In a recent review paper on neuroendocrine tumors of the lung, based on a number of previous published papers which included biopsy and resected specimens, Rekhtman [17] reported a weighted Ki-67 index mean value of 1.5% (range 0–2.3%) for TC and 7.7% (range 0–17%) for AC compared to 64% (25–96%) for small-cell lung carcinoma and 46% (20–90%) for LCNEC. This evidence concerns the gene MKI67 and lung neuroendocrine neoplasm.