GSTM1 and head and neck squamous cell carcinoma: (d) In another study of 153 HNSCC cases and 145 controls with no current or previous diagnosis of cancer [37], authors examined CYP1A1, CYP1A2, CYP2E1, GSTM1, and GSTT1 SNPs as risk factors in HNSCC; a significant difference (P < 0.001) was detected for tobacco and alcohol consumption between cases and controls; moreover, the CYP1A2*1D (OR 16.24) variant and GSTM1(0/0) null alleles (OR 0.02) conferred increased risk of HNSCC, and alcohol consumption in HNSCC patients was associated with the CYP2E1*5B variant allele (P < 0.0001, OR 190.6).