Low value of whole-body dual-modality [18f]fluorodeoxyglucose positron emission tomography/computed tomography in primary staging of stage I–II nasopharyngeal carcinoma: a nest case-control study

Abstract

Objectives The value of using PET/CT for staging of stage I–II NPC remains unclear. Hence, we aimed to investigate the survival benefit of PET/CT for staging of early-stage NPC before radical therapy. Methods A total of 1003 patients with pathologically confirmed NPC of stages I–II were consecutively enrolled. Among them, 218 patients underwent both PET/CT and conventional workup ([CWU], head-and-neck MRI, chest radiograph, liver ultrasound, bone scintigraphy) before treatment. The remaining 785 patients only underwent CWU. The standard of truth (SOT) for lymph node metastasis was defined by the change of size according to follow-up MRI. The diagnostic efficacies were compared in 218 patients who underwent both PET/CT and CWU. After covariate adjustment using propensity scoring, a cohort of 872 patients (218 with and 654 without pre-treatment PET/CT) was included. The primary outcome was overall survival based on intention to treat. Results Retropharyngeal lymph nodes were metastatic based on follow-up MRI in 79 cases. PET/CT was significantly less sensitive than MRI in detecting retropharyngeal lymph node lesions (72.2% [62.3–82.1] vs. 91.1% [84.8–97.4], p = 0.004). Neck lymph nodes were metastatic in 89 cases and PET/CT was more sensitive than MRI (96.6% [92.8–100.0] vs. 76.4% [67.6–85.2], p < 0.001). In the survival analyses, there was no association between pre-treatment PET/CT use and improved overall survival, progression-free survival, local relapse-free survival, regional relapse-free survival, and distant metastasis-free survival. Conclusions This study showed PET/CT is of little value for staging of stage I–II NPC patients at initial imaging. Key Points • PET/CT was more sensitive than MRI in detecting neck lymph node lesions whereas it was significantly less sensitive than MRI in detecting retropharyngeal lymph node lesions. • No association existed between pre-treatment PET/CT use and improved survival in stage I–II NPC patients.

Benefit of 18F-FDG PET/CT in Treatment Naïve Nasopharyngeal Carcinoma

“…In fact, this was not the rst report of advantage of PET/CT over MRI in diagnostic lymph nodes of nasopharyngeal carcinoma. But different from previous study [4,15], the included 460 lymph nodes were pathologically con rmed in our study, instead of clinical follow up. The nding of PET/CT superior to MRI was also consistent with the results of studies in head and neck cancer [16].…”

“…In terms of N0-1 patients with Epstein-Barr virus (EBV)-DNA lower than 4000 copies/mL, however, prior study [3] insisted the low risk of distant metastasis and the comparable value of conventional work-up to PET/CT at initial staging, and nally did not recommend PET/CT considering the economic effectiveness. Also, a recent study con rmed that there was no survival bene t of adding PET/CT to conventional work-up for stage I-II nasopharyngeal carcinoma [4]. We suppose that precise detection of metastatic cervical lymph nodes and correct N-stage perhaps more affect the prognosis of these patients, instead of focusing on the value of detecting occult distant metastasis.…”

Benefit of [18F]-FDG PET/CT for treatment-naïve nasopharyngeal carcinoma

“…In fact, this is not the first report of the advantage of PET/CT over MRI for diagnosing lymph nodes in patients with nasopharyngeal carcinoma. However, different from previous studies [ 4 , 15 ], the 460 lymph nodes included in our study were pathologically confirmed instead of by clinical follow-up. Certainly, the mistakes and biased of mapping biopsied lymph nodes on PET/CT and MRI images cannot be absolutely avoided, although we included solitary lymph nodes, the largest lymph node, and other nodes that could be definitely located without any uncertainty according to the ultrasonic reports and graphs with detailed characteristics of the biopsied node, such as the exact size, level, extranodal extension, and distance from the skin, muscles, vein, artery, or other landmark structures.…”

“…For N0-1 patients with Epstein-Barr virus (EBV) DNA less than 4000 copies/mL, a prior study [ 3 ] insisted on a low risk of distant metastasis and the comparable value of conventional work-up versus PET/CT for initial staging and finally did not recommend PET/CT due to its cost. Additionally, a recent study confirmed that there was no survival benefit of adding PET/CT to conventional work-up for stage I–II nasopharyngeal carcinoma [ 4 ]. We suppose that precise detection of metastatic cervical lymph nodes and correct N-stage perhaps more affects the prognosis of these patients, instead of focusing on the value of detecting occult distant metastasis.…”

Development and validation of radiologic scores for guiding individualized induction chemotherapy in T3N1M0 nasopharyngeal carcinoma

“…Additionally, accurate diagnosis of T3N1M0 patients is another key point. [ 18 F]FDG PET/CT has advantages in detecting metastatic cervical lymph nodes and distant metastasis over MRI, but it is inferior in determining local tumor invasion and retropharyngeal nodal metastasis [ 23 , 24 ]. This conclusion was based on the judgment of metastatic lymph nodes by clinical follow-up instead of pathologic confirmation.…”