A study has shown that decreased mRNA expression of TCF21, a tumor suppressor, is a core predictor for poor prognosis in patients with lung cancers in two studies [33–35], agree with what we found the prognosis association from TCGA LUAD with gene set “CUI_TCF21_TARGETS_2_UP” (P = 1.30 × 10− 4). This evidence concerns the gene TCF21 and lung cancer.