PIK3CA and metastatic malignant neoplasm in the lymph nodes: However, after excluding the patients with lymph node metastasis, the disease-free survival curves drawn using the Kaplan-Meier method about 59 patients without lymph node metastasis (N stage = N0 patients) indicated that the patients with PIK3CA copy number amplification (n = 16) showed earlier recurrence than those without PIK3CA copy number amplification (n = 43) (log-rank test, p =0.026) (Figure 2).