PIK3CA mutational status in tissue and plasma as a prognostic biomarker in HR+/HER2- breast cancer.

Introduction: Hotspots (HS) mutations in the PIK3CA gene may lead to poorer oncological outcomes and endocrine resistance in advanced breast cancer (BC), but their prognostic role in early-stage disease remains controversial. The overall agreement within plasma and tissue methods has not been well explored. Our aim was to correlate tissue and plasma approaches and to analyze the prognostic impact of PIK3CA mutations (PIK3CAm) in HR+/HER2- BC.