design: Paraffin-embedded tumor tissue samples underwent extraction using the CTAB method, with identical protocols applied to all negative controls. To minimize contamination risks from hospital and laboratory environments as well as various stages of sample handling and processing, a comprehensive set of controls was included. These controls consisted of sampling controls, DNA extraction controls, and no-template PCR amplification controls. For 16S rRNA gene amplification and sequencing, five regions of the 16S rRNA gene were amplified in multiplex. Sequencing was performed on the Illumina NovaSeq 6000 platform. Post-sequencing, reads were demultiplexed by sample, filtered, and mapped to each of the five amplified regions based on primer sequences. The Short MUltiple Regions Framework (SMURF) method was employed to integrate read counts across regions, generating a coherent microbial profile through maximum likelihood estimation. The reference database used was GreenGenes.