In TTF-1 positive and central type SCLCs, PD-L1 expression was associated with poorer PFS (p = 0.014 and p = 0.042, respectively) and OS (p = 0.009 and p = 0.019, respectively), and in peripheral type SCLC, with poorer OS (p = 0.005). Here, TTF1 is linked to small cell lung carcinoma.