In the latter study, DLL3 expression was higher in TTF-1 expressing SCLC samples (p = 0.006), smokers (p = 0.023), and males (p = 0.041), whereas high DLL3 expression was associated with female sex (p = 0.03) in a study conducted by Xie et al. (13). This evidence concerns the gene TTF1 and small cell lung carcinoma.