Tumor microbiome diversity influences papillary thyroid cancer invasionOriginal paper
Karen Pendergrass is a microbiome researcher specializing in microbiome-targeted interventions (MBTIs). She systematically analyzes scientific literature to identify microbial patterns, develop hypotheses, and validate interventions. As the founder of the Microbiome Signatures Database, she bridges microbiome research with clinical practice. In 2012, based on her own investigative research, she became the first documented case of FMT for Celiac Disease, four years before the first published case study.
Read MoreWhat was studied?
This study probed the intratumor microbiome of papillary thyroid carcinoma and its link to tumor invasion. It tested whether tumor bacteria differ across clinical T stages. Bacteria within resected tumor tissue were profiled by 16S rRNA gene sequencing of the V3-V4 region on an Illumina MiSeq platform. Negative controls checked for contamination. Analyses compared alpha and beta diversity across stages, identified stage-associated genera with LEfSe, built a predictive taxa signature via ROC analysis, and correlated bacteria with thyroid hormones and autoimmune thyroid antibodies. PICRUSt2 predicted functional pathways.
Who was studied?
The main cohort was 80 patients with newly diagnosed, histologically confirmed papillary thyroid carcinoma, treated at Tangdu Hospital in Xi'an, China, from 2013 to 2018. Other thyroid cancer types were excluded. Patients were grouped by TNM T stage, contrasting mild lesions (T1/T2) with advanced lesions (T3/T4). Sex, age, and lymphatic metastasis status were recorded. A separate validation set of T1/T2 patients was recruited in November 2021 to test the bacterial signature against T3/T4 samples. All samples were human tumor tissue.
What were the most important findings?
Tumor bacterial alpha diversity was significantly higher in advanced T3/T4 lesions than in mild T1/T2 lesions (Shannon p = 0.0309, Simpson p = 0.0088). Beta diversity also differed by stage (p = 0.001). An eight-genus signature discriminated invasion status with an AUC of 0.83 for T1_2 versus T3_4, 0.91 for T1 versus T4, and 0.79 in the validation set. T3_4 tumors were enriched for Streptococcus, Granulicatella, and Haemophilus. Specific genera correlated with thyroid hormones (FT4, FT3, T3, T4, TSH) and with anti-TPO, anti-TG, and anti-TSHR autoantibodies. Females showed higher tumor microbiome diversity than males.
What are the greatest implications of this study?
Papillary thyroid tumors harbor a measurable intratumor microbiome whose diversity and composition track invasion status. The eight-genus signature could become a marker of aggressive disease. Because bacterial diversity differed independent of tumor genomics, microbial host factors may influence tumor behavior. Correlations with thyroid hormones and autoimmune antibodies suggest a possible link to thyroid function. These are correlations from a single-center cohort of 80 patients, and mechanisms were not tested. The work does not establish that tumor bacteria cause invasion, and environmental factors like diet and smoking were not accounted for.