PIK3CA and gastric adenocarcinoma: In STAD patients, PIK3CA + HMCN1 mutation yielded a substantial beneficial survival effect by interacting with LRP1B (HR = 3.78 × 10− 8, p-value = 0.0361) and AHNAK2 (HR = 3.86 × 10− 8, p-value = 0.0493) mutations.