Provisionally, in investigational setting, LCNEC that exhibit Rb mutations/loss, particularly when associated with extremely high Ki67 rates (70–100%), could be regarded as likely representing a SCLC-related variant of LCNEC, and patients could be stratified accordingly for clinical outcomes analysis; studies of this type are currently in progress104. This evidence concerns the gene MKI67 and large cell neuroendocrine carcinoma.