The first example studied the interaction between the polymorphism of the gene excision repair cross-complementing group 2 (ERCC2) and smoking exposure in lung cancer [32], where two ERCC2 polymorphisms Asp312Asn and Lys751Gln were typed in 1,092 Caucasian lung cancer patients and 1,240 spouse and friend controls collected at Massachusetts General Hospital. This evidence concerns the gene ERCC2 and lung cancer.