PIK3CA and metastatic malignant neoplasm in the lymph nodes: Levels of PIK3CA and PTEN expression in breast carcinoma tissue were similar in patients with and without lymph node metastases (p = 0.72 and p = 0.48) (Figure 3) There was no association between elevated PIK3CA expression and lymph node metastases (p = 0.71) or between reduced PTEN expression and lymph node metastases (p = 0.32) (Table 2).