Free DNA and carcinoembryonic antigen serum levels: an important combination for diagnosis of colorectal cancer.
OBJECTIVE
The identification of new molecular markers for the early detection of colorectal cancer has become an important objective. We compared the sensitivity and specificity of free circulating DNA with that of the more conventional carcinoembryonic antigen (CEA) and evaluated the two markers in combination.


METHODS
The study was carried out on 75 healthy donors and 75 colorectal cancer patients. Free DNA was determined in serum with quantitative PCR analysis. The diagnostic accuracy of each assay was calculated using receiver operating characteristic (ROC) curves. The diagnostic relevance of the two-marker combination was analyzed by the logistic regression model.


RESULTS
Median free DNA concentration was approximately 5-fold higher in patients than in healthy donors (P < 0.001). The area under the ROC curve was 0.86, and when 12.5 ng/mL was used as cutoff, 81.3% sensitivity and 73.3% specificity were observed for the overall series. As CEA and free DNA provided independent diagnostic information, they were also considered in combination. ROC curve analysis of the combined CEA and free DNA algorithms showed a higher diagnostic capacity (area under the ROC curve, 0.92) than that of markers considered singly, with 84% sensitivity and 88% specificity.


CONCLUSIONS
Free circulating DNA, especially when used in combination with CEA, represents a potentially useful tool for the diagnosis of early-stage colorectal cancer.
Flamini
Emanuela
E
Department of Medical Oncology, Morgagni-Pierantoni Hospital, Forlì, Italy. e.flamini@ausl.fo.it
Mercatali
Laura
L
Nanni
Oriana
O
Calistri
Daniele
D
Nunziatini
Roberta
R
Zoli
Wainer
W
Rosetti
Paola
P
Gardini
Nice
N
Lattuneddu
Arturo
A
Verdecchia
Giorgio Maria
GM
Amadori
Dino
D
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D014408:Biomarkers, Tumor / Q000097:blood*; D002272:Carcinoembryonic Antigen / Q000097:blood*; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D004247:DNA / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D012044:Regression Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity
D014408:Biomarkers, Tumor; D002272:Carcinoembryonic Antigen; D004247:DNA