Nasopharyngeal cancer: Impact of skull base invasion on patients prognosis and its potential implications on TNM staging

Radiotherapy-Related Neurologic Complications in Patients with Nasopharyngeal Carcinoma: A Multicenter Epidemiologic Study in Southern China

BACKGROUND

We aim at describing the incidence, potential predisposing factors, and progression of major radiotherapy-related neurologic complications (RRNC) in nasopharyngeal carcinoma (NPC)-endemic regions, especially southern China.

METHODS

We performed a multicenter longitudinal retrospective study with clinical follow-ups in 22,302 patients with post-radiotherapy NPC between January 2003 and June 2017 covering three major residential areas. Epidemiology, potential predisposing/protective factors, clinicopathologic progression, and survival conditions of each RRNC were separately recorded and analyzed on the basis of their related clinical, radiologic, and laboratory parameters.

RESULTS

949 new cases of RRNCs occurred among the 22,302 patients with post-radiotherapy NPC during 101,714 person years' follow-up, which is equal to an incidence density rate of 9.3 new cases per 1000 person year. Radiation-induced cranial nerve palsy showed the highest incidence (2.68%, 597/22,302) with the earliest onset (median latency, 4.45 years) as well. Patients benefited from intensity-modulated radiotherapy (IMRT) over conventional radiotherapy (CRT) in both overall survival (median survival 13.2 years for IMRT vs. 8.3 years for CRT) and RRNC-free survival (except for epilepsy and cranial nerve palsy). Causes of death varied substantially between patients with or without RRNCs.

CONCLUSIONS

Our study indicates a non-negligible incidence of RRNC spectrum in southern China in the past ten years. IMRT is one of the most significant protectors against development and progression of RRNCs.

IMPACT

Our findings support the hypothesis that patients with NPC with preexisting predispositions would receive long-term benefits from IMRT and other dose-related modulations (like hyperfractionation and dose conformation).

Predicting Bone Metastasis Risk Based on Skull Base Invasion in Locally Advanced Nasopharyngeal Carcinoma

Objective

To develop and validate a bone metastasis prediction model based on skull base invasion (SBI) in patients with locally advanced nasopharyngeal carcinoma (LA-NPC).

Methods

This retrospective cohort study enrolled 290 patients with LA-NPC who received intensity-modulated radiation therapy in two hospitals from 2010 to 2020. Patient characteristics were grouped by SBI and hospital. Both unadjusted and multivariate-adjusted models were used to determine bone metastasis risk based on SBI status. Subgroup analysis was performed to investigate heterogeneity using a forest graph. Cox proportional hazard regression analysis was used to screen for risk factors of bone metastasis-free survival (BMFS). A nomogram of BMFS based on SBI was developed and validated using C-index, receiver operating characteristic curve, calibration curves, and decision curve analysis after Cox proportional hazard regression analysis.

Results

The incidence of bone metastasis was 14.83% (43/290), 20.69% (24/116), and 10.92% (19/174) in the overall population, SBI-positive group, and SBI-negative group, respectively. In the unadjusted model, SBI was associated with reduced BMFS [HR 2.43 (1.32–4.47), P = 0.004], and the results remained stable after three continuous adjustments (P <0.05). No significant interaction was found in the subgroup analyses (P for interaction >0.05). According to Cox proportional hazard regression analysis and clinical value results, potential risk factors included SBI, Karnofsky performance status, TNM stage, induction chemotherapy, concurrent chemoradiotherapy, and adjuvant chemotherapy. Using a training C-index of 0.80 and a validation C-index of 0.79, the nomogram predicted BMFS and demonstrated satisfactory prognostic capability in 2, 3, and 5 years (area under curve: 83.7% vs. 79.6%, 81.7% vs. 88.2%, and 79.0% vs. 93.8%, respectively).

Conclusion

Skull base invasion is a risk factor for bone metastasis in patients with LA-NPC. The SBI-based nomogram model can be used to predict bone metastasis and may assist in identifying LA-NPC patients at the highest risk of bone metastasis.

Value of skull base invasion subclassification in nasopharyngeal carcinoma: implication for prognostic stratification and use of induction chemotherapy

OBJECTIVES

Prognoses for nasopharyngeal carcinoma (NPC) between categories T2 and T3 in the Eighth American Joint Committee on Cancer (AJCC) staging system were overlapped. We explored the value of skull base invasion (SBI) subclassification in prognostic stratification and use of induction chemotherapy (IC) to optimize T2/T3 categorization for NPC patients.

METHODS

We retrospectively reviewed 1752 NPC patients from two hospitals. Eight skull base bone structures were evaluated. Survival differences were compared between slight SBI (T3 patients with pterygoid process and/or base of the sphenoid bone invasion only) and severe SBI (T3 patients with other SBIs) with or without IC using random matched-pair analysis. We calculated the prognosis and Harrel concordance index (C-index) for the revised T category and compared IC outcomes for the revised tumor stages.

RESULTS

Compared to severe SBI, slight SBI showed better 5-year overall survival (OS) (81.5% vs. 92.3%, p = 0.001) and progression-free survival (PFS) (71.5% vs. 83.0%, p = 0.002). Additional IC therapy did not significantly improve OS and PFS in slight SBI. The proposed T category separated OS, PFS, and locoregional recurrence-free survival in T2 and T3 categories with statistical significance. An improved C-index for OS prediction was observed in the proposed T category with combined confounding factors, compared to the AJCC T staging system (0.725 vs. 0.713, p = 0.046). The survival benefits of IC were more obvious in the advanced stage.

CONCLUSIONS

NPC patients with slight SBI were recommended to downstage to T2 category. The adjustment for T category enabled better prognostic stratification and guidance for IC use.

KEY POINTS

• For nasopharyngeal carcinoma (NPC) patients in T3 category, slight skull base invasion was a significant positive predictor for OS and PFS. • NPC patients with slight SBI might not gain significant survival benefits from induction chemotherapy. • Downstaging slight SBI NPC patients to T2 category would make a more accurate risk stratification, improve the predicting performance in OS, and have a better guidance in the use of IC for patients in advanced stage.

MiR196a-5p in extracellular vesicles released from human nasopharyngeal carcinoma enhance the phagocytosis and secretion of microglia by targeting ROCK1

The microenvironment of the brain has become increasingly recognized as an essential regulator in metastatic and primary brain tumors. Recent studies demonstrate that circulating tumor-derived exosomes are critical for the brain tumor microenvironment. Nasopharyngeal carcinoma (NPC), a malignant tumor of the head and neck, often invades the skull base but infrequently extends to brain parenchyma. Neurobiological communication between microglia and tumor-derived extracellular vesicles (EVs) has been extensively studied, but how NPC cells regulate the immune microenvironment in the brain remains unknown. Here, we report that NPC derived EVs lead to increased microglial phagocytosis and proliferation, and heightened levels of IL-6, IL-8, CXCL1 and TGF-β1. Analysis of microRNAs in EVs reveal that miR196a-5p is the major effector microRNA. Moreover, we demonstrate an enrichment of miR196a-5p in the plasmatic EVs of NPC patients. Further investigation demonstrated that miR196a-5p was transferred to microglia and regulated microglial structure and functions by downregulating the expression of ROCK1. Therefore, these data indicate that NPC-derived EVs are potent modulators of microglial functions in brain microenvironment. Regardless of brain colonization, EVs-mediated functional changes in microglia may be a universal phenomenon that results in the alteration of the tumor host's microenvironment in the brain.

MR Imaging of Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma is endemic in parts of the world such as southern China and Southeast Asia. It is predominantly an undifferentiated carcinoma with a strong genetic basis and a close association with the Epstein-Barr virus. The ability of MR imaging to depict the boundaries of the primary tumor and its relationship with the complex structures of the skull base makes it the technique of choice for imaging of this disease in the head and neck. This article describes the MR imaging findings pertinent to staging and management and a new role of MR imaging in early cancer detection, in addition to a brief discussion of differential diagnoses.

Observer agreement and accuracy of 18F-sodium fluoride PET/computed tomography in the diagnosis of skull-base bone invasion and osseous metastases in newly diagnosed nasopharyngeal carcinoma

OBJECTIVES

To evaluate the interobserver agreement and the diagnostic performance in F-sodium fluoride (F-NaF) PET/computed tomography (CT) for the detection of skull-base bone invasion (SBBI) and osseous metastases in patients with newly diagnosed nasopharyngeal carcinoma (NPC).

METHODS

One hundred seventeen patients with newly diagnosed NPC between 2017 and 2019 who underwent F-NaF PET/CT was in included. Two experienced observers independently evaluated the F-NaF PET/CT of SBBI and osseous metastases on a patient level using a two-category scale present on a dichotomous scale, respectively. On a patient level, the diagnostic performance was calculated using a sensitivity analysis.

RESULTS

The interobserver agreement on a patient level of SBBI and osseous metastases were perfect on a patient-level (κ: 0.85), (κ: 0.808), respectively. On a lesion level of detection of osseous metastases, the observers agreed on the number as well as the location of osseous metastases in 101 (86.3%) patients. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of detection of SBBI and osseous metastases were ranged 0.911-0.962, 0.921-0.974, 0.932-0.957, 0.962-0.986, and 0.841-0.923, and ranged 0.917-0.958, 0.899-0.957, 0.906-0.949, 0.863-0.936, and 0.939-0.970, respectively.

CONCLUSION

The interobserver agreement of F-NaF PET/CT for the detection of SBBI and osseous metastases in patients with NPC were both very high among trained observers. Moreover, the diagnostic performance of NaF PET/CT was satisfactory, rendering NaF PET/CT a robust tool in the diagnostic armamentarium.

Grading of MRI-detected skull-base invasion in nasopharyngeal carcinoma with skull-base invasion after intensity-modulated radiotherapy

Background

The aim of this study is to evaluate the prognostic value of grading MRI–detected skull-base invasion in nasopharyngeal carcinoma (NPC) with skull-base invasion after intensity-modulated radiotherapy (IMRT).

Methods

This study is a retrospective chart review of 469 non-metastatic NPC patients with skull-base invasion. Patients were classified as extensive skull-base invasion (ESBI) group and limited skull-base invasion (LSBI) group.

Results

Multivariate analysis showed that the skull-base invasion (LSBI vs. ESBI) was an independent prognostic predictor of progression free survival (PFS). The estimated 5-year local failure free survival (LFFS), distant metastasis free survival (DMFS), PFS, and overall survival (OS) rates for patients in the T3-LSBI and T3-ESBI group were 92.9% versus 93.5, 89.8% versus 86.1, 81.6% versus 76.4, and 93.5% versus 86.3%, respectively (P > 0.05).

Conclusion

Grading of MRI-detected skull-base invasion is an independent prognostic factor of NPC with skull-base invasion. It is scientific and reasonable for skull-base invasion as a single entity to be classified as T3 classification.

Bone Subtraction Iodine Imaging Using Area Detector CT for Evaluation of Skull Base Invasion by Nasopharyngeal Carcinoma

BACKGROUND AND PURPOSE

Conventional CT has generally lower detectability of bone marrow invasion than MR imaging due to lower tissue contrast. The purpose of this study was to compare the diagnostic performance of conventional CT alone or in combination with bone subtraction iodine imaging using area detector CT for the evaluation of skull base invasion in patients with nasopharyngeal carcinoma.

MATERIALS AND METHODS

Forty-four consecutive patients who underwent contrast-enhanced CT using 320-row area detector CT and contrast-enhanced MR imaging for nasopharyngeal carcinoma staging between April 2012 and November 2017 were enrolled in this retrospective study. Bone subtraction iodine images were generated by subtracting pre- and postcontrast volume scans using a high-resolution deformable registration algorithm. Two blinded observers evaluated skull base invasion at multiple sites (sphenoid body, clivus, bilateral base of the pterygoid process, and petrous bone) using conventional CT images alone or in combination with bone subtraction iodine images. Examination of MR and CT images by an experienced neuroradiologist was the reference standard for evaluating sensitivity, specificity, and area under the receiver operating characteristic curve.

RESULTS

Twenty-six patients (59%) showed skull base invasion at 84 sites on the reference standard. Conventional CT plus bone subtraction iodine images showed higher sensitivity (92.9% versus 78.6%, P = .02) and specificity (95.6% versus 86.1%, P = .01) than conventional CT images alone for evaluating skull base invasion. The area under the receiver operating characteristic curve for conventional CT plus bone subtraction iodine (0.98) was significantly larger (P < .001) than the area under the receiver operating characteristic curve for conventional CT alone (0.90).

CONCLUSIONS

Conventional CT plus bone subtraction iodine performs more closely to the accuracy of combining CT and MR imaging compared with conventional CT alone.

Correlation Between Superoxide Dismutase Serum Level Alteration with Neck Metastatic Tumor Post Cisplatin-Paclitaxel Chemotherapy Response in Nasopharyngeal Carcinoma Patients

Nasopharyngeal carcinoma (NPC) is a malignant tumor in the nasopharynx. The patients treated with neoadjuvan combination chemotherapy cisplatin-paclitaxel while waiting a radiotherapy. This combination can produce a very high reactive oxygen species (ROS) level. Our body has a protective mechanism against oxidant through superoxide dismutase (SOD) that can inhibit DNA chain damage from ROS induction produced by chemotherapy in NPC patients. This study aimed to analyze the correlation between SOD level alteration with neck metastatic tumor response after cisplatin-paclitaxel chemotherapy. This was a cohort study. Thirty samples examined for neck metastasis tumor volume (VTM) and serum SOD were examined with ELISA pre- and postchemotherapy. Statistical significance was defined as p < 0.05. Mean SOD serum level pre-chemotherapy and post-chemotherapy were was 179.5 and 209.1, respectively. Mean tumor metastaic volume pre and post chemotherapy were 127.3 and 62.7, respectively. The correlation test with the result (r) 0.180 and p = 0.340. There was no correlation between SOD serum level alteration with VTM volume post cisplatin-paclitaxel chemotherapy in NPC patients.

Comparative diagnostic value of 18F-fluoride PET-CT versus MRI for skull-base bone invasion in nasopharyngeal carcinoma

PURPOSE

This study compared the diagnostic value of F-fluoride PET-computed tomography (PET-CT) and MRI in skull-base bone erosion in nasopharyngeal carcinoma (NPC) patients.

METHODS

A total of 93 patients with biopsy-confirmed NPC were enrolled, including 68 men and 25 women between 23 and 74 years of age. All patients were evaluated by both F-fluoride PET-CT and MRI, and the interval between the two imaging examinations was less than 20 days. The patients received no treatment either before or between scans. The studies were interpreted by two nuclear medicine physicians or two radiologists with more than 10 years of professional experience who were blinded to both the diagnosis and the results of the other imaging studies. The reference standard was skull-base bone erosion at a 20-week follow-up imaging study.

RESULTS

On the basis of the results of the follow-up imaging studies, 52 patients showed skull-base bone erosion. The numbers of true positives, false positives, true negatives, and false negatives with F-fluoride PET-CT were 49, 4, 37, and 3, respectively. The numbers of true positives, false positives, true negatives, and false negatives with MRI were 46, 5, 36, and 6, respectively. The sensitivity, specificity, and crude accuracy of F-fluoride PET-CT were 94.23, 90.24, and 92.47%, respectively; for MRI, these values were 88.46, 87.80, and 88.17%. Of the 52 patients, 43 showed positive findings both on F-fluoride PET-CT and on MRI. Within the patient cohort, F-fluoride PET-CT and MRI detected 178 and 135 bone lesions, respectively.

CONCLUSION

Both F-fluoride PET-CT and MRI have high sensitivity, specificity, and crude accuracy for detecting skull-base bone invasion in patients with NPC. F-fluoride PET-CT detected more lesions than did MRI in the skull-base bone. This suggests that F-fluoride PET-CT has a certain advantage in evaluating the skull-base bone of NPC patients. Combining the two methods could improve the diagnostic accuracy of skull-base bone invasion for NPC.

A Study of 358 Cases of Locally Advanced Nasopharyngeal Carcinoma Receiving Intensity-Modulated Radiation Therapy: Improving the Seventh Edition of the American Joint Committee on Cancer T-Staging System

To evaluate the rationality and limitations of the seventh edition of the American Joint Committee on Cancer (the 7th AJCC edition) T-staging system for locally advanced nasopharyngeal carcinoma (NPC). The prognosis of 358 patients with stage T3/T4 NPC treated with intensity-modulated radiotherapy (IMRT) was analyzed with the Kaplan–Meier method or the log-rank test. The 7th AJCC staging system of NPC has some limitations in that the T category is neither the significant factor in OS/LRFS nor the independent prognostic factor in OS/LRFS/DMFS/DFS (P > 0.05). After adjustment by anatomic structures, univariate analysis has shown that the adjusted-T category has statistical significance between T3 and T4 for OS (86.4% and 71.3%, P = 0.002), LRFS (97% and 90.9%, P = 0.048), DMFS (90.9% and 77.2%, P = 0.001), and DFS (86.2% and 67.5%, P = 0.000), and multivariate analysis has shown that the adjusted-T category is an independent prognostic factor for OS/DMFS/DFS (with the exception of LRFS). Then, GTV-P was taken into consideration. Multivariate analysis showed that these nT categories serve as suitable independent prognostic factors for OS/DMFS/DFS (P < 0.001) and LRFS (HR = 3.131; 95% CI, 1.090–8.990; P = 0.043). The 7th AJCC staging system has limitations and should be improved by including the modifications suggested, such as anatomic structures and tumor volume adjustment.

CT-diagnosed severe skull base bone destruction predicts distant bone metastasis in early N-stage nasopharyngeal carcinoma

Bone metastasis is the most frequent type of distant metastasis in nasopharyngeal carcinoma (NPC). In this study, we investigated the correlation between the skull base bone destruction and the distant bone metastasis in patients with NPC. A total of 449 cases with NPC who were diagnosed and had definitive radiotherapy from 2001 to 2006 were enrolled in this study. The skull base bone destruction was diagnosed by computed tomography (CT) in all cases, and 191 patients also underwent magnetic resonance imaging scan. Kaplan–Meier method was adopted to perform the univariate analysis; Cox regression model was used to perform multivariate analysis to determine whether the skull base bone destruction when diagnosed by CT was an independent impact factor of the distant bone metastases. The group with skull base bone destruction had a distant bone metastases rate of 9.0% (14/155), whereas the group without skull base bone destruction had rate of 4.1% (12/294). The multivariate analysis showed that the skull base bone destruction, when diagnosed by CT, was an independent impact factor of the distant bone metastases-free survival in the early N-staging cases, but was not an independent impact factor when diagnosed by MRI. The skull base bone destruction diagnosed by CT in patients with NPC had predictive value for the distant bone metastases, especially for the early N-staging cases.

Nasopharyngeal carcinoma patients with retropharyngeal lymph node metastases: a minimum axial diameter of 6 mm is a more accurate prognostic predictor than 5 mm

OBJECTIVE

The criteria for the diagnosis of metastatic retropharyngeal lymph nodes (RLNs) have not yet been resolved and are not included in the current edition of the American Joint Committee on Cancer (AJCC) staging system (seventh edition) for the staging of nasopharyngeal carcinoma (NPC). The aim of this study was to use MRI to identify an RLN size criterion that can accurately predict prognosis in patients with NPC.

MATERIALS AND METHODS

Eight hundred seventeen patients with newly diagnosed localized NPC were identified. All of the patients underwent MRI before treatment with definitive radiation therapy. All the MRI studies and medical records were reviewed retrospectively. Overall survival (OS), distant metastasis-free survival (DMFS), and local relapse-free survival (LRFS) were assessed using SPSS software (version 17.0).

RESULTS

RLN size cutoffs of ≥ 5 mm and of ≥ 6 mm were used. There was no significant difference in OS (p = 0.216), DMFS (p = 0.081), or LRFS (p = 0.067) in patients with RLNs ≥ 5 mm and in those with RLNs < 5 mm. When 6 mm was used as a size cutoff, significant differences in OS (p = 0.000) and DMFS (p = 0.001) were identified; there was no significant difference observed for LRFS (p = 0.380).

CONCLUSION

A minimum axial RLN diameter of 6 mm was a more accurate prognostic predictor in NPC patients with RLN metastases than 5 mm.

Multi-modality imaging to determine the cellular heterogeneity of nasopharyngeal carcinoma components

Nasopharyngeal carcinoma (NPC) is an endemic public health problem in South and Southeast Asian countries. The disease components at the molecular level are unclear and need exploration for the development of future individualized molecular medicine. The purpose of this study was to test the feasibility of target-specific agents to detect different components of NPC. The binding capability of human NPC cell lines was determined by incubation with either agents that specifically target the metabolic status, host cytokines, and stroma. Mice bearing human NPC xenografts were injected with the same test agents plus a clinical molecular imaging agent (18F-fluorodeoxyglucose) and computer tomography (CT) contrast agent. In vitro cell studies have demonstrated that target-specific agents bind to NPC cells with significantly higher signal intensities. Those agents not only bound to the cell membrane but also penetrated into the cytosol and cell nuclei. In vivo imaging demonstrated that the human NPC xenografts revealed high glucose uptake and a profound vasculature in the tumor. All agents were bound to the tumor regions with a high tumor-to-muscle ratio. Finally, all imaging data were validated by histopathological results. Multiple, target-specific agents determine the dynamic and heterogeneous components of NPC at the molecular level.

Staging of nasopharyngeal carcinoma--the past, the present and the future

This article reviews the evolution of the International Union Against Cancer/American Joint Committee on Cancer staging system for nasopharyngeal carcinoma. With the increasing availability of newer imaging methods, more sophisticated radiotherapy techniques and rapidly evolving molecular assays, we also examine newer clinical features that might have impact on staging. A new version of the staging system taking into account of some of these factors is also proposed.