Intensity-modulated radiotherapy in nasopharyngeal carcinoma: dosimetric advantage over conventional plans and feasibility of dose escalation

Semi-supervised model based on implicit neural representation and mutual learning (SIMN) for multi-center nasopharyngeal carcinoma segmentation on MRI

BACKGROUND

The issue of using deep learning to obtain accurate gross tumor volume (GTV) and metastatic lymph nodes (MLN) segmentation for nasopharyngeal carcinoma (NPC) on heterogeneous magnetic resonance imaging (MRI) images with limited labeling remains unsolved.

METHOD

We collected 918 patients with MRI images from three hospitals to develop and validate models and proposed a semi-supervised framework for the fine delineation of multi-center NPC boundaries by integrating uncertainty-based implicit neural representations named SIMN. The framework utilizes the deep mutual learning approach with CNN and Transformer, incorporating dynamic thresholds. Additionally, domain adaptive algorithms are employed to enhance the performance.

RESULTS

SIMN predictions have a high overlap ratio with the ground truth. Under the 20 % labeled cases, for the internal test cohorts, the average DSC in GTV and MLN are 0.7981 and 0.7804, respectively; for external test cohort Wu Zhou Red Cross Hospital, the average DSC in GTV and MLN are 0.7217 and 0.7581, respectively; for external test cohorts First People Hospital of Foshan, the average DSC in GTV and MLN are 0.7004 and 0.7692, respectively. No significant differences are found in DSC, HD95, ASD, and Recall for patients with different clinical categories. Moreover, SIMN outperformed existing classical semi-supervised methods.

CONCLUSIONS

SIMN showed a highly accurate GTV and MLN segmentation for NPC on multi-center MRI images under Semi-Supervised Learning (SSL), which can easily transfer to other centers without fine-tuning. It suggests that it has the potential to act as a generalized delineation solution for heterogeneous MRI images with limited labels in clinical deployment.

Neurological complications of modern radiotherapy for head and neck cancer

Radiotherapy is one of the mainstay treatment modalities for the management of non-metastatic head and neck cancer (HNC). Notable improvements in treatment outcomes have been observed in the recent decades. Modern radiotherapy techniques, such as intensity-modulated radiotherapy and charged particle therapy, have significantly improved tumor target conformity and enabled better preservation of normal structures. However, because of the intricate anatomy of the head and neck region, multiple critical neurological structures such as the brain, brainstem, spinal cord, cranial nerves, nerve plexuses, autonomic pathways, brain vasculature, and neurosensory organs, are variably irradiated during treatment, particularly when tumor targets are in close proximity. Consequently, a diverse spectrum of late neurological sequelae may manifest in HNC survivors. These neurological complications commonly result in irreversible symptoms, impair patients' quality of life, and contribute to a substantial proportion of non-cancer deaths. Although the relationship between radiation dose and toxicity has not been fully elucidated for all complications, appropriate application of dosimetric constraints during radiotherapy planning may reduce their incidence. Vigilant surveillance during the course of survivorship also enables early detection and intervention. This article endeavors to provide a comprehensive review of the various neurological complications of modern radiotherapy for HNC, summarize the current incidence data, discuss methods to minimize their risks during radiotherapy planning, and highlight potential strategies for managing these debilitating toxicities.

A comprehensive predictive model for radiation-induced brain injury in risk stratification and personalized radiotherapy of nasopharyngeal carcinoma

BACKGROUND AND PURPOSE

Radiation-induced brain injury (RBI) is a severe radiotoxicity for nasopharyngeal carcinoma (NPC) patients, greatly affecting their long-term life quality and survival. We aim to establish a comprehensive predictive model including clinical factors and newly developed genetic variants to improve the precision of RBI risk stratification.

MATERIALS AND METHODS

By performing a large registry-based retrospective study with magnetic resonance imaging follow-up on RBI development, we conducted a genome-wide association study and developed a polygenic risk score (PRS) for RBI in 1189 NPC patients who underwent intensity-modulated radiotherapy. We proposed a tolerance dose scheme for temporal lobe radiation based on the risk predicted by PRS. Additionally, we established a nomogram by combining PRS and clinical factors for RBI risk prediction.

RESULTS

The 38-SNP PRS could effectively identify high-risk individuals of RBI (P = 1.42 × 10-34). Based on genetic risk calculation, the recommended tolerance doses of temporal lobes should be 57.6 Gy for individuals in the top 10 % PRS subgroup and 68.1 Gy for individuals in the bottom 50 % PRS. Notably, individuals with high genetic risk (PRS > P50) and receiving high radiation dose in the temporal lobes (D0.5CC > 65 Gy) had an approximate 50-fold risk over individuals with low PRS and receiving low radiation dose (HR = 50.09, 95 %CI = 24.27-103.35), showing an additive joint effect (Pinteraction < 0.001). By combining PRS with clinical factors including age, tumor stage, and radiation dose of temporal lobes, the predictive accuracy was significantly improved with C-index increased from 0.78 to 0.85 (P = 1.63 × 10-2).

CONCLUSIONS

The PRS, together with clinical factors, could improve RBI risk stratification and implies personalized radiotherapy.

Case Reports: A role of postoperative radiation therapy in completely resected early stage intrathyroid thymic carcinoma: a case report and literature review of the diagnosis and treatment

Background

Intrathyroid thymic carcinoma (ITTC) is a rare malignant tumor of the thyroid, probably arising from ectopic thymus or branchial pouch remnants. Most of the literature recommended radical resection as the fundamental treatment for ITTC, and postoperative radiation appears to be able to reduce the recurrence rate in patients with advanced ITTC. However, the issue of adjuvant radiotherapy in completely resected early-stage ITTC has been controversial.

Case presentation

Here, we reported a new case of early-stage ITTC that treated with total thyroidectomy and the right central neck dissection. Postoperative external beam radiation therapy (50.0 Gy/25 fractions) was given to the thyroid bed and bilateral cervical lymph node area since the tumor involved part of the sternal thyroid muscle. At 4-year follow-up after completion of radiotherapy, she is without evidence of locally recurrent or distant disease.

Conclusion

Since there are no current guidelines for early-stage ITTC, in combination with this case and previous literature, we may suggest routine adjuvant radiotherapy should be considered in patients with incompletely resected tumors and extraparenchymal extension of ITTC. Moreover, we summarized comprehensive and advanced diagnosis, treatment, prognosis of ITTC and comparison between ITTC, primary squamous cell carcinoma of thyroid gland, differentiated thyroid cancer, and anaplastic thyroid cancer.

Prioritizing sufficient dose to gross tumor volume over normal tissue sparing in intensity-modulated radiotherapy treatment of T4 nasopharyngeal carcinoma

BACKGROUND

In intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC), priority is often given minimize dose to the critical organs at risk (OARs) to avoid potential morbid sequelae. However, in T4 NPC, dosimetric inadequacy enforced by dose constraints on OARs may significantly impact tumor control.

METHODS

This was a single-institute cohort that patients diagnosed between July 2005 and December 2010 with T4 NPC treated with IMRT. All patients were re-classification according to the 7th-AJCC stage.

RESULTS

Overall, the average doses such as Dmax , D1% , D2% and D1cc for various Central nervous system (CNS) OARs including brainstem, optic nerve, chiasm, temporal lobes and spinal cord were found to exceed published guidelines as RTOG0225. However, no clinical toxicities were seen during the follow-up period except for 13% patients with temporal lobe necrosis.

CONCLUSION

Our retrospective review showed that its feasible to maximize gross tumor volume dose coverage while exceeding most CNS OAR constraint standards, with ideal local control and no obvious increase of craniocerebral toxicity.

Effect of radiotherapy interruption on nasopharyngeal cancer

Nasopharyngeal carcinoma (NPC) is a malignant tumor originating from the epithelial cells of the nasopharynx with a unique geographic distribution, and is particularly prevalent in East and Southeast Asia. Due to its anatomical location, the surgery is difficult to access and the high sensitivity of nasopharyngeal cancer to radiotherapy (RT) makes it the main treatment modality. Radical radiotherapy is the first-line treatment for early-stage nasopharyngeal carcinoma and the cornerstone of multidisciplinary treatment for patients with locally advanced nasopharyngeal carcinoma. Nevertheless, radiotherapy interruption is inevitable as a consequence of unavoidable factors such as public holidays, machine malfunction, patient compliance, and adverse response to treatment, which in turn leads to a reduction in bioactivity and causes sublethal loss of tumor cells to repair. Unirradiated tumor cells are more likely to repopulate at or near their original fastest growth rate during this interval. If no measures are taken after the radiotherapy interruption, such as increasing the dose of radiotherapy and systemic therapy, the tumor is most likely to go uncontrolled and then progress. This review describes the effects of radiotherapy interruption on nasopharyngeal carcinoma, the mechanism of the effect, and explores the measures that can be taken in response to such interruption.

Deep learning-based accurate delineation of primary gross tumor volume of nasopharyngeal carcinoma on heterogeneous magnetic resonance imaging: A large-scale and multi-center study

BACKGROUND AND PURPOSE

The problem of obtaining accurate primary gross tumor volume (GTVp) segmentation for nasopharyngeal carcinoma (NPC) on heterogeneous magnetic resonance imaging (MRI) images with deep learning remains unsolved. Herein, we reported a new deep-learning method than can accurately delineate GTVp for NPC on multi-center MRI scans.

MATERIAL AND METHODS

We collected 1057 patients with MRI images from five hospitals and randomly selected 600 patients from three hospitals to constitute a mixed training cohort for model development. The resting patients were used as internal (n = 259) and external (n = 198) testing cohorts for model evaluation. An augmentation-invariant strategy was proposed to delineate GTVp from multi-center MRI images, which encouraged networks to produce similar predictions for inputs with different augmentations to learn invariant anatomical structure features. The Dice similarity coefficient (DSC), 95 % Hausdorff distance (HD95), average surface distance (ASD), and relative absolute volume difference (RAVD) were used to measure segmentation performance.

RESULTS

The model-generated predictions had a high overlap ratio with the ground truth. For the internal testing cohorts, the average DSC, HD95, ASD, and RAVD were 0.88, 4.99 mm, 1.03 mm, and 0.13, respectively. For external testing cohorts, the average DSC, HD95, ASD, and RAVD were 0.88, 3.97 mm, 0.97 mm, and 0.10, respectively. No significant differences were found in DSC, HD95, and ASD for patients with different T categories, MRI thickness, or in-plane spacings. Moreover, the proposed augmentation-invariant strategy outperformed the widely-used nnUNet, which uses conventional data augmentation approaches.

CONCLUSION

Our proposed method showed a highly accurate GTVp segmentation for NPC on multi-center MRI images, suggesting that it has the potential to act as a generalized delineation solution for heterogeneous MRI images.

Endoscopic surgery is superior to intensity-modulated radiotherapy in the treatment of advanced recurrent nasopharyngeal carcinoma

BACKGROUND

The choice between endoscopic surgery and re-radiotherapy as the main treatment modality in patients with advanced recurrent nasopharyngeal carcinoma (rNPC) remains controversial. Therefore, in this study, we compared the efficacies of endoscopic surgery and intensity-modulated radiotherapy (IMRT) in patients with rNPC.

METHODS

All patients with advanced rNPC (T3 and T4) who underwent salvage treatment were enrolled from January 2009 to December 2020. Overall survival (OS) was analyzed using a log-rank analysis. Univariate and multivariate analyses of OS were performed using a Cox regression model. Common treatment-related complications of endoscopic surgery were compared with those of IMRT.

RESULTS

The numbers of patients with T3 and T4 tumors were 163 (64.2%) and 91 (35.8%), respectively; 192 patients underwent endoscopic surgery, 51 received IMRT, and 11 received three-dimensional conformal radiotherapy (3D-CRT). The 3-year OS of patients treated with endoscopic surgery was 59.3%, which was significantly higher than that of patients treated with IMRT (34.7%, p < 0.001) or 3D-CRT (43.6%, p = 0.012). Multivariate analyses showed that IMRT was an independent risk factor for OS compared with endoscopic surgery (hazard ratio, 2.068; 95% confidence interval, 1.395-3.069, p < 0.001). Complications of aural fullness (p = 0.001), nasopharyngeal necrosis (p = 0.004), nasopharyngeal hemorrhage (p = 0.004), dysphagia (p < 0.001), and cerebral infarction (p = 0.030) were significantly lower in the endoscopic surgery group than in the IMRT group.

CONCLUSION

Endoscopic surgery may be a more promising salvage treatment than IMRT to maximize survival and minimize treatment-related complications in advanced rNPC. These results will be significant in deciding the optimal treatment for patients with advanced rNPC.

Optimal plan target in cases with locally advanced nasopharyngeal cancer: Comparison of VMAT, IMRT, hybrid, and tomotherapy results

PURPOSE

In locally advanced nasopharyngeal cancer (NC), the spread of the disease, proximity to critical structures, and high dose requirement for tumor control may complicate the treatment plan. In this study, VMAT/IMRT/hybrid/tomotherapy plans were made to reach the safest and most effective dose distribution for each of the patients and the results were compared.

METHODS

Double volumetric-modulated arc therapy (VMAT) and 7- and 9-field intensity-modulated radiation therapy (IMRT) plans were made to 21 locally advanced NCs with Varian Trilogy System. It was observed that appropriate dose distributions could not be achieved with IMRT or VMAT, and hybrid IMRT-VMAT plans were made. All cases were also planned with Tomotherapy Precision System, and the data of four different techniques were compared retrospectively.

RESULTS

For normal tissue tolerances in 73 structures could not be obtained with VMAT and 38 structures with IMRT whereas the desired tolerance was provided with the hybrid plan. Hybrid plans were made with an average of 14 VMATs and 20 IMRTs. The maximum brainstem and spinal cord doses were found significantly lower in hybrid and tomotherapy techniques. Homogeneity index (HI) and conformity index (CI) values were the best in hybrid plans. No statistically significant difference between the hybrid plan and tomotherapy in terms of normal tissue tolerance doses and HI whereas a significant difference was found in the hybrid plan for CI.

CONCLUSION

It was observed that the most ideal plans for the locally advanced NC could be obtained with tomotherapy and hybrid plan techniques that the better protection in critical structures and desired dose distribution at target volumes.

Long-term results of the phase II dose and volume de-escalation trial for locoregionally advanced nasopharyngeal carcinoma

OBJECTIVE

Patients with locoregionally advanced nasopharyngeal carcinoma (LANPC) were assigned to dose and volume de-escalated intensity-modulated radiation therapy (IMRT) based on response to induction chemotherapy (IC) to limit treatment related toxicity while preserving efficacy.

METHODS AND MATERIALS

A single-arm de-escalated phase II trial was performed in this study. Patients with LANPC received two cycles of IC with docetaxel 60 mg/m² d1, cisplatin 25 mg/m²/day d1-3 and 5-fluorouracil 500 mg/m²/day d1-5 q21d, followed by IMRT. The gross tumor volume of the primary intracavity nasopharyngeal tumor and involved lymph nodes were delineated based on the post-IC tumor extension. Part of the prescribed doses were reduced from 70.4 Gy to 66 Gy for T3-4 diseases. The primary end point was 5-year progression-free survival (PFS) in stage III and IVA-B NPC compared with historical controls of 50% and 35%.

RESULTS

Between January 2010 and November 2013, 48 and 83 eligible patients with stage III and IVA-B NPC were accrued to this trial. With a median follow-up of 92 months, the 5-year and 8-year estimated PFS were 89.6% and 76.0%, 63.9% and 58.0% for patients with stage III and IVA-B disease, which were all improved in comparison with historical controls. Grade 3 acute mucositis were developed in 27.5% patients. Cranial neuropathy and asymptomatic temporal lobe necrosis were found in 2.3% and 1.5% patients.

CONCLUSION

Dose and volume de-escalated IMRT was associated with high PFS and mild late neurological toxicities for IC responders. Further exploration of de-escalation strategies in appropriate patients is needed.

CLINICAL TRIAL REGISTRATION

Clinical trials.gov identifier: NCT03389295.

Predicting gamma evaluation results of patient-specific head and neck volumetric-modulated arc therapy quality assurance based on multileaf collimator patterns and fluence map features: A feasibility study

The purpose of this study was to develop a predictive model for patient-specific VMAT QA results using multileaf collimator (MLC) effect and texture analysis. The MLC speed, acceleration and texture analysis features were extracted from 106 VMAT plans as predictors. Gamma passing rate (GPR) was collected as a response class with gamma criteria of 2%/2 mm and 3%/2 mm. The model was trained using two machine learning methods: AdaBoost classification and bagged regression trees model. GPR was classified into the "PASS" and "FAIL" for the classification model using the institutional warning level. The accuracy of the model was assessed using sensitivity and specificity. In addition, the accuracy of the regression model was determined using the difference between predicted and measured GPR. For the AdaBoost classification model, the sensitivity/specificity was 94.12%/100% and 63.63%/53.13% at gamma criteria of 2%/2 mm and 3%/2 mm, respectively. For the bagged regression trees model, the sensitivity/specificity was 94.12%/91.89% and 61.18%/68.75% at gamma criteria of 2%/2 mm and 3%/2 mm, respectively. The root mean square error (RMSE) of difference between predicted and measured GPR was found at 2.44 and 1.22 for gamma criteria of 2%/2 mm and 3%/2 mm, respectively. The promising result was found at tighter gamma criteria 2%/2 mm with 94.12% sensitivity (both bagged regression trees and AdaBoost classification model) and 100% specificity (AdaBoost classification model).

Local control and failure patterns after intensity modulated radiotherapy with reduced target volume delineation after induction chemotherapy for patients with T4 nasopharyngeal carcinoma

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Induction chemotherapy combined with radiotherapy achieved excellent local control.

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In-field recurrence is major local failure pattern for T4 nasopharyngeal carcinoma.

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Radiotherapy with reduced target volume after induction chemotherapy is feasible.

Background

The delineation of target volume after induction chemotherapy(IC) for nasopharyngeal carcinoma(NPC) is currently controversial. In this study, we aimed to analyze the long-term local control(LC) and failure patterns of T4 NPC treated with reduced target volume radiotherapy after IC.

Methods

From September 2007 to January 2013, 145 patients with T4 NPC were retrospectively reviewed. All patients received at least 1 cycle of IC followed by intensity modulated radiotherapy(IMRT). The gross tumor volume(GTV) was delineated according to the post-IC images for intracavity tumors and lymph nodes. The LC and overall survival (OS) rates were calculated using the Kaplan-Meier method. The location and extent of local failures were transferred to the pretreatment planning computed tomography (CT) for dosimetric analysis.

Results

With a median follow-up time of 95 months (range, 16–142 months), 23 local failures were found. The estimated 10-year LC and OS rates were 81.1%and 54.8% respectively. Among the 20 local failures with available diagnostic images, 18(90%) occurred within the 95% isodose lines and were considered in-field failures and 2(10%) were marginal. There was no outside-field failure.

Conclusions

In-field failure was the major pattern of local failure for T4 NPC. IMRT with reduced target volume after IC seems to be feasible. Further researches exploring optimal volume and radiation dose for local advanced NPC in the era of IC are warranted.

Volumetric modulated arctherapy for locally advanced nasopharyngeal carcinoma: Clinical efficacy and late toxicity

PURPOSE

We report our experience of 86 consecutive patients with locally advanced nasopharyngeal carcinoma who were treated with volumetric modulated arc therapy.

MATERIALS AND METHODS

We retrospectively reviewed the medical records of 86 patients with histologically proven primary nasopharyngeal carcinoma treated with volumetric modulated arctherapy technique radiotherapy. Primary endpoints were local, regional, distant control, and overall survival, second endpoint was late toxicity.

RESULTS

The median age was 47.5 years (range: 13-79 years) with sex ratio 1.09. At diagnosis, rhinologic symptoms represented the most common clinical presentation, reported by 61 patients (70.9%). Almost 88.4% of patients presented non-keratinizing undifferentiated carcinoma histology (n=76). Most of the patients presented a locally advanced disease defined by stage III and IVa (95.3%). Therefore, 31 patients were treated by concurrent chemoradiation (36%), 52 patients received induction chemotherapy followed by concurrent chemoradiotherapy (57%), three patients received induction chemotherapy followed by exclusive radiotherapy (3.5%). and three patients treated with exclusive irradiation (3.5%). With a median follow up of 15.7 months (range: 4-33.3 months), nine patients died (10.4%), three presented local or locoregional relapse (3.4%), while nine patients presented distant recurrences (10.4%). The two years overall and disease-free survival rates were 88.7% and 83.1% respectively, locoregional control was 100% at 12 months and 96.2% at 24 months, and the two years distant failure-free survival was 86.7%. Time to relapse was the only prognostic factor in univariate analysis for overall survival in our study. The therapeutic tolerance was good with 61.7% of grade 3 and 2.3% grade 4 hyposialia respectively, 46.5% of otological disorders and no radionecrosis was noted.

CONCLUSION

Volumetric modulated arctherapy technique with concurrent chemoradiotherapy is an effective treatment for nasopharyngeal carcinoma with excellent overall and locoregional control without severe toxicity. Distant metastasis is the major site of failure, so induction chemotherapy added to chemoradiotherapy must be discussed in multidisciplinary consultation meeting because it significantly improved recurrence-free survival and overall survival, as compared with chemoradiotherapy alone.

Long-Term Results of Intensity-Modulated Radiotherapy for T4 Nasopharyngeal Carcinoma: New Insight into the Value of Concurrent Chemotherapy

The aim of the study was to report long-term results of intensity-modulated radiotherapy for patients with T4 classification nasopharyngeal carcinoma (NPC). From September 2007 to January 2013, 155 patients were retrospectively analyzed. The estimated 10-year local recurrent-free survival (LRFS), regional recurrent-free survival (RRFS), distant metastasis-free survival (DMFS), and overall survival (OS) rates were 79.4%, 93.2%, 69.0%, and 54.2%, respectively. Cycle number of chemotherapy was a significant predictor of LRFS, OS, and progression-free survival. There was no significant difference in survival rates between patients treated with induction chemotherapy (IC) plus concurrent chemoradiotherapy (CCRT) and patients with IC plus IMRT and adjuvant chemotherapy (AC).

Prognostic models for 1-year survival of NPC after radiotherapy in different ages

PURPOSE

Previous studies have shown that approximately 10% of nasopharyngeal cancer (NPC) patients die within a year of disease onset, and that age is an independent predictor. However, no predictive model has been developed. We aimed to establish novel prognostic models to predict the 1-year cancer-specific survival (CSS) of young, middle-aged, and older patients with NPC after radiotherapy.

METHODS

The data of 2822 NPC patients who underwent radiotherapy between 2004 and 2015 were reviewed from the surveillance, epidemiology, and end results database. We divided them into young, middle-aged, and older people groups according to age (< 44 years, 45-59 years, and ≥ 60 years, respectively). Multivariate analyses were performed, and prognostic models were constructed.

RESULTS

Multivariate analyses indicated that age, ethnicity, histological subtype, T, and M stage were independent predictors of 1-year CSS in the older people group. In contrast, ethnicity and age were not found to have predictive value in the young and middle-aged groups, respectively. Accordingly, three prognostic models with excellent predictive values were established for the three groups (C-indices: 0.791 [95% CI 0.722-0.859], 0.763 [95% CI 0.721-0.806] and 0.723 [95% CI 0.683-0.763], respectively). These predictive values are higher than those of the eighth edition American joint committee cancer tumor-node-metastasis (TNM) classification system.

CONCLUSION

Three prognostic models for predicting the 1-year CSS of young, middle-aged, and older NPC patients after radiotherapy showed better predictive power than the TNM classification system. These models may guide treatment strategies and clinical decision-making in different cohorts.

Durability of the parotid-sparing effect of intensity-modulated radiotherapy (IMRT) in early stage nasopharyngeal carcinoma: A 15-year follow-up of a randomized prospective study of IMRT versus two-dimensional radiotherapy

BACKGROUND

The durability of improved xerostomia with intensity-modulated radiotherapy (IMRT) in patients with early stage nasopharyngeal carcinoma (NPC) is uncertain. We conducted a long-term prospective assessment of participants treated with IMRT or two-dimensional radiotherapy (2DRT) in a prior randomized study.

METHODS

Parent study participants (IMRT, n = 28; 2DRT, n = 28) who were free of second malignancy or recurrence were eligible. Long-term radiotherapy-related toxicities were graded according to the Radiation Therapy Oncology Group (RTOG) criteria. Long-term patient-reported outcomes were assessed by the six-item xerostomia (XQ) and two European Organisation for Research and Treatment of Cancer (EORTC) questionnaires (QLQ-C30, QLQ-H&N35). Overall survival (OS), locoregional relapse-free survival (LRFS), distant relapse-free survival (DRFS), and the rate of symptomatic late complications (SLCs) were estimated for the entire cohort (n = 56).

RESULTS

Totally, 21 (IMRT, n = 10; 2DRT, n = 11) patients gave consent and were assessed for an overall median follow-up of 15.5 years. There was significantly less RTOG ≥grade 2 xerostomia with IMRT versus 2DRT (20% vs. 90%; p = 0.001), but no significant difference in XQ scores. Patients in the IMRT arm reported lower mean scores for the "dry mouth" domain of EORTC QLQ-H&N35 (p = 0.02) and showed trends toward better 15-year OS (81.5% vs. 53.8%, p = 0.06), LRFS (70.6% vs. 53.8%, p = 0.38), and DRFS (81.5% vs. 53.8%, p = 0.07). SLCs were more frequent in the 2DRT arm.

CONCLUSIONS

The parotid-sparing effect of IMRT in NPC treatment is durable, with significantly less physician- and patient-scored xerostomia at 15 years. IMRT results in better long-term survival and fewer SLCs.

Split-field versus extended-field step-and-shoot IMRT techniques in nasopharyngeal cancer: a report of acute and late toxicities

Aim:

This study aimed to evaluate acute and late toxicities in nasopharyngeal cancer (NPC) patients who were treated between split-field (SF) and extended-field (EF) step-and-shoot intensity-modulated radiotherapy (IMRT) techniques.

Materials and methods:

Between January 2011 and October 2011, 21 NPC patients with stage I-IVB (7th edition American Joint Committee on Cancer Staging) were randomly assigned to undergo radiotherapy with SF or EF step-and-shoot IMRT technique.

Results:

At a median follow-up time of 60 months (range 3–77), we reported the comparable acute and late toxicities between the two techniques. One patient (9%) in SF-IMRT arm developed grade 3 acute skin toxicity.

Findings:

Both SF and EF step-and-shoot IMRT techniques for NPC patients did not produce any statistically significant differences in both acute and late toxicities. Although no difference in toxicity was observed, technical problems due to field matching management were the obstacles in utilisation of SF-IMRT in our routine practice.

Normal tissue complication probability (NTCP) models for predicting temporal lobe injury after intensity-modulated radiotherapy in nasopharyngeal carcinoma: A large registry-based retrospective study from China

PURPOSE

To develop predictive models with dosimetric and clinical variables for temporal lobe injury (TLI) in nasopharyngeal carcinoma (NPC) after intensity-modulated radiotherapy (IMRT).

MATERIALS AND METHODS

Data of 8194 NPC patients who received IMRT-based treatment were retrospectively reviewed. TLI was diagnosed by magnetic resonance imaging. Dosimetric factors were selected by penalized regression and machine learning, with area under the receiver operating curve (AUC) calculated. Cox proportional hazards models containing the most predictive dosimetric factor with/without clinical variables were performed. A nomogram was generated as a visualization of Cox regression for predicting TLI-free survival.

RESULTS

During median follow-up of 66.8 months (interquartile range [IQR] 54.2-82.2 months), 12.1% of patients (989/8194) developed TLI. Median latency from IMRT to TLI was 36 months (IQR 28-47 months). D_0.5cc (dose delivered to 0.5-cm³ temporal-lobe volume) was the most predictive dosimetric factor (AUC: 0.799). Tolerance dose for 5% and 50% probabilities to develop TLI in 5 years were 65.06 Gy (95% confidence interval [CI]: 64.19-65.92) and 89.75 Gy (95% CI: 87.39-92.11), respectively. A nomogram comprising age, T stage, and D_0.5cc significantly outperformed the model with only D_0.5cc in predicting TLI (C-index: 0.78 vs. 0.737 in train set; 0.775 vs. 0.73 in test set; both P < 0.001). The nomogram-defined high-risk group had worse 5-year TLI-free survival.

CONCLUSIONS

D_0.5cc of 65.06 Gy was the tolerance dose of the temporal lobe. Reducing D_0.5cc decreased risk of TLI, especially in older patients with advanced T stage. The nomogram could predict TLI precisely and allow individualized follow-up management.

Long term complications and prognostic factors in locally advanced nasopharyngeal carcinoma treated with docetaxel, cisplatin, 5-fluorouracil induction chemotherapy followed by concurrent chemoradiotherapy: A retrospective cohort study

This study was conducted to evaluate the long term complications and their risk factors including of survival outcomes in patients with locally advanced nasopharyngeal cancer (NPC) treated with docetaxel, cisplatin and 5-fluorouracil (TPF) induction chemotherapy followed by concurrent chemoradiotherapy (CCRT).Among the patients who were diagnosed as NPC, we consecutively evaluated the late complications in 104 patients who completed 3 cycles of TPF induction chemotherapy followed by CCRT and received regular follow-up by otolaryngologist and oncologist. The prognostic factors for overall survival, relapse free survival and each complication were analyzed based on clinical characteristics.Over a median follow-up of 54 months (range, 7.9-152.9 months), 5-year overall survival rate was 87% for stage II, 89% for stage III, 87% for stage IV patients. The significant prognostic factor for survival is complete response rate after CCRT in multivariate analysis. The most frequent toxicity was ear complication (29.8%) including of hearing loss requiring hearing aid (6.7%) and bone necrosis (3.8%). Decreased renal function over grade 2 was occurred in only 4 patients (3.8%) regardless of the cumulative dose of cisplatin. The long term complications did not affect the survival outcome. Patients who received radiation therapy more than 5400 cGy had better survival outcome than those who did not. However, ear complication was significantly related to radiation dose (≥ 6,600 cGy) and type of radiation therapy (conventional). Age over 65 years was a significant risk factor for both ear and renal toxicity. In conclusion, close follow-up to monitor long-term complications should be performed in patients treated with TPF induction chemotherapy followed by CCRT treatment, especially in elderly patients. Reestablishing the optimal chemotherapeutic agent during CCRT and adjustment of radiation dose after induction chemotherapy could be helpful to reduce the toxicity associated with the subsequent treatment strategy for locally advance NPC patients.

Second primary cancer after intensity-modulated radiotherapy for nasopharyngeal carcinoma: A territory-wide study by HKNPCSG

OBJECTIVES

Long-term risk of second primary cancer (SPC) after definitive intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC) remains unclear. This study aims to evaluate the risk, predictive factors and survival impact of SPC in a large territory-wide cohort of NPC survivors in an endemic region.

MATERIALS AND METHODS

In this multicenter study, consecutive NPC patients (n = 3166) who underwent definitive IMRT in all six public oncology centers in Hong Kong between 2001 and 2010 were included. SPC risks were quantified by standardized incidence ratios (SIRs) and absolute excess risks (AERs) estimated from corresponding age-, sex-, and calendar year-specific population cancer incidence data from the Hong Kong Cancer Registry. Predictive factors and SPC-specific mortality were analyzed.

RESULTS

Over a median follow-up period of 10.8 years, 290 cases of SPC were observed with a crude incidence of 9.2%. Cancer risk in NPC survivors was 90% higher than that in general population [SIR, 1.9; 95% confidence interval (CI), 1.7-2.2], with an AER of 52.1 (95% CI, 36.8-67.3) per 10,000 person-years at risk. Significant excess cancer risks were observed for oral cavity, sarcoma, oropharynx, paranasal sinus, salivary gland, thyroid, skin and lung. Advanced age, smoking, hepatitis B status, and re-irradiation were independent predictive factors. SPC accounted for 9.4% of all deaths among NPC survivors during the study period, and 10-year SPC-specific mortality was 3.4%.

CONCLUSIONS

Second cancer risk after IMRT was substantial among NPC patients. SPC impairs long-term survival, and close surveillance is warranted as part of survivorship care.

Variations of Clinical Target Volume Delineation for Primary Site of Nasopharyngeal Cancer Among Five Centers in China

Purpose

The purpose of this study is to investigate the current status of clinical target volume (CTV) delineation for primary site of nasopharyngeal cancer (NPC) among five large tertiary cancer centers in China.

Materials and Methods

The simulation CT and MR images of a patient with T3N2M0 NPC were sent to the centers participating. Fourteen experienced physicians contoured the targets independently, and the outlined structures were compared. The consistency and differences among these 14 CTVs are discussed.

Results

Two different CTV designs were used in the centers. "One-CTV" design defines one CTV with a dose of 60 Gy, whereas "two-CTV" design has a high-risk CTV with dose of 60 Gy and a medium risk CTV with dose of 54 Gy. We found that the coverage of prophylactic area is very consistent between these two designs. The variances on the coverage of some sites were also significant among physicians, including covering cavernous sinus at un-involved side, posterior space of styloid process, and caudal border on posterior pharyngeal wall.

Conclusions

Standardization is the main requirement for personalization of care; our study shows that among the 14 physicians in the five centers the coverage of prophylactic areas is in excellent agreement. Two distinct strategies on CTV design are currently being used, and multiple controversies were found, suggesting further optimization of CTV for primary site of NPC is needed.

Early Stage Markers of Late Delayed Neurocognitive Decline Using Diffusion Kurtosis Imaging of Temporal Lobe in Nasopharyngeal Carcinoma Patients

Purpose: To determine whether the early assessment of temporal lobe microstructural changes using diffusion kurtosis imaging (DKI) can predict late delayed neurocognitive decline after radiotherapy in nasopharyngeal carcinoma (NPC) patients. Methods and Materials: Fifty-four NPC patients undergoing intensity-modulated radiotherapy (IMRT) participated in a prospective DKI magnetic resonance (MR) imaging study. MR imaging was acquired prior to IMRT (-0), 1 month (-1), and 3 (-3) months after IMRT. Kurtosis (Kmean, Kax, Krad) and Diffusivity (Dmean, Dax, Drad) variables in the temporal lobe gray and white matter were computed. Neurocognitive function tests (MoCA) were administered pre-radiotherapy and at 2 years post-IMRT follow-up. All the patients were divided into neurocognitive function decline (NFD group) and neurocognitive function non-decline groups (NFND group) according to whether the MoCA score declined ≥3 2 years after IMRT. All the DKI metrics were compared between the two groups, and the best imaging marker was chosen for predicting a late delayed neurocognitive decline. Results: Kurtosis (Kmean-1, Kmean-3, Kax-1, Kax-3, Krad-1, and Krad-3) and Diffusivity (Dmean-1 and Dmean-3) of white matter were significantly different between the two groups (p<0.05). Axial Kurtosis (Kax-1, Kax-3) of gray matter was significantly different between the two groups (p<0.05). By receiver operating characteristic (ROC) curves, Kmean-1 of white matter performed best in predicting of MoCA scores delayed decline (p<0.05). The radiation dose was also significantly different between NFD and NFND group (p=0.031). Conclusions: Temporal lobe white matter is more vulnerable to microstructural changes and injury following IMRT in NPC. Metrics derived from DKI should be considered as imaging markers for predicting a late delayed neurocognitive decline. Both temporal lobe white and gray matter show microstructural changes detectable by DKI. The Kmean early after radiotherapy has the best prediction performance.

Adding Concurrent Chemotherapy to Intensity-Modulated Radiotherapy Does Not Improve Treatment Outcomes for Stage II Nasopharyngeal Carcinoma: A Phase 2 Multicenter Clinical Trial

Purpose: To explore the efficacy of concomitant chemotherapy in intensity-modulated radiotherapy (IMRT) to treat stage II nasopharyngeal carcinoma (NPC). Methods and Materials: In this randomized phase 2 study [registered with ClinicalTrials.gov (NCT01187238)], eligible patients with stage II (2010 UICC/AJCC) NPC were randomly assigned to either IMRT alone (RT group) or IMRT combined with concurrent cisplatin (40 mg/m², weekly) (CCRT group). The primary endpoint was overall survival (OS). The second endpoints included local failure-free survival (LFFS), regional failure-free survival (RFFS), disease-free survival (DFS), distant metastasis-free survival (DMFS), and acute toxicities. Results: Between May 2010 to July 2012, 84 patients who met the criteria were randomized to the RT group (n = 43) or the CCRT group (n = 41). The median follow-up time was 75 months. The OS, LFFS, RFFS, DFS, and DMFS for the RT group and CCRT group were 100% vs. 94.0% (p = 0.25), 93.0% vs. 89.3% (p = 0.79), 97.7% vs. 95.1% (p = 0.54), 90.4% vs. 86.6% (p = 0.72), and 95.2% vs. 94.5% (p = 0.77), respectively. A total of 14 patients experienced disease failure, 7 patients in each group. The incidence of grade 2 to 4 leukopenia was higher in the CCRT group (p = 0.022). No significant differences in liver, renal, skin, or mucosal toxicity was observed between the two groups. Conclusion: For patients with stage II NPC, concomitant chemotherapy with IMRT did not improve survival or disease control but had a detrimental effect on bone marrow function.

Different Risk Target Volumes for Nasopharyngeal Carcinoma Treated with Simultaneous Integrated Boost Intensity-Modulated Radiotherapy

Background and Objectives: Although intensity-modulated radiotherapy (IMRT) provides promising survival advantages and fewer late complications in patients with nasopharyngeal cancer (NPC), appropriated target volumes and prescribed doses are still being explored. This study aimed to propose different risk target volumes and corresponding prescribed doses in our center and to evaluate the physical basis and efficacy of this protocol based on the long-term survival of NPC patients. Methods and Materials: We retrospectively assessed patients with histology-proven non-metastatic NPC treated with definitive IMRT using our protocol of different risk target volumes and corresponding prescribed doses based on the orderly stepwise pattern of tumor spread. We described the delineation for different risk target volumes and the design of IMRT planning for an NPC case. Additionally, we compared the dosimetric distributions between the China protocol and our protocol through two NPC cases. The patterns of failure and locoregional control were the primary endpoints. All survival outcomes were calculated using the Kaplan-Meier method. Results: From January 2013 to December 2014, a total of 335 patients were treated; the median follow-up for patients who survived was 70 months. All patients completed IMRT using our protocol. Twenty-five patients developed locoregional recurrence, and all recurrences occurred within the high-dose target volumes. The rates of locoregional recurrence-free survival, distant metastasis-free survival, progression-free survival, and overall survival at 5 years were 92.2%, 92.1%, 85.9%, and 86.3%, respectively. The biological effective doses of the prescribed doses in our protocol were similar to those of the China and 0615 protocols. Moreover, our protocol offered a reduction in D1 and D2 in the primary gross tumor volume (GTV), while V30 and V40 in normal tissues were lower. Conclusion: Our protocol of different risk target volume delineations and corresponding prescribed doses based on the stepwise pattern of tumor spread resulted in favorable locoregional control with no relapse outside the GTV.

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.

DW-MRI-Guided Dose Escalation Improves Local Control of Locally Advanced Nasopharyngeal Carcinoma Treated with Chemoradiotherapy

Background

Nasopharyngeal carcinoma (NPC) is one of the most highly radiosensitive malignancies; however, some locally advanced NPC patients experienced local recurrence even though they received aggressive treatment regimens. Defining the tumor volume precisely is important to escalate the total dose required for the primary tumor. In this study, we aimed to investigate the feasibility and efficacy of dose escalation guided by DW-MRI in patients with locally advanced NPC.

Patients and Methods

A total of 230 patients with locally advanced NPC treated with intensive modulated radiotherapy (IMRT) at Sichuan Cancer Hospital between January 2010 and January 2015 were enrolled in this retrospective study. All the patients were treated with all-course of simultaneous integrated boost-IMRT. DW-MRI-guided dose escalation with 2.2–2.5 Gy/F, qd for 1–3 days or 1.2–1.5 Gy/F, bid for 1–3 days were prescribed to 123 patients. Survival and complication of the patients were evaluated, and multivariate analysis was performed.

Results

The median follow-up of patients in the DW-MRI-guided dose-escalation group and the conventional group was 48 months (range 8–88 months) and 52 months (range 6–90 months), respectively. The 5-year overall survival rate, distant metastasis-free survival rate, progression-free survival, and local recurrence-free survival (LRFS) of patients in the dose-escalation group and the conventional group were 88% vs 82.5% (p = 0.244), 86.1% vs 83.3% (p = 0.741), 82.2% vs 76.6% (p = 0.286), and 89.1% vs 80.1% (p = 0.029), respectively. Multivariate analysis showed that dose escalation was independent prognostic factor for LRFS (HR 0.386, 95% CI 0.163–0.909, p = 0.03).

Conclusion

DW-MRI-guided dose escalation is a feasible strategy to improve local control of patients with locally advanced NPC. The treatment-related complications are tolerable.

Clinical outcomes for nasopharyngeal cancer with intracranial extension after taxane-based induction chemotherapy and concurrent chemo-radiotherapy in the modern era

Objective

To evaluate the survival outcomes for a cohort of nasopharyngeal cancer with intracranial extension (ICE) treated with induction chemotherapy (ICT) followed by chemo-intensity-modulated radiotherapy (CTRT) at a tertiary cancer center.

Methods

We retrospectively analyzed 45 patients with histologically proven, non-metastatic NPC with ICE treated at our institute between October 2008 and October 2016. Patients were classified as minor ICE or major ICE, based on the extent of ICE. All the patients received 2–3 cycles of a taxane-based ICT regimen followed by CTRT. Radiotherapy was delivered with “risk-adapted” intensity-modulated radiotherapy (IMRT) technique in all patients.

Results

After a median follow up of 45 months (range: 8–113 months), the estimated 5-year DFS, LRFS, DMFS, and OS of the entire cohort was 58%, 82%, 67% and 74% respectively. On multivariate analysis, histological subtype was an independent predictor of LRFS, and age was an independent predictor of DFS. The extent of ICE showed only a trend towards worse DFS (P = 0.06). None of the factors significantly predicted for DMFS or OS. Gender, N-stage, and response to ICT did not significantly affect any of the outcomes. Grade 2 or worse subcutaneous fibrosis was seen in 22% of patients and grade 2 or worse xerostomia was seen in 24% of patients at last follow up. Thirty-three percent of the patients developed clinical hypothyroidism at last follow up. None of the patients experienced any neurological or vascular complications.

Conclusions

Taxane-based induction chemotherapy followed by chemo-intensity modulated radiotherapy resulted in excellent locoregional control and survival with acceptable toxicities in patients of nasopharyngeal cancer with intracranial extension. Distant metastasis continues to be the predominant problem in these patients.

Appropriate reduction of the fragmentation level of subfield sequences to improve the accuracy of field delivery in IMRT for nasopharyngeal carcinoma

Objective:

Due to the influence of gravity, inertia and friction, there will be deviation between the position of multileaf collimator (MLC) in the delivered field and the initial intensity modulated radiotherapy (IMRT) plan. This study explores the effects of the fragmentation level of subfield sequences on this deviation and seeks ways to improve the accuracy of field delivery in IMRT for nasopharyngeal carcinoma (NPC).

Methods:

30 patients with NPC were selected, and two groups (groups A and B) of IMRT plans were made in Pinnacle planning system. Different planning parameters were used for optimization so that the subfield sequence fragmentation level of Group B was significantly lower than that of Group A. With the MapCheck2, verification plan was implemented in two ways: 0^o gantry angle and the actual treatment angle, then the differences between the two verification results of each group plan were analyzed.

Results:

The γ-passing rate verified at the actual treatment angle was lower than that of 0^o gantry angle for each group plan, whereas the Group B plan shows small reduction. Mean change value (Δ) was decreased from 1.01% (Group A) to 0.40% (Group B) with 3%/3 mm criteria and 2.88% (Group A) to 1.52% (Group B) with 2%/2 mm criteria, respectively. The smaller the difference (Δ), the actual output dose of the field is more consistent with the original plan. There was no significant correlation between this change and the angle of the field.

Conclusion:

Appropriately reducing the fragmentation level of subfield sequence can reduce the effect of field angle on MLC position and improve the delivery accuracy of IMRT plan.

Advances in knowledge:

The fragmentation level of the subfield sequence may have an impact on the accuracy of the delivery of the plan. This study demonstrates this assumption by comparing the differences between 0° and actual angle verification. Mean change value (Δ) was decreased from Group A to Group B. The smaller the difference (Δ), the actual output dose of the field is more consistent with the original plan. The result of this study may help us to understand that appropriately increasing the subfield area and reducing the fragmentation level of the subfield sequence can reduce the difference between the two verification results, which can further improve the accuracy of the plan delivery in IMRT and tumor treatment.

Comparison of Radiation-Induced Secondary Malignancy Risk Between Sequential and Simultaneous Integrated Boost for the Treatment of Nasopharyngeal Carcinoma: Intensity-Modulated Radiotherapy versus Volumetric-Modulated Arc Therapy

PURPOSE

This study aimed to compare the secondary cancer risk (SCR) between the sequential boost (SEQ) technique and simultaneous integrated boost (SIB) technique in intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT) in patients with nasopharyngeal carcinoma (NPC) using the concepts of organ equivalent dose (OED) and excess absolute risk (EAR).

PATIENTS AND METHODS

IMRT-SEQ, VMAT-SEQ, IMRT-SIB, and VMAT-SIB plans were created with identical objective functions for five patients with early-stage NPC. Three different planning tumor volumes (PTVs; PTV1, PTV2, and PTV3) were delineated for each patient, and the prescribed doses were 50 Gy, 60 Gy, and 70 Gy (2 Gy/fraction), respectively, for the SEQ technique and 52.8 Gy, 59.4 Gy, and 69.3 Gy (33 fractions), respectively, for the SIB technique.

RESULTS

All plans were clinically acceptable. There was no difference in most OED-based SCRs between IMRT and VMAT when the same fractionation scheme was used. Compared with the SEQ technique, the SIB technique in IMRT and VMAT was associated with the lowest OEDs for the oral cavity, pharynx, parotids, and submandibular glands, resulting in SCR reduction. SCR for the parotids was much lower than that for the other assessed organs when the SIB technique was used.

CONCLUSION

Our findings suggest that OED-based SCRs are lower with the SIB technique than with the SEQ technique in IMRT and VMAT in most organs for which SCR was calculated; furthermore, SCR for the parotids is much lower than that for other organs when the SIB technique is used in patients with NPC.

Superiority of intensity-modulated radiation therapy in nasopharyngeal carcinoma with skull-base invasion

PURPOSE

To compare the clinical results and functional outcomes between two-dimensional conventional radiation therapy (2DRT) and intensity-modulated radiation therapy (IMRT) in nasopharyngeal carcinoma (NPC) with skull-base invasion.

METHODS

A total of 1258 patients were subclassified into two groups: mild skull-base invasion group (792; 63%) and severe skull-base invasion group (466; 37%). Patients were pair matched (1:1 ratio) using six clinical factors into 2DRT or IMRT groups. The Kaplan-Meier method and Cox regression model were performed to assess overall survival (OS), disease-free survival (DFS), locoregional relapse-free survival (LRRFS) and distant metastasis-free survival (DMFS). Toxicities were evaluated.

RESULTS

IMRT significantly improved four-year OS compared with 2DRT (65.6% vs. 81.8%, P = 0.000), DFS (57.3% vs. 73.3%, P = 0.000) and LRRFS (76.5% vs. 87.5%, P = 0.003) in NPC with severe skull-base invasion, but similar results were observed in patients with mild skull-base invasion (P > 0.05). In patients with severe invasion, radiation therapy techniques were found to be an independent prognostic factor for OS (HR = 0.457, P = 0.000), DFS (HR = 0.547, P = 0.000) and LRRFS (HR = 0.503, P = 0.004). IMRT was associated with better OS. In subgroups analysis, IMRT group also had a better survival in OS, DFS (P < 0.05 for all rates) for patients received concurrent chemotherapy and sequential chemotherapy compared to 2DRT in the severe invasion group. The IMRT group displayed lower incidence of mucositis, xerostomia, trismus (< 1 cm) and temporal lobe necrosis than the 2DRT group.

CONCLUSIONS

IMRT significantly improved patient survival compared with 2DRT in NPC patients with severe skull-base invasion, but a similar survival rate was noted in mild invasion patients. Chemotherapy can improve survival in NPC patients with severe invasion. Among the two therapies, IMRT significantly decreased therapy-related toxicity.

Dosimetric evaluation of automatic and manual plans for early nasopharyngeal carcinoma to radiotherapy

To investigate dosimetric differences and plan qualities between manual plans and automatic plans for nasopharyngeal carcinoma (NPC) in early stage, and provide better options to maximize the benefits. Sixteen cases diagnosed with early NPC were retrospectively investigated. Conventional step and shoot IMRT with 7-fields and full arc volumetric-modulated arc therapy (VMAT) with double arcs were manually generated by experienced planners and automatically generated by Auto-Planning module in Pinnacle³ respectively, such as IMRT manual-planning (mIMRT), IMRT auto-planning (aIMRT), VMAT manual-planning (mVMAT), and VMAT auto-planning (aVMAT) for each patient. Target coverage, organs at risk sparing, monitor units, and planning times were compared and evaluated. All parameters of plans are able to fulfill International Commission on Radiation Units and Measurements repor (ICRU) 83 recommendations. Automatic plans are comparable or superior to manual plans without time-consuming planning process. The CI and HI for PTVs are better in aVMAT when compared with aIMRT and mVMAT, but those are similar between aIMRT and mVMAT. Automatic plans not only have superior dose homogeneity and conformity in PTVs, but also have better sparing for spinal cord or slightly reduce the doses received by other OARs, while the VMAT plans have better sparing for brain stem, especially the aVMAT plans. However, Dmax, V30, and V40 of brain stem are similar between aIMRT and mVMAT without significant difference. The monitor units and planning time for treatment plans have been significantly decreased through automatic planning technique. The automatic VMAT plan has greater clinical advantages and should be recommended to a better option for treating NPC in early stage, while automatic IMRT would be preferentially considered instead of manual VMAT.

Target Coverage in Head and Neck Cancer Treated with Intensity-Modulated Radiotherapy: A Comparison between Conventional and Conformal Techniques

Aims and background

We designed a comparative planning study aimed at quantifying the advantages of intensity-modu-lated radiotherapy (IMRT) over the conventional 3-field technique (3FT) and a 5-field conformal technique (5FCT) for head and neck (HN) cancer.

Methods

We selected 9 patients treated at our institution with curative radiotherapy for a HN cancer. For all cases 4 plans were generated: 2 plans using the “standard” techniques (3FT and 5FCT), a third plan using IMRT, and a fourth “mixed” plan using IMRT followed by a conventional boost.

Results

Our study confirmed literature data on the ability of IMRT to significantly decrease the dose received by organs at risk, compared with previous techniques. Target coverage was systematically better with 5FCT and IMRT than with 3FT. However, the increase in coverage of both PTV2 and PTV1 was only about 3-5% and this was achieved at the price of a similar increase in maximum dose (D1%). Volumetric parameters (V100%, V95%) were much more sensitive in detecting the improvement with IMRT.

Conclusions

The improvement of target coverage attained by IMRT, as compared with conventional and conformal techniques, might be overestimated by data currently available in the medical literature. If treatment with conventional techniques is planned using all tools provided by currently available fully 3-D planning systems, excellent target coverage can be obtained.

The effectiveness of intensity-modulated radiation therapy versus 2D-RT for the treatment of nasopharyngeal carcinoma: A systematic review and meta-analysis

BACKGROUND

At present, the management of nasopharyngeal carcinoma (NPC) is mainly based on radiotherapy, but there are many radiation delivery techniques such as intensity-modulated radiotherapy (IMRT) and 2-dimensional radiotherapy (2D-RT).

MATERIALS AND METHODS

We searched all the eligible studies through the PubMed, Cochrane Library, Medline, and Embase. The endpoint events in meta-analysis were overall survival (OS), tumor local control including local-regional free survival (LRFS), progression-free survival (PFS), and distant metastasis-free survival (DMFS), and late toxicities.

RESULTS

A total of ten publications met the criteria and were identified through searches of the databases and references. We included 13304 patients in the meta-analysis, of whom 5212 received IMRT and 8092 were allocated to 2D-RT alone group. Compared with 2D-RT treatment, the IMRT group was associated with a better 5-year OS (OR = 1.70; 95% CI = 1.36-2.12), LRFS (OR = 2.08; 95% CI = 1.82-2.37), and PFS (OR = 1.40; 95% CI = 1.26-1.56). Additionally, the incidence of late toxicities such as late xerostomia (OR = 0.21; 95% CI = 0.09-0.51), trismus (OR = 0.16; 95% CI = 0.04-0.60), and temporal lobe neuropathy (TLN) (OR = 0.40; 95% CI = 0.24-0.67) for NPC patients in IMRT group were significantly lower than 2D-RT.

CONCLUSIONS

The meta-analysis demonstrates that IMRT provides improved long-term tumor overall survival and local control including LRFS and PFS. Additionally, IMRT yields a lower incidence of late toxicities induced by irradiation in NPC patients. Compared to 2D-RT, IMRT may be an effective treatment for patients with NPC. Further intensive studies should be pursued to examine the association.

PD-1 high expression predicts lower local disease control in stage IV M0 nasopharyngeal carcinoma

BACKGROUND

Tumor-infiltrating lymphocytes (TILs) play a critical role in tumor immune surveillance and immune suppression. Understanding tumor infiltrating T cell subset density, location and PD-1/PD-L1 expression might provide insight for the prediction of tumor therapeutic response and clinical outcome. The purpose of this study was to evaluate the expression and localization of CD8, FoxP3, PD-1, and PD-L1 in primary tumor tissues and their effects on prognosis of stage IV M0 locally advanced nasopharyngeal carcinoma (NPC) patients.

METHODS

Sixty NPC patients with stage IV M0 locally advanced disease were treated with definitive chemoradiation. Tumor biopsies from primary lesion were analyzed for the expression and localization of CD8, FoxP3, PD-1, and PD-L1 by immunohistochemistry. Their associations with local disease control and survival of NPC were analyzed.

RESULTS

The average follow-up time was 43 months (range from 14 to 61 months). High expression of CD8^+, FoxP3⁺, PD-1⁺ and PD-L1⁺ was observed in 60, 86.7, 56.7, and 91.7% of patients, respectively. There was no correlation between clinicopathological features and the expression of these immune markers. High PD-1 expression was found to be associated with lower local disease control (5-year LRFS 23.2% vs 96.8%, p < 0.001) and unfavorable clinical outcome (5-year OS 47.4% vs 73.3%, p = 0.014). In multivariate analysis, PD-1 expression was also an adverse prognostic factor for 5-year OS (HR: 3.68, P = 0.023) and LRFS (HR: 16.89, 1.27-11.84, P = 0.007). Those with PD-1 distribution in both stroma and tumor region had the poorest prognosis. However, PD-1 expression has no significant correlation with 5-year RRFS (p = 0.980) and DMFS (p = 0.865). Patients with both PD-1 and PD-L1 high expression had significant poor local disease control (5-year LRFS 96.0% vs 43.0%, p < 0.001) and overall survival (5-year OS 80.8% vs 45.1%, p < 0.001) compared with the others. Other immune markers were not found having corrections with disease control and survival.

CONCLUSIONS

PD-1 high expression, especially with PD-L1 co-expression, is associated with high local recurrence and unfavorable clinical outcome for stage IV M0 NPC patients, and might be a potential target for immunotherapy.

Treatment of Locally Advanced Nasopharyngeal Carcinoma by Helical Tomotherapy: An Observational, Prospective Analysis

Nasopharyngeal carcinoma (NPC) is endemic in southern China. Due to the unique anatomical and biological properties of NPCs, radiotherapy or combined modality based on radiotherapy is an effective treatment option. Helical tomotherapy (HT) is an emerging intensity modulated radiotherapy technology. The advantages of dose homogeneity, steepness of dose gradient, and protection of normal organs are reflected in the treatment of head and neck cancers. We present the preliminary (2-year) clinical outcomes of HT in 85 patients with locally advanced NPC (LA-NPC). Of these patients, 3 patients (3.5%) experienced treatment interruption due to severe pulmonary infection, and 82 (96.5%) completed radiation treatments. The 2-year estimate of progression-free survival, local relapse-free survival, nodal relapse-free survival, distant metastases-free survival, and overall survival rate were 90%, 96.3%, 98.8%, 96.3%, and 96.3%, respectively. Among the three patients that died, one had stage III disease and died from fatal nasopharyngeal bleeding after radiotherapy, while the other two patients succumbed to local recurrence. Our experience suggests that HT can achieve promising disease control and survival in the treatment of LA-NPC patients with mild acute and late toxicity profiles.

Dosimetric comparison of vaginal vault brachytherapy vs applicator-guided stereotactic body radiotherapy with volumetric modulated arc therapy and helical tomotherapy for endometrium cancer patients

We performed this dosimetric study to compare a nonstandard volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT) techniques with high-dose rate (HDR) brachytherapy (BRT) plan of vaginal vault in patients with postoperative endometrial cancer (EC). Twelve postoperative patients with early stage EC were included in this study. Three plans were performed for each patient; dosimetric and radiobiological comparisons were made using dose-volume histograms and equivalent dose for determining the planning target volume (PTV) coverages in brachytherapy and external beam radiotherapy, and organs-at-risk (OARs) doses between three different delivery techniques. All the plans achieved adequate dose coverage for PTV; however, the VMAT plan yielded better dose conformity, and the HT plan showed better homogeneity for target volume. With respect to the OARs, the bladder D_2cc was significantly lower in the BRT plan than in the VMAT and HT plans, with the highest bladder D_2cc value being observed in the HT plan. However, no difference was observed in the rectum D_2cc of the three plans. Other major advantages of the BRT plan over the VMAT and HT plans were the relatively lower body integral doses and femoral head doses as well as the fact that the integral doses were significantly lower in the BRT plan than in the VMAT and HT plans. This is the first dosimetric comparison of vaginal vault treatment for EC with BRT, VMAT, and HT plans. Our analyses showed the feasibility of stereotactic body radiotherapy technique as an alternative to HDR-BRT for postoperative management of EC patients.

Local regression and control of T1-2 nasopharyngeal carcinoma treated with intensity-modulated radiotherapy

OBJECTIVE

To observe the local regression and control in T1-2 nasopharyngeal carcinoma (NPC) patients treated with intensity-modulated radiotherapy (IMRT) and to analyze the related influencing factors.

METHODS

Between January 2006 and June 2014, 247 consecutive T1-2 NPC patients treated with IMRT were retrospectively analyzed, with 126 (51.0%) N0-1 disease and 121 (49.0%) N2-3 disease. Among them, 72.9% received platinum-based chemotherapy. The prescribed dose to gross tumor volume was 66 Gy/30 fractions.

RESULTS

By the end of IMRT, the chemoradiotherapy (CRT) group had higher local complete response (CR) rate compared with IMRT alone group (92.2% vs 74.6%, P < 0.001), but no significant difference was discovered in 5-year local control (LC) rate (95.1% vs 94.9%, P = 0.968). Of the rest 31 patients with residual nasopharyngeal lesions after IMRT, those received boost irradiation (67.7%) also showed no improvement in 5-year LC rate compared with the observational group (95.0% vs 100.0%, P = 0.307). With a median follow-up of 63 months, the estimated 5-year LC rate for the whole group was 95.1% (T1 vs T2: 95.9% vs 94.7%, P = 0.186). Prognostic factors for LC were found neither in univariate nor in multivariate analysis. Advanced N stage was found to be the only adverse prognostic factor for all the other survivals.

CONCLUSIONS

Excellent LC could be achieved in T1-2 NPC treated with IMRT. The addition of chemotherapy may offer short-term response benefit, but no significant LC benefit, so did boost irradiation. Attention should be attached to advanced N stage, the exploration of the recurrence-related factors, and the necessities of the additional treatment.

Proposed modifications and incorporation of plasma Epstein-Barr virus DNA improve the TNM staging system for Epstein-Barr virus-related nasopharyngeal carcinoma

BACKGROUND

The prognosis of patients who have Epstein-Barr virus (EBV)-related nasopharyngeal carcinoma (NPC) in which the tumor tissues harbor EBV have a better prognosis than those without EBV-related NPC. Therefore, the eighth edition of the TNM staging system could be modified for EBV-related NPC by incorporating the measurement of plasma EBV DNA.

METHODS

In total, 979 patients with NPC who received intensity-modulated radiotherapy (IMRT) were retrospectively reviewed. Recursive partitioning analysis was conducted based on tumor (T) classification, lymph node (N) classification, and EBV DNA measurement to derive objectively the proposed stage groupings. The validity of the proposed stage groupings was confirmed in a prospective cohort of 550 consecutive patients who also received with IMRT.

RESULTS

The pretreatment plasma EBV DNA level was identified as a significant, negative prognostic factor for progression-free survival and overall survival in univariate analysis (all P < .001) and multivariate analysis (all P < .05). Recursive partitioning analysis of the primary cohort to incorporate EBV DNA generated the following proposed stage groupings: stage RI (T1N0), RIIA (T2-T3N0 or T1-T3N1, EBV DNA ≤2000 copies/mL), stage RIIB (T2-T3N0 or T1-T3N1, EBV DNA >2000 copies/mL; T1-T3N2, EBV DNA ≤2000 copies/mL), stage RIII (T1-T3N2, EBV DNA >2000 copies/mL; T4N0-N2), and stage RIVA (any T and N3). In the validation cohort, the 5-year progression-free survival rate was 100%, 87.9%, 76.7%, 68.7%, and 50.4% for proposed stage RI, RIIA, RIIB, RIII, and RIV NPC, respectively (P < .001). Compared with the eighth edition TNM stage groupings, the proposed stage groupings incorporating EBV DNA provided better hazard consistency, hazard discrimination, outcome prediction, and sample size balance.

CONCLUSIONS

The proposed stage groupings have better prognostic performance than the eighth edition of the TNM staging system. EBV DNA titers should be included in the TNM staging system to assess patients who have EBV-related NPC.

Intensity-modulated radiation therapy for definitive treatment of cervical cancer: a meta-analysis

Background

To compare the efficacies and toxicities of intensity-modulated radiotherapy (IMRT) with three-dimensional conformal radiotherapy (3D-CRT) or conventional two-dimensional radiotherapy (2D-RT) for definitive treatment of cervical cancer.

Methods

A meta-analysis was performed using search engines, including PubMed, Cochrane Library, Web of Science, and Elsevier. In the meta-analysis, odds ratios (ORs) were compared for overall survival (OS), disease-free survival (DFS), and acute and chronic toxicities.

Results

Included data were analysed using RevMan 5.2 software. Six studies encompassing a total of 1008 patients who received definitive treatment (IMRT = 350, 3-DCRT/2D-RT = 658) were included in the analysis. A comparison of 3-year OS and 3-year DFS revealed no significant differences between IMRT and 3D-CRT or 2D-RT (3-year OS: OR = 2.41, 95% confidence interval [CI]: 0.62–9.39, p = 0.21; 3-year DFS: OR = 1.44, 95% CI: 0.69–3.01, p = 0.33). The incidence of acute gastrointestinal (GI) toxicity and genitourinary (GU) toxicity in patients who received IMRT was significantly lower than that in the control group (GI: Grade 2: OR = 0.5, 95% CI: 0.28–0.89, p = 0.02; Grade 3 or higher: OR = 0.55, 95% CI: 0.32–0.95, p = 0.03; GU: Grade 2: OR = 0.41, 95% CI: 0.2–0.84; p = 0.01; Grade 3 or higher: OR = 0.31, 95% CI: 0.14–0.67, p = 0.003). Moreover, the IMRT patients experienced fewer incidences of chronic GU toxicity than did the control group (Grade 3: OR = 0.09, 95% CI: 0.01–0.67, p = 0.02).

Conclusion

IMRT and conventional radiotherapy demonstrated equivalent efficacy in terms of 3-year OS and DFS. Additionally, IMRT significantly reduced acute GI and GU toxicities as well as chronic GU toxicity in patients with cervical cancer.

Dosimetric comparison between three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) in the treatment of different stages of nasopharyngeal carcinoma

Background

This work aims to compare the dosimetric performance of three-dimensional conformal radiotherapy (3D-CRT), a relatively available technique in developing countries, to intensity-modulated radiotherapy (IMRT) in the treatment of different stages of nasopharyngeal carcinoma (NPC).

Materials and Methods

According to the diagnostic stages, 40 NPC patients were divided into two equal groups. Three planning techniques such as 3D-CRT, seven-field IMRT (7F-IMRT) and nine-field IMRT (9F-IMRT) were compared. Dose prescriptions of 70 and 66 Gy were delivered in 35 fractions to gross planning target volume (PTV1) and bilateral retropharyngeal carcinoma (PTV2), respectively.

Results

Stage I dose data for almost all of the three investigated planning techniques obey the international recommendations. The dose delivered to PTV1 and PTV2 for 3D-CRT and 7F-IMRT are statistically similar, whereas 9F-IMRT is significantly better than 3D-CRT. For organs at risk (OARs), the delivered dose is significantly better for 9F-IMRT compared with the other two techniques, whereas 7F-IMRT is significantly better than 3D-CRT.

Conclusions

3D-CRT is an acceptable alternative treatment technique for stage I NPC patients in developing countries suffering from the lack of advanced radiotherapy treatment techniques. 3D-CRT and 7F-IMRT have comparable performance in PTVs, while 9F-IMRT is superior in PTVs and OARs.

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.

Pattern of geometric changes of parotid gland in conventional and intensity-modulated radiotherapy in nasopharyngeal cancer patients

Introduction

This study compared the pattern of radiation induced parotid changes between conventional (ConRT) and intensity modulated radiotherapy (IMRT) in nasopharyngeal carcinoma patients.

Methods

56 adult NPC patients treated with IMRT (n=28) and conventional radiotherapy (n=28) were recruited. CT scans were acquired before radiotherapy, at 10th, 20th and 30th fractions, and 3 months after treatment. Parotid gland was delineated in the corresponding CT slices and its mean dose was calculated. The volumetric and geometric changes of the parotid gland at various time intervals were compared against the pre-treatment structure set. The pattern of changes was compared between the two techniques.

Results

The mean parotid dose of IMRT (37.5±9.5 Gy) was significantly lower than ConRT (49.1±7.4 Gy). The parotid gland volume, DICE similarity coefficient and lateral dimension of patient head gradually decreased during the radiotherapy course and partially recovered in 3 months post-treatment. The differences between two groups were not significant until at 3 month after treatment, where IMRT showed significantly better volume recovery.

Conclusion

Similar parotid gland size and location changes were observed during the treatment course in both ConRT and IMRT. However IMRT demonstrated better parotid volume recovery after treatment.

Temporal lobe injury patterns following intensity modulated radiotherapy in a large cohort of nasopharyngeal carcinoma patients

OBJECTIVES

To analyze the correlation between dose-volume-histograms (DVHs) with three patterns (edema, enhancement, and necrosis) of temporal lobe injury (TLI) in patients receiving intensity modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC) and to determine optimal thresholds to predict the incidence of each TLI pattern, with particular emphasis on the relationship between edema volume and the risk of enhancement and necrosis.

MATERIALS AND METHODS

A cohort of 4186 NPC patients treated with IMRT was retrospectively reviewed with TLI presenting in 188 patients. The atlases of complication incidence (ACI) for each pattern were constructed using DVH curves of temporal lobes. Optimal threshold for predicting incidence of each pattern was determined using the point closest to top-left of the plot. The accuracy of using edema volume to predict enhancement and necrosis incidence was evaluated via area under curve (AUC) of receiver operator characteristics (ROC).

RESULTS

All DVH parameters, D_mean, D_max, D_0.25cc, D_0.5cc, D_1cc, D_3cc, D_6cc, V_20Gy, V_30Gy, V_40Gy, V_50Gy, V_60Gy, and V_70Gy, except D_min showed statistically significant differences between subgroups of each pattern (p < 0.05). For predicting incidence of each pattern, optimal DVH thresholds over the range of D_0.25-D_1cc, D_mean and V₂₀-V₇₀ were derived. The optimal thresholds of edema volume for predicting enhancement were 0.96 and 2.2cc and for predicting necrosis were 0.94 and 11.5cc.

CONCLUSION

Optimal DVH thresholds were generated for limiting risk of each injury pattern. Edema volume was a strong predictor for risk of enhancement and necrosis, which could potentially be reduced by lowering edema volume below threshold.

Concurrent Chemoradiotherapy versus Intensity-modulated Radiotherapy Alone for Elderly Nasopharyngeal Carcinoma Patients with Pre-treatment Epstein-Barr Virus DNA: A Cohort Study in an Endemic Area with Long-term Follow-up

Purpose: To date, no guidelines exist for elderly nasopharyngeal carcinoma (NPC) patients (60 years of age or older) due to a lack of prospective clinical trials. This study evaluated the efficacy of concurrent chemotherapy (CCRT) for NPC in elderly patients treated with intensity-modulated radiotherapy (IMRT). Methods: Patients were identified from a prospectively maintained database. A total of 198 consecutive cases of elderly patients with NPC receiving IMRT, including 103 patients treated with IMRT plus CCRT and 95 patients treated with IMRT alone, were analysed from January 2002 to December 2013. Multivariate analysis (MVA) using the Cox proportional hazards model and propensity score analysis (PSA) were performed for overall survival (OS) and disease-free survival (DFS). Finally, sensitivity analysis was performed. Results: The median follow-up time was 55.3 months (range, 3-135.6 months). In the entire cohort, both MVA and PSA models showed that compared with IMRT alone, IMRT plus CCRT significantly improved survival (hazard ratio [HR] 2.143, 95% confidence interval [95% CI] 1.180-3.890; HR 1.961, 95% CI, 1.117-3.443, for OS and DFS, respectively). Similar results were found in the subgroups with high levels of Epstein-Barr virus (EBV) DNA, except in the low-EBV-DNA cohort. The total rates of severe acute toxicity, including leukopenia, neutropenia, stomatitis, and emesis, were significantly higher in the IMRT+CCRT group than in the IMRT-alone group (P < 0.001) but were similar to the rates of severe late toxicity (P = 0.818). Sensitivity analysis confirmed the robustness of our analysis. Conclusions: In the era of IMRT, CCRT retained survival benefits at high EBV DNA levels but not at low EBV DNA levels for elderly NPC patients. Randomized clinical trials are needed to confirm our findings.

The plasma Epstein-Barr virus DNA level guides precision treatment for nasopharyngeal carcinoma in the intensity-modulated radiotherapy era: a large population-based cohort study from an endemic area

Background:

In the intensity-modulated radiotherapy (IMRT) era, the survival benefit of concurrent chemotherapy for locoregionally advanced nasopharyngeal carcinoma (LA-NPC) remains undetermined. This study aimed to evaluate the benefits of IMRT with concurrent chemotherapy compared with IMRT alone for LA-NPC patients with different plasma Epstein–Barr virus (EBV) DNA levels.

Methods:

Patients were identified from a prospectively maintained database in an endemic area between November 2002 and December 2013. Cox proportional hazards models, propensity score matching, and inverse probability weighting models were established for survival analysis. Stratification analysis was performed based on interaction effects analysis. Finally, sensitivity analysis was performed considering unmeasured confounders.

Results:

A total of 1357 eligible patients were enrolled (median follow up 62.4 months; range 3.5–155.8 months). No significant survival differences were observed between groups in the entire cohort. Notably, a significant interaction effect was observed between treatment regimens and EBV DNA levels. In patients with high EBV DNA levels (>4000 copies/ml), all three models showed that IMRT with concurrent chemotherapy significantly improved overall survival [hazard ratio (HR) 2.521, 95% confidence interval (CI) 1.218–5.216], disease-free survival (HR 2.168, 95% CI 1.349–3.483), and distant metastasis-free survival (HR 2.331, 95% CI 1.194–4.551) compared with IMRT alone. No differences were found in patients with low EBV DNA levels. Sensitivity analysis confirmed the robustness of the results.

Conclusion:

In the IMRT era, concurrent chemotherapy treatment of LA-NPC patients with high EBV DNA levels is reasonable. However, the optimal regimen for LA-NPC patients with low EBV DNA levels needs further validation in randomized clinical trials.