GENOTYPE AND PHENOTYPE OF GLUTATHIONE-S-TRANSFERASE-MU IN TESTICULAR CANCER-PATIENTS

The incidence rate of testicular cancer has been steadily increasing d uring the last 50 years, and only cryptorchidism, i.e. undescended tes tes, has been identified as an important risk factor. An interplay bet ween changing environmental factors and genetic susceptibility e.g. in foreign compound metabolizing enzymes, may have important influences on the risk. The aim of this study was to investigate if glutathione S -transferase mu (GST mu) deficiency, which in previous studies has bee n associated with malignant melanoma and cancers of the lung and bladd er, is a risk factor of testicular cancer. Three hundred and seventy-e ight men participated (80 seminomas, 104 non-seminomas and 194 control s) in a population-based case-control study. The phenotype of GST mu w as determined in 366 men by ELISA, the genotype was determined in 324 men by polymerase chain reaction. The concordance between geno- and ph enotype tvas 94.4%. The odds ratio of having the GST mu negative pheno type and testicular cancer was 1.08, (0.72-1.64; 95% confidence interv al (CI)), and the odds ratio of having the GSTM1 null genotype and tes ticular cancer was 1.10; CI95% (0.71-1.70). This study provides no evi dence of an association between phenotypically determined GST mu defic iency or GSTM1 null genotype and testicular cancer. The narrow confide nce intervals rule out GST mu as a major single risk factor for testic ular cancer.