Nijmegen breakage syndrome 1 (NBS1) gene polymorphism and chemotherapy-induced neutropenic fever in breast cancer patients

Abstract

574 Background: Neutropenic fever (NF) is a serious complication of the chemotherapies given to breast cancer patients and often limits their use. Hence, identifying which patients are at increased risk to develop NF is very important. The NBS1 gene product is important for the repair of double-strand DNA breaks and is activated by chemotherapy. The objective of this study was to determine if genetic variations of NBS1 polymorphisms predict the risk of chemotherapy-induced NF in breast cancer patients. Methods: Blood from 306 newly diagnosed breast cancer patients treated with chemotherapy were prospectively collected on a study approved by the institutional review board. The relationship of chemotherapy administration (e.g. dose, timing) and growth factor use were correlated with the absolute neutrophil count (ANC) and NF development. For each patient, we assessed three polymorphisms (924T>C, 8360G>C, and 30537G>C) of NBS1 gene using polymerase chain reaction-restriction fragment length polymorphism method. Two-sided Chi-square test was used for univariate analysis and a multivariable logistical regression analysis was used to calculate odds ratios. Results: In total, 167 (55%) patients experienced ANC less than 1,000 cells/microliter (CIN1000) and 30 (10%) patients developed NF. For 8360G>C polymorphism, 9.7% of patients had a 8360CC variant genotype and these patients had increased risk of NF than the other genotypes (NF in CC 20.7% vs. in others 8.1%; Odds Ratio [OR] = 3.0; 95% confidence interval [CI] = 1.1 - 8.0, p = 0.034). In multivariable logistic regression model, 8360CC genotype (OR = 5.0, 95% CI = 1.6 - 16.1, p = 0.007) and growth factor support (OR = 19.6, 95% CI = 4.4 - 87.6, p < 0.001) were significantly associated with NF development. No genotypes of 924T>C and 30537G>C polymorphisms increased the risk of NF and there was no statistical association between the three NBS1 gene polymorphisms and CIN1000. Conclusions: Breast cancer patients with 8360CC variant polymorphism in NBS1 gene have increased risk in developing NF with systemic chemotherapy. Analysis of polymorphisms of NBS1 and other DNA repair genes could potentially help identify who will develop chemotherapy-induced bone marrow toxicities. No significant financial relationships to disclose.