Quantitative analysis of circulating plasma DNA as a tumor marker in thoracic malignancies.
Author(s): Herrera LJ, Raja S, Gooding WE, El-Hefnawy T, Kelly L, Luketich JD, Godfrey TE
Publication: Clin Chem, 2005, Vol. 51, Page 113-8
PubMed ID: 15539466 PubMed Review Paper? No
Purpose of Paper
The purpose of this paper was to determine if centrifugation protocol and a diagnosis of esophageal cancer impact cell-free plasma DNA levels.
Conclusion of Paper
Although a significant effect of diagnosis on plasma DNA levels was observed in retrospectively collected specimens centrifuged once for 5 min, a similar difference was not observed in prospectively collected specimens centrifuged twice for 10 min.
Studies
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Study Purpose
The purpose of this study was to determine if centrifugation protocol and a diagnosis of esophageal cancer impact cell-free plasma DNA levels. Prospectively collected blood from 38 patients with esophageal cancer, 25 patients with lung cancer, 28 patients with gastroesophageal reflux disease and 11 healthy controls were compared with retrospectively collected blood from 20 patients with esophageal cancer and 23 patients with gastroesophageal reflux disease (GERD). Both prospective and retrospective specimens were collected into 10 mL EDTA tubes, centrifuged at 1600 x g within 1 h and stored as frozen plasma at -80ºC. However, retrospectively collected specimens were centrifuged once for 5 min, while prospectively collected specimens were centrifuged twice for 10 min. DNA was extracted from all specimens using the QIAamp Blood DNA Mini Kit. Cell-free DNA was quantified by real-time PCR amplification of beta-actin.
Summary of Findings:
While significantly higher levels of plasma DNA were found in retrospectively collected esophageal cancer specimens than in control patients with GERD (p=0.0287), there was no effect of diagnosis on plasma DNA levels in prospectively collected specimens. ANOVA analysis identified a significant interaction between collection (prospective versus retrospective) and diagnosis (GERD versus esophageal cancer) (p=0.0400), which the authors attribute to differences in specimen centrifugation protocol (once for 5 min versus twice for 10 min).
Biospecimens
Preservative Types
- Frozen
Diagnoses:
- Neoplastic - Carcinoma
- Other diagnoses
- Normal
Platform:
Analyte Technology Platform DNA Real-time qPCR Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Biospecimen Aliquots and Components Centrifugation Different number of centrifugation steps compared
Multiple durations compared
Preaquisition Diagnosis/ patient condition GERD
Esophageal cancer
Lung cancer
Healthy