Similar to the IHC, also the Ki-67 mRNA levels were highly significantly increased in AC compared to TC (U = −3.199, p = 0.001) and in SCLC/LCNEC compared to AC (U = −5.062, p < 0.001/U = −3.446, p < 0.001) (see Figure 2). Here, MKI67 is linked to small cell lung carcinoma.