PIK3CA and metastatic malignant neoplasm in the lymph nodes: Multivariate Cox regression analysis indicated that PIK3CA amplification is a predictor of poor prognosis for gastric cancer patients (HR = 2.59, 95% CI = 1.39-4.82, P = 0.003) as an independently variable with respect to age, differentiation, lymph node metastasis, and TNM stage (Table 3).