No statistically significant differences in RB, p53, or p16 expression patterns were identified between LCNEC and grade 3 NET (RB loss, aberrant p53, and diffuse p16 in 50% LCNEC vs 0% grade 3 NET, p = 0.091, p = 0.091, and p = 0.109, respectively). Here, RB1 is linked to large cell neuroendocrine carcinoma.