Some studies found that HIF-2α had more tumor specificities; for example, there was a low expression level of HIF-2α in small cell lung cancer (SCLC) patients which did not affect the survival of tumor cells [22], whereas the patients of nonsmall cell lung cancer (NSCLC) with a high expression of HIF-2α had poor prognosis and significantly shortened survival time [23], suggesting that HIF-2α may be an independent prognostic indicator. This evidence concerns the gene EPAS1 and small cell lung carcinoma.