Bussu et al. have analysed serum IL-9 levels in 31 HNSCC patients (16 patients of oral cavity SCC and 15 LSCC patients) and six healthy controls using multiplex biometric ELISA and have found that there were no statistically significant differences between selected groups (33.54 ± 18.85 vs. 46.59 ± 25.72 pg/mL, respectively) [54]. This evidence concerns the gene IL9 and oral cavity squamous cell carcinoma.