This is in line with the existing evidence on the involvement of DRD2 rs1800497 in nicotine dependence in outpatients affected by cancer [34], in outpatients visited for cancer screening and on Helicobacter pylori treatment [35], and in a Caucasian random sample of the general population [36], despite showing some divergencies [37,38]. This evidence concerns the gene DRD2 and nicotine dependence.