Small cell lung carcinoma (SCLC), the prototypical poorly-differentiated NEC, demonstrates near-universal biallelic inactivation of tumor suppressor genes TP53 and RB135, and frequent TP53/RB1 co-alteration has also been identified in small cell/poorly-differentiated NEC of the pancreas, prostate, bladder, and colon/rectum, and in Merkel cell carcinoma36–42. Here, RB1 is linked to small cell lung carcinoma.