MUC3A was highly expressed in lung cancer and relevant to the poor survival in database and tissue microarray. (A) The 20× and 200× representative images of IHC. (B) The expression levels of MUC3A protein were significantly higher in NSCLC tissues than those in the paired normal tissues. The tissue microarray results included 92 pairs (p < 0.001, paired t-test). (C) MUC3A expression levels in lung cancer tissues subgrouped by staging (p < 0.001, ANOVA). (D) MUC3A expression levels in lung cancer tissues subgrouped by differentiation (p < 0.001, ANOVA). (E) Kaplan-Meier plot of 92 patients with survival data (from tissue arrays) stratified by MUC3A expression levels. Patients expressing less MUC3A displayed higher overall survival than the other patients (p = 0.045, Kaplan-Meier survival test). (F) Kaplan-Meier plot of 720 patients with survival data stratified by MUC3A mRNA levels. Patients expressing more MUC3A displayed shorter overall survival than the other patients (p = 0.00051, Kaplan-Meier survival test).