These tumors were characterized by MKI67 gene expression levels higher than seen in other carcinoid molecular subtypes, high estimated levels of neutrophil infiltration, altered pathways related to chemotaxis and degranulation of neutrophil, high levels of expression of immune checkpoint receptors and ligands (such as PDL1 and CTLA4), and upregulation of other immunosuppressive genes (including HLA-G and interferon gamma). Here, MKI67 is linked to carcinoid tumor.