Systematic evaluation of TCGA tumor microbiota reveals context-dependent reliability.

Microbial profiles from The Cancer Genome Atlas (TCGA) are widely used to study the tumor microbiota, a key component of the cancer ecosystem, yet their reliability remains unclear. Here, we systematically benchmarked two leading TCGA microbial profiles (TMPs) to define their consistency, accuracy, and reliability in host-microbe association studies across 24 cancer types, with a primary focus on the bacterial component. We found that while the TMPs showed substantial agreement in microbial composition, their accuracy in detecting known oncomicrobes was variable, ranging from excellent for human papillomavirus (HPV) to poor for IMPORTANCE: Bacteria living inside tumors can influence how cancer grows and responds to treatment, but the field has been hampered by controversy over the reliability of the data. Our study provides a much-needed road map for researchers. We rigorously tested the massive Cancer Genome Atlas data set and developed a statistical framework to separate true biological signals from random noise. We discovered that many widely reported links are statistically unreliable and likely false leads. Importantly, our framework successfully pinpoints trustworthy signals. We used it to identify a specific bacterium,