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Glutathione‐S‐transferase polymorphisms and risk of squamous‐cell carcinoma of the head and neck

Differences in genetic susceptibility to tobacco‐induced carcinogenesis appear to modulate an individual's risk of squamous‐cell carcinoma of the head and neck (SCCHN). Risk for SCCHN may be associated with the null alleles of the carcinogen‐metabolizing genes glutathione‐S‐transferase (GST) T1 and GSTM1. In this study, we evaluated the association between GSTM1 and GSTT1 null genotypes and risk of SCCHN in a matched case‐control study of 162 patients with SCCHN and 315 healthy controls. Our results showed that 53.1% of cases and 42.9% of controls were null for GSTM1, whereas 32.7% of cases and 17.5% of controls were null for GSTT1 (p < 0.05 and p < 0.001, respectively). Furthermore, 19.8% of cases but only 7.9% of controls were null for both genes (p < 0.001). Multivariate analysis using logistic regression models, including age, sex, ethnicity, smoking status, alcohol status and GST genotypes, showed that both of these genotypes remained independent risk factors for disease [adjusted odds ratios (ORs) = 1.50 and 2.27, respectively; 95% confidence intervals (CIs) = 1.01–2.23 and 1.43–3.60, respectively). When the genotypes were divided into neither null, either null or both null, there was a dose‐response relationship (adjusted OR = 1.50, 95% CI = 0.98–2.30) for the either‐null group and (adjusted OR = 3.64, 95% CI = 1.94–6.84) for the both‐null group (p < 0.001, trend test). Our findings suggest that the GSTM1 and GSTT1 null genotypes are independent risk factors for SCCHN and markers for genetic susceptibility to tobacco‐induced carcinogenesis. Int. J. Cancer (Pred. Oncol.) 84:220–224, 1999. © 1999 Wiley‐Liss, Inc.