Association of PIK3CA mutations and amplification with clinical outcome in patients with gastric cancer. Kaplan-Meier analysis of survival was performed according to the presence of PIK3CA mutations or amplification in a large cohort of gastric cancers. (A) Kaplan-Meier survival curves show that PIK3CA mutations were not associated with poor survival of the patients. (B) The patients with PIK3CA amplification had poorer survival than the patients without PIK3CA amplification. (C) PIK3CA amplification was extremely significantly associated with poor survival in the patients who had early-stage tumors (P = 0.004). (D) PIK3CA amplification was marginally significantly associated with poor survival in the patients who had late-stage tumors (P = 0.06). PIK3CA Mu, PIK3CA mutations; PIK3CA Am, PIK3CA amplification; +, harboring PIK3CA mutations or amplification; -, the lack of PIK3CA mutations or amplification.