RB1 and leukoencephalopathy with calcifications and cysts: TP53 and RB1 mutations as trunk clonal events were nearly universal in all cSCLC-LCC/LCNEC tumors (Fig. 4A), occurring in the early stages of cSCLC-LCC/LCNEC tumor evolution (Additional file 1: Figure S6A, Additional file 2: Table S12).