Abstract 2786: Differences in gene-specific DNA methylation in blood DNA as a biomarker for early detection of hepatocellular carcinoma in populations at risk
Authors: Lubecka Katarzyna , Kurzava Lucinda , Flower Kirsty , Buvala Hannah , Gawrieh Samer , Liangpunsakul Suthat , Chalasani Naga , Flanagan James M. , Stefanska Barbara 
Published: July 2016

Abstract
Hepatocellular carcinoma (HCC), the most prevalent type of primary liver cancer, is the second leading cause of cancer death worldwide. It is estimated that early HCC detection would increase the cure rate from 5% to 80%. Approximately 85% of individuals with HCC have underlying liver cirrhosis which is the main risk factor for developing HCC. Every year up to 5% of cirrhotic patients are diagnosed with HCC. The biggest challenge that physicians face today is to distinguish cirrhotic patients that will develop cancer from those that will not. Thus, early detection biomarkers that can be implemented as screening tools in populations at risk are of high interest.
In our previous genome-wide study, we demonstrated that blood DNA has different DNA methylation patterns specific to HCC samples collected before diagnosis (pre-diagnostic) compared to healthy individuals without cancer. We established 10 differentially methylated probes corresponding to 10 genes that distinguish pre-diagnostic HCC blood samples from healthy controls. In the current study using pyrosequencing, we tested the diagnostic potential of these probes in blood samples from a prospective cohort of cirrhotic patients without HCC at the time of blood collection. Twenty eight of these patients developed HCC within 4 years of follow-up. These 28 cases were matched with 23 cirrhotic controls on gender, age, ethnicity, hepatitis C, and diabetes.
Five out of the 10 tested probes distinguished cirrhotic patients who subsequently developed HCC (cases) from those who stayed cancer free (controls) (p&lt;0.05, Mann-Whitney U test). The highest differences were observed at CpG sites located within BARD1 whose methylation was consistently lower in cases vs. controls. Using this probe, 22 cases were correctly identified as cases (79% sensitivity), whereas only 6 controls were falsely included into cases (74% specificity). Analysis of the panel of the 5 probes increased sensitivity to 86% with a threshold of 2 positive probes, while maintaining 74% specificity. Receiver Operating Characteristics (ROC) curve analysis confirmed high predictive value for the 5 probes in the cirrhotic population [Area Under the Curve (AUC) = 0.80]. The established DNA methylation biomarkers have better values of performance compared to current recommended methods for HCC surveillance, such as serum alpha-fetoprotein (AFP) that can miss up to 40% of patients.
Our results establish the possible diagnostic value of gene-specific DNA methylation in blood DNA for HCC early detection in populations at risk such as individuals with liver cirrhosis. This study was supported by Showalter Trust and PCCR Awards granted to BS.
Citation Format: Katarzyna Lubecka, Lucinda Kurzava, Kirsty Flower, Hannah Buvala, Samer Gawrieh, Suthat Liangpunsakul, Naga Chalasani, James M. Flanagan, Barbara Stefanska. Differences in gene-specific DNA methylation in blood DNA as a biomarker for early detection of hepatocellular carcinoma in populations at risk. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2786.