Consistently, the GSVA-derived PI3K signaling score in METABRIC breast tumors correlated significantly with the stemness score (Fig 1A; Spearman’s Rho = 0.5, p < 2.2e-16) as well as tumor grade status (Fig 1B), a measure of tumor dedifferentiation based on histopathological assessment. This evidence concerns the gene PIK3CA and breast neoplasm.