CD8A and head and neck squamous cell carcinoma: Moreover, cell count impairment in circulating and tumor-infiltrating cytotoxic CD8+ T lymphocytes have also been reported in patients with HNSCC.57,59 An amplification in circulating Tregs in patients with HNSCC has also been considered a poor prognostic factor.60,61 In oropharyngeal cancer, it has been shown that while increased levels of cytotoxic CD8+ T lymphocytes is a favorable prognostic factor, the effect of Tregs still remains controversial.62