They reported that the rs16969968 variant allele (A) was associated with a lower likelihood of smoking cessation and the AA genotype was associated with a 4-year delay in the median age of quitting compared with the GG genotype, and homozygous variant AA genotype carriers for the CHRNA5 rs16969968 polymorphism had a 4-years earlier age of diagnosis of lung cancer due to smoking (Chen et al., 2015). Here, CHRNA5 is linked to lung cancer.