Variant landscape analysis in processed samples (n = 536) was reflective of HNSCC, with a high prevalence of TP53 (70%), PIK3CA (29%), KMT2D (26%), NOTCH1 (18%), FAT1 (18%), and LRP1B (18%) alterations (Supplementary Fig. 2). Here, PIK3CA is linked to head and neck squamous cell carcinoma.