Optimal Modality for Detecting Distant Metastasis in Primary Nasopharyngeal Carcinoma during Initial Staging: A Systemic Review and Meta-analysis of 1774 Patients

Abstract

Purpose: To compare the diagnostic performance of two modalities commonly used for detecting distant metastasis in primary nasopharyngeal carcinoma (NPC): ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) and conventional work-ups (CWUs). Methods: All topic-related studies were comprehensively searched and included. We determined sensitivities and specificities across studies, calculated negative and positive likelihood ratios (LR- and LR+, respectively), and constructed summary receiver operating characteristic curves. Moreover, we compared the diagnostic performance of PET/CT and CWUs by analyzing studies that reported the results of these diagnostic methods on the same patients. Results: The pooled sensitivity and specificity were 85.7% and 98.1% for PET/CT (1474 patients), and 38.0% and 97.6% for CWUs (1329 patients). In the head-to-head comparison of PET/CT and CWUs (1029 patients), PET/CT showed a significantly higher sensitivity (83.7% vs. 40.1%, P < 0.001) and lower LR- (0.169 vs. 0.633, P < 0.001) than CWUs on a per-patient basis; no significant difference was observed in pooled specificity (97.7% vs. 97.8%, P = 0.892) or LR+ (36.416 vs. 16.845, P = 0.149). The superiority of PET/CT over CWUs was due mainly to the better diagnostic performance on bone metastasis. However, suboptimal sensitivity of PET/CT was reported in the aspect of detection of liver metastasis. Sensitivity analyses showed relatively poor sensitivity and LR- of PET/CT compared to the original analysis. Conclusions: PET/CT was superior to CWUs in detecting distant metastasis in primary NPC. However, the efficacy of PET/CT in detecting liver metastasis still requires further optimization.

Keywords: Positron emission tomography/computed tomography; diagnosis; distant metastasis; meta-analysis.; nasopharyngeal carcinoma.

Figure 1

Flow chart describing the identification, inclusion and exclusion of studies.

Figure 2

Forest plots of ¹⁸F-FDG PET/CT on a per-patient basis in sensitivity (A), specificity (B), positive likelihood ratio (C), and negative likelihood ratio (D). CI: confidence interval; LR: likelihood ratio. Circles are the point estimates of studies with the 95% CIs indicated by horizontal bars. The size of the circles indicates the weight of each study. Diamonds are the summary estimates from the pooled studies with the 95% CIs indicated by horizontal bars. All pooled results were slightly different from the results reported in the text because of rounding.

Figure 3

Forest plots of CWUs on a per-patient basis in sensitivity (A), specificity (B), positive likelihood ratio (C), and negative likelihood ratio (D). CI: confidence interval; LR: likelihood ratio. Circles are the point estimates of studies with the 95% CIs indicated by horizontal bars. The size of the circles indicates the weight of each study. Diamonds are the summary estimates from the pooled studies with the 95% CIs indicated by horizontal bars. All pooled results were slightly different from the results reported in the text because of rounding.

Figure 4

Summary receiver operating characteristic (SROC) curves for the diagnostic performance of ¹⁸F-FDG PET/CT (A) and CWUs (B). AUC: area under the curve; SE: standard error. The size of the circles indicates the weight of each study.

Figure 5

Deeks' funnel plots of ¹⁸F-FDG PET/CT (A) and CWUs (B) to evaluate potential publication bias. ESS: effective sample size. P = 0.787 and 0.914 indicate symmetrical funnel shapes and suggest no publication bias.