HP and gastric cancer: In particular, the gut microbiome of the TC group was characterized by the relative dominance of Neisseria and Streptococcus, which have also been associated with the development of gastric cancer in the absence of Hp infection [60], Streptococcus accounting for the largest proportion in Hp-negative gastric cancer at the family level [61] and related to colorectal carcinogenesis, as well [62], supporting the potential of these bacteria possibly playing a role in thyroid disease.