In detail, APC, RARβ2, and RASSF1A showed statistically different methylation levels between AdC, SCC and SCLC (p < 0.0001) (Figure 3A), whereas HOXA9 methylation levels were higher in SCC in comparison with AdC (p < 0.001) (Figure 3A). This evidence concerns the gene RASSF1 and small cell lung carcinoma.