Pan‐cancer analysis revealed robust correlations between C1R abundance (at both protein and RNA levels) and EMT signatures across multiple cancer types, including BRCA, CCRCC, COAD, GBM, HNSCC, LSCC, LUAD, OV, PDAC, and UCEC (Figure S1A). This evidence concerns the gene C1R and head and neck squamous cell carcinoma.