Higher GSTT1 [-] and GSTM1 [-] polymorphism frequencies were observed by Drummond et al.21, 22 in Brazilian smokers with oral cavity squamous cell carcinoma (81.8% for GSTT1 [-] and 70.5% for GSTM1 [-]). The gene discussed is GSTM1; the disease is oral cavity squamous cell carcinoma.