High expression of WTAP is related to poor prognosis in nasopharyngeal carcinoma.

Wilms' tumor 1-associated protein (WTAP), a component of the m6A methyltransferase complex, recruits the m6A methyltransferases METTL3 and METTL14 to the corresponding mRNA targets to participate in the formation of N6-methyladenosine. However, the molecular mechanism of WTAP in the tumorigenesis and progression of nasopharyngeal carcinoma (NPC) remains unclear. This study aimed to explore the prognostic value and biological function of WTAP in NPC. We assessed WTAP expression and its prognostic significance using microarray datasets from the Gene Expression Omnibus (GSE12452) database and 100 NPC tissues via bioinformatics analysis and immunohistochemistry (IHC), respectively. Moreover, gene ontology (GO) and gene set enrichment analysis (GSEA) were performed. In addition, the correlation of WTAP expression with the expression of immune cell biomarkers was analyzed. The results showed that WTAP expression was significantly overexpressed in NPC tissues in GSE12452. The overexpression of WTAP was validated by the external datasets including NPC tissues (GSE150430) and NPC cell lines (GSE39826). GO analysis suggested enrichment in the nucleoplasm (cellular component) and cell cycle (biological process). The GSEA revealed that differentially expressed genes were enriched in E2F-targets, Myc_targets_v1, G2M checkpoint, Myc_targets_v2, and Interferon-alpha-response. In IHC analysis, WTAP was upregulated in NPC tissues, and high levels of WTAP expression were significantly correlated with the advanced T stage (p=0.047) and advanced N stage (p=0.018). Cox regression demonstrated that WTAP overexpression was an independent biomarker of poor prognosis for overall survival (hazard ratio [HR], 4.747; 95% confidence interval [CI], 1.671-13.482; p=0.003). In IHC analysis, the expression of WTAP was positively correlated with CD206 (biomarker for M2 macrophages) (p=0.018) but negatively correlated with CD8a (biomarker for cytotoxic T cells) (p=0.001). In conclusion, WTAP is a promising prognostic biomarker and may participate in the regulation of immune cell infiltration in NPC.

Deep Learning for Automated Contouring of Primary Tumor Volumes by MRI for Nasopharyngeal Carcinoma.

Background Nasopharyngeal carcinoma (NPC) may be cured with radiation therapy. Tumor proximity to critical structures demands accuracy in tumor delineation to avoid toxicities from radiation therapy; however, tumor target contouring for head and neck radiation therapy is labor intensive and highly variable among radiation oncologists. Purpose To construct and validate an artificial intelligence (AI) contouring tool to automate primary gross tumor volume (GTV) contouring in patients with NPC. Materials and Methods In this retrospective study, MRI data sets covering the nasopharynx from 1021 patients (median age, 47 years; 751 male, 270 female) with NPC between September 2016 and September 2017 were collected and divided into training, validation, and testing cohorts of 715, 103, and 203 patients, respectively. GTV contours were delineated for 1021 patients and were defined by consensus of two experts. A three-dimensional convolutional neural network was applied to 818 training and validation MRI data sets to construct the AI tool, which was tested in 203 independent MRI data sets. Next, the AI tool was compared against eight qualified radiation oncologists in a multicenter evaluation by using a random sample of 20 test MRI examinations. The Wilcoxon matched-pairs signed rank test was used to compare the difference of Dice similarity coefficient (DSC) of pre- versus post-AI assistance. Results The AI-generated contours demonstrated a high level of accuracy when compared with ground truth contours at testing in 203 patients (DSC, 0.79; 2.0-mm difference in average surface distance). In multicenter evaluation, AI assistance improved contouring accuracy (five of eight oncologists had a higher median DSC after AI assistance; average median DSC, 0.74 vs 0.78; P < .001), reduced intra- and interobserver variation (by 36.4% and 54.5%, respectively), and reduced contouring time (by 39.4%). Conclusion The AI contouring tool improved primary gross tumor contouring accuracy of nasopharyngeal carcinoma, which could have a positive impact on tumor control and patient survival. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Chang in this issue.

Long-term outcome and late toxicities of simultaneous integrated boost-intensity modulated radiotherapy in pediatric and adolescent nasopharyngeal carcinoma.

The application of simultaneous integrated boost-intensity modulated radiotherapy (SIB-IMRT) in pediatric and adolescent nasopharyngeal carcinoma (NPC) is underevaluated. This study aimed to evaluate long-term outcome and late toxicities in pediatric and adolescent NPC after SIB-IMRT combined with chemotherapy. Thirty-four patients (aged 8-20 years) with histologically proven, non-disseminated NPC treated with SIB-IMRT were enrolled in this retrospective study. The disease stage distribution was as follows: stage I, 1 (2.9%); stage III, 14 (41.2%); and stage IV, 19 (55.9%). All patients underwent SIB-IMRT and 30 patients also underwent cisplatin-based chemotherapy. The prescribed dose of IMRT was 64-68 Gy in 29-31 fractions to the nasopharyngeal gross target volume. Within the median follow-up of 52 months (range, 9-111 months), 1 patient (2.9%) experienced local recurrence and 4 (11.8%) developed distant metastasis (to the lung in 3 cases and to multiple organs in 1 case). Four patients (11.8%) died due to recurrence or metastasis. The 5-year locoregional relapse-free survival, distant metastasis-free survival, disease-free survival, and overall survival rates were 97.1%, 88.2%, 85.3%, and 88.2%, respectively. The most common acute toxicities were grades 3-4 hematologic toxicities and stomatitis. Of the 24 patients who survived for more than 2 years, 16 (66.7%) and 15 (62.5%) developed grades 1-2 xerostomia and ototoxicity, respectively. Two patients (8.3%) developed grade 3 ototoxicity; no grade 4 toxicities were observed. SIB-IMRT combined with chemotherapy achieves excellent long-term locoregional control in pediatric and adolescent NPC, with mild incidence of late toxicities. Distant metastasis is the predominant mode of failure.

Prognostic scoring system for locoregional control among the patients with nasopharyngeal carcinoma treated by intensity-modulated radiotherapy.

The prognostic value of T category for locoregional control in patients with nasopharyngeal carcinoma (NPC) has decreased with the extensive use of intensity-modulated radiotherapy (IMRT). We aimed to develop a prognostic scoring system (PSS) that incorporated tumor extension and clinical characteristics for locoregional control in NPC patients treated with IMRT. The magnetic resonance imaging scans and medical records of 717 patients with nonmetastatic NPC treated with IMRT at Sun Yat-sen University Cancer Center between January 2003 and January 2008 were reviewed. Age, pathologic classification, primary tumor extension, primary gross tumor volume (GTV-p), T and N categories, and baseline lactate dehydrogenase (LDH) level were analyzed. Hierarchical cluster analysis as well as univariate and multivariate analyses were used to develop the PSS. Independent prognostic factors for locoregional relapse included N2-3 stage, GTV-p ≥26.8 mL, and involvement of one or more structures within cluster 3. We calculated a risk score derived from the regression coefficient of each factor and classified patients into four groups: low risk (score 0), intermediate risk (score >0 and ≤1), high risk (score >1 and ≤2), and extremely high risk (score >2). The 5-year locoregional control rates for these groups were 97.4%, 93.6%, 85.2%, and 78.6%, respectively (P < 0.001). We have developed a PSS that can help identify NPC patients who are at high risk for locoregional relapse and can guide individualized treatments for NPC patients.

Association between Cervical Lymph Node Metastasis and the Incidence of Radiation-Induced Hypothyroidism in Nasopharyngeal Carcinoma.

BACKGROUND: It is controversial and unclear how N-stage would increase the risk of incidence of hypothyroidism (HT) for patients with nasopharyngeal carcinoma (NPC) after radiotherapy. Our study aimed to explore the correlation between cervical lymph node metastasis and the incidence of HT in NPC. MATERIALS AND METHODS: A total of 206 patients with NPC treated at the Cancer Hospital of University of Chinese Academy of Sciences, and their clinical information were retrospectively collected. A series of univariate logistic regression models were performed to explore the association of clinical and lymph node indices with the development of HT. Significant features in univariate analysis were then used to construct three prediction models, for HT prediction using multivariate logistic regression based on Bayesian information criterion. Prediction performance of those models was measured by area under the receiver operating characteristic curve (AUC) using 10-fold cross-validation. RESULTS: A total of 111 patients developed HT, and the incidence of HT in N 2-3 and N 0-1 patients was 58.82% and 44.29%, respectively. Compared to Model 1 (consisted of pretreatment TSH concentration, thyroid volume, and N-stage) whose AUCs were 0.801 and 0.766 in training and validation sets, with N-stage be replaced by shortest distance from thyroid, Model 2 achieved more stable AUCs of 0.824 and 0.801. While with numbers of positive lymph nodes in Level IIb additionally added, Model 3 improved its AUCs to 0.841 and 0.813. CONCLUSION: The shortest distance between the lymph nodes and thyroid gland and the number of lymph nodes in IIb are better predictors of radiation-induced HT than the N-stage.

Research progress of radiation-induced hypothyroidism in head and neck cancer.

This paper reviews the factors related to hypothyroidism after radiotherapy in patients with head and neck cancer to facilitate the prevention of radiation-induced hypothyroidism and reduce its incidence. Hypothyroidism is a common complication after radiotherapy in patients with head and neck cancer, wherein the higher the radiation dose to the thyroid and pituitary gland, the higher the incidence of hypothyroidism. With prolonged follow-up time, the incidence of hypothyroidism gradually increases. Intensity modulated radiotherapy should limit the dose to the thyroid, which would reduce the incidence of hypothyroidism. In addition, the risk factors for hypothyroidism include small thyroid volume size, female sex, and previous neck surgery. The incidence of radiation-induced hypothyroidism in head and neck cancer is related to the radiation dose, radiotherapy technique, thyroid volume, sex, and age. A prospective, large sample and long-term follow-up study should be carried out to establish a model of normal tissue complications that are likely to be related to radiation-induced hypothyroidism.

Apatinib in treating patients with recurrent or metastatic nasopharyngeal carcinoma who had failed prior platinum-based chemotherapy.

BACKGROUND: Platinum-based chemotherapy is the standard first-line treatment for recurrent/metastatic nasopharyngeal carcinoma (NPC); however, there is no standard regimen for those who failed first-line treatment. This study aimed to evaluate the efficacy and safety of apatinib in treating patients with recurrent/metastatic NPC who failed prior platinum-based chemotherapy. METHODS: Patients aged 18-65 years with recurrent/metastatic NPC were treated with apatinib at an initial dose of 500 mg once daily and continued until disease progression, patient withdrawal, or unacceptable toxic effects. The primary endpoints were clinical benefit rate (CBR) and toxicity. Secondary endpoints included progression-free survival (PFS) and overall survival (OS). RESULTS: Nineteen patients were enrolled in this study. At the final follow-up, the CBR was 52.6% (95% CI: 29.8-76.2%) in the intention-to-treat population. The median PFS and OS were 3.7 (95% CI: 0.6-6.8) months and 12.9 (95% CI: 9.3-16.5) months, respectively. The most common grade 3-4 adverse events (AEs) were hand-foot syndrome [3 (15.8%)], neutropenia [2 (10.5%)], proteinuria [2 (10.5%)], oral mucosal pain [2 (10.5%)], hypertension [1 (5.3%)], hyponatremia [1 (5.3%)], artery dissection [1 (5.3%)], and nasopharyngeal hemorrhage [1 (5.3%)]. A serious AEs was reported in one patient who died of nasopharyngeal hemorrhage. Treatment with apatinib did not significantly influence patient-reported quality-of-life, except for nausea/vomiting and pain (P<0.05). CONCLUSIONS: Apatinib achieved modest disease control with acceptable toxicity in recurrent/metastatic NPC patients pretreated with platinum-based chemotherapy.

Thyroid V50 is a risk factor for hypothyroidism in patients with nasopharyngeal carcinoma treated with intensity-modulated radiation therapy: a retrospective study.

BACKGROUND: We investigated the risk factors of radiation-induced thyroid dysfunction, then combined the clinical factors and optimum thyroid dosimetric parameters to predict the incidence rate of hypothyroidism (HT) and to guide individualized treatment. METHODS: A total of 206 patients with histologically proven nasopharyngeal carcinoma (NPC) treated at the Cancer Hospital of the University of Chinese Academy of Sciences between January 2015 and August 2018 were included. Dose-volume histogram (DVH) data, including mean dose, absolute volume, V20, V25, V30, V35, V40, V45, V50, V55, and V60 were extracted and used as dosimetric parameters. A logistic regression analysis model was built to identify predictors related to HT occurring within 2 years. RESULTS: Sex, N stage, thyroid volume, mean thyroid dose, and thyroid V20 and V50 were significantly different between patients with and without HT. Logistic regression analysis showed that N stage, thyroid volume, and thyroid V50 were independent predictors of HT. The radiosensitivity of the thyroid decreased as the thyroid volume increased. Patients with N stage > 1 had significantly higher HT incidence (37.38%) than patients with N stage ≤1 (13.11%). The incidence of HT was 54.55% in patients with thyroid V50 > 24% and was 34.15% in patients with thyroid V50 ≤ 24%. CONCLUSIONS: The incidence of HT is significantly associated with N stage, thyroid volume, and thyroid V50. More attention should be paid to patients with NPC with thyroid volume ≤ 12.82 cm3 and advanced N stage disease.

Hematological Indexes Can Be Used to Predict the Incidence of Hypothyroidism in Nasopharyngeal Carcinoma Patients after Radiotherapy.

BACKGROUND: This study explored the relationship between thyroid-associated antibodies, immune cells, and hypothyroidism to establish a predictive model for the incidence of hypothyroidism in patients with nasopharyngeal carcinoma (NPC) after radiotherapy. METHODS: A total of 170 patients with NPC treated at the Cancer Hospital of University of Chinese Academy of Sciences between January 2015 and August 2018 were included. The complete blood count, biochemical, coagulation function, immune cells, and thyroid-associated antibodies tested before radiotherapy were evaluated. A logistic regression model was performed to elucidate which hematological indexes were related to hypothyroidism development. A predictive model for the incidence of hypothyroidism was established. Internal verification of the multifactor model was performed using the tenfold cross-validation method. RESULTS: The univariate analysis showed that immune cells had no statistically significant differences among the patients with and without hypothyroidism. Sex, N-stage, antithyroid peroxidase antibody (TPO-Ab), antithyroglobulin antibody (TG-Ab), thyroglobulin (TG), and fibrinogen (Fb) were associated with hypothyroidism. Males and early N-stage were protective factors of thyroid function, whereas increases in TPO-Ab, TG-Ab, TG, and Fb counts were associated with an increased rate of hypothyroidism incidence. The multivariate analysis showed that TPO-Ab, TG-Ab, TG, and Fb were independent predictors of hypothyroidism. The comprehensive effect of the significant model, including TPO-Ab, TG-Ab, TG, and Fb counts, represented the optimal method of predicting the incidence of radiation-induced hypothyroidism (AUC = 0.796). Tenfold cross-validation methods were applied for internal validation. The AUCs of the training and testing sets were 0.792 and 0.798, respectively. CONCLUSION: A model combining TPO-Ab, TG-Ab, TG, and Fb can be used to screen populations at a high risk of developing hypothyroidism after radiotherapy.

A prognostic model combining CD4/CD8 ratio and N stage predicts the risk of distant metastasis for patients with nasopharyngeal carcinoma treated by intensity modulated radiotherapy.

This study aimed to evaluate the correlation between circulating lymphocyte subsets and clinical variables, and design an effective prognostic model for distant metastasis-free survival (DMFS) in NPC. In this study, subsets of circulating lymphocytes were determined in 719 non-metastatic NPC patients before treatment. Overall survival and DMFS was monitored. Significant prognostic factors were identified using univariate and multivariate analyses. Results showed that the percentage of CD19+ lymphocytes correlated negatively with TNM stage (r = -0.082, P = 0.028). Patients with higher CD4/CD8 ratios (≥ 1.77) showed better 5-year DMFS than patients with lower ratios (91.9% vs. 85.4%, P < 0.001). Multivariate analysis revealed that CD4/CD8 ratio (HR, 0.450; 95% confidence interval [CI], 0.266-0.760; P = 0.003) and N classification (HR, 2.294; 95% CI, 1.370-3.839; P = 0.002) were independently prognostic factors for DMFS. The prognostic N-R model was developed and divided patients into three groups: (1) low-risk (early N stage and CD4/CD8 ratio ≥ 1.77); (2) intermediate-risk (advanced N stage or CD4/CD8 ratio < 1.77) and (3) high-risk (advanced N stage and CD4/CD8 ratio < 1.77) of distant metastasis. In conclusion our prognostic model, based on clinical N stage and CD4/CD8 ratio, may predict the risk of distant metastasis, allowing individualized treatment for NPC.

Reduction of clinical target volume in patients with lateralized cancer of the nasopharynx and without contralateral lymph node metastasis receiving intensity-modulated radiotherapy.

BACKGROUND: This study investigated lymph node distribution in patients with lateralized cancer of the nasopharynx to identify areas suitable for clinical target volume (CTV) reduction. METHODS: A total of 1680 patients with nasopharyngeal carcinoma (NPC) whose tumor involvement was assessed by MRI were reviewed retrospectively. RESULTS: One hundred and twelve patients (7%) had a lateralized primary lesion. Of these, 9 patients (8%) had contralateral lymph nodes including 4 (4%) who had contralateral cervical lymph nodes (CLNs). The rates of contralateral level III/Va metastasis were <1% (1 of 104) and 12.5% (1 of 8) in patients without and with contralateral retropharynx/level II involvement, respectively. No known risk factors were significantly associated with contralateral lymph node metastasis. CONCLUSION: Reduced cervical CTV coverage, including the contralateral level II, is feasible in patients with lateralized primary NPC, which may help to better protect the cervical OAR, including the thyroid, larynx, and esophagus. © 2015 Wiley Periodicals, Inc. Head Neck 38: E468-E472, 2016.

The C-reactive Protein/Albumin Ratio Is an independent Prognostic Factor for Overall Survival in Patients with Nasopharyngeal Carcinoma Receiving Intensity-Modulated Radiotherapy.

This study aims to investigate the prognostic value of the C-reactive protein/albumin (CRP/ALB) ratio in nasopharyngeal carcinoma (NPC) in the intensity-modulated radiotherapy (IMRT) era. A total of 719 patients with NPC treated between January 2007 and December 2012 were retrospectively reviewed. Serum albumin and CRP levels were measured before treatment. The associations between the CRP/ALB ratio and clinicopathological parameters were analyzed. Multivariate analyses using the Cox proportional hazards model were performed to identify significant prognostic factors associated with overall survival (OS). The prognostic value of the CRP/ALB ratio was determined using receiver operating characteristic (ROC) curve analysis. The optimal CRP/ALB ratio cutoff value was 0.141. High CRP/ALB ratio was significantly associated with older age (P < 0.001), more advanced T category (P < 0.001) and advanced TNM stage (P = 0.024). Patients with an elevated CRP/ALB ratio (≥ 0.141) had poorer OS than those with a CRP/ALB ratio < 0.141 (5-year OS rates: 91.9% vs. 78.1%; P < 0.001). Multivariate analysis suggested clinical T category [hazard ratio (HR) 2.284; 95% confidence interval (CI), 1.429-3.652; P = 0.001]; clinical N category (HR 1.575; 95% CI, 1.007-2.464; P = 0.047) and CRP/ALB ratio (HR 2.173; 95% CI, 1.128-3.059; P = 0.015) were independently associated with OS. In conclusion, pretreatment CRP/ALB ratio is an objective biomarker with significant prognostic value for OS in NPC. The CRP/ALB ratio can enhance conventional TNM staging to stratify patients and may help facilitate individualized treatment of high-risk cases.

Predicting the Response of Neoadjuvant Therapy for Patients with Esophageal Carcinoma: an In-depth Literature Review.

Currently, the most promising strategy to improve the prognosis of advanced esophageal cancer is neoadjuvant chemoradiation (CRT) followed by surgery. However, patients who achieved pathological complete response can experience more survival benefit. Therefore, it is critical to identify the responders early in the course of treatment. Published data demonstrate that clinic-histopathological factors, molecular biomarkers, and functional imaging are predictive of neoadjuvant therapy. The existing biomarkers, including epidermal growth factor receptors, angiogenetic factors, transcription factors, tumor suppressor genes, cell cycle regulators, nucleotide excision repair pathway, cytokines, and chemotherapy associated genes, need to be validated and novel biomarkers warrant further exploration. Positron emission tomography (PET) is useful for differentiating the responders of neoadjuvant CRT. The most valuable parameters and the time point of performing PET in the course of treatment remains to be elucidated. Furthermore, predictive models incorporating the multiple categories of factors need to be established with a large, prospective, and homogeneous patient cohort in the future. Standardization of staging, biomarker detection method, and image acquisition protocol will be critical for the generalization of this model. Prospective, multi-center controlled trials, which stratified patients according to these predictive factors, will help guide individualized treatment strategies for patients with esophageal cancer.

Multi-subject atlas-based auto-segmentation reduces interobserver variation and improves dosimetric parameter consistency for organs at risk in nasopharyngeal carcinoma: A multi-institution clinical study.

BACKGROUND AND PURPOSE: To assess whether consensus guideline-based atlas-based auto-segmentation (ABAS) reduces interobserver variation and improves dosimetric parameter consistency for organs at risk (OARs) in nasopharyngeal carcinoma (NPC). MATERIALS AND METHODS: Eight radiation oncologists from 8 institutes contoured 20 OARs on planning CT images of 16 patients via manual contouring and manually-edited ABAS contouring. Interobserver variation [volume coefficient of variation (CV), Dice similarity coefficient (DSC), three-dimensional isocenter difference (3D-ICD)] and dosimetric parameters were compared between the two methods of contouring for each OAR. RESULTS: Interobserver variation was significant for all OARs in manual contouring, resulting in significant dosimetric parameter variation (P<0.05). Edited ABAS significantly improved multiple metrics and reduced dosimetric parameter variation for most OARs; brainstem, spinal cord, cochleae, temporomandibular joint (TMJ), larynx and pharyngeal constrictor muscle (PCM) obtained most benefit (range of mean DSC, volume CV and main ICD values was 0.36-0.83, 12.1-84.3%, 2.2-5.0mm for manual contouring and 0.42-0.86, 7.2-70.6%, 1.2-3.5mm for edited ABAS contouring, respectively; range of dose CV reduction: 1.0-3.0%). CONCLUSION: Substantial objective interobserver differences occur during manual contouring, resulting in significant dosimetric parameter variation. Edited ABAS reduced interobserver variation and improved dosimetric parameter consistency, particularly for brainstem, spinal cord, cochleae, TMJ, larynx and PCM.

Comparison of long-term survival and toxicity of cisplatin delivered weekly versus every three weeks concurrently with intensity-modulated radiotherapy in nasopharyngeal carcinoma.

BACKGROUND: We aimed to compare the long-term survival outcomes and acute toxicity of cisplatin administered weekly versus every three weeks concurrently with intensity-modulated radiotherapy (IMRT) in patients with nasopharyngeal carcinoma (NPC). METHODS: This was a retrospective review of 154 patients with histologically proven, non-disseminated NPC who were treated using IMRT between January 2003 and December 2007. Seventy-three patients (47.4%) received 5-7 weeks of 30-40 mg/m2 cisplatin weekly; 81 patients (52.6%) received two or three cycles of 80 mg/m2 cisplatin every three weeks. IMRT was delivered at 68 Gy/30 fractions to the nasopharyngeal gross target volume and 60-66 Gy to the involved neck area. RESULTS: The clinical characteristics and treatment factors of the two groups were well-balanced. The median follow-up was 74 months (range, 6-123 months), and the 5-year overall survival, disease-free survival, locoregional relapse-free survival, and distant metastasis-free survival rates were 85.2% vs. 78.9% (P = 0.318), 71.6% vs. 71.0% (P = 0.847), 93.5% vs. 92.6% (P = 0.904), and 80.9% vs. 80.1% (P = 0.925) for the group treated every three weeks and weekly, respectively. Subgroup analyses indicated no significant differences in the survival rates of the two groups among patients with early- or advanced-stage disease. The incidence of acute toxicities was similar between groups. CONCLUSION: IMRT with concurrent cisplatin administered weekly or every three weeks leads to similar long-term survival outcomes and acute toxicity in NPC regardless of whether patients have early- or advanced-stage disease.

Recommendation for a contouring method and atlas of organs at risk in nasopharyngeal carcinoma patients receiving intensity-modulated radiotherapy.

BACKGROUND AND PURPOSE: To recommend contouring methods and atlas of organs at risk (OARs) for nasopharyngeal carcinoma (NPC) patients receiving intensity-modulated radiotherapy, in order to help reach a consensus on interpretations of OARs delineation. METHODS AND MATERIALS: Two to four contouring methods for the middle ear, inner ear, temporal lobe, parotid gland and spinal cord were identified via systematic literature review; their volumes and dosimetric parameters were compared in 41 patients. Areas under the receiver operating characteristic curves for temporal lobe contouring were compared in 21 patients with unilateral temporal lobe necrosis (TLN). RESULTS: Various contouring methods for the temporal lobe, middle ear, inner ear, parotid gland and spinal cord lead to different volumes and dosimetric parameters (P<0.05). For TLN, D1 of PRV was the most relevant dosimetric parameter and 64Gy was the critical point. We suggest contouring for the temporal lobe, middle ear, inner ear, parotid gland and spinal cord. A CT-MRI fusion atlas comprising 33 OARs was developed. CONCLUSIONS: Different dosimetric parameters may hinder the dosimetric research. The present recommendation and atlas, may help reach a consensus on subjective interpretation of OARs delineation to reduce inter-institutional differences in NPC patients.