A series subgroup analyses was conducted according to clinicopathological characteristics such as gender, smoking history, etc. Results suggested that dual-negative expression of Nrf2 and NQO1 is a prognostic factor for OS in females (P = 0.006), non-smokers (P = 0.006), and advanced-stage NSCLC patients (stage III–IV) (P = 0.023), but no such significance was found in males, smokers, and patients with early stage NSCLC (stage I–II) (Figure 3). This evidence concerns the gene NQO1 and non-small cell lung carcinoma.