In HNSCC, RAC1 copy number increases are very common, accounting for 38.8% of cases [37% of cases with RAC1 gain (188/510) and 2% of cases with RAC1 amplification (10/510); TCGA-HNSCC Firehose], while heterozygous loss is only found in 4.7% of cases (24/510 cases). This evidence concerns the gene RAC1 and head and neck squamous cell carcinoma.