Accessible Requires Authentication Published by De Gruyter March 23, 2009

MYC quantitation in cell-free plasma DNA by real-time PCR for gastric cancer diagnosis

Kyoung Un Park, Hee Eun Lee, Do Joong Park, Eun Ji Jung, Junghan Song, Hyung-Ho Kim, Gheeyoung Choe, Woo Ho Kim and Hye Seung Lee

Abstract

Background: Detection of tumor-associated genetic alterations in plasma of cancer patients has recently been suggested to be an accurate method for detecting early or recurrent cancer.

Methods: We performed quantitative real-time PCR for MYC and GAPDH in tissue and plasma samples of 57 patients with gastric cancer and in plasma of 79 cancer-free individuals. We also performed two-color MYC fluorescence in situ hybridization (FISH) in tissue from the 57 patients with gastric cancer.

Results: The tissue MYC/GAPDH ratio by real-time PCR was significantly correlated with MYC status by FISH (p<0.001). The mean ratio of plasma MYC/GAPDH was 5.226±3.578 (range: 1.25–18.35) in gastric cancer patients, and 2.436±0.881 (range: 1.00–5.00) in the healthy volunteers (p<0.001). We used receiver-operating characteristics (ROC) curve analysis to select two optimal plasma MYC/GAPDH cut-offs of 2.725 and 5.225. The sensitivity and specificity were 75.4% and 76.9% at 2.725, 38.6% and 100% at 5.225, respectively. The plasma MYC/GAPDH ratio from cancer patients was significantly correlated with the tissue MYC/GAPDH ratio (p=0.009), and tissue MYC status by FISH (p=0.024).

Conclusions: These findings suggest that the plasma MYC/GAPDH ratio, as determined by real-time PCR, may be an alternative non-invasive approach for detecting gastric cancer.

Clin Chem Lab Med 2009;47:530–6.


Corresponding author: Hye Seung Lee, MD, Department of Pathology, Seoul National University Bundang Hospital, 300 Gumi-dong, Bundang-gu, Seongnam-si, Gyeonggi-do, 463-707, Korea Phone: +82-31-787-7714, Fax: +82-31-787-4012,

Received: 2008-12-25
Accepted: 2009-2-9
Published Online: 2009-03-23
Published in Print: 2009-05-01

©2009 by Walter de Gruyter Berlin New York