Gene methylation levels of SHOX2 and RASSF1A display higher specificity and sensitivity for early lung cancer detection than the traditional cytological method as well as dual genes (RASSF1A-RARβ2, SHOX2-PTGER4, and p16-RARβ2, which could become possible biomarkers for early diagnosis [70]. Here, RASSF1 is linked to lung cancer.