LCNEC tumors have also been subdivided into two primary categories: type I, which are highly neuroendocrine and enriched for STK11 and KEAP1 mutations, and type II, which exhibit less neuroendocrine features, including enrichment of RB1 mutations and upregulation of the NOTCH pathway [7]. Here, RB1 is linked to large cell neuroendocrine carcinoma.