Effects of Prolonged Storage of Whole Plasma or Isolated Plasma DNA on the Results of Circulating DNA Quantification Assays

• Published in: JNCI : Journal of the National Cancer Institute Vol. 97; no. 24; pp. 1848 - 1850
• Main Authors: Sozzi, Gabriella, Roz, Luca, Conte, Davide, Mariani, Luigi, Andriani, Francesca, Verderio, Paolo, Pastorino, Ugo
• Format: Journal Article
• Language: English
• Published: Cary, NC Oxford University Press 21.12.2005; Oxford Publishing Limited (England)
• Subjects: Biological and medical sciences; Biomarkers, Tumor - blood; Blood Preservation; Case-Control Studies; Deoxyribonucleic acid; DNA; DNA, Neoplasm - blood; Humans; Immunoassay; Long term; Lung Neoplasms - genetics; Medical sciences; Plasma; Pneumology; Polymerase Chain Reaction; Reproducibility of Results; Storage; Time Factors; Tumors; Tumors of the respiratory system and mediastinum; Human; Lung disease; Respiratory disease; Lung cancer; Malignant tumor; Molecular marker; Blood plasma; Cancerology; Storage; DNA; Bronchus disease; Genetics; Quantitative analysis; Prolonged
• ISSN: 0027-8874; 1460-2105; 1460-2105
• DOI: 10.1093/jnci/dji432

Analysis of molecular markers in biological fluids has been proposed as a tool for early detection and monitoring of cancer. Circulating plasma DNA concentrations have been found to be higher in cancer patients than in cancer-free control subjects, but little is known about the effect of specimen storage on plasma DNA concentrations. Here we investigated the impact of long-term storage of both plasma samples and purified plasma DNA on the reproducibility of plasma DNA quantification as determined using real-time polymerase chain reaction analysis. The analysis was performed on samples from a subset of 34 lung cancer patients and 28 matched control subjects selected from 200 subjects in our previously published case–control study and from 117 cancer-free smokers enrolled in a lung cancer screening program. Two samples of plasma and isolated DNA were assessed for each patient, with a median of 41 months between the first and second assessments for participants in the case–control study and 9 months for participants in the screening study. DNA levels declined substantially between the two assessments at an average rate of approximately 30% per year. These data provide valuable information for the rational planning of retrospective studies of banked series of biological samples, particularly if collected over a long period of time, as can occur in large clinical trials.