Studies have shown that both estrogen receptors of ERα and ERβ were expressed in lung tumor tissue [19], while ERβ is the dominant ER isoform in NSCLC, expressed in about 90% of all NSCLC cases, ERα isoform expression is relatively low and expressed as variant fragment protein forms, not full-length protein, which can only be recognized by C-terminal antibody [7, 20, 21]. This evidence concerns the gene ESR2 and non-small cell lung carcinoma.