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Purpose: We longitudinally evaluated the tumour growth and metabolic activity of three nasopharyngeal carcinoma (NPC) cell line models (C666-1, C17 and NPC43) and two xenograft models (Xeno76 and Xeno23) using a micropositron emission tomography and magnetic resonance (microPET/MR). With a better understanding of the interplay between tumour growth and metabolic characteristics of these NPC models, we aim to provide insights for the selection of appropriate NPC cell line/xenograft models to assist novel drug discovery and evaluation., Methods: Mice were imaged by 18 F-deoxyglucose ([ 18 F]FDG) microPET/MR twice a week for consecutive 3-7 weeks. [ 18 F]FDG uptake was quantified by standardized uptake value (SUV) and presented as SUVmean tumour-to-liver ratio (SUVRmean). Longitudinal tumour growth patterns and metabolic patterns were recorded. SUVRmean and histological characteristics were compared across the five NPC models. Cisplatin was administrated to one selected optimal tumour model, C17, to evaluate our imaging platform., Results: We found variable tumour growth and metabolic patterns across different NPC tumour types. C17 has an optimal growth rate and higher tumour metabolic activity compared with C666-1. C666-1 has a fast growth rate but is low in SUVRmean at endpoint due to necrosis as confirmed by H&E. NPC43 and Xeno76 have relatively slow growth rates and are low in SUVRmean, due to severe necrosis. Xeno23 has the slowest growth rate, and a relative high SUVRmean. Cisplatin showed the expected therapeutic effect in the C17 model in marked reduction of tumour size and metabolism., Conclusion: Our study establishes an imaging platform that characterizes the growth and metabolic patterns of different NPC models, and the platform is well able to demonstrate drug treatment outcome supporting its use in novel drug discovery and evaluation for NPC., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC) in endemic regions may have undetectable plasma EBV DNA., Methods: We prospectively recruited 518 patients with non-metastatic NPC and measured their pre-treatment plasma EBV DNA. The stage distribution and prognosis between pre-treatment plasma EBV DNA-negative (0-20 copies/ml) and EBV DNA-positive (>20 copies/ml) patients following radical treatment were compared., Results: Seventy-eight patients (15.1%) were plasma EBV DNA-negative, and 62 in this subset (12.0%) had 0 copy/ml. Only 23/78 (29.5%) plasma EBV DNA-negative patients with advanced NPC (stage III-IVA) had strong EBV encoded RNA (EBER) positivity (score 3) in their tumours compared to 342/440 (77.7%) EBV DNA-positive patients of the same stages (p < 0.001). Though EBV DNA-negative patients had more early-stage disease (p < 0.001) and smaller volumes of the primary tumour and the positive neck nodes (p < 0.001), they had similar 5-year overall survival and cancer-specific survival to those EBV DNA-positive counterparts by stage. Similar results were also seen when plasma EBV DNA cut-off was set at 0 copy/ml., Conclusions: Patients with low-volume NPC may not be identified by plasma/serum tumour markers and caution should be taken in its utility as a screening tool for NPC even in endemic regions., Clinical Trial Registration: Clinicaltrials.gov Identifier: NCT02476669.

The eighth edition of the American Joint Committee on Cancer (AJCC)/Union for International Cancer Control (UICC) stage classification (TNM) for nasopharyngeal carcinoma (NPC) was launched. It remains unknown if incorporation of nonanatomic factors into the stage classification would better predict survival. We prospectively recruited 518 patients with nonmetastatic NPC treated with radical intensity-modulated radiation therapy ± chemotherapy based on the eighth edition TNM. Recursive partitioning analysis (RPA) incorporating pretreatment plasma Epstein-Barr virus (EBV) DNA derived new stage groups. Multivariable analyses to calculate adjusted hazard ratios (AHRs) derived another set of stage groups. Five-year progression-free survival (PFS), overall survival (OS) and cancer-specific survival (CSS) were: Stage I (PFS 100%, OS 90%, CSS 100%), II (PFS 88%, OS 84%, CSS 95%), III (PFS 84%, OS 84%, CSS 90%) and IVA (PFS 71%, OS 75%, CSS 80%) (p < 0.001, p = 0.066 and p = 0.002, respectively). RPA derived four new stages: RPA-I (T1-T4 N0-N2 & EBV DNA <500 copies per mL; PFS 94%, OS 89%, CSS 96%), RPA-II (T1-T4 N0-N2 & EBV DNA ≥500 copies per mL; PFS 80%, OS 83%, CSS 89%), RPA-III (T1-T2 N3; PFS 64%, OS 83%, CSS 83%) and RPA-IVA (T3-T4 N3; PFS 63%, OS 60% and CSS 68%) (all with p < 0.001). AHR using covariate adjustment also yielded a valid classification (I: T1-T2 N0-N2; II: T3-T4 N0-N2 or T1-T2 N3 and III: T3-T4 N3) (all with p < 0.001). However, RPA stages better predicted survival for PS and CSS after bootstrapping replications. Our RPA-based stage groups revealed better survival prediction compared to the eighth edition TNM and the AHR stage groups., (© 2018 UICC.)

We aim to evaluate the quantitative parameters of 18 F-FDG PET/CT (metabolic parameters) and MRI (morphologic parameters) for prognostication and risk stratification in nasopharyngeal carcinoma (NPC). 200 (147 males, aged 50 ± 13 years-old, mean ± S.D.) newly diagnosed patients with NPC (T x N x M 0 ) were prospectively recruited. Primary tumor and nodal lesions were identified and segmented for both morphologic (volume, VOL) and metabolic (SUV and MTV) quantification. Independent predictive factors for recurrence free survival (RFS) and overall survival (OS) were morphologic nodal volume (VOL&#95;N, p < 0.001), TNM-stage (p = 0.022), N-Stage (p = 0.024) for RFS, and VOL&#95;N (p = 0.014) for OS. Using Classification and Regression Tree (CART) analysis, three risk-layers were identified for RFS: Stage I/II with VOL&#95;N < 18cc (HR = 1), stage III /IV with VOL&#95;N < 18cc (HR = 2.93), VOL&#95;N ≥ 18cc (HR = 7.84) regardless of disease stage (p < 0.001). For OS, two risk layers were identified: VOL&#95;N < 18cc (HR = 1), VOL&#95;N ≥ 18cc (HR = 4.23) (p = 0.001). The 18cc threshold for morphologic nodal volume was validated by an independent cohort (n = 105). Based on the above risk-classification, 35 patients (17.5%) would have a higher risk than suggested by the TNM-staging system. Thus, morphologic nodal volume is an important factor in prognostication and risk stratification in NPC, and should be incorporated into the staging system, while PET parameters have no advantage for this purpose in our cohort.

Objective: To determine if the perfusion parameters by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) of regional nodal metastasis are helpful in characterizing nodal status and to understand the relationship with those of primary tumor of nasopharyngeal carcinoma (NPC)., Materials and Methods: Newly diagnosed patients imaged between August 2010 and January 2014 and who were found to have enlarged retropharyngeal/cervical lymph nodes suggestive of nodal disease were recruited. DCE-MRI was performed. Three quantitative parameters, K trans , v e , and k ep , were calculated for the largest node in each patient. Kruskal-Wallis test was used to evaluate the difference in the parameters of the selected nodes of different N stages. Spearman's correlation was used to evaluate the relationship between the DCE-MRI parameters in nodes and in primary tumors., Results: Twenty-six patients (7 females; 25~67 years old) were enrolled. K trans was significantly different among the patients of N stages (N1, n = 3; N2, n = 17; N3, n = 6), P = 0.015. Median values (range) for N1, N2, and N3 were 0.24 min -1 (0.17~0.26 min -1 ), 0.29 min -1 (0.17~0.46 min -1 ), and 0.46 min -1 (0.29~0.70 min -1 ), respectively. There was no significant correlation between the parameters in nodes and primary tumors., Conclusion: DCE-MRI may play a distinct role in characterizing the metastatic cervical lymph nodes of NPC.

Plasma Epstein-Barr virus (EBV) DNA titers have been used to monitor treatment response and provide prognostic information on survival for nasopharyngeal carcinoma (NPC). However, the long-term prognostic role of pretreatment and posttreatment titers after radical contemporaneous radiation therapy remains uncertain. We recruited 260 evaluable patients with non-metastatic NPC treated with radical intensity-modulated radiation therapy (IMRT) with or without adjunct chemotherapy. Plasma EBV DNA titers at baseline and then 8 weeks and 6 months after IMRT were measured. Cox regression models were employed to identify interaction between post-IMRT 8th week and 6th month undetectable titers and 3-year survival endpoints. Concordance indices (Ct) from time-dependent receiver-operating characteristics (TDROC) were compared between patients with post-IMRT undetectable and those with detectable titers. After a median follow-up duration of 3.4 years (range 1.4-4.6 years), patients with post-IMRT 8th week and 6th month undetectable plasma EBV DNA titers enjoyed longer 3-year survival endpoints than those who had detectable titers at the same time points. Post-IMRT 8th week, and more significantly, post-IMRT 6th month undetectable plasma EBV DNA were the only significant prognostic factors of 3-year survival endpoints. Ct values for all 3-year survival endpoints for both post-IMRT 8th week and 6th month undetectable plasma EBV DNA were significantly higher in those with stage IVA-IVB diseases compared to stage I-III counterparts. Early post-IMRT undetectable plasma EBV DNA titers were prognostic of 3-year survival endpoints in patients with non-metastatic NPC. Intensified treatment should be further explored for patients with persistently detectable titers after IMRT.

Purpose: To determine the utility of stretched exponential diffusion model in characterisation of the water diffusion heterogeneity in different tumour stages of nasopharyngeal carcinoma (NPC)., Materials and Methods: Fifty patients with newly diagnosed NPC were prospectively recruited. Diffusion-weighted MR imaging was performed using five b values (0-2,500 s/mm(2)). Respective stretched exponential parameters (DDC, distributed diffusion coefficient; and alpha (α), water heterogeneity) were calculated. Patients were stratified into low and high tumour stage groups based on the American Joint Committee on Cancer (AJCC) staging for determination of the predictive powers of DDC and α using t test and ROC curve analyses., Results: The mean ± standard deviation values were DDC = 0.692 ± 0.199 (×10(-3) mm(2)/s) for low stage group vs 0.794 ± 0.253 (×10(-3) mm(2)/s) for high stage group; α = 0.792 ± 0.145 for low stage group vs 0.698 ± 0.155 for high stage group. α was significantly lower in the high stage group while DDC was negatively correlated. DDC and α were both reliable independent predictors (p < 0.001), with α being more powerful. Optimal cut-off values were (sensitivity, specificity, positive likelihood ratio, negative likelihood ratio) DDC = 0.692 × 10(-3) mm(2)/s (94.4 %, 64.3 %, 2.64, 0.09), α = 0.720 (72.2 %, 100 %, -, 0.28)., Conclusion: The heterogeneity index α is robust and can potentially help in staging and grading prediction in NPC., Key Points: • Stretched exponential diffusion models can help in tissue characterisation in nasopharyngeal carcinoma • α and distributed diffusion coefficient (DDC) are negatively correlated • α is a robust heterogeneity index marker • α can potentially help in staging and grading prediction.

Objectives: To evaluate the differences in prognostic values of static and dynamic PET-CT in nasopharyngeal carcinoma (NPC)., Material and Methods: Forty-five patients who had static scan were recruited. Sixteen had dynamic scan. The primary lesions were delineated from standardized uptake value (SUV) maps from static scan and K i maps from dynamic scan. The average follow-up lasted for 34 months. The patients who died or those with recurrence/residual disease were considered "poor outcome"; otherwise they were considered "good outcome." Fisher's exact test and ROC analysis were used to evaluate the prognostic value of various factors., Results: Tumor volume thresholded by 40% of maximal SUV (VOLSUV40) significantly predicted treatment outcome (p = 0.024) in the whole cohort. In 16 patients with dynamic scan, all parameters by dynamic scan were insignificant in predicting the outcome. The combination of maximal SUV, maximal K i , VOLSUV40, and VOL K i 37 (the tumor volume thresholded by 37% maximal K i ) achieved the highest predicting accuracy for treatment outcome with sensitivity, specificity, and accuracy of 100% in these 16 patients; however this improvement compared to VOLSUV40 was insignificant., Conclusion: Tumor volume from static scan is useful in NPC prognosis. However, the role of dynamic scanning was not justified in this small cohort.

Nasopharyngeal carcinoma (NPC) is common in Southeast Asia. Early detection and accurate staging are imperative for optimal treatment planning, helping to improve clinical outcome and survival rate. Both magnetic resonance (MR) and 18-fluoro-2-deoxy-glucose ((18)F-FDG) positron emission tomography with computed tomography (PET/CT) imaging are essential in the diagnosis, staging and post-treatment assessment of NPC, carrying important roles in different stages of the disease and are often complementary to each other. MR imaging, given its excellent soft tissue contrast resolution, is the best imaging modality of choice in the depiction and delineation of local tumor extent whilst whole body (18)F-FDG PET/CT imaging, with its added functional information, is superior in correct identification of the metastatic lymph node and distant metastasis. It is also valuable in the treatment response assessment during the early treatment and post-treatment periods, potentially facilitating the concept of adaptive radiation therapy during treatment so as to minimize complications. In this article, we will review the roles and limitations of MR and (18)F-FDG PET/CT imaging in the different stages of patient management in NPC. Also, the diagnostic challenge in differentiation between residual/recurrent disease and post-chemoradiation fibrosis in the post-treatment period will be addressed. Finally, the value of the quantitative parameters derived from functional MR and (18)F-FDG PET/CT imaging as prognostic markers in the prediction of treatment outcome will also be discussed., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Objective: To explore intravoxel incoherent motion (IVIM) characteristics of nasopharyngeal carcinoma (NPC) and relationships with different tumour stages., Methods: We prospectively recruited 80 patients with newly diagnosed undifferentiated NPC. Diffusion-weighted MR imaging was performed and IVIM parameters (D, pure diffusion; f, perfusion fraction; D*, pseudodiffusion coefficient) were calculated. Patients were stratified into low and high tumour stage groups based on American Joint Committee on Cancer (AJCC) and TNM staging for determination of the predictive powers of IVIM parameters using t test, multiple logistic regression and ROC curve analyses., Results: D, f and D* were all statistically significantly lower in high-stage groups in AJCC, T and N staging. D, f and D* were all independent predictors of AJCC staging, f and D* were independent predictors of T staging, and D was an independent predictor of N staging. D was most powerful for AJCC and N staging, whereas f was most powerful for T staging. Optimal cut-off values (area under the curve, sensitivity, specificity, positive likelihood ratio, negative likelihood ratio) were as follows: AJCC stage, D = 0.782 × 10(-3) mm(2)/s (0.915, 93.3 %, 76.2 %, 3.92, 0.09); T staging, f = 0.133 (0.905, 80.5 %, 92.5 %, 10.73, 0.21); N staging, D = 0.761 × 10(-3) mm(2)/s (0.848, 87.5 %, 66.7 %, 2.62, 0.19). Multivariate analysis showed no diagnostic improvement., Conclusion: Nasopharyngeal carcinoma has distinctive intravoxel incoherent motion characteristics parameters in different tumour staging, potentially helping pretreatment staging., Key Points: • Magnetic resonance imaging is increasingly used to assess nasopharyngeal carcinoma (NPC). • NPC has distinctive diffusion/perfusion characteristics at different stages. • Non-invasive MR imaging may help pretreatment staging prediction. • Diffusion properties of NPC best correlate with AJCC and N staging. • Perfusion properties of NPC best correlate with T staging.

Objectives: To compare the intravoxel incoherent motion (IVIM) diffusion and perfusion characteristics of nasopharyngeal carcinoma (NPC) and post-chemoradiation fibrosis to aid in their differentiation., Methods: Fifty-three (64 %) patients with newly diagnosed NPC and 30 (36 %) patients with biopsy-proven post-chemoradiation fibrosis were recruited into tumour and fibrosis groups respectively. Diffusion-weighted magnetic resonance (MR) imaging was performed using 13 b values (0-1,000 s/mm(2)). Their respective IVIM parameters (D, pure diffusion; f, perfusion fraction; D, pseudodiffusion coefficient) were obtained., Results: D and f were significantly lower in NPC (D = 0.752 ± 0.194 × 10(-3) mm(2)/s, P <0.001; f = 0.122 ± 0.095, P <0.001) than in fibrosis (D = 1.423 ± 0.364 × 10(-3) mm(2)/s; f = 0.190 ± 0.120); while D was significantly higher in NPC (111.366 ± 65.528 × 10(-3) mm(2)/s, P <0.001) than in fibrosis (77.468 ± 62.168 × 10(-3) mm(2)/s). Respective cut-off values with sensitivity, specificity and accuracy were: D = 1.062 × 10(-3) mm(2)/s (100 %, 100 %, 100 %); f = 0.132 (66.0 %, 100 %, 78.3 %); D = 85.283 × 10(-3) mm(2)/s (100 %, 90.7 %, 96.4 %)., Conclusion: NPC and post-chemoradiation fibrosis have distinctive IVIM parameters. IVIM MR imaging is potentially useful in discrimination between NPC and fibrosis., Key Points: • New MRI techniques offer greater help in the assessment of nasopharyngeal carcinoma. • Tumour and post-chemoradiation fibrosis have distinctive intravoxel incoherent motion diffusion/perfusion parameters. • Non-invasive IVIM MRI may help differentiate between tumour and fibrosis. • Pure diffusion is a robust independent discriminating factor which improves diagnostic confidence.

Objectives: To evaluate dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for characterising nasopharyngeal carcinoma (NPC)., Methods: Forty-five newly diagnosed NPC patients were recruited. The initial enhancement rate (E R ), contrast transfer rate (k ep ), elimination rate (k el ), maximal enhancement (MaxEn) and initial area under the curve (iAUC) were calculated from semiquantitative analysis. The K (trans) (volume transfer constant), v e (volume fraction) and k ep were calculated from quantitative analysis. Student's t-test was used to evaluate the differences among tumour stages. Pearson's correlation between the two sets of k ep was performed., Results: Comparing tumours of T1/2 stage (n = 18) and T3/4 stage (n = 27), MaxEn (P = 0.030) and iAUC (P = 0.039) were both significantly different; however, the iAUC was the only independent variable with 69.6 % sensitivity and 76.5 % specificity respectively; v e was also significantly different (P = 0.010) with 69.6 % sensitivity and 70.6 % specificity respectively. No significant difference was found among N stages. The two sets of k ep s were highly correlated (r = 0.809, P < 0.001). Forty-three patients had chemoradiation, one palliative chemotherapy and one radiotherapy only. In the four patients with poor outcome, k el, E R, MaxEn and iAUC tended to be higher., Conclusions: Neovasculature in higher T stage NPC exhibits some parameters of increased permeability and perfusion. Thus, DCE-MRI may be helpful as an adjunctive technique in evaluating NPC., Key Points: • The correct assessment of nasopharyngeal carcinoma (NPC) is important for planning treatment. • Neovasculature in higher T stage NPC exhibits increased permeability and perfusion. • Correlation between quantitative and semi-quantitative analysis validates the robustness of DCE-MRI. • DCE-MRI may be helpful as an adjunctive parameter in evaluating NPC.

Purpose: Positron emission tomography/computed tomography (PET/CT) has established values for imaging of head and neck cancers, including the nasopharyngeal carcinoma (NPC), utilizing both morphologic and functional information. In this paper, we introduce a computerized system for automatic detection of NPC, targeting both the primary tumor and regional nodal metastasis, on PET/CT., Methods: Candidate lesions were extracted based on the features from both PET and CT images and a priori knowledge of anatomical features and subsequently classified by a support vector machine algorithm. The system was validated with 25 PET/CT examinations from 10 patients suffering from NPC. Lesions manually contoured by experienced radiologists were used as the gold standard., Results: Results showed that the system successfully identified all 53 hypermetabolic lesions larger than 1 cm in size and excluded normal physiological uptake in brown fat, muscles, bone marrow, brain, and salivary glands., Conclusion: The system combined both imaging features and a priori clinical knowledge for classification between pathological and physiological uptake. Preliminary results showed that the system was highly accurate and promising for adoption in clinical use.

Objective: The purpose of this study was to quantitatively evaluate the role of intratumoral heterogeneity of (18)F-FDG uptake in characterizing nasopharyngeal carcinoma (NPC)., Subjects and Methods: Forty consecutively registered patients with newly diagnosed NPC underwent PET/CT. The heterogeneity factor, defined as the derivative of a volume threshold function, was computed for each tumor. The relations between heterogeneity factor and maximum standardized uptake value (SUV(max)), tumor volume, and TNM category were determined by two-tailed Spearman correlation. Factors that potentially affect outcome determined by disease-free survival were studied by Kaplan-Meier analysis with a log-rank test for univariate analysis and the Cox proportional hazard model for multivariate analysis., Results: The heterogeneity factor ranged from -1.80 to -0.13 (mean, -0.40 [SD, 0.40]) and significantly correlated with SUV(max) (r = -0.372; p = 0.018), tumor volume (r = -0.983; p < 0.001), and T category (r = -0.457; p = 0.003) but not with N and M categories. There was a significant difference in heterogeneity factor between T1 and T2 tumors and T3 and T4 tumors (p = 0.012). The 2-year disease-free survival rate among the 38 patients was 67.4%. According to the results of Kaplan-Meier analysis with the log-rank test, heterogeneity factor and M category significantly affected disease-free survival. Patients with tumors that had a heterogeneity factor greater than -0.24 (less-heterogeneous group) (p = 0.0498) or M0 status (p < 0.001) had better disease-free survival rates. Multivariate analysis showed only M category to be an independent predictor of disease-free survival (p < 0.001)., Conclusion: The intratumoral heterogeneity of FDG uptake varies across NPC tumors, significantly correlates with tumor aggressiveness, and is predictive of patient outcome. These findings may be useful for characterizing NPC, predicting survival, and improving patient care.

Objectives: To investigate the optimal PET protocol and analytical method to characterize the glucose metabolism in nasopharyngeal carcinoma (NPC)., Methods: Newly diagnosed NPC patients were recruited and a dynamic PET-CT scan was performed. The optimized threshold to derive the arterial input function (AIF) was studied. Two-tissue compartmental kinetic modeling using three, four, and five parameters, Patlak graphical analysis, and time sensitivity (S-factor) analysis were performed. The best compartmental model was determined in terms of goodness of fit, and correlated with Ki from Patlak graphical analysis and the S-factor. The methods with R>0.9 and P<0.05 were considered acceptable. The protocols using two static scans with its retention index (RI=(SUV(2)/SUV(1)-1)×100%, where SUV is the standardized uptake value) were also studied and compared with S-factor analysis., Results: The best threshold of 0.6 was determined and used to derive AIF. The kinetic model with five parameters yields the best statistical results, but the model with k4=0 was used as the gold standard. All Ki values and some S-factors from data between various intervals (10-30, 10-45, 15-30, 15-45, 20-30, and 20-45 min) fulfilled the criteria. The RIs calculated from the S-factor were highly correlated to RI derived from simple two-point static scans at 10 and 30 min (R=0.9, P<0.0001)., Conclusion: The Patlak graphical analyses and even a 20-min-interval S-factor analysis or simple two-point static scans were shown to be sufficient to characterize NPC metabolism, confirming the clinical feasibility of applying a short dynamic with image-derived AIF or simple two-point static PET scans for studying NPC.

Purpose: We evaluated the use of metabolic parameters of F-18 fluorodeoxyglucose positron emission tomography (FDG PET) for the assessment of the primary tumor and nodal metastasis in predicting survival in nasopharyngeal carcinoma (NPC) patients., Materials and Methods: The F-18 FDG PET/CT (computed tomography) scans of 46 consecutive newly diagnosed NPC patients were retrospectively reviewed. Maximal standardized uptake value (SUVmax) corrected for lean body mass of primary tumor (pSUVmax) and highest SUVmax of cervical lymph nodes (nSUVmax) were recorded. The association of FDG uptake and 2-year disease-free survival (DFS) was examined., Results: Significantly better DFS was found in patients with pSUVmax <7.5 and nSUVmax <6.5 (P = 0.042 and P = 0.019, respectively). In multivariate analysis, both pSUVmax and nSUVmax were significant independent predictors of DFS., Conclusions: The SUVmax of the primary tumor and nodal metastasis are useful parameters for predicting DFS in NPC patients.

Purpose: We aimed to evaluate the relationships between primary tumour; maximum standardized uptake value (SUVmax), metabolic tumour volume (TV) and total lesion glycolysis (TLG) and tumour-node metastases (TNM) classification in nasopharyngeal carcinoma (NPC) patients., Methods: Fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography scans of 57 consecutive newly diagnosed NPC patients (age range, 15-80 years) were retrospectively reviewed. SUVmax, TV and TLG were recorded. Two-tailed Spearman's correlation was used to analyse the relationships between the metabolic parameters and the TNM staging system., Results: Positive correlations were observed between SUVmax (P<0.001, R=0.516), TV (P<0.001, R=0.504) and TLG (P<0.001, R=0.620) and T-stage, and both TV and SUVmax were independent variables that significantly affected T-stage (P<0.001, adjusted R=0.370). No other significant correlations were found between the metabolic parameters and TNM classification system., Conclusion: The metabolic parameters derived from fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography were positively correlated with T-stage in primary NPC. Our findings may suggest a complementary role of these parameters to TNM staging in prognostication of NPC patients.