The metabolic subtype is associated with the upregulation of genes involved in drug metabolism by cytochrome P450 and retinol metabolism, such as GSTA1, ADH7, UGT1A10 and UGT1A3. High expression of WFDC2, PEG10, Wnt signalling modulator SFRP1 and squamous cell carcinoma (SCC) stem cell marker LGR615 defined the stemness subtype (Fig. 1a and Supplementary Data 2). This evidence concerns the gene SFRP1 and squamous cell carcinoma.