PIK3CA and cancer: Because (1) the tumorigenesis of most cancer types are similar; (2) cancer genes bearing mutations in EC are similar to other cancer types2,12–14, e.g., TP53, PIK3CA and KRAS; and (3) some mutational signatures of cancers are similar18, we wondered how well GATKcan trained by partial TCGA EC tumors can be applied to other cancer types.