Familial Nasopharyngeal Carcinoma 6

Prognostic Factors in Nasopharyngeal Cancer 109(p = 0.02) were significantly lower in the patients withpretreatment plasma EBV DNA ³ 1500 copies/ml thanin those with plasma EBV DNA < 1500 copies/ml.Fourth, the plasma EBV DNA load before, during, andat the end of neoadjuvant chemotherapy declined significantly(p < 0.001). In addition, the plasma EBVDNA remained persistently low or undetectable inpatients with clinically complete remission. Fifth, allpatients with tumor relapse showed a rebound ofplasma EBV DNA concentrations, which might bedetected six months before clinical evidence of relapse.In addition, the presence or absence of plasma EBVDNA one week after the whole treatment showed significantcorrelation with subsequent tumor relapse.Survival analyses demonstrated that the pre and posttreatmentplasma EBV DNA levels were the mostimportant prognostic factors, and dominated all otherclinical parameters, including age, gender, performancestatus, histological type, T- and N-classifications,and overall stage. These results were confirmed byextending analysis from 99 patients to 149 patientswith longer follow-up.In order to evaluate the long-term prognosticimpact of plasma EBV DNA in NPC, stock plasma of152 NPC patients who received a uniform scheduleof concurrent chemoradiation with adequate followuptime (median 78 months) were retrospectivelyassayed with a real-time quantitative PCR using theminor groove binder-probe (Lin et al. 2007). Theyconfirmed the superior effects of plasma EBV DNAcompared to other clinical parameters (includingage, gender, performance status, pathological type,T-classification, N-classification, and overall stage) inprognosis prediction of NPC by multivariate Coxanalysis. A recent study of direct comparison ofserum anti-EBV antibody titer and plasma EBV DNAlevel on 114 previously untreated NPC patientsclearly demonstrated that plasma EBV DNA is superiorto serum anti-EBV antibody in prognostic predictions(Twu et al. 2007). Table 9.5 lists major studiesof plasma/serum EBV DNA in NPC.Plasma EBV DNA level can be a very useful molecularmarker in the screening, monitoring, and prognosticprediction of NPC. Of note, the circulating DNAmeasured by PCR-based techniques as a tumor markerhas some issues to be addressed. First, different segmentsof the same viral DNA or different viral genesmight result in varying sensitivities in PCR assay. Twogroups reported similar results and detection limitsusing BamHI-W region or EBNA-1 gene by Lo et al.(1999a), or using polymerase-1, latent membraneprotein-2, and BamHI-W by Le et al. (2005) in detectingplasma EBV DNA in NPC. BamHI-W assay yieldedthe highest concentrations due to multiple repeats indifferent EBV genomes compared to single-copy genes(EBNA-1, polymerase-1 or latent membrane protein-2)assay. Second, a great discrepancy exists in differentgroups using the same primer/probe sets andexperimental conditions (Lo et al. 1999a,b, 2000a, b, c;Chan et al. 2002; Lin et al. 2004; Leung et al. 2006). InLin’s study (2004), the median concentration (1461copies/ml) of 99 previously untreated NPC patientswith Stage III/IV disease was much lower than theHong Kong group (Lo et al. 1999a,b, 2000a, b, c; Chanet al. 2002). Even in the same group’s reports, the medians(2,353–41,756 copies/ml) and ranges of pretreatmentcirculating EBV-DNA levels in newly diagnosedNPC patients varied considerably from study to studyusing the same assay conditions (Lo et al. 1999a,b,2000a, b, c; Chan et al. 2002a, b; Leung et al. 2006).Third, circulating DNA levels declined substantially intwo assessments at an average rate of 30% per year(Sozzi et al. 2005). Thus, degradation rate of DNAfrom stored blood samples at different time intervalsmay produce some difficulty in data correction. Theseissues should be appropriately resolved before theEBV DNA assay becomes a universal clinical routinein NPC management.9.4.4Other Serum/Plasma BiomarkersTable 9.6 lists some other potential serum/plasmabiomarkers with prognostic impact on NPC. Amongthese markers, serum lactate dehydrogenase (LDH)level has been reported as a prognostic indicator inmalignant lymphoma and other carcinomas of epithelialorigin. High level of serum LDH usually indicateslarger tumor burden or close association withdistant metastasis, resulting in a poor prognosis.Liaw et al. (1997) retrospectively investigated 465NPC patients and demonstrated that higher serumLDH levels were found in patients with distant metastasisor relapse than those in remission or normalcontrols. For 118 Stage IV M0 patients, pretreatmentserum LDH affected overall survival significantly.Hong et al. (2001) confirmed that pretreatmentserum LDH level was an independent prognostic factorof overall survival in 111 Stage III–IV NPCpatients by multivariate analysis. Cheng et al. (2006a)proposed a prognostic scoring system for locoregional