Study of serum cell free DNA in patients with gastric cancer by branched DNA

Abstract

Objective To quantify cell free DNA (cf-DNA) in blood of patients with gastric cancer by a branched DNA (bDNA) -based Alu assay and analyze the relationship between serum cf-DNA levels and clinical and pathological features as well as the applicational value of the aided diagnosis of cf-DNA in GC. Methods A case-control study was conducted.Ninety-nine patients with GC diagnosed by pathological diagnosis and 100 normal controls presenting to the Nantong tumor hospital from September 2011 to February 2012 were recruited.Thirty-two patients with gastric benign tumor presenting to the Affiliated Hospital of Nantong University from March 2010 to February 2012 were also recruited.The concentration of cf-DNA was detected by bDNA and the concetrations of carcinoembryonic antigen (CEA),carcinoembryonic antigen 19-9 (CA19-9),carcinoembryonic antigen 50 (CA50),and carcinoembryonic antigen 72-4 (CA72-4) were assayed by chemiluminescence.The Dunn′s test was used to compare the difference of cf-DNA between patients with GC and control groups (gastric benign tumor and healthy individuals).The diagnostic value of the five indicators was evaluated by drawing the Receiver Operating Characteristic curves (ROC).The Mann-Whitney test was used to analyze the difference of cf-DNA levels of the patient′s gender and age.Kruskal-Wallis test was used to compare cf-DNA correlation with the patient′s tumor site,tumor differentiation,American Joint Committee on Cancer. Results The levels of cf-DNA in patients with GC,patients with gastric benign tumor and healthy individuals were 2316.0 (1028.7-3742.1),423.3 (256.3-519.2),317.5 (172.5-499.7) μg/L,respectively.There were significant differences between GC patients and gastric benign tumor patients (q=7.612,P 0.05).The optimal diagnostic thresholds of the five indicators were 973.6μg/L,4.0μg/L,32.8 kU/L,12.8 kU/L,5.1 kU/L,respectively.The areas under the ROC curves and sensitivity assessing cf-DNA level[0.94,76.8% (76/99)]were significantly larger than traditional indicators of serum CEA[0.66,31.3% (31/99)],CA19-9[0.63,16.2% (16/99)],CA50[0.83,44.4% (44/99)],CA72-4[0.67,35.4% (35/99)] for GC patients.Specificity of cf-DNA[96% (96/100)]was closer to traditional indicators of serum CEA[98% (98/100)],CA19-9[78% (78/100)],CA50[97% (97/100)],CA72-4[98% (98/100)]. Conclusions cf-DNA levels detected by bDNA are higher specificity and better sensitivity than traditional tumor markers (CEA,CA19-9,CA50,CA72-4) for GC patients.Certain guiding significance and application value was existed by detecting cf-DNA level in the serum of GC patients.(Chin J Lab Med,2013,36:699-703) Key words: Stomach neoplasms; DNA; Branched DNA signal amplification assay