Reasons for exclusion included irrelevant manuscripts which did not tackle the role of Tregs in oral and oropharyngeal cancer (n = 478), manuscripts that focused on tumors other than oral or oropharyngeal; laryngeal/esophageal (n = 82), salivary gland (n = 44), thyroid gland (n = 32) or gastric tumors (n = 18), review articles (n = 13), one study looked at the role of Tregs in periodontal disease and two articles were excluded because they assessed the expression of Foxp3 in tumor cells rather than assessing Tregs. This evidence concerns the gene FOXP3 and periodontal disorder.