XRCC1 and glutathione-S-transferase gene polymorphisms and susceptibility to radiotherapy-related malignancies in survivors of Hodgkin disease

Abstract

Background: One of the most serious late effects of treatment for childhood cancer is the occurrence of subsequent malignancy. Survivors of Hodgkin disease (HD), in particular, have been shown to be at high risk of subsequent malignancy, the occurrence of which has been associated strongly with exposure to radiotherapy.

Methods: In the current study, the authors investigated the association between polymorphisms in 3 genes--glutathione-S-transferase M1 (GSTM1), glutathione-S-transferase T1 (GSTT1), and XRCC1, with roles in protection from a variety of DNA-damaging agents-and the risk of subsequent malignancy in 650 survivors of HD enrolled in the Childhood Cancer Survivor Study who had received radiotherapy.

Results: Individuals lacking GSTM1 but not GSTT1 were at increased risk of any subsequent malignancy (odds ratio [OR], 1.5; 95% confidence interval [CI], 1.0-2.3), and for subsequent cancer within the radiation field (OR, 1.4; 95% CI, 0.9-2.1). A nonsignificant increased risk of thyroid carcinoma was observed in individuals lacking either GSTM1 (OR, 2.9; 95% CI, 0.8-10.9) or GSTT1 (OR, 3.7; 95% CI, 0.6-23.5). Individuals having the genotype of the arginine/glutamine polymorphism at codon 399 in the XRCC1 gene (R399) showed a nonsignificant increased risk of breast carcinoma compared with those without (OR, 1.4; 95% CI, 0.7-2.7), and a nonsignificant decreased risk against a subsequent thyroid carcinoma (OR, 0.6; 95% CI, 0.2-1.6). No differences in genotype frequencies were observed between survivors with basal cell carcinoma when compared with survivors without a subsequent cancer.

Conclusions: These data illustrated the potential value of incorporating the collection of genomic DNA in longitudinal cohort studies of populations with well defined, potentially carcinogenic exposures. Evaluation of additional genetic polymorphisms in this cohort may help define genes that influence individual sensitivity to radiotherapy.