GSTM1 - Genepolymorphism in patients with head and neck cancer.

Glutathion S-Transferase mu (GSTM) is a phase II detoxification enzyme, whi ch rapidly detoxifies carcinogens found in tobacco smoke. The prevalence of this polymorphism is about 50% in the caucasian population. The lack of GS TM1 has been linked with an increased susceptibility of smoking related can cers. A homocygote deletion of the GSTM-gene results in a missing gene prod uct. The objective of this study was to investigate the frequency of the GS TM1 nullgenotype in squamous cell carcinoma of head and neck, especially th e larynx and hypopharynx and to analyse the occurrence with respect to cert ain anatomical sites of cancer. Material and methods: The GSTM1 genotypes o f 83 patients with head and neck cancers and 60 healthy controls were deter mined by polymerase chain reaction (PCR) using blood leukocyte DNA. The pre sence or absence of the PCR-product after electrophoretic separation in an 2.0% agarose gel revealed the positive or negative genotype. Results: The a bsence of the GSTM1 gen (nullgenotype) was found in 64% of all head and nec k cancer patients and in 48% of the healthy controls (p < 0.05). Separating for cancer site, the nullgenotype was found in 44% of patients with hypoph aryngeal cancer and in 78% of patients with laryngeal cancer (p < 0.05). Th e protein concentration of GSTM-enzyme correlated with the genotype. Conclu sions: The results suggest that GSTM1 deficiency predisposes to head and ne ck cancer, especially to cancer of the larynx, which is particularly expose d to tobacco smoke carcinogens.