02 BOOK OF ABSTRACTS .indd

Increased plasma DNA concentration in patients with
lung cancer
Darko ^erne 1 , Miha Sok 2 , Jana Luka~ Bajalo 3
1
University of Primorska, College of Health Care Isola, Isola, Slovenia; 2 Medical Centre
Ljubljana, Department of Thoracic Surgery, Ljubljana, Slovenia; 3 University of Ljubljana,
Faculty of Pharmacy, Ljubljana, Slovenia
Background: Concentration of cell-free DNA in plasma (plasma DNA) was reported
to be elevated in patients with various tumors, autoimmune diseases, traumatic
conditions (stroke, multiple trauma, sepsis), other benign disorders (diabetes) and
prenatal complications. Increased level was proposed as a novel tumor marker
reflecting tumor cell turnover (lysis of circulating cancer cells, tumor necrosis and
apoptosis) or spontaneous and active release from cancer cells.
Aim of the study: Our aim was to determine reference values of plasma DNA
concentration in apparently health subjects and to test the hypothesis that patient
with lung cancer have increased values when compared to the reference group.
To test the hypothesis we measured plasma DNA concentrations with reagents
Nucleospin® and PicoGreen® in 51 apparently health subjects and in 29 patients
with lung cancer. In 10 patients blood was taken on a day of tumor resection and in
19 patients 1-3 months after operation.
Results: In healthy subjects acute and chronic diseases were excluded clinically,
and on the basis of patient history and values of fundamental laboratory tests
within reference range. The median (25 th percentiles; 75 th percentiles) {minimum;
maximum} of plasma DNA concentrations was 2.85 (2.05; 4.30) {0.1; 15.85} µg/L.
The reference range was from 0.30 to 9.75 µg/L. In patients concentrations of DNA
in plasma on a day of operation were 2.47 times higher (medians 7.05 vs. 2.85 µg/L;
p = 0.0270) and after operation 3.72 times higher (medians 10.60 vs. 2.85 µg/L;
p < 0.0001) when compared to the health subjects. No difference was found between
the both subgroups of patients. Furthermore, plasma DNA concentration did not
correlate with a stage of cancer and did not differ within individual histological
type of tumor, neither within both subgroups separately, nor in all patients gathered
as one group. Plasma concentration higher than 4.45 µg/L distinguished patients
(considered as one group) from apparently health subjects with the sensitivity of
89.7 % and specificity of 80.4 %. The area under ROC curve was 0.870 with 95 % of
confidence limit from 0.776 to 0.934.
Discussion: Patients with lung cancer have increased plasma DNA concentration
when compared to apparently healthy subjects. Elevated plasma DNA concentration
lacks disease specificity, but may be beneficially used for screening the patients at
high risk for lung cancer.
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