Abstract 4729: Association of mitochondrial DNA copy number variation in peripheral blood leucocytes with risk and prognosis of gallbladder cancer

Abstract

Abstract Gallbladder Cancer (GBC) is the most common malignancy of the biliary tract with very high incidence in Northern India, especially around Gangetic belt. Late diagnosis and poor prognosis are the important features of this disease. For improving treatment strategies and outcomes, novel non invasive prognostic biomarkers are needed. Variations in peripheral blood mitochondrial DNA (mtDNA) copy number in various cancers are widely studied but information in relation to gallbladder malignancy is unknown. In this pilot study, we investigated leucocytes mtDNA copy number variation in relation to risk and prognosis of GBC. A total of 300 histologically confirmed or fine needle aspiration cytology proven GBC patients were recruited along with equal number of age and sex matched controls. The mtDNA copy number was measured by real-time polymerase chain reaction through absolute quantification using SYBR green chemistry. We also explore prognostic utility of mtDNA content in relation to overall survival of GBC patients. Statistical analysis was done by Student’s test and survival data was compared using Kaplan Meier method. Two tailed p value less than 0.05 was considered to be significant. We observed high mtDNA content in cases as compared with controls (mean±standard deviation, 1.21±0.88 vs. 1.02±0.76). Higher mtDNA copy number was significantly associated with increased gallbladder cancer risk (p=0.005). In this study, we compared overall survival (OS) for gallbladder cancer patients in relation to mtDNA copy number median value (median, 1.12). Kaplan Meir survival curve predicts decrease in OS (p=0.03, Hazard ratio=2.54; 95% CI = 1.79-5.86) for GBC patients in relation to high mtDNA content (>median) as compared with low mtDNA copy number (<median). This study supports an association between increased mtDNA copy number with susceptibility to gallbladder cancer in this endemic belt. Future studies are warranted to confirm these findings and to elucidate the biological role of mtDNA copy number in relation to gallbladder cancer. Citation Format: Abhijit Chandra, Hasan R. Kazmi, Leena K. Satyam, Saket Kumar. Association of mitochondrial DNA copy number variation in peripheral blood leucocytes with risk and prognosis of gallbladder cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4729. doi:10.1158/1538-7445.AM2017-4729