Objective: To investigate the relationship between nasopharyngeal cancer (NPC) pathological type, EBV positivity and uptake of 18F-Fluorodeoxyglucose (FDG) as measured on PETCT

Methods: This retrospective investigation included 15 patients consisting of 10 males and 5 females (age range: 18-84 years old) who were referred to our department for whole-body positron emission tomography-computed tomography (PETCT) with newly diagnosed, biopsy-proven nasopharyngeal carcinoma (NPC). Medical records and PETCT images were reviewed to obtain the histological subtypes, the tumour staging (T), EBV positivity and the FDG uptake, measured as maximum standardized uptake value (SUV) of the primary tumour.

Results: The histopthologic subtypes were: squamous keratinizing WHO Type I (n=3), n=1 in each of T2, T3 and T4; non-keratinizing squamous WHO Type II (n=4), all 4 are of T1; and undifferentiated WHO Type III (n=8), T1(n=3), T3(n=3) and T4(n=2). The SUV of the primary tumour ranges from 4.5-32.8. The mean SUV is 12.3, 15.2 and 11.1 for histological type I, II and III respectively (p=0.49). There is also no significant association between SUV and tumour grade (p=0.71). 6 (Type II: n=3; Type III: n=3) out of 15 patients are positive for EBV. The mean SUV for positive and negative EBV group is 14.6+/-10.1 and 11.0+/-7.2 respectively (p=0.43).

Conclusions: Our study observed that Type II NPC exhibited a higher FDG uptake than either Type I or Type III; also higher SUV is found in EBV positive tumour. However, the difference do not reach statistical significant. Further study with bigger sample size is necessary.