EVALUATION OF MUTANT FREQUENCIES AT THE HPRT AND THE T-CELL RECEPTOR LOCI IN PEDIATRIC CANCER-PATIENTS BEFORE TREATMENT

Mutant frequencies (Mfs) at the two genetic loci, the hypoxanthine pho sphoribosyl transferase (hprt) gene and the T-cell receptor (TCR) gene were evaluated in pediatric cancer patients before starting chemother apy or radiotherapy. The study population consisted of 27 patients wit h various solid tumors (mean age +/- SD; 5.5 +/- 5.1 years, range; 0.2 -14.5 years), 5 patients with acute leukemia (10.3 +/- 6.1, 1.3-17.0 y ears), and 26 healthy controls (11.6 +/- 3.0, 4.4-22.2. years). Althou gh the age distributions were different, the mean Mf values of the hpr t and the TCR loci were comparable among these three groups. On an ind ividual basis taking the age factor into consideration, the hprt-Mfs o f 3 patients with solid tumors, i.e., two patients with Hodgkin's dise ase and one patient with Askin tumor, were found to be well above the 95% confidence limit. There were no patients with a TCR-Mf exceeding t he 95% confidence limit. These data suggest the possibility that some patients with solid tumors may be predisposed to mutational susceptibi lity before treatment, The assay of the hprt-Mf appears more sensitive than the TCR-Mf assay in distinguishing these patients. (C) 1998 Else vier Science B.V.