Pre-treatment plasma Epstein Barr virus –DNA (pEBV DNA) level and association with magnetic resonance imaging (MRI)-delineated tumor volume and positron-emission tomography (PET) FDG-uptake in undifferentiated nasopharyngeal carcinoma (NPC)

Abstract

5526 Background: As post-treatment pEBV DNA level reflects post-radiotherapy (RT) residual tumor load in NPC (JNCI 2002:94(21);1416–29), we examine any correlation between pEBV DNA level, MRI-delineated volume and FDG-PET uptake of primary tumor (T) and regional nodes (N) in patients (pts) with NPC before undergoing chemoradiation (chemo-RT). Methods: Pts enrolled in an ongoing clinical trial involving chemo-RT at an institution entered this parallel study. Eligible pts had non-metastatic UICC stage III-IV NPC based on “conventional” staging: nasopharyngoscopy, physical examination, computered tomography (CT) of nasopharynx (NP), chest X-ray, bone scan, abdominal ultrasound. Consented pts underwent pre-treatment PET-CT (whole body excluding brain), MRI (NP- neck), pEBV DNA (copies/ml) analysis using real-time polymerase chain reaction. Net volume (cm3) of T (MRI-Tv), N (MRI-Nv), total tumor volume (TTv = Tv + Nv) were quantified on axial MR images. FDG-PET uptake expressed as maximum standard uptake value (SUVmax) for T (SUVmaxT) and N (SUVmaxN) were anatomically matched with CT images of the PET-CT scan. Lesions with SUVmax≥ 2.0 were considered malignant. Results: 28 pts were enrolled (21 males/ mean age 48 yrs/ UICC stage (conventional staging): No. of pts: III=15, IVa=6, IVb=7). PET showed no metastatic disease. Mean pEBV DNA level = 7190 copies/ml (range 0–92840), mean SUVmaxT=10 (range 4.2–21), mean SUVmaxN= 27 (range 2–77); mean MRI-Tv = 3325cm3, mean MRI-Nv = 3795 cm3. pEBV DNA level correlated with MRI-Tv (p<0.01, Spearman correlation, r = 0.50, 95%CI=0.15–0.74), MRI-TTv (p< 0.01, r = 0.51, 95% CI= 0.17–0.74), but not MRI-Nv (p=0.10). pEBV DNA did not correlate with SUVmaxT or SUVmaxN. Conclusions: Pre-treatment pEBV DNA level may quantitatively reflect tumor burden at primary NP. Sample size expansion is warranted and accrual continues. Post-treatment PET-CT will be obtained to examine the significance of elevated pEBV DNA following chemo-RT. No significant financial relationships to disclose.