γ-H2AX as a novel prognostic marker in patients with non-small lung cancer.

Abstract

e17553 Background: Phosphorylation of the H2AX histone is an early indicator of DNA double-strand breaks and of the resulting DNA damage response. In the present study we assessed the expression of γ-Η2ΑΧ in a cohort of 96 patients with non-small cell lung carcinoma and evaluated its role as a prognostic indicator in resectable NCSLC patients. Methods: 96 parafin-embedded specimens of non-small lung cancer patients were examined. All patients underwent radical thoracic surgery of primary tumor (lobectomy or pneumonectomy) and regional lymph nodes dissection. γ-Η2ΑΧ expression was assessed by standard immunohistochemistry.Multivariate Cox proportional hazards regression analysis, using a backward selection approach, were performed to explore the independent effect of variables on survival. All tests were two tailed and statistical significance was considered for p values <0.05. Results: Follow-up was available for all patients; mean duration of follow-up was 27.50 ± 14.07 months (range 0.2-57 months, median 24 months). Sixty-three patients (65.2%) died during the follow-up period. The mean survival time was 32.2 ± 1.9 months (95% CI = 28.5 to 35.8 months; median 30.0 months); one, two and three-year survival rates were 86.5 ± 3.5%, 57.3 ± 5.1% and 37.1 ± 5.4% respectively. Low γ-H2AX expression was associated with a significant better survival as compared with those having high γ-H2AX expression (23.2 months for high γ-Η2ΑΧ expressin vs 35.3 months for low γ-H2AX expression, p=0.009; HR=1.95, 95% CI=1.15-3.30). Further investigation with multivariate Cox proportional hazards regression analysis revealed that high expression of γ-H2AX remained independent prognostic factors of worse overall survival (HR=2.15, 95% CI=1.22-3.79, p=0.026). Conclusions: Our study is the first study to demonstrate that overexpression of γ-Η2ΑΧ is an independent prognostic indicator of worse overall survival in patients with non-small lung cancer. Further studies are needed to confirm our results.