Tumor specific circulating cfDNA may be related to FDG PET imaging: A study on VX2 tumor bearing rabbits

Objectives To investigate the relationship between 18F-FDG PET/CT imaging characteristics and circulating cell free tumor specific DNA copies , and to explore its’ potential clinical values.

Methods The VX2 tumor rabbit animal models were established by transplanting VX2 tumor fragment into leg muscles(n=6) . Two weeks post transplant, tumor size and glucose metabolic parameters were observed by 18F-FDG PET/CT scan. The Shope virus DNA in tumor tissues and plasma was quantified by a fluorescent quantitative real-timepolymerase chain reaction (PCR) method as the tumor specific circulating cell free DNA. The copies of circulating Shope virus DNA and FDG PET finding were compared.

Results Before tumor transplantation, no viral DNA was examined in peripheral blood, 14 days after transplantation circulating Shope virus specific DNA fragments could be examined. Concentration of Shope virus DNA in tumor tissue (mean (4.9±1.9)×10^6 copies/l) was significantly higher than that in the plasma (mean (1.3±0.9)×10^3 copies/l). There is a positive relationship between circulating Shope DNA level and 18F-FDG-PET/CT maximum standard uptake value, but no significant association was observed between plasma Shope virus DNA level and VX2 tumor size.

Conclusions Plasma circulating cell free Shope viral DNA may be a tumor-marker of VX2 tumor animal model, and the quantitive of circulating cell free tumor specific DNA may be related to FDG PET imaging. Tumor specific circulating cfDNA is proposed as an novel early detectable bio-marker as well as an inexpensive, noninvasive assay to cancer management.