Significance of primary tumor volume and T-stage on prognosis in nasopharyngeal carcinoma treated with intensity-modulated radiation therapy

Patterns of failure in patients with nasopharyngeal cancer of Northeastern region of India: a retrospective observational study

PURPOSE

We aimed to analyze patterns of failure and disease volume-treatment outcomes in patients with Nasopharyngeal carcinoma (NPC) treated with definitive radiation with or without concurrent chemotherapy at a tertiary cancer centre in northeast India.

METHODS

From February 2018 to February 2022, 99 histopathologically proved non-metastatic NPC patients treated with curative-intent RT with or without chemotherapy were retrospectively analyzed. Locally advanced patients received neoadjuvant or adjuvant chemotherapy. The Cox proportional hazards model was used to investigate the impact of various prognostic factors on locoregional free survival (LRFS), distant metastasis free survival (DMFS), progression free survival (PFS) and overall survival (OS). The log-rank test and Kaplan-Meir curves compared outcome variables based on ROC analysis-classified tumor volume.

RESULTS

During a median follow up of 25.4 months (17.3-39.2), 35(35.4%) patients developed recurrence. Twenty-three patients developed locoregional failures, of which 11 were in-field; 12 patient showed an out-field failure. The 3-year LRFS, DMFS, PFS and OS was 71.10%, 70.90%, 64.10% and 74.10% respectively. There was statistically significant difference in LRFS according to T staging (p < 0.0001). Gross tumor volume (GTVp) and gross nodal volume (GTVn) were an independent prognostic factor for OS, PFS, LRFS and DMFS. The cut-off volumes for GTVp and GTVn for distant metastases and locoregional failure, respectively, were found to be 13 and 22.7 mL and 3.7 and 39.2 mL, respectively, by ROC curve analysis. Based on this, 99 patients were divided into three subgroups. OS demonstrated significant differences among patients in different volume subgroups for GTVp (p = 0.03) and GTVn (p = 0.00024).

CONCLUSIONS

For NPC patients who undergo curative IMRT, primary tumour and nodal volumes are independent prognostic indicators. GTVp and GTVn are highly predictive of local control, distant metastases, disease-free survival, and overall survival. This justifies their use as quantitative prognostic indicator for NPC.

Significance of radiologic extranodal extension in locoregionally advanced nasopharyngeal carcinoma with lymph node metastasis: a comprehensive nomogram

OBJECTIVE

We aimed to assess the significance of rENE and creat a predictive tool (nomogram) for estimating Overall Survival (OS) in locoregionally advanced Nasopharyngeal Carcinoma (NPC) patients with Lymph Node Metastasis (LNM) based on their clinical characteristics and Radiologic Extranodal Extension (rENE).

METHODS

Five hundred and sixty-nine NPC patients with LNM were randomly divided into training and validation groups. Significant factors were identified using univariate and multivariate analyses in the training cohort. Then, the nomogram based on the screening results was established to predict the Overall Survival (OS). Calibration curves and the Concordance index (C-index) gauged predictive accuracy and discrimination. Receiver Operating Characteristic (ROC) analysis assessed risk stratification, and clinical utility was measured using Decision Curve Analysis (DCA). The nomogram's performance was validated for discrimination and calibration in an independent validation cohort.

RESULTS

A total of 360 (63.2%) patients were present with radiologic extranodal extension at initial diagnosis. Patients with rENE had significantly lower OS than other patients. Multivariate analysis identified the five factors, including rENE, for the nomogram model. The C-index was 0.75 (0.71-0.78) in the training cohort and 0.76 (0.69-0.83) in the validation cohort. Notably, the nomogram outperformed the 8th TNM staging system, as evident from the higher AUC values (0.77 vs. 0.60 for 2year and 0.75 vs. 0.65 for 3year) and well-calibrated calibration curves. Decision curve analysis indicated improved Net Benefit (NB) with the nomogram for predicting OS. The log-rank test confirmed significant survival distinctions between risk groups in both training and validation cohorts.

CONCLUSIONS

We demonstrated the prognostic value of rENE in nasopharyngeal carcinoma and developed a nomogram based on rENE and other factors to provide individual prediction of OS for locoregionally advanced nasopharyngeal carcinoma with lymph node metastasis.

LEVEL OF EVIDENCE

III.

Optimized Nomogram for Nasopharyngeal Carcinoma Prognosis Prediction in Younger Patients (Aged 18-59): Development and Validation

PURPOSE

To develop a nomogram model for the predicted overall survival (OS) in patients aged 18 to 59 years with nasopharyngeal carcinoma (NPC) and assess the value of the clinical application.

METHODS

In total, 1334 registers of NPC patients from 2010 to 2015 were retrieved from the Surveillance, Epidemiology, and End Results database. Univariate and multivariate Cox analysis were used to screen out independent risk factors affecting patients. Cox analysis predicted OS for patients with NPC at 3, 5, and 8 years. Nomogram performance was validated using the concordance index (C-index), receiver operating characteristic, calibration curve, and decision curve analysis (DCA).

RESULTS

Age, sex, race, marital, histological type, tumor size, AJCC stage, and radiotherapy were independent risk factors. The C-index of the nomogram was 0.69 [95% confidence interval (CI): 0.68-0.71] for the training set, and the C-index of the AJCC stage was 0.63 (95% CI: 0.62-0.65), both statistically significant (P < .01). The area under the curve for the nomogram at these intervals (0.755, 0.729, and 0.729, respectively) was higher than that of the AJCC stage (0.667, 0.646, and 0.646, respectively), indicating better predictive accuracy. The calibration curves revealed a high degree of agreement between the observation and the prediction. Compared to the American Joint Committee on Cancer (AJCC) stage, DCA showed better clinical utility.

CONCLUSION

The nomogram as novel predictor for nasopharyngeal carcinoma patients' survival.

Two web-based dynamically interactive nomograms and risk stratification systems for predicting survival outcomes and guiding treatment in non-metastatic nasopharyngeal carcinoma

BACKGROUND

A nomogram is a valuable and easily accessible tool for individualizing cancer prognosis. This study aims to establish and validate two prognostic nomograms for long-term overall survival (OS) and cancer-specific survival (CSS) in non-metastatic nasopharyngeal carcinoma (NPC) patients and to investigate the treatment options for the nomogram-based risk stratification subgroups.

METHODS

A total of 3959 patients with non-metastatic NPC between 2004 and 2015 were identified from the Surveillance, Epidemiology, and End Results (SEER) database. The patients were randomly allocated to the training and validation cohorts in a 7:3 ratio. Prognostic nomograms were constructed to estimate OS and CSS by integrating significant variables from multivariate Cox regression employing a backward stepwise method. We examined the correlation indices (C-index) and areas under the curves (AUC) of time-dependent receiver operating characteristic curves to assess the discriminative ability of our survival models. The comprehensive enhancements of predictive performance were evaluated with net reclassification operating improvement (NRI) and integrated discrimination improvement (IDI). Reliability was validated using calibration plots. Decision curve analysis (DCA) was used to estimate clinical efficacy and capability. Finally, the nomogram-based risk stratification system used Kaplan-Meier survival analysis and log-rank tests to examine differences between subgroups.

RESULTS

The following independent parameters were significant predictors for OS: sex, age, race, marital status, histological type, median household income, AJCC stage tumor size, and lymph node size. Except for the race variables mentioned above, the rest were independent prognostic factors for CSS. The C-index, AUC, NRI, and IDI indicated satisfactory discriminating properties. The calibration curves exhibited high concordance with the exact outcomes. Moreover, the DCA demonstrated performed well for net benefits. The prognosis significantly differed between low- and high-risk patients (p < 0.001). In a treatment-based stratified survival analysis in risk-stratified subgroups, chemotherapy benefited patients in the high-risk group compared to radiotherapy alone. Radiotherapy only was recommended in the low-risk group.

CONCLUSIONS

Our nomograms have satisfactory performance and have been validated. It can assist clinicians in prognosis assessment and individualized treatment of non-metastatic NPC patients.

Recommendation for imaging follow-up strategy based on time-specific disease failure for nasopharyngeal carcinoma

BACKGROUND

To develop a common follow-up strategy for appropriate imaging examination at an appropriate time for nasopharyngeal carcinoma (NPC).

METHODS

Independent prognostic factors were identified by Cox regression analysis, and a nomogram model was developed. Random survival forest (RSF) model was constructed to depict probability of disease failure during a 5-year follow-up and establish a reasonable risk-based follow-up strategy.

RESULTS

The nomogram model finally categorized the patients into three risk groups. RSF model demonstrated distribution trends for local and regional recurrences, bone metastasis, liver metastasis, and lung metastasis of NPC. Adequate imaging at follow-up should be considered between 10 and 21 months for patients at moderate-risk of recurrence or metastasis and 7-36 months for those at high-risk.

CONCLUSIONS

The temporal distribution of incidence rates of recurrence or metastasis varied among different risk groups. We recommend implementing a focused and targeted imaging surveillance intervention at appropriate times to improve its efficiency and reduce costs.

Biological target volume based on fluorine-18-fluorode-oxyglucose positron emission tomography/computed tomography imaging: a spurious proposition?

PURPOSE

To assess whether the high metabolic region of fluorine-18-fluorode-oxyglucose (¹⁸F-FDG) in the primary lesion is the crux for recurrence in patients with nasopharyngeal carcinoma (NPC), to assess the feasibility and rationale for use of biological target volume (BTV) based on ¹⁸F-FDG positron emission tomography/computed tomography (¹⁸F-FDG-PET/CT).

METHODS

The retrospective study included 33 patients with NPC who underwent ¹⁸F-FDG-PET/CT at the time of initial diagnosis as well as the time of diagnosis of local recurrence. Paired ¹⁸F-FDG-PET/CT images for primary and recurrent lesion were matched by deformation coregistration method to determine the cross-failure rate between two lesions.

RESULTS

The median volume of the V_pri (primary tumor volume using the SUV thresholds of 2.5), the V_high (the volume of high FDG uptake using the SUV50%max isocontour), and the V_recur (the recurrent tumor volume using the SUV thresholds of 2.5) were 22.85, 5.57, and 9.98 cm³, respectively. The cross-failure rate of V_recur∩high showed that 82.82% (27/33) of local recurrent lesions had < 50% overlap volume with the region of high FDG uptake. The cross-failure rate of V_recur∩pri showed that 96.97% (32/33) of local recurrent lesions had > 20% overlap volume with the primary tumor lesions and the median cross rate was up to 71.74%.

CONCLUSION

¹⁸F-FDG-PET/CT may be a powerful tool for automatic target volume delineation, but it may not be the optimal imaging modality for dose escalation radiotherapy based on applicable isocontour. The combination of other functional imaging could delineate the BTV more accurately.

Analysis of risk characteristics for metachronous metastasis in different period of nasopharyngeal carcinoma

OBJECTIVE

To identify the main risk factors for metachronous metastatic nasopharyngeal carcinoma (NPC) in different periods after radiotherapy and estimate the weight of various factors in the early or late metachronous metastasis (EMM/LMM) groups.

METHODS

This retrospective registry consists of 4434 patients with newly diagnosed NPC. Cox regression analysis was used to assess the independent significance of various risk factors. The Interactive Risk Attributable Program (IRAP) was used to calculate the attributable risks (ARs) for metastatic patients during different periods.

RESULTS

Among 514 metastatic patients, 346 (67.32%) patients diagnosed with metastasis within 2 years after treatment were classified into the EMM group, while other 168 patients were classified into the LMM group. The ARs of T-stage, N-stage, pre-Epstein-Barr virus (EBV) DNA, post-EBV DNA, age, sex, pre-neutrophil-to-lymphocyte ratio, pre-platelet-to-lymphocyte ratio, pre-hemoglobin (HB), and post-HB were 20.19, 67.25, 2.81, 14.28, 18.50, - 11.17%, 14.54, 9.60, 3.74% and - 9.79%, respectively, in the EMM group. In the LMM group, the corresponding ARs were 3.68, 49.11, - 18.04%, 2.19, 6.11, 0.36, 4.62, 19.77, 9.57 and 7.76%, respectively. After multivariable adjustment, the total AR for tumor-related factors was 78.19%, and that for patient-related factors was 26.07% in the EMM group. In the LMM group, the total AR of tumor-related factors was 43.85%, while the weights of patient-related factors was 39.97%. In addition, except for these identified tumor- and patient-related factors, other unevaluated factors played a more important role in patients with late metastasis, with the weight increasing by 15.77%, from 17.76% in the EMM group to 33.53% in the LMM group.

CONCLUSION

Most metachronous metastatic NPC cases occurred in the first 2 years after treatment. Early metastasis was mainly affected by tumor-related factors, which accounted for a declining percentage in the LMM group.

The effect of primary tumor volume on the prognosis of nasopharyngeal carcinoma in era of volumetric modulated arc therapy: a propensity score matched cohort study

OBJECTIVE

The role of Primary Tumor Volume (PTV) in Nasopharyngeal Carcinoma (NPC) treated with Volumetric Modulated Arc Therapy (VMAT) is still unclear. The aim of this study was to access the effect of PTV in prognosis prediction of nasopharyngeal carcinoma in era of VMAT.

METHODS

Between January 20 and November 2011, 498 consecutive NPC patients with stage I-IVA disease who received VMAT at a single center were retrospectively analyzed. Receiver Operating Characteristic (ROC) was performed to access the cut-off point of PTV. Univariate Kaplan-Meier and multivariate Cox regression analyses were used to evaluate prognostic value for PTV. The Propensity Score Matching (PSM) was used to adjust baseline potential confounders.

RESULTS

The 5-year Locol-Regional Failure-Free (L-FFR), Distant Failure-Free Survival (D-FFR), Disease-Free Survival (DFS) and Overall Survival (OS) were 90.6%, 83.7%, 71.5% and 79.3%, respectively. Before PSM, the 5-year L-FFR, D-FFR, DFS, OS rates for NPC patients with PTV ≤ 38 mL vs. PTV > 38 mL were 94.1% vs. 90.4% (p = 0.063), 87.9% vs. 76.3% (p < 0.001), 78.5% vs. 58.5% (p < 0.001) and 86.3% vs. 66.7% (p < 0.001) respectively. Multivariate analysis showed PTV was an independent prognostic factor for D-FFS (p = 0.034), DFS (p = 0.002) and OS (p = 0.001). PTV classified was still an independent prognostic factor for OS after PSM (HR = 2.034, p = 0.025.

CONCLUSIONS

PTV had a substantial impact on the prognosis of NPC patients treated with VMAT before and after PSM simultaneously. PTV > 38 mL may be considered as an indicator of the clinical stage of nasopharyngeal carcinoma.

LEVEL OF EVIDENCE

III.

Which evaluation criteria of the short-term efficacy can better reflect the long-term outcomes for patients with nasopharyngeal carcinoma?

•

1D, 2D, and 3D measurements were all significantly correlated with PTV measurement.

•

The 1D measurement more closely agreed with the PTV measurement than the 2D and 3D measurements.

•

1D tumor response assessment of the short-term efficacy can reflect the PFS for patients with nasopharyngeal carcinoma.

Purpose

To compare the consistency of one-dimensional Response Evaluation Criteria in Solid Tumors (1D-RECIST), two-dimensional WHO criteria (2D-WHO), and three-dimensional (3D) measurement for therapeutic response assessment of nasopharyngeal carcinoma (NPC).

Materials and methods

Retrospective data of 288 newly diagnosed NPC patients were reviewed. Tumor size was assessed on magnetic resonance imaging (MRI) according to the 1D-RECIST, 2D-WHO, and 3D measurement criteria. Agreement between tumor responses was assessed using unweighted k statistics. The receiver operating characteristic (ROC) curve was used to determine the optimal cut-off point of the PTV. The Kaplan–Meier method and Cox regression were used for the survival analysis.

Results

The optimal cut-off point of the PTV for progression-free survival (PFS) was 29.6%. Agreement with PTV measurement was better for 1D measurement than for 2D and 3D measurements (kappa values of 0.646, 0.537, and 0.577 for 1D, 2D, and 3D measurements, respectively; P < 0.05). The area under the curve of the 1D measurement (AUC=0.596) was similar to that of the PTV measurement (AUC=0.621). Compared with 2D and 3D measurements, 1D measurement is superior for predicting prognosis in NPC (C-index of 0.672, 0.663, and 0.646 were for 1D, 2D, and 3D measurements, respectively; P < 0.005). Survival analysis showed that patients with non-responders had worse prognosis (P < 0.05).

Conclusions

The 1D measurement more closely agreed with the PTV measurement than the 2D and 3D measurements for predicting therapeutic responses in NPC. Therefore, we recommend using the less time-consuming 1D-RECIST criteria in routine clinical practice.

Prognostic Relevance of Change in Body Mass Index in Patients With Nasopharyngeal Carcinoma Undergoing Volumetric Modulated Arc Therapy: A Retrospective Study

Objective

To assess the effect of pretreatment body mass index (BMI) and the extent of change in BMI (ΔBMI) during the treatment course on the treatment outcomes in patients with nasopharyngeal carcinoma (NPC) receiving volumetric modulated arc therapy (VMAT).

Methods

Data pertaining to 498 consecutive NPC patients with stage I–IVA disease who received VMAT between January 2010 and November 2011 at a single center were retrospectively analyzed. Univariate Kaplan-Meier and multivariate Cox regression analyses were used to evaluate the prognostic significance of pretreatment BMI and ΔBMI. Receiver operating characteristic (ROC) curve analysis was used to determine the optimal cut-off point of ΔBMI.

Results

The 5-year loco-regional failure-free (L-FFR), distant failure-free survival (D-FFR), disease-free survival (DFS), and overall survival (OS) rates were 90.6%, 83.7%, 71.5% and 79.3%, respectively. The 5-year L-FFR, D-FFR, DFS, OS rates for NPC patients with ΔBMI ≤1 kg/m² vs ΔBMI >1 kg/m² were 92.3% vs 89.3% (P = .137), 90.9% vs 78.5% (P < .001), 80.4% vs 65.1% (P < .001), and 88.0% vs 73.0% (P < .001), respectively. ΔBMI >1 kg/m² was an independent predictor of D-FFR (P = .002), DFS (P = .002), and OS (P = .001).

Conclusions

ΔBMI during treatment course may have a significant impact on the prognosis of NPC patients receiving VMAT.

Tumor Blood Flow Is a Predictor of Radiotherapy Response in Patients With Nasopharyngeal Carcinoma

Purpose

The aim of this study was to evaluate tumor blood flow (TBF) as a predictor of radiotherapy response for nasopharyngeal carcinoma (NPC).

Materials and Method

A total of 134 patients were divided into two groups, the complete response (CR) group and the partial response (PR) group based on RECIST 1.1 recommendations. The statistical difference was evaluated for pre- and mid- or post-treatment TBF and changes of TBF for tumors and metastatic lymph nodes between CR and PR, respectively. The receiver operation characteristic (ROC) curve was utilized to evaluate the accuracy of TBF in predicting the response of radiation therapy. The association between TBF and SUVmax was also investigated.

Results

The reduction of TBF in CR was significantly lower than that in PR for primary tumors (P <0.001) and metastatic lymph nodes (P <0.001). The multivariate logistic regression analysis indicated that the reduction of TBF is an independent predictor of the response of radiation therapy for primary tumors (P <0.001) and metastatic lymph nodes (P <0.001). The accuracy of TBF reduction in predicting the response of radiation therapy was 0.817 in primary tumors and 0.924 in metastatic lymph nodes, respectively. No significant correlation was observed between the TBF values and SUVmax of primary tumors (r = -0.008, P = 0.954) and metastasis lymph nodes (r = -0.061, P = 0.652).

Conclusion

This study suggests that the reduction of TBF is a promising parameter for evaluating the response of radiation therapy.

Prognostic value of neutrophils for patients with nasopharyngeal carcinoma

OBJECTIVE

To investigate the relationship between absolute neutrophils count (ANC) in different periods of treatment and the outcomes of patients and assess effect of longitudinal neutrophils variation during radiotherapy (RT) on prognosis in patients with nasopharyngeal carcinoma (NPC).

METHODS

A total of 1753 patients with newly diagnosed NPC were retrospectively analyzed. Complete blood counts of patients were obtained before treatment, before, during, and end of RT. The survival rate was calculated by Kaplan-Meier method and the result was compared by the log-rank test. The univariate and multivariate COX regression analyses were performed to investigate the association between the variation of ANC and survival for patients in different periods.

RESULTS

Higher ANC pretreatment (>4 × 109/L) and pre-RT (>7 × 109/L) were correlated with poor OS (89.7% vs 85.6%, P = .009; 88.3% vs 77.3%, P = .002, respectively). An increase >5 × 109/L of ANC during RT was associated with adverse OS (87.9% vs 73.6%, P = .042). The multivariate Cox regression analysis showed that high ANC of pre-RT (>7 × 109/L) and a high increase (>5 × 109/L) of ANC during RT were independent prognostic factors of patients with NPC (P = .002, .044, respectively).

CONCLUSION

Our results demonstrated that ANC was an independent prognostic factor for survival in patients with NPC who received RT. Neutrophils may promote tumor resistance to radiotherapy in NPC.

LEVEL OF EVIDENCE

2a.

Grading Soft Tissue Involvement in Nasopharyngeal Carcinoma Using Network and Survival Analyses: A Two-Center Retrospective Study

BACKGROUND

Soft tissue involvement (STI) indicates poor prognosis in nasopharyngeal carcinoma (NPC). However, only a few studies have systematically assessed this extension using network analysis.

PURPOSE

To investigate the prognostic value of STI and to propose an improved STI grading system for NPC therapy.

STUDY TYPE

Retrospective study.

POPULATION

A total of 1225 consecutive patients with pathologically confirmed NPC treated with intensive-modulated radiotherapy from January 2010 to March 2014 were enrolled from two centers.

FIELD STRENGTH/SEQUENCE

T1- and T2-weighted imaging and enhanced T1-weighted imaging with fast spin echo sequence at 1.5 or 3.0 T.

ASSESSMENT

The levator veli palatini and tensor veli palatini involvement were graded "mild," prevertebral muscle involvement, "moderate," medial pterygoid, lateral pterygoid, and the infratemporal fossa involvement, "severe" STI. The above STI sites were evaluated separately by three radiologists using MRI images and graded using network analysis. Overall survival (OS) and progression-free survival (PFS) were assessed.

STATISTICAL TESTS

Kaplan-Meier method, Cox's proportional hazards model, and concordance index (C-index) were used.

RESULTS

Five-year OS and PFS rates between mild and moderate groups (90.5% vs. 81.7%, P < 0.05 and 82.9% vs. 72.5%, P < 0.05, respectively) and between moderate and severe groups (81.7% vs. 70.4%, P < 0.05 and 72.5% vs. 61.2%, P < 0.05, respectively) revealed significant differences. The C-index of the nomogram with STI grading was higher compared with current T-classification (OS 0.641 vs. 0.604, P < 0.05 and PFS 0.605 vs. 0.581, P < 0.05, respectively). Significant OS differences were observed between patients with severe STI who underwent induction chemotherapy (IC) and those who did not (84.5% vs. 70.7%, P < 0.05).

DATA CONCLUSION

STI grading was an independent prognostic factor for OS and PFS in NPC patients and it may be help to improve the accuracy in predicting survival outcomes. Patients with severe STI might benefit from IC to improve OS.

LEVEL OF EVIDENCE

4 TECHNICAL EFFICACY: Stage 2.

Significance of boost dose for T4 nasopharyngeal carcinoma with residual primary lesion after intensity-modulated radiotherapy

BACKGROUND

Previous studies showed poorer survival in T4 disease with residual lesion. To evaluate the efficacy and toxicity of a boost dose for T4 nasopharyngeal carcinoma (NPC), patients with a residual primary lesion after intensity-modulated radiotherapy (IMRT).

METHODS

398 T4 NPC patients with residual primary lesions after radical IMRT were retrospectively reviewed. An IMRT boost dose of 4-6.75 Gy was delivered to the residual lesions in 2-3 fractions. Propensity score matching (PSM) was applied to balance potential confounders between groups (ratio, 1:2). The presence of Epstein-Barr virus (EBV) DNA in plasma after IMRT was used for risk stratification.

RESULTS

Patients who received boost radiation had significantly improved overall survival (OS) and local recurrence-free survival (LRFS) compared with those who did not (all P < 0.05). In the matched cohort, 3-year OS was 86.6% in the boost radiation group and 72.7% in the non-boost group (P = 0.022). Three-year LRFS was 93.4% in the boost radiation group and 83.5% in the non-boost group (P = 0.022). In the subgroup analysis, boost dose was shown to significantly improve 3-year OS (88.0% vs. 74.1%, P = 0.021) in the low-risk group (with undetectable plasma EBV DNA after IMRT). The administration of a boost dose also improved 3-year OS in the high-risk group (with detectable plasma EBV DNA after IMRT) (66.7% vs. 60.0%, P = 0.375). Multivariate analysis demonstrated that boost dose was the only protective prognostic factor.

CONCLUSION

The addition of a boost dose for T4 NPC patients with residual primary lesion after radical IMRT provides satisfactory tumor control and clinical benefit. Additional timely and effective strengthening treatments are recommended for patients with detectable levels of plasma EBV DNA after radiotherapy.

Development and Validation of Prognostic Nomograms Based on Gross Tumor Volume and Cervical Nodal Volume for Nasopharyngeal Carcinoma Patients With Concurrent Chemoradiotherapy

PURPOSE

Our study aimed to establish and validate prognostic nomograms based on gross tumor volume (GTV) and cervical nodal volume (CNV) for nasopharyngeal carcinoma (NPC) patients treated with two cycles of concurrent chemoradiotherapy (CCRT).

METHODS

From 2012 to 2015, 620 eligible patients who received radical treatment at the Cancer Hospital of Shantou University Medical College were recruited for a nomogram study. Variables were determined in a training set of 463 patients from 2012 to 2014 by X-tile analysis, univariate and multivariate Cox proportional hazard analyses, and the least absolute shrinkage and selection operator (LASSO). Another cohort of 157 patients in 2015 was validated with bootstrap resampling. The concordance index (C-index) and calibration curves were applied to assess its predictive discriminative and accuracy ability, while decision curve analysis (DCA), X-tile analysis and Kaplan-Meier curve for clinical application.

RESULTS

Independent prognostic variables for overall survival (OS) were age, GTV, CNV, cranial nerve, positive cervical lymph node laterality below the caudal border of cricoid cartilage (LNBC), and were selected for the nomogram. Optimal prognostic factors including Karnofsky performance status (KPS), age, GTV, CNV, LNBC were incorporated in the nomogram for progression-free survival (PFS). In the training set, the C-index of our nomograms for OS and PFS were 0.755 (95% CI, 0.704 to 0.807) and 0.698 (95% CI, 0.652 to 0.744). The calibration curve showed good agreement between nomogram-predicted and actual survival. DCA indicated that our nomograms were of clinical benefit.

CONCLUSION

Our nomograms are capable of effective prognostic prediction for patients with NPC.

Three-dimensional (3D) magnetic resonance volume assessment and loco-regional failure in anal cancer: early evaluation case-control study

Background

The primary aim was to test the hypothesis that deriving pre-treatment 3D magnetic resonance tumour volume (mrTV) quantification improves performance characteristics for the prediction of loco-regional failure compared with standard maximal tumour diameter (1D) assessment in patients with squamous cell carcinoma of the anus undergoing chemoradiotherapy.

Methods

We performed an early evaluation case-control study at two UK centres (2007–2014) in 39 patients with loco-regional failure (cases), and 41 patients disease-free at 3 years (controls). mrTV was determined using the summation of areas method (Vol_sum). Reproducibility was assessed using intraclass concordance correlation (ICC) and Bland-Altman limits of agreements. We derived receiver operating curves using logistic regression models and expressed accuracy as area under the curve (ROC_AUC).

Results

The median time per patient for Vol_sum quantification was 7.00 (inter-quartile range, IQR: 0.57–12.48) minutes. Intra and inter-observer reproducibilities were generally good (ICCs from 0.79 to 0.89) but with wide limits of agreement (intra-observer: − 28 to 31%; inter-observer: − 28 to 46%). Median mrTVs were greater for cases (32.6 IQR: 21.5–53.1 cm³) than controls (9.9 IQR: 5.7–18.1 cm³, p < 0.0001). The ROC_AUC for mrT-size predicting loco-regional failure was 0.74 (95% CI: 0.63–0.85) improving to 0.82 (95% CI: 0.72–0.92) when replaced with mrTV (test for ROC differences, p = 0.024).

Conclusion

Preliminary results suggest that the replacement of mrTV for mrT-size improves prediction of loco-regional failure after chemoradiotherapy for squamous cell carcinoma of the anus. However, mrTV calculation is time consuming and variation in its reproducibility are drawbacks with the current technology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-020-07613-7.

Using deep learning to model the biological dose prediction on bulky lung cancer patients of partial stereotactic ablation radiotherapy

PURPOSE

To develop a biological dose prediction model considering tissue bio-reactions in addition to patient anatomy for achieving a more comprehensive evaluation of tumor control and promoting the automatic planning of bulky lung cancer.

METHODS

A database containing images and partial stereotactic ablation boost radiotherapy (P-SABR) plans of 94 bulky lung cancer patients was studied. Patient-specific parameters of gross tumor boost volume (GTVb), planning gross target volume (PGTV), and identified organs at risk (OARs) were extracted via Numpy and simple ITK. The original dose and structure maps for P-SABR patients were resampled to have a voxel resolution of 3.9 × 3.9 × 3 mm³ . Biological equivalent dose (BED) distributions were reprogrammed based on physical dose volumes. A developed deep learning architecture, Nestnet, was adopted as the training framework. We utilized two approaches for data organization to correlate the structures and BED: (a) BED programming before training model (B-Nestnet); (b) BED programming after the training process (D-B Nestnet). The early-stop mechanism was adopted on the validation set to avoid overfitting. The evaluation criteria of predictive accuracy contain the minimum BED of GTVb and PGTV, the maximum and the mean BED of all targets, BED-volume metrics. For comparison, we also used the original Unet for BED prediction. The absolute differences were statistically analyzed with the paired-samples t test.

RESULTS

The statistical outcomes demonstrate that D-B Nestnet model predicts biological dose distributions accurately. The average absolute biases of [max, mean] BED for GTVb, PGTV are [2.1%, 3.3%] and [2.1%, 4.7%], respectively. Averaging across most of OARs, the D-B Nestnet model is capable of predicting the errors of the max and mean BED within 6.3% and 6.1%, respectively. While the compared models performed worse with averaged max and mean BED prediction errors surpassing 10% on some specific OARs.

CONCLUSIONS

The study developed a D-B Nestnet model capable of predicting BED distribution accurately for bulky lung cancer patients in P-SABR. The predicted BED map enables a quick intuitive evaluation of tumor ablation, modification of the ablation range to improve BED of tumor targets, and quality assessment. It represents a major step forward toward automated P-SABR planning on bulky lung cancer in real clinical practice.

Effectiveness and cost-effectiveness analysis of nimotuzumab for the radiotherapy of locoregionally advanced nasopharyngeal carcinoma

BACKGROUND

This study aimed to assess the effectiveness and cost-effectiveness of nimotuzumab in patients with locoregionally advanced nasopharyngeal carcinoma (LA-NPC).

METHODS

LA-NPC patients treated between October 2013 and December 2016 were retrospectively reviewed. A well-balanced cohort of patients who received nimotuzumab in addition to standard treatment (n = 50) and patients who did not receive nimotuzumab (n = 100) was selected using propensity score-matching method (1:2 ratio) for the cost-effectiveness analysis.

RESULTS

Compared with concurrent chemoradiotherapy (CCRT) alone, addition of nimotuzumab to CCRT significantly improved the 3-year overall survival (OS) (98.00% vs. 91.00%, P = 0.032). On multivariate analysis, nimotuzumab (hazard ratio = 0.124, 95% confidence interval: 0.017-0.902, P = 0.039) showed prognostic significance for OS. No serious treatment-related adverse events were observed in the nimotuzumab group (P > 0.05). Cost-effectiveness analysis revealed that addition of nimotuzumab increased the average treatment costs by $14,364.63. The additional cost for every one percent increase in OS rate was $ 2,052.09.

CONCLUSION

Addition of nimotuzumab to CCRT for LA-NPC confers significant survival benefits; however, it is not cost-effective.

Outcomes and Experiences of Child-Bearing Women with Nasopharyngeal Carcinoma

Purpose

Nasopharyngeal carcinoma (NPC) is more common among women in Southeast Asia. An important issue is whether it is safe for them to bear children after treatment and when it is safe to do so. We conducted this study to explore the relation between fertility and prognosis in child-bearing women with NPC.

Patients and Methods

Child-bearing women were defined as young women between the ages of 18 and 30. A total of 127 eligible child-bearing NPC patients were identified from December 2003 to December 2014. The patients were divided into two groups, depending on whether or not they had post-therapeutic births. The Kaplan–Meier method was used for survival analyses. The Log rank test was used to compare two survival curves and the independent significances of different prognostic factors were assessed by Cox proportional hazards regression analysis.

Results

The 5-year overall survival (OS) and disease-free survival (DFS) in the Childbirth group were significantly higher than those in the Non-Childbirth group (100% vs 88.8%, P = 0.026 and 100% vs 77.5%, P = 0.007, respectively). In the Childbirth group, no difference was found in the 5-year DFS between different birth interval times, from 1 to 5 years after treatment. The clinical stage was identified as the risk factor of OS (HR = 101.725, 95% CI: 2.160–4790.910, P = 0.019), and consequent childbirth after treatment was associated with favorable DFS (HR = 0.148, 95% CI: 0.034–0.643, P = 0.011).

Conclusion

Post-therapeutic birth did not increase the mortality risk of child-bearing women with NPC. There was no significant correlation between the subsequent birth time window after treatment and the prognosis.

Metastatic Patterns and Prognosis of de novo Metastatic Nasopharyngeal Carcinoma in the United States

OBJECTIVE

To evaluate the distant metastatic patterns and prognostic factors for overall survival (OS) and cancer-specific survival (CSS) in de novo metastatic nasopharyngeal carcinoma (mNPC) using the Surveillance, Epidemiology, and End Results (SEER) database.

METHODS

Patients with de novo mNPC who had been diagnosed between 2004 and 2016 were identified from the SEER database. Kaplan-Meier analysis was used to calculate OS and CSS. Log-rank tests were employed to measure survival variation among subgroups. Individual predictors of CSS and OS were examined using Cox proportional-hazards regression models in patients with de novo mNPC.

RESULTS

We evaluated 224 patients with de novo mNPC who matched our inclusion criteria. Three-year CSS and OS for the whole cohort was 29.8% and 27.9%, respectively. Univariate analysis indicated that CSS and OS were influenced by age, histology, radiotherapy, chemotherapy, and liver metastasis. Neither the number of metastatic sites nor their specific location in bone, lungs, distant lymph nodes or brain significantly affected CSS or OS. The aforementioned independent prognosticators continued to significantly influence survival following multivariate analysis. Taking distant metastasis without liver involvement as a reference, liver metastasis was associated significantly with shorter OS at a hazard ratio (HR) of 1.581 (P = .021) and CSS at a HR of 1.643 (P = .016). Older age, keratinizing squamous cell carcinoma, no chemotherapy, and no radiotherapy were also prognosticators for poor OS (P < .05). Similar results were documented for CSS (P < .05).

CONCLUSION

For patients with de novo mNPC, liver metastasis is an independent prognosticator for inferior CSS and OS.

LEVEL OF EVIDENCE

3a Laryngoscope, 131:E1130-E1138, 2021.

The comparison of prognostic value of tumour volumetric regression ratio and RECIST 1.1 criteria after induction chemotherapy in locoregionally advanced nasopharyngeal carcinoma

PURPOSE

To compare the prognostic value of the sum volumetric regression ratio (SVRR) of the primary tumour and metastatic lymph nodes with treatment response based on RECIST 1.1 criteria after induction chemotherapy in locoregionally advanced nasopharyngeal carcinoma (NPC).

METHODS AND MATERIALS

A total of 117 stage III-IVA NPC patients treated with induction chemotherapy followed by concurrent chemoradiotherapy (CCRT) were retrospectively reviewed. The SVRR and the treatment response based on RECIST 1.1 were measured using contrast-enhanced computed tomography (CT) localisations before and after induction chemotherapy. The receiver operating characteristic (ROC) curve analysis was used to identify the optimal cutoff point of the SVRR and compare the prognostic value of the SVRR and RECIST 1.1criteria.

RESULTS

The optimal cutoff points of SVRR for progression-free survival (PFS), locoregional failure-free survival (LRFFS) and distant metastasis-free survival (DMFS) were all 25.15%, while for overall survival (OS) it was 16.63%. The area under the ROC curve (AUC) of optimal cutoff points of SVRR was superior than that of RECIST 1.1 for PFS (AUC: 0.716 vs. 0.578; P = 0.0022), LRFFS (AUC: 0.700 vs. 0.574; P = 0.0080) and DMFS (AUC: 0.736 vs. 0.606; P = 0.0053), respectively. The 3-year PFS, DMFS and OS rates for SVRR less than vs. greater than or equal to the cutoff points were 55.8% vs. 92.2% (P < 0.001, hazard ratio (HR): 0.209, 95% confidence interval (CI): 0.091-0.480), 59.7% vs. 96.7% (P < 0.001, HR: 0.120, 95% CI: 0.043-0.336) and 66.7% vs. 98.1% (P < 0.001, HR: 0.069, 95% CI: 0.014-0.342), while the responses [stable disease (SD), partial response (PR)] based on RECIST 1.1 were not significantly associated with 3-year survival rates. Multivariate analysis indicated that SVRR was an independent prognostic factor for PFS, DMFS and OS (all P < 0.05).

CONCLUSIONS

The sum volumetric regression ratio and response based on RECIST 1.1 were related to the prognosis in locoregionally advanced NPC after induction chemotherapy. Sum volumetric regression ratio is an independent outcome predictor for survival in locoregionally advanced NPC, playing a better prognostic role than RECIST 1.1.

Comparison of the efficacy between concurrent chemoradiotherapy with or without adjuvant chemotherapy for stage II nasopharyngeal carcinoma

BACKGROUND

Although common, the use of concurrent chemoradiotherapy with adjuvant chemotherapy for stage II nasopharyngeal carcinoma (NPC) is controversial due to its undefined clinical benefits. We, therefore, conducted a retrospective cohort study to investigate whether adjuvant chemotherapy confers survival gains to stage II NPC patients.

METHODS

In this study, we examined whether combining adjuvant chemotherapy (AC) and/or concurrent chemotherapy with radiotherapy (CCRT) improved survival in patients with stage II NPC. Three hundred thirty-five stage II NPC patients were retrospectively analyzed between June 2003 and June 2016 and received CCRT; some patient groups also received AC every 3 weeks for 2 to 3 cycles.

RESULTS

The median follow-up duration was 72 months for all patients (range, 26-151 months) and the estimated 5-year locoregional relapse-free survival (LRRFS), distant metastasis-free survival (DMFS), progression-free survival (PFS), and overall survival (OS) rates were 95.1%, 97.8%, 93.5%, and 94.3%. At the last follow-up, there were no statistically significant differences among the CCRT and CCRT+AC groups in 5-year LRRFS (95.2% vs 94.9%, P = .599), DMFS (98.5% vs 92.4%, P = .152), PFS (93.8% vs 90.2%, P = .599), or OS (95.5% vs 93.9%, P = .682) rates.

CONCLUSION

The analyses revealed that a combined regimen was not an independent prognostic factor for any survival outcome. However, patients who received CCRT plus AC experienced more acute adverse events than those who received CCRT alone. Thus, the addition of AC to CCRT did not improve survival outcomes, but was associated with higher incidences of acute treatment-associated toxicities than CCRT alone in patients with stage II NPC.

Prognosis viewing for nasopharyngeal carcinoma treated with intensity-modulated radiation therapy: application of nomogram and decision curve analysis

OBJECTIVE

To view and evaluate the prognosis factors in patients with nasopharyngeal carcinoma (NPC) treated with intensity modulated radiation therapy using nomogram and decision curve analysis (DCA).

METHODS

Based on a primary cohort comprising consecutive patients with newly confirmed NPC (n = 1140) treated between January 2014 and December 2015, we identified independent prognostic factors of overall survival (OS) to establish a nomogram. The model was assessed by bootstrap internal validation and external validation in an independent validation cohort of 460 patients treated between January 2013 and December 2013. The predictive accuracy and discriminative ability were measured by calibration curve, concordance index (C-index) and risk-group stratification. The clinical usefulness was assessed by DCA.

RESULTS

The nomogram incorporated T-stage, N-stage, age, concurrent chemotherapy and primary tumour volume (PTV). The calibration curve presented good agreement for between the nomogram-predicted OS and the actual measured survival probability in both the primary and validation cohorts. The model showed good discrimination with a C-index of 0.741 in the primary cohort and 0.762 in the validation cohort. The survival curves of different risk-groups were separated clearly. Decision curve analysis demonstrated that the nomogram provided a higher net benefit (NB) across a wider reasonable range of threshold probabilities for predicting OS.

CONCLUSION

This study presents a predictive nomogram model with accurate prediction and independent discrimination ability compared with combination of T-stage and N-stage. The results of DCA supported the point that PTV can help improve the prognostic ability of T-stage and should be added to the TNM staging system.

Effect of relevant factors on radiation-induced nasopharyngeal ulcer in patients with primary nasopharyngeal carcinoma treated with intensity-modulated radiation therapy

OBJECTIVE

To analyze the correlation between relevant factors and radiation-induced nasopharyngeal ulcer (RINU) in primary nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiation therapy (IMRT).

METHODS

Clinical data were collected for 599 patients with newly diagnosed NPC who had completed IMRT. The entire cohort was randomly divided into two subgroups. The relationship between RINU and IMRT dose-volume were statistically analyzed with ROC curves and the Chi-square test. Nutritional status during and after treatment was compared between patients with vs without RINU.

RESULTS

The results obtained showed that dose-volume had no effect on the incidence of RINU (P > .05). Nutrition-related parameters differed significantly between patients with vs without RINU (P < .05).

CONCLUSION

The results obtained show that the incidence of RINU is not related to IMRT dose-volume in the treatment of primary NPC. The incidence of RINU was found to be related to nutritional status during and after radiation therapy.

LEVEL OF EVIDENCE

2a.

Selection of a high-level physician may help improve outcomes of nasopharyngeal carcinoma

BACKGROUND

To assess the relationship between the level of clinical radiation oncologist and the prognosis of patients with nasopharyngeal carcinoma (NPC). To our knowledge, no previous study has explicitly assessed the relationship with cancer prognosis and clinical radiation oncologists level. The effect of physicians on the prognosis has been entirely ignored.

METHODS

Clinical data were collected for 1140 patients with newly diagnosed NPC. Based on the 3-year overall survival, the treating physicians were classified into 3 grades: high-level group, medium-level group, and low-level group. Cox proportional hazards regression analysis was used to assess the independent significance of different prognostic factors. Propensity score matching (PSM) was used to minimize the influence of confounders so that difference in outcomes provides an unbiased estimate of the influence of physician. Interactive Risk Attributable Program (IRAP) was used to calculate the attribution risk of individual risk factors or a combination of multiple factors.

RESULTS

The 3-year OS in the high-level, medium-level, and low-level groups was 92.9%, 87.7%, and 83.5%, respectively (p = 0.003). After propensity score matching, the 3-year OS was 92.4%, 87.4%, and 82.9%, respectively (p = 0.004). IRAP was used to calculate the attribution risk of mortality risk. After multivariable adjustment, patient-related factors including tumor accounted for 90.02% [95% confidence interval (CI), 73.43-96.84%) and physician factors accounted for 17.66% (95% CI, 5.39-44.65%) of the mortalityrisk. All related factors, including patient-related factors and physician factors accounted for 92.02% (95% CI, 77.83-97.43%).

CONCLUSION

Our study demonstrated obvious differences in the prognosis of patients treated by various clinical radiation oncologists. The largest share of prognosis risk was found to be at the patient level, while variation in prognosis was, in part, attributable to differences among physicians.

Prognostic value of nasopharynx tumour volume in local-regional advanced nasopharyngeal carcinoma

Background

To investigate the prognostic value of pretreatment primary gross tumor with (GTVp) and without retropharyngeal lymph nodes (GTVnx) for predicting survival outcomes in patients with local-regional advanced nasopharyngeal carcinoma (NPC) after intensity-modulated radiation therapy (IMRT).

Methods

From Jan 2012 to Dec 2017, 148 patients with local-regional advanced NPC who had undergone definitive radiotherapy were identified. GTVnx volume and retropharyngeal lymph nodes (GTVrLNs) volume were measured based on registration of MRI with contrast-enhanced CT images. The Kaplan-Meier method was used for survival analysis. Univariate and multivariate prognostic analyses was performed by using the Cox proportional hazard model. Receiver operating characteristic (ROC) curves were used to identify the cut-off point and assess the prognostic value for GTVnx, GTVp and GTVrLNs.

Results

The median follow-up time for the entire group was 27 months (ranging 7 to 80 months). The 3-year overall survival (OS) rate was 85%, and the 3-year local failure-free rate (LFFR), distant failure-free rate (DFFR) and disease-free survival (DFS) rates were 93%, 81%, and 73%, respectively. A positive correlation between GTVnx or GTVp volume and T stage was observed (both P<0.001). The 3-year LFFR, OS, and DFS rate, but not for DMFS, in NPC patients with GTVnx ≤42.7 cm³ was significantly better than those with >42.7 cm³ (all P<0.05). Multivariate analysis indicated that GTVnx volume (P=0.041) was the only independent prognostic factor for LFFR, while age and AJCC stage were two independent prognostic factors for OS.

Conclusions

The GTVnx is an independent prognostic factor for local control, while the prognostic value of GTVrLNs is limited. Physicians are recommended to distinguish between GTVnx and retropharyngeal lymph nodes (RLN) involvement when assessing the risk for local recurrence in advanced NPC.

The relations of dosimetric parameters with long-term outcomes and late toxicities in advanced T-stage nasopharyngeal carcinoma with IMRT

BACKGROUND

Balancing the dose requirements between targets and normal tissue is a challenge in radiation of nasopharyngeal carcinoma (NPC). The purpose of this study is to evaluate the dosimetric parameters and clinical outcomes in NPC.

METHODS

We presented a retrospective review of patients with T3-4 NPC treated by intensity-modulated radiation therapy (IMRT). Patient characteristics, dosimetric parameters, and the follow-up data for survival and late toxicities were analyzed.

RESULTS

The 5-year overall survival, local relapse-free survival, and distant metastasis-free survival were 83.0%, 90.1%, and 82.4%, respectively. Multivariate analysis revealed that the volume of involved lymph node was an independent prognostic factor. The volume of primary tumor and the maximal dose were significant factors affecting temporal lobe injury.

CONCLUSIONS

IMRT provided satisfactory local control for advanced T-stage NPC, with acceptable late toxicities. The dose constraint criteria of selected critical structures can be appropriately loosen.

The long-term impact of tumor burden in pT3N0M0 esophageal squamous cell carcinoma: A propensity score-matched analysis

The purpose of this study was to assess the impact of tumor burden on the survival of patients with pathologic T3N0M0 (pT3N0M0) esophageal squamous cell carcinoma (ESCC).A total of 84 patients with pathologic T3N0M0 ESCC treated with radical esophagectomy and 3-field lymphadenectomy (3-FL) from January 2008 to December 2009 in our center were analyzed. Receiver-operating characteristic (ROC) curve analysis was performed to calculate the optimal cutoff value. The Kaplan-Meier method and log-rank test were used to assess the overall survival (OS) differences between groups. A regression model was applied to identify prognostic factors for OS. Propensity score matching (PSM) was performed to adjust for the imbalance and indication biases in the 2 groups.The median follow-up time was 62 months (range, 1-84 months), and the 5-year OS rate was 62% (95% confidence interval, 52.2-71.8%). According to the ROC curve analysis, the optimal cutoff values for the maximal esophageal wall thickness, tumor length, and tumor volume were 1.3 cm, 5.9 cm, and 18.6 cc, respectively. Univariate analysis revealed that maximal esophageal wall thickness >1.3 cm (P = .014), tumor volume >18.6 cc (P < .001), and vascular invasion (P < .001) were significantly associated with OS. The multivariate Cox regression model identified tumor volume and vascular invasion as factors affecting OS. After propensity matching, patients with a tumor volume ≤18.6 cc had a better OS than those with a tumor volume >18.6 cc (5-year OS, 85% vs 50%, P = .008).Tumor volume may serve as a good prognostic factor for patients with pT3N0M0 ESCC treated with radical esophagectomy and 3-FL. Larger-scale studies are warranted to validate these findings.

Depicting distant metastatic risk by refined subgroups derived from the 8th edition nasopharyngeal carcinoma TNM

BACKGROUND

Tumor-nodal-metastasis (TNM) is the most important survival predictor in nasopharyngeal carcinoma (NPC). Distant metastasis (DM) is the predominant failure pattern of NPC in the intensity-modulated radiotherapy (IMRT) era. The DM risk appears to be different for T-N subsets within the same clinical stage. Appropriately depicting DM risk has emerged as an important issue in tailoring individualized treatment and underpins the reason for this study.

METHODS

A total of 1616 non-metastatic (M0) NPC patients treated with IMRT were included. All were re-staged according to the 8th edition AJCC/UICC TNM (TNM-8). DM-free survival (DMFS) was calculated and compared among T-N subsets within each stage and DM risk groups were derived by Recursive-partitioning analysis (RPA) based on ordinal T and N categories.

RESULTS

Significant heterogeneity in DM risk was evident among T-N subsets within cTNM-8 stages II-IV. The RPA algorithm classified patients into four DM risk groups: RPA-I (T1N0-1 and T2-3N0), RPA-II (T2-3N1), RPA-III (T4N0-1 and T1-3N2) and RPA-IV (T4N2 and T1-4N3), with 5-year DMFS of 93.4% (95% CI: 91.3-96.1), 84.3% (80.8-87.8), 78.9% (75.4-82.4) and 63.6% (56.3-70.9), respectively (p < 0.001). Compared to cTNM-8 stage grouping, RPA grouping had a lower Akaike information criterion (AIC) and higher Harrell's concordance index (c-index) for DMFS.

CONCLUSIONS

Significant heterogeneity in DM risk exists among T-N subsets within cTNM-8 stages. The RPA groups demonstrated improved intra-group hazard consistency compared to cTNM-8 stage groups. While further validation is warranted, these RPA prognostic groupings provide a strong anatomic foundation to augment DM prediction for optimal targeting in future clinical trials.

Novel stereotactic body radiation therapy (SBRT)-based partial tumor irradiation targeting hypoxic segment of bulky tumors (SBRT-PATHY): improvement of the radiotherapy outcome by exploiting the bystander and abscopal effects

Background

Despite the advances in oncology, patients with bulky tumors have worse prognosis and often receive only palliative treatments. Bulky disease represents an important challenging obstacle for all currently available radical treatment options including conventional radiotherapy. The purpose of this study was to assess a retrospective outcome on the use of a newly developed unconventional stereotactic body radiation therapy (SBRT) for PArtial Tumor irradiation of unresectable bulky tumors targeting exclusively their HYpoxic segment (SBRT-PATHY) that exploits the non-targeted effects of radiotherapy: bystander effects (local) and the abscopal effects (distant).

Materials and methods

Twenty-three patients with bulky tumors received partial bulky irradiation in order to induce the local non-targeted effect of radiation (bystander effect). The hypoxic tumor segment, called the bystander tumor volume (BTV), was defined using PET and contrast-enhanced CT, as a hypovascularized-hypometabolic junctional zone between the central necrotic and peripheral hypervascularized-hypermetabolic tumor segment. Based on tumor site and volume, the BTV was irradiated with 1–3 fractions of 10–12 Gy prescribed to 70% isodose-line. The pathologic lymph nodes and metastases were not irradiated in order to assess the distant non-targeted effects of radiation (abscopal effect). No patient received any systemic therapy.

Results

At the time of analysis, with median follow-up of 9.4 months (range: 4–20), 87% of patients remained progression-free. The bystander and abscopal response rates were 96 and 52%, respectively. Median shrinkage of partially irradiated bulky tumor expressing intensity of the bystander effect was 70% (range 30–100%), whereas for the non-irradiated metastases (intensity of the abscopal effect), it was 50% (range 30–100%). No patient experienced acute or late toxicity of any grade.

Conclusions

SBRT-PATHY showed very inspiring results on exploitation of the radiation-hypoxia-induced non-targeted effects that need to be confirmed through our ongoing prospective trial.

Present study has been retrospectively registered by the local ethic committee under study number A 26/18.

Tumor volume/metabolic information can improve the prognostication of anatomy based staging system for nasopharyngeal cancer? Evaluation of the 8th edition of the AJCC/UICC staging system for nasopharyngeal cancer

Purpose

We evaluated prognostic value of the 8th edition of the American Joint Committee on Cancer/International Union for Cancer Control (AJCC/UICC) staging system for nasopharyngeal cancer and investigated whether tumor volume/metabolic information refined prognostication of anatomy based staging system.

Materials and Methods

One hundred thirty-three patients with nasopharyngeal cancer who were staged with magnetic resonance imaging (MRI) and treated with intensity-modulated radiotherapy (IMRT) between 2004 and 2013 were reviewed. Multivariate analyses were performed to evaluate prognostic value of the 8th edition of the AJCC/UICC staging system and other factors including gross tumor volume and maximum standardized uptake value of primary tumor (GTV-T and SUV-T).

Results

Median follow-up period was 63 months. In multivariate analysis for overall survival (OS), stage group (stage I-II vs. III-IVA) was the only significant prognostic factor. However, 5-year OS rates were not significantly different between stage I and II (100% vs. 96.2%), and between stage III and IVA (80.1% vs. 71.7%). Although SUV-T and GTV-T were not significant prognostic factors in multivariate analysis, those improved prognostication of stage group. The 5-year OS rates were significantly different between stage I-II, III-IV (SUV-T ≤ 16), and III-IV (SUV-T > 16) (97.2% vs. 78% vs. 53.8%), and between stage I, II-IV (GTV-T ≤ 33 mL), and II-IV (GTV-T > 33 mL) (100% vs. 87.3% vs. 66.7%).

Conclusion

Current anatomy based staging system has limitations on prognostication for nasopharyngeal cancer despite the most accurate assessment of tumor extent by MRI. Tumor volume/metabolic information seem to improve prognostication of current anatomy based staging system, and further studies are needed to confirm its clinical significance.

Evaluation of Volume of Nasopharyngeal Cancers by the Cavalieri Principle

Prediction of tumor volume using the Cavalieri method may be helpful in management of therapy and evaluation of treatment results. The aim of this study was to adapt the Cavalieri stereological method to magnetic resonance imaging for determining volume of nasopharyngeal cancers and assess changes after treatment using the Cavalieri method. Serial MRI images in the sagittal plane were obtained from a total of 33 patients with nasopharyngeal carcinomas (11 with stage T2, 11 with stage T3, and 11 with stage T4 lesions). The images were analyzed retrospectively before and two months following the cessation of radiochemotherapy for comparison. Average tumor volumes before and after treatment in patients with stage T2 were 21. 5±10.5 cm3 and 2.82±3.43 cm³, respectively (p=0.000). The respective figures were 35.1±19.0 cm3 and 6.27±7.82 cm³ (p=0.000) for stage T3 cases, and 62.8±27.8 cm3 and 11. 6±11.9 cm3 (p=0.000) for stage T4. Post-treatment tumor volumes were statistically reduced when compared to pre-treatment volumes in all stages.

Prognostic value of tumor burden in nasopharyngeal carcinoma

BACKGROUND

The prognostic value of primary tumor volume (TV) in nasopharyngeal carcinoma (NPC) has been confirmed. However, studies of the prognosis value of tumor burden, including TV and nodal volume (NV), have been relatively infrequent. Therefore, the aim of this study was to evaluate the prognostic value of tumor burden in NPC patients treated with intensity-modulated radiotherapy.

METHODS

Receiver operating characteristics curves were generated to determine rational cutoff points for TV and NV. The volumes identified included 12.5, 25.0, and 50.0 mL, and 0, 12.5, and 25 mL, respectively. According to these cutoff volumes, four subgroups were established for TV as TV1-TV4, and four subgroups were established for NV as NV0-NV3. Then, the entire cohort (992 NPC patients) was divided into 16 subgroups according to these four levels of TV and NV. Based on similarities in the 5-year overall survival (OS) rates for these 16 subgroups, four patient groups were established, G1-G4.

RESULTS

The mean TV and NV values for our cohort were 39.5±30.8 mL and 16.5±17.6 mL, respectively. The 5-year distant failure-free rate, the 5-year disease-free survival rate, and the 5-year OS rate for G3 and G4 were significantly lower than those for G1 and G2. In particular, the OS curves of the four patient groups were significantly separated. A multivariate analysis identified TV >50 mL, T-stage (3-4), and N-stage (2-3) as adverse prognostic factors for OS.

CONCLUSIONS

The results of this study demonstrate that tumor burden has a significant prognostic value for NPC patients treated with intensity-modulated radiotherapy. Hence, tumor burden, including TV and NV, should be incorporated into the current staging system for NPC to improve prognostic significance.

Unidimensional measurement may be superior to assess primary tumor response after neoadjuvant chemotherapy for nasopharyngeal carcinoma

Application of current response evaluation criteria in solid tumors (RECIST 1.1) for assessment of irregularly shaped nasopharyngeal carcinoma (NPC) is a gray area with much ambiguity. Our aim was to compare unidimensional measurements (UDM) and bidimensional measurements (BDM) on magnetic resonance images in alternative planes for measurement of tumor response after neoadjuvant chemotherapy (NACT) in patients with locally advanced NPC. 59 patients with untreated non-metastatic NPC were prospectively enrolled. The size or change in size of the primary tumor and retropharyngeal nodes was assessed by UDM and BDM on axial and coronal planes before and after 2 cycles of NACT. Tumor volume was considered as the reference standard. Correlation between volume and diameter was analyzed using a general linear model. The degree of agreement and discordance of response classification based on different measures were evaluated with κ statistic and McNemar's test, respectively. Both axial UDM (RECIST 1.1) and axial BDM (WHO) showed a significant association with volumetric standard. However, the agreement of axial UDM with VM was better than that of axial BDM (κ value: 0.514 to 0.372). In addition, when increasing coronal planes to evaluate tumor response with UDM and BDM, an inferior agreement between coronal BDM and VM was still observed. Notably, coronal UDM showed the best consistency with volume (κ = 0.585). Hence, axial UDM showed better correlation with volumetric measurements than axial BDM. Since coronal UDM showed high correlation to VM, we suggest further research to assess its use for response assessment of NPC after NACT.

The prognostic value of pretreatment tumor apparent diffusion coefficient values in nasopharyngeal carcinoma

Background

Diffusion-weighted MR imaging (DWI) has increasingly contributed to the management of nasopharyngeal carcinoma (NPC) patients. The objective of this paper was to explore the prognostic significance of apparent diffusion coefficient (ADC) values in 93 NPC patients.

Methods

This retrospective study included 93 newly diagnosed NPC patients. Pretreatment ADC values were determined and compared with patients’ age, gender, alcohol intake, smoking, tumor volume, pathological type, tumor stage, and nodal stage. Using the Kaplan-Meier method, overall survival (OS), local relapse-free survival (LRFS), and distant metastasis-free survival (DMFS) were calculated and the values compared between the low and high ADC groups. Multivariate analysis of ADC values and other 9 clinical parameters was performed using a Cox proportional hazards model to test the independent significance for OS, LRFS and DMFS.

Results

The mean ADC value for the initial nasopharyngeal tumors was 0.72 × 10⁻³ mm²/s (range: 0.48–0.97 × 10⁻³ mm²/s). There was no significant difference between pretreatment ADCs and patient’ gender, age, smoking, alcohol intake, or tumor stage. A significant difference in the ADCs for different N stages (P = 0.022) and correlation with initial tumor volume (r = −0.26, P = 0.012) were observed. In comparison, the ADC value for undifferentiated carcinoma was lower than that for other 3 pathological types. With a median follow-up period of 50 months, the 3-year and 5-year OS rates were 88.2% and 83.3%, respectively, 3-year and 5-year LRFS rates were 93.5% and 93.3%, respectively, and 3-year and 5-year DMFS rates were 83.9% and 83.3%, respectively. Patients with tumor ADC values ≥0.72 × 10⁻³ mm²/s exhibited longer OS and LRFS periods compared with tumor ADC values <0.72 × 10⁻³ mm²/s, with P values 0.036 and 0.018, respectively. In addition, patients with deaths or recurrences or distant metastasis had significant lower ADC values than those without disease failures. According to a multivariate analysis using the Cox proportional hazard test, ADC values showed a significant correlation with OS (P = 0.0004), LRFS (P = 0.0009), and DMFS (P < 0.0001), respectively.

Conclusions

Pretreatment tumor ADC values supposed to be a noninvasive important prognostic parameter for NPC.

Standardized tumor volume: an independent prognostic factor in advanced nasopharyngeal carcinoma

The study evaluated the prognostic effect of standardized tumor volume in patients with advanced nasopharyngeal carcinoma (NPC) treated with concurrent chemoradiotherapy. Between Jan 1, 2009 and December 30, 2012, 143 patients diagnosed with NPC in UICC stage III–IVb by histopathology were enrolled in the study. These patients underwent intensity-modulated radiotherapy combined with concurrent chemotherapy. The three-dimensional images of tumor volume were reconstructed automatically by the treatment planning system. SGTVnx was calculated based on GTVnx/person’s volume. SGTVnd was calculated based on GTVnd/person’s volume. SGTVnx was significantly associated with the 5-year overall survival (OS), disease-free survival (DFS), DMFS, and LRFS rates in univariate and multivariate analyses. Although SGTVnd was associated with the 5-year OS, DFS, and DMFS rates, it was not an independent prognostic factor for LRFS. In receiver operating characteristic (ROC) curve analysis, 1.091 and 0.273 were determined as the cut-off points for SGTVnx and SGTVnd, respectively. The 5-year OS, DFS, DMFS, and LRFS rates for patients with a SGTVnx > 1.091 vs. SGTVnx ≤ 1.091 was 65.4% vs. 93.4% (P < 0.001), 65.2% vs. 94.8% (P < 0.001), 71.4% vs. 97.4% (P < 0.001), and 84.8% vs. 97.3% (P = 0.003), respectively, for SGTVnd > 0.273 vs. SGTVnd ≤ 0.273 was 70.3% vs. 96.5% (P < 0.001), 70.1% vs. 94.8% (P < 0.001), 77.5% vs. 98.2% (P < 0.001), and 88.5% vs. 96.6% (P = 0.049), respectively. UICC stage grouping, T classification, N classification, and sex were not found to be independent prognostic factors for NPC. Standardized tumor volume was an independent prognostic factor for NPC that might improve the current NPC TNM classification system and provide new clinical evidence for personalized treatment strategies.

The value of the Prognostic Nutritional Index (PNI) in predicting outcomes and guiding the treatment strategy of nasopharyngeal carcinoma (NPC) patients receiving intensity-modulated radiotherapy (IMRT) with or without chemotherapy

PURPOSE

The purpose of this study was to investigate the significance of the Prognostic Nutritional Index (PNI) in predicting prognoses and guiding treatment choices of nasopharyngeal carcinoma (NPC) patients receiving intensity-modulated radiotherapy (IMRT).

METHODS

The 539 patients with newly diagnosed non-metastatic NPC were retrospectively analysed. The PNI was calculated as 10 × serum albumin (g/dL) + 0.005 × total lymphocyte count (per mm³). All patients were split randomly into a training set and a testing set. Receiver operating characteristic (ROC) curves were used to identify the cut-off value of PNI and test its prognostic validity. Survival curves were calculated by Kaplan-Meier method, and differences were compared with log-rank test.

RESULTS

The median follow-up time was 109.5 months. The 5-year locoregional recurrence-free survival (LRRFS), distant metastasis-free survival (DMFS), disease-specific survival (DSS) and overall survival (OS) of the whole cohort were 90.6, 85.8, 85.3 and 82.7%, respectively. The PNI cut-off value was 52.0 in the training set, which was significant in predicting DMFS, DSS and OS in the testing set. According to the PNI cut-off value, 220 patients of II-IVb stage treated by concurrent chemoradiotherapy (CCRT) were classified into PNI ≤ 52.0 and >52.0 groups and the 5-year LRRFS, DMFS, DSS, and OS of PNI ≤ 52.0 group were significantly worse than the PNI > 52.0 group.

CONCLUSION

Our results suggest that the PNI is a reliable independent prognostic factor in NPC patients treated with IMRT. For stage II-IVb patients with PNI ≤ 52.0, CCRT alone does not achieve satisfactory outcomes, and further studies on treatment optimization are needed.

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.

Prognostic value and predictive threshold of tumor volume for patients with locally advanced nasopharyngeal carcinoma receiving intensity-modulated radiotherapy

Background

Gross target volume of primary tumor (GTV-P) is very important for the prognosis prediction of patients with nasopharyngeal carcinoma (NPC), but it is unknown whether the same is true for locally advanced NPC patients treated with intensity-modulated radiotherapy (IMRT). This study aimed to clarify the prognostic value of tumor volume for patient with locally advanced NPC receiving IMRT and to find a suitable cut-off value of GTV-P for prognosis prediction.

Methods

Clinical data of 358 patients with locally advanced NPC who received IMRT were reviewed. Receiver operating characteristic (ROC) curves were used to identify the cut-off values of GTV-P for the prediction of different endpoints [overall survival (OS), local relapse-free survival (LRFS), distant metastasis-free survival (DMFS), and disease-free survival (DFS)] and to test the prognostic value of GTV-P when compared with that of the American Joint Committee on Cancer T staging system.

Results

The 358 patients with locally advanced NPC were divided into two groups by the cut-off value of GTV-P as determined using ROC curves: 219 (61.2%) patients with GTV-P ≤46.4 mL and 139 (38.8%) with GTV-P >46.4 mL. The 3-year OS, LRFS, DMFS, and DFS rates were all higher in patients with GTV-P ≤46.4 mL than in those with GTV-P > 46.4 mL (all P < 0.05). Multivariate analysis indicated that GTV-P >46.4 mL was an independent unfavorable prognostic factor for patient survival. The ROC curve verified that the predictive ability of GTV-P was superior to that of T category (P < 0.001). The cut-off values of GTV-P for the prediction of OS, LRFS, DMFS, and DFS were 46.4, 57.9, 75.4 and 46.4 mL, respectively.

Conclusion

In patients with locally advanced NPC, GTV-P >46.4 mL is an independent unfavorable prognostic indicator for survival after IMRT, with a prognostic value superior to that of T category.

Tumor Volume Predicts Survival Rate of Advanced Nasopharyngeal Carcinoma Treated with Concurrent Chemoradiotherapy

Objective

To delineate the prognostic value of primary gross tumor volume (GTVp) for patients with locoregionally advanced nasopharyngeal carcinoma (NPC) treated with concurrent chemoradiotherapy.

Study Design

Analysis of prognostic variables in a prospective cohort.

Setting

Department of Radiotherapy, First Affiliated Hospital of Guangxi Medical University, China.

Subjects and Methods

Between January 2006 and August 2008, 249 patients with stage III-IVb NPC, all treated by intensity-modulated radiotherapy plus concurrent chemotherapy, were included in this multicenter prospective study. GTVp was measured with treatment-planning computed tomography or magnetic resonance imaging scans.

Results

GTVp was significantly associated with locoregional control, distant metastasis, and overall survival for patients with advanced NPC. Furthermore, T classification was not an independent prognostic factor. In receiver operator receiver operating characteristic curve analysis, 33 mL was determined as the cutoff points of GTVp for OS and locoregional control. Patients with a GTVp ≥33 mL had poorer OS, worse locoregional control, and more distant metastasis than patients with a GTVp <33 mL ( P = .006, .009, .002, and .007, respectively).

Conclusions

GTVp had significant prognostic value for patients with advanced NPC. The incorporation of GTVp could improve the current TNM classification system.

Prognostic value of the distance between the primary tumor and brainstem in the patients with locally advanced nasopharyngeal carcinoma

BACKGROUND

Brainstem dose limitations influence radiation dose reaching to tumor in the patients with locally-advanced nasopharyngeal cancer (NPC).

METHODS

A retrospective analysis of the prognostic value of the distance between the primary tumor and brainstem (Dbs) in 358 patients with locally-advanced NPC after intensity-modulated radiation therapy (IMRT). Receiver operating characteristic (ROC) curves were used to identify the cut-off value to analyze the impact of Dbs on tumor dose coverage and prognosis.

RESULTS

The three-year overall survival (OS), local relapse-free survival (LRFS), distant metastasis-free survival (DMFS), and disease-free survival (DFS) were 88.8 vs. 78.4% (P = 0.007), 96.5 vs. 91.1% (P = 0.018), 87.8 vs. 79.3% (P = 0.067), and 84.1 vs. 69.6% (P = 0.002) for the patients with the Dbs > 4.7 vs. ≤ 4.7 mm, respectively. ROC curves revealed Dbs (4.7 mm) combined with American Joint Committee on Cancer (AJCC) T classification had a significantly better prognostic value for OS (P < 0.05).

CONCLUSIONS

Dbs (≤ 4.7 mm) is an independent negative prognostic factor for OS/LRFS/DFS and enhances the prognostic value of T classification in the patients with locally-advanced NPC.

Prognostic score models for survival of nasopharyngeal carcinoma patients treated with intensity-modulated radiotherapy and chemotherapy

PURPOSE

To establish accurate prognostic score models to predict survival for patients with nasopharyngeal carcinoma (NPC), treated with intensity-modulated radiotherapy (IMRT) and chemotherapy.

MATERIALS AND METHODS

Six hundred and seventy-five patients with newly diagnosed, nonmetastatic and histologically proven NPC who were treated with IMRT and chemotherapy were analyzed retrospectively. Samples were split randomly into a training set (n = 338) and a test set (n = 337) to analyze. All data from the training set were used to perform an extensive survival analysis and to develop multivariate nomograms based on Cox regression. Data from the test set was used as an external validation set. Risk group stratification was proposed for the nomograms.

RESULTS

The nomograms are able to predict survival with a C-index for external validation of local recurrence-free survival (LRFS; 0.66, 95% CI: 0.58-0.74), distant metastasis-free survival (DMFS; 0.73, 95% CI: 0.66-0.79), and disease-specific survival (DSS; 0.73, 95% CI: 0.67-0.79). The calibration curve for probability of survival showed good agreement between prediction by nomogram and actual observation. The C-index of the nomogram for LRFS, DMFS and DSS were statistically higher than the C-index values of the AJCC seventh edition (P < 0.001). In the test set, the nomogram discrimination was also superior to the AJCC Staging systems (P < 0.001). The stratification in risk groups allows significant distinction between Kaplan-Meier curves for outcome.

CONCLUSIONS

Prognostic score models were successfully established and validated to predict LRFS, DMFS, and DSS over a 5-year period after IMRT and chemotherapy, which will be useful for individual treatment.

Subdivision of M category for nasopharyngeal carcinoma with synchronous metastasis: time to expand the M categorization system

INTRODUCTION

The current metastatic category (M) of nasopharyngeal carcinoma (NPC) is a "catch-all" classification, covering a heterogeneous group of tumors ranging from potentially curable to incurable. The aim of this study was to design an M categorization system that could be applied in planning the treatment of NPC with synchronous metastasis.

METHODS

A total of 505 NPC patients diagnosed with synchronous metastasis at Sun Yat-sen University Cancer Center between 2000 and 2009 were involved. The associations of clinical variables, metastatic features, and a proposed M categorization system with overall survival (OS) were determined by using Cox regression model.

RESULTS

Multivariate analysis showed that Union for International Cancer Control (UICC) N category (N1-3/N0), number of metastatic lesions (multiple/single), liver involvement (yes/no), radiotherapy to primary tumor (yes/no), and cycles of chemotherapy (>4/≤4) were independent prognostic factors for OS. We defined the following subcategories based on liver involvement and the number of metastatic lesions: M1a, single lesion confined to an isolated organ or location except the liver; M1b, single lesion in the liver and/or multiple lesions in any organs or locations except the liver; and M1c, multiple lesions in the liver. Of the 505 cases, 74 (14.7%) were classified as M1a, 296 (58.6%) as M1b, 134 (26.5%) as M1c, and 1 was not specified. The three M1 subcategories showed significant difference in OS [M1b vs. M1a, hazard ratio (HR) = 1.69, 95% confidence interval (CI) = 1.16-2.48, P = 0.007; M1c vs. M1a, HR = 2.64, 95% CI = 1.75-3.98, P < 0.001].

CONCLUSIONS

We developed an M categorization system based on the independent factors related to the prognosis of patients with metastatic NPC. This system may be helpful to further optimize individualized care for NPC patients.