DNA polymerase delta 1 in rectal adenocarcinoma: Multi-cohort validation of overexpression, genomic correlates, and association with the tumor immune microenvironment

BACKGROUNDRectal adenocarcinoma (READ) accounts for roughly 30% of colorectal cancer and remains clinically aggressive, yet validated molecular markers for its diagnosis and risk stratification are still lacking.DNA polymerase delta 1 (POLD1) encodes the catalytic, proofreading-proficient subunit of DNA polymerase delta and is essential for DNA replication and repair.Beyond its established role in hereditary cancer susceptibility, its expression pattern, genomic regulation and clinical relevance in READ have not been examined across independent cohorts. AIMTo investigate the expression pattern, genomic regulation, and clinical significance of POLD1 in READ across multiple independent cohorts, and to explore its association with the tumor immune microenvironment.