[31] Our preliminary analysis showed that silencing of the TAC1 gene by methylation may be a critical event in tumor progression of HNSCC and that TAC1 promoter methylation was associated with reduced overall survival rates.[16] Furthermore, the methylation of galanin significantly correlated with GALR1 and GALR2 methylation and reduced DFS. This evidence concerns the gene GAL and head and neck squamous cell carcinoma.