PIK3CA and neoplasm: Conversely, no statistically significant associations were identified between mtDNA-CN and variables such as sex (P = 0.4429), age (P = 0.2670), tumor location (P = 0.7793), stage N (P = 0.7598), CEA (P = 0.1050), carbohydrate antigen 19-9 (CA19-9) (P = 0.5747), vascular invasion (P = 0.9856), tissue type (P = 0.5789), KRAS status (P = 0.3157), BRAF status (P = 0.1046), NRAS status (P = 0.2400), and PIK3CA status (P = 0.9533).