Plasma level determination of EB virus DNA for diagnosis making and prognosis estimating among cases with nasopharyngeal carcinoma

Objective To investigate the value of plasma level determination of EB virus (EBV) DNA for diagnosis making and prognosis estimating among cases with nasopharyngeal carcinoma(NPC).Methods Included in this study were 100 cases with untreated NPC,106 NPC cases following radiotherapy,finally diagnosed in our Hospital from Mar,2002 to Jun,2003, and 40 healthy persons as control.Their plasma samples were collected respectively and the plasma levels of EBV DNA were determined by real-time PCR techniques among them.Then,a comparative analysis was made to see the differences of EBV DNA copies and their clinical implications among healthy controls,unreated NPC cases,NPC cases with distal metastasis after radiation,ones with locally reoccurring NPC following radiotherapy,and ones still with nasopharyngeal lesion remission after treatment.Results The positive rates of plasma EBV DNA determination were 97.0%(97/100),96.5%(27/28)and 100.0%(18/18)for untreated NPC cases,NPC cases with distal metastasis after radiation,and ones with locally reoccurring NPC following radiotherapy,with significantly higher rates than the positive rate of 7.5% (3/40)among healthy controls,that of 10.0%(6/60)among cases still with nasopharyngeal lesion remission after treatment,and that of the cases with other kinds of tumors(P0.001).As a diagnos-tic test,plasma EBV DNA determination held a sensitivity of 97.0% and a specificity of 92.0% for the diagnosis of untreated NPC cases. Furthermore,another 3 cases were confirmed at last with the nasopharyngeal focus reoccurred or being distal metastatic during the following up period lasted for 6 months,while they were all seen still with nasopharyngeal lesion remission after treatment but with elevated plasma level of EBV DNA at the time point of trial starting.Conclusion Plasma level determinattion of EBV DNA is a sensitive and reliable test for diagnosing of untreated NPC cases,monitoring of such a case following therapy,and estimating of prognosis of cases with NPC.