TTF1 and neoplasm: TTF-1 expression was inversely related to smoking habit (P = 0.0025), tumor size (P < 0.0001), tumor differentiation (P = 0.0011), and p-TNM stage (P = 0.0051), whereas there was no significant association between TTF-1 expression and age, gender, nodal status, vascular invasion, lymphatic invasion, pleural invasion or adjuvant chemotherapy.