PIK3CA and neuroendocrine carcinoma: For gastrointestinal NEC patients, TP53 associated genes were most commonly altered (N = 54), followed by APC (N = 28), EGFR (N = 18), ERBB2 (N = 11), NF1 (N = 11), KRAS (N = 10), CCNE1 (N = 10), BRCA2 (N = 10), BRCA1 (N = 9), PIK3CA (N = 9), RB1 (N = 8), MYC (N = 7), BRAF (N = 7), CDK6 (N = 5), MTOR (N = 4), MET (N = 3), and FGFR1 (N = 3).