[GSTM1 gene polymorphism in patients with head and neck tumors]

Glutathione S-Transferase mu (GSTM) is a phase II detoxification enzyme, which rapidly detoxifies carcinogens found in tobacco smoke. The prevalence of this polymorphism is about 50% in the caucasian population. The lack of GSTM1 has been linked with an increased susceptibility of smoking related cancers. A homozygote deletion of the GSTM-gene results in a missing gene product. The objective of this study was to investigate the frequency of the GSTM1 null genotype in squamous cell carcinoma of head and neck, especially the larynx and hypopharynx and to analyse the occurrence with respect to certain anatomical sites of cancer.

The GSTM1 genotypes of 83 patients with head and neck cancers and 60 healthy controls were determined by polymerase chain reaction (PCR) using blood leukocyte DNA. The presence or absence of the PCR-product after electrophoretic separation in an 2.0% agarose gel revealed the positive or negative genotype.

The absence of the GSTM1 gene (null genotype) was found in 64% of all head and neck cancer patients and in 48% of the healthy controls (p < 0.05). Separating for cancer site, the null genotype was found in 44% of patients with hypopharyngeal cancer and in 78% of patients with laryngeal cancer (p < 0.05). The protein concentration of GSTM-enzyme correlated with the genotype.

The results suggest that GSTM1 deficiency predisposes to head and neck cancer, especially to cancer of the larynx, which is particularly exposed to tobacco smoke carcinogens.