RET and adenocarcinoma: In NSCLC, RET rearrangements occur in approximately 1–2% of cases, particularly more frequently in relatively younger patients (≤60 years old) with poorly differentiated adenocarcinomas and with little to no smoking history, who are typically characterized by low PD-L1 expression levels and a low tumor mutation burden (TMB).60 RET rearrangements usually do not overlap with genetic variations in EGFR, ROS1, BRAF, MET exon 14 skipping, and ALK, however, there might be sporadic instances of co-mutations with KRAS.45,61