunity and tumor behavior. Importantly, intratumoral microbiota represent low-biomass samples, highly susceptible to contamination from reagents, environment, and laboratory procedures. Therefore, this study incorporates rigorous quality controls-including negative controls, process blanks, batch records, contaminant identification, spatial localization validation, and cross-platform verification-to ensure data reliability. Using residual tissue specimens, archived pathological slides, and comprehensive clinicopathological data from prostate cancer patients, we will employ 16S rRNA sequencing, metagenomic/metatranscriptomic sequencing, spatial transcriptomics, spatial proteomics, immunofluorescence, immunohistochemistry, and bioinformatic analyses to profile intratumoral microbiota. Our specific objectives are: (1) to compare microbial composition, abundance, and diversity among tumor, adjacent-normal, and benign tissues