PIK3CA and breast cancer: Multivariate Cox regression analysis further found that PIK3CA rs2699887 GA/AA genotypes acted as protective prognostic factors (DFS: adjusted HR=0.384, 95% CI=0.170-0.867, P=0.021;OS: adjusted HR=0.192, 95% CI=0.059-0.619, P=0.006) adjusted by age, menopausal status, family history of BC, tumor size, clinical stages, lymph node metastasis, outlined in Table 3.