GSTM1 and cancer: In studies of ethnic differences in GSTM1 gene polymorphisms, The evidence showed that the frequency of GSTM1-null in Asians was higher than that in Caucasians and the interaction of GSTM1-null and smoking increased the risk of oral cancer in Asians than Caucasians.[114,115] Our study showed that the overall cancer risks in GSTM1-null carriers were 1.515-fold among Asian and 1.312-fold among Caucasian smokers, respectively, suggesting that cancer risks related to GSTM1-null might be slightly higher in Asian smokers.