Toxicity Profiles and Survival Outcomes Among Patients With Nonmetastatic Nasopharyngeal Carcinoma Treated With Intensity-Modulated Proton Therapy vs Intensity-Modulated Radiation Therapy

Evaluating the Efficacy of Different Treatment Intensities in Nasopharyngeal Carcinoma Patients: A Nationwide Cancer Registry-Based Study

OBJECTIVE

The aim of this study was to evaluate the efficacy of different treatment intensities (TIs) in patients with nasopharyngeal carcinoma (NPC).

METHODS

The study assessed newly diagnosed, non-metastatic NPC patients from the Taiwan Cancer Registry between 2010 and 2017. TIs were divided into four groups: TI1 [radiotherapy (RT) alone or induction chemotherapy (IC) followed by RT); TI2 (concurrent chemoradiotherapy (CRT) alone); TI3 (IC followed by CRT or CRT followed by adjuvant chemotherapy (AC)]; and TI4 (IC followed by CRT followed by AC). The primary outcome was cancer-specific survival (CSS).

RESULTS

The study included 9863 patients. For stage I-II NPC patients, there was no significant difference in CSS among the different TI groups. For stage III patients, those receiving TI3 had better CSS (hazard ratio [HR] 0.69) compared with those receiving TI1. No significant differences in CSS were noted among those receiving TI2, TI3, and TI4. For stage IVA-B patients, those receiving TI2 (HR 0.70), TI3 (HR 0.49), and TI4 (HR 0.43) had better CSS compared with those receiving TI1. Compared with stage IVA-B patients receiving TI2, those receiving TI3 (HR 0.70) and TI4 (HR 0.61) had significantly better CSS. No differences in CSS were noted between those receiving TI3 and TI4.

CONCLUSIONS

For stage I-II NPC patients, RT alone is appropriate. For stage III and IVA-B patients, IC + CRT or CRT + AC may be needed to achieve optimal outcomes. No advantage of IC + CRT + AC over IC + CRT or CRT + AC was observed.

Efficacy and safety of proton therapy versus intensity-modulated radiation therapy in the treatment of head and neck tumors: A systematic review and meta-analysis

To comprehensively evaluate the therapeutic efficacy and safety when utilizing proton therapy (PT) versus intensity-modulated radiation therapy (IMRT) in head and neck cancer patients. Pubmed, ScienceDirect, Embase, Scopus, and Web of Science were systematically searched for studies on comparative PT and IMRT outcomes. We performed a random effect model meta-analysis to estimate the hazard ratio (HR) and odds ratio (OR) for efficacy and safety outcome variables between PT and IMRT. From 641 identified articles, 11 studies met the inclusion criteria, comprising 3087 patients (606 treated with PT and 2481 with IMRT). On toxicity analysis, PT is associated with decreased acute grade 1 nausea (OR = 0.34, 95% CI: 0.13-0.84, p = 0.02) compared to IMRT. In grade 2 toxicity, PT showed significant advantages over IMRT in mucositis (OR = 0.44, p < 0.0001), dysgeusia (OR = 0.35, p = 0.02), dysphagia (OR = 0.36, p < 0.0001), fatigue (OR = 0.29, p = 0.001), pain (OR = 0.34, p = 0.01), and weight loss (OR = 0.54, p = 0.02). Proton therapy also exhibited increased safety in grade 3 dysphagia incidence (OR = 0.44, p < 0.0001) compared to IMRT. PT demonstrated improved overall survival (OS) compared to IMRT across multiple time points: 1-year OS (HR = 0.43, p = 0.02), 2-year OS (HR = 0.44, p < 0.0001), and 5-year OS (HR = 0.78, p = 0.004). In terms of disease-free survival (DFS), PT also showed improved outcomes at 2-year DFS (HR = 0.65, p = 0.03) and 5-year DFS (HR = 0.81, p = 0.03). Proton therapy demonstrated superior overall survival (OS), disease-free survival (DFS), and better local control rate (LCR) compared to IMRT. The data also showed better safety outcomes in PT patients, particularly when involving grade 2 acute toxicity events.

Post-irradiation dysbiosis in patients with nasopharyngeal carcinoma having received radiotherapy - A pilot study

OBJECTIVE

To compare the changes in the sinonasal mucosa microbiome in patients with nasopharyngeal carcinoma (NPC) before and after radiotherapy (RT), and to explore the pathogenesis of post-irradiation chronic rhinosinusitis (PI-CRS) and its association with dysbiosis.

STUDY DESIGN

Prospective cohort study.

SETTING

Unicenter, Tertiary referral hospital.

METHODS

Included patients newly diagnosed with NPC. Samples of ostiomeatal complex mucosa were collected before and after RT. Microbiome analysis was conducted using 16S rRNA sequencing, and statistical analysis was performed. Subgroup analyses based on RT modality (proton therapy or photon therapy) RESULTS: Total of 18 patients were enrolled in the study, with 62.1% receiving intensity-modulated proton therapy (IMPT). Corynebacterium was the most dominant genus identified in both the pre- and post-RT groups, with a visible increase in Staphylococcus and a decrease in Fusobacterium genus in post-RT group. Alpha-diversity did not significantly differ between groups, although the beta-diversity analysis revealed a dispersed microbiota in the post-RT group. The functional prediction indicated a higher relative abundance of taxonomies associated with biofilm formation in the post-RT group. The subgroup analysis revealed the above changes to be more significant in patients who received photon therapy (Intensity modulated radiation therapy, IMRT).

CONCLUSIONS

This is the first study to analyze the microbiome of patients with NPC after IMPT. We identified similarities between the post-RT microenvironment and that reported in patients with CRS, with a more apparent change noted in patients treated with IMRT. Further investigation is required to further elucidate the pathogenesis of PI-CRS and its relationship to post-RT dysbiosis, particularly IMPT.

Dosimetric parameters predict radiation-induced temporal lobe necrosis in nasopharyngeal carcinoma patients: A systematic review and meta-analysis

This systematic review examines the role of dosimetric parameters in predicting temporal lobe necrosis (TLN) risk in nasopharyngeal carcinoma (NPC) patients treated with three-dimensional conformal RT (3D-CRT), intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). TLN is a serious late complication that can adversely affect the quality of life of NPC patients. Understanding the relationship between dosimetric parameters and TLN can guide treatment planning and minimize radiation-related complications. A comprehensive search identified relevant studies published up to July 2023. Studies reporting on dosimetric parameters and TLN in NPC patients undergoing 3D-CRT, IMRT, and VMAT were included. TLN incidence, follow-up duration, and correlation with dosimetric parameters of the temporal lobe were analyzed. The review included 30 studies with median follow-up durations ranging from 28 to 110 months. The crude incidence of TLN varied from 2.3 % to 47.3 % and the average crude incidence of TLN is approximately 14 %. Dmax and D1cc emerged as potential predictors of TLN in 3D-CRT and IMRT-treated NPC patients. Threshold values of >72 Gy for Dmax and >62 Gy for D1cc were associated with increased TLN risk. However, other factors should also be considered, including host characteristics, tumor-specific features and therapeutic factors. In conclusion, this systematic review highlights the significance of dosimetric parameters, particularly Dmax and D1cc, in predicting TLN risk in NPC patients undergoing 3D-CRT, IMRT, and VMAT. The findings provide valuable insights that can help in developing optimal treatment planning strategies and contribute to the development of clinical guidelines in this field.

Immune System Dose With Proton Versus Photon Radiotherapy for Treatment of Locally Advanced NSCLC

Purpose

Emerging data have illuminated the impact of effective radiation dose to immune cells (EDIC) on outcomes in patients with locally advanced, unresectable non-small cell lung cancer (NSCLC) treated with intensity-modulated radiotherapy (IMRT). Hypothesizing that intensity-modulated proton therapy (IMPT) may reduce EDIC versus IMRT, we conducted a dosimetric analysis of patients treated at our institution.

Materials and Methods

Data were retrospectively collected for 12 patients with locally advanced, unresectable NSCLC diagnosed between 2019 and 2021 who had physician-approved IMRT and IMPT plans. Data to calculate EDIC from both Jin et al (PMID: 34944813) and Ladbury et al's (PMID: 31175902) models were abstracted. Paired t tests were utilized to compare the difference in mean EDIC between IMPT and IMRT plans.

Results

IMPT decreased EDIC for 11 of 12 patients (91.7%). The mean EDIC per the Jin model was significantly lower with IMPT than IMRT (3.04 GyE vs 4.99 Gy, P < .001). Similarly, the mean EDIC per the Ladbury model was significantly lower with IMPT than IMRT (4.50 GyE vs 7.60 Gy, P < .002). Modeled 2-year overall survival was significantly longer with IMPT than IMRT (median 71% vs 63%; P = .03).

Conclusion

IMPT offers a statistically significant reduction in EDIC compared to IMRT. Given the emergence of EDIC as a modifiable prognostic factor in treatment planning, our dosimetric study highlights a potential role for IMPT to address an unmet need in improving oncologic outcomes in patients with locoregionally advanced NSCLC.

Proton Therapy: Current Status and Controversies

Expert commentary on the evolving role of proton therapy, discussing the current status and controversies of proton therapy in the modern era.

Current Status and Future Directions of Proton Therapy for Head and Neck Carcinoma

The growing interest in proton therapy (PT) in recent decades is justified by the evidence that protons dose distribution allows maximal dose release at the tumor depth followed by sharp distal dose fall-off. But, in the holistic management of head and neck cancer (HNC), limiting the potential of PT to a mere dosimetric advantage appears reductive. Indeed, the precise targeting of PT may help evaluate the effectiveness of de-escalation strategies, especially for patients with human papillomavirus associated-oropharyngeal cancer (OPC) and nasopharyngeal cancer (NPC). Furthermore, PT could have potentially greater immunogenic effects than conventional photon therapy, possibly enhancing both the radiotherapy (RT) capability to activate anti-tumor immune response and the effectiveness of immunotherapy drugs. Based on these premises, the aim of the present paper is to conduct a narrative review reporting the safety and efficacy of PT compared to photon RT focusing on NPC and OPC. We also provide a snapshot of ongoing clinical trials comparing PT with photon RT for these two clinical scenarios. Finally, we discuss new insights that may further develop clinical research on PT for HNC.

A retrospective study on the investigation of potential dosimetric benefits of online adaptive proton therapy for head and neck cancer

PURPOSE

Proton therapy is sensitive to anatomical changes, often occurring in head-and-neck (HN) cancer patients. Although multiple studies have proposed online adaptive proton therapy (APT), there is still a concern in the radiotherapy community about the necessity of online APT. We have performed a retrospective study to investigate the potential dosimetric benefits of online APT for HN patients relative to the current offline APT.

METHODS

Our retrospective study has a patient cohort of 10 cases. To mimic online APT, we re-evaluated the dose of the in-use treatment plan on patients' actual treatment anatomy captured by cone-beam CT (CBCT) for each fraction and performed a templated-based automatic replanning if needed, assuming that these were performed online before treatment delivery. Cumulative dose of the simulated online APT course was calculated and compared with that of the actual offline APT course and the designed plan dose of the initial treatment plan (referred to as nominal plan). The ProKnow scoring system was employed and adapted for our study to quantify the actual quality of both courses against our planning goals.

RESULTS

The average score of the nominal plans over the 10 cases is 41.0, while those of the actual offline APT course and our simulated online course is 25.8 and 37.5, respectively. Compared to the offline APT course, our online course improved dose quality for all cases, with the score improvement ranging from 0.4 to 26.9 and an average improvement of 11.7.

CONCLUSION

The results of our retrospective study have demonstrated that online APT can better address anatomical changes for HN cancer patients than the current offline replanning practice. The advanced artificial intelligence based automatic replanning technology presents a promising avenue for extending potential benefits of online APT.

The role of the soft palate dose regarding normal tissue toxicities in older adults with head and neck cancer undergoing definitive radiotherapy

PURPOSE

The number of older adults with head and neck squamous cell carcinoma (HNSCC) is continuously increasing. Older HNSCC patients may be more vulnerable to radiotherapy-related toxicities, so that extrapolation of available normal tissue complication probability (NTCP) models to this population may not be appropriate. Hence, we aimed to investigate the correlation between organ at risk (OAR) doses and chronic toxicities in older patients with HNSCC undergoing definitive radiotherapy.

METHODS

Patients treated with definitive radiotherapy, either alone or with concomitant systemic treatment, between 2009 and 2019 in a large tertiary cancer center were eligible for this analysis. OARs were contoured based on international consensus guidelines, and EQD2 doses using α/ß values of 3 Gy for late effects were calculated based on the radiation treatment plans. Treatment-related toxicities were graded according to Common Terminology Criteria for Adverse Events version 5.0. Logistic regression analyses were carried out, and NTCP models were developed and internally validated using the bootstrapping method.

RESULTS

A total of 180 patients with a median age of 73 years fulfilled the inclusion criteria and were analyzed. Seventy-three patients developed chronic moderate xerostomia (grade 2), 34 moderate dysgeusia (grade 2), and 59 moderate-to-severe (grade 2-3) dysphagia after definitive radiotherapy. The soft palate dose was significantly associated with all analyzed toxicities (xerostomia: OR = 1.028, dysgeusia: OR = 1.022, dysphagia: OR = 1.027) in the multivariable regression. The superior pharyngeal constrictor muscle was also significantly related to chronic dysphagia (OR = 1.030). Consecutively developed and internally validated NTCP models were predictive for the analyzed toxicities (optimism-corrected AUCs after bootstrapping: AUCxerostomia=0.64, AUCdysgeusia=0.60, AUCdysphagia=0.64).

CONCLUSIONS

Our data suggest that the dose to the soft palate is associated with chronic moderate xerostomia, moderate dysgeusia and moderate-to-severe dysphagia in older HNSCC patients undergoing definitive radiotherapy. If validated in external studies, efforts should be undertaken to reduce the soft palate dose in these patients.

Toxicity profile of patients treated with proton and carbon-ion therapy for primary nasopharyngeal carcinoma: A systematic review and meta-analysis

BACKGROUND

Proton and carbon-ion therapy may spare normal tissues in regions with many critical structures surrounding the target volume. As toxicity outcome data are emerging, we aimed to synthesize the published data for the toxicity outcomes of proton or carbon-ion therapy (together known as particle beam therapy [PBT]) for primary nasopharyngeal carcinoma (NPC).

MATERIALS AND METHODS

We searched PubMed and Scopus electronic databases to identify original studies reporting toxicity outcomes following PBT of primary NPC. Quality assessment was performed using NIH's Quality Assessment Tool. Reports were extracted for information on demographics, main results, and clinical and dose factors correlates. Meta-analysis was performed using the random-effects model.

RESULTS

Twelve studies were selected (six using mixed particle-photon beams, five performed comparisons to photon-based therapy). The pooled event rates for acute grade ≥2 toxicities mucositis, dermatitis, xerostomia weight loss are 46% (95% confidence interval [95% CI]-29%-64%, I2 = 87%), 47% (95% CI-28%-67%, I2 = 87%), 16% (95% CI-9%-29%, I2 = 76%), and 36% (95% CI-27%-47%, I2 = 45%), respectively. Only one late endpoint (xerostomia grade ≥2) has sufficient data for analysis with pooled event rate of 9% (95% CI-3%-29%, I2 = 77%), lower than intensity-modulated radiotherapy 27% (95% CI-10%-54%, I2 = 95%). For most endpoints with significant differences between the PBT and photon-based therapies, PBT resulted in better outcomes. In two studies where dose distribution was studied, doses to the organs at risk were independent risk factors for toxicities.

CONCLUSION

PBT may reduce the risk of acute toxicities for patients treated for primary NPC, likely due to dose reduction to critical structures. The pooled event rate for toxicities derived in this study can be a guide for patient counseling.

Quality of life in patients with nasopharyngeal carcinoma receiving IMRT vs IMPT: a multicenter prospective longitudinal study

PURPOSE

Nasopharyngeal carcinoma (NPC) patients may experience symptom distress and depression during and after radiation therapy, which negatively impacts quality of life (QOL). We sought to identify trajectories of symptom distress, depression, social support, and QOL in patients with NPC receiving intensity-modulated radiation therapy (IMRT) vs intensity-modulated proton therapy (IMPT).

METHODS

A multicenter prospective longitudinal study recruited NPC patients from two leading medical centers in Taiwan. The 121 NPC patients were followed from before RT (T0), at 4 weeks after beginning RT (T1), at 6 weeks of RT or the end of treatment (T2), and at 4 weeks post-RT (T3). Generalized estimating equation analysis was used to identify the factors related to QOL.

RESULTS

Patients' symptom distress and depression increased from T0, peaked at T2, and decreased at T3. Physical-QOL and psychosocial-QOL decreased from T0 to T2, then increased by T3. Patients who had early-stage cancer, received a lower RT dose, had less symptom distress, and had less depression were more likely to have better QOL. Greater physical-QOL was associated with IMPT receipt, higher education level, early cancer stage, lower radiation dose, less symptom distress, and less depression. Patients who had good physical performance, received a lower radiation dose, had less symptom distress, and had less depression were more likely to have better psychosocial-QOL.

CONCLUSION

Radiation dose, symptom distress, and depression were the most important factors affecting QOL in patients with NPC. Understanding the factors associated with the trajectory of QOL can guide care during radiation treatment.

Radiation oncology for the rhinologist

PURPOSE OF REVIEW

This comprehensive review explores evolving treatment strategies for sinonasal and nasopharyngeal malignancies. It analyzes the role of adjuvant radiotherapy, the potential of intensity-modulated proton therapy (IMPT), and the relevance of de-escalation strategies nasopharyngeal carcinoma (NPC). Additionally, it discusses hyperfractionation in re-irradiation in NPC.

RECENT FINDINGS

Adjuvant radiotherapy remains pivotal for sinonasal tumors, improving locoregional control and survival, notably in squamous cell carcinomas, adenocarcinomas, and adenoid cystic carcinomas. IMPT promises enhanced outcomes by sparing healthy tissues, potentially improving patients' quality of life. For select stage II/T3N0 NPC, radiotherapy alone offers comparable outcomes to concurrent chemoradiotherapy, with fewer adverse events and improved quality of life. Selective neck irradiation in NPC patients with uninvolved necks maintains oncologic outcomes while reducing late toxicity. Hyperfractionation in re-irradiation shows promise in lowering late toxicities and improving overall survival, particularly in undifferentiated sinonasal carcinomas.

SUMMARY

This review underscores the significance of adjuvant radiotherapy and the potential of advanced radiation techniques in optimizing sinonasal and nasopharyngeal malignancy outcomes. It emphasizes evolving de-escalation methods and individualized, evidence-based approaches. Future research will further refine strategies for these challenging malignancies.

High Expression of NLR and SII in patients With Nasopharyngeal Carcinoma as Potential Prognostic Observations

PURPOSE

To assess the value of pretreatment neutrophil-to-lymphocyte ratio (NLR) and systemic immunoinflammatory index (SII) in the prognosis of nasopharyngeal carcinoma (NPC) patients.

METHODS

This retrospective study analyzed a total of 185 NPC patients who visited the clinic from June 2015 to December 2018 and were selected as study subjects. The NLR and SII were calculated based on the collection of demographic information, clinical characteristics, and pre-treatment lymphocyte counts, neutrophil counts, and platelet counts. Predictive efficacy was evaluated using the receiver operating characteristic (ROC) curve, and survival analysis was performed through life table methods and Cox risk-proportional regression.

RESULTS

Using the X-tile software, significant differences were found in clinical factors among NPC patients based on NLR (>2.91) and SII (>535.47). Age, TNM staging, SII, and NLR were identified as independent prognostic factors in a Cox regression analysis. SII had the highest area under the curve (AUC) for predicting 1-year survival, TNM staging had the highest AUC for predicting 3-year survival, and NLR had the highest AUC for predicting 5-year survival. The combined model showed superior predictive accuracy across all time points.

CONCLUSION

NLR and SII, as biomarkers of inflammation and immune status, have significant clinical applications in the prognostic assessment of NPC. The integrated prediction model combining age, TNM staging, SII, and NLR significantly improved the accuracy of survival prediction and provided a reliable basis for individualised treatment of NPC.

Precision medicine in nasopharyngeal carcinoma: comprehensive review of past, present, and future prospect

Nasopharyngeal carcinoma (NPC) is an aggressive malignancy with high propensity for lymphatic spread and distant metastasis. It is prominent as an endemic malignancy in Southern China and Southeast Asia regions. Studies on NPC pathogenesis mechanism in the past decades such as through Epstein Barr Virus (EBV) infection and oncogenic molecular aberrations have explored several potential targets for therapy and diagnosis. The EBV infection introduces oncoviral proteins that consequently hyperactivate many promitotic pathways and block cell-death inducers. EBV infection is so prevalent in NPC patients such that EBV serological tests were used to diagnose and screen NPC patients. On the other hand, as the downstream effectors of oncogenic mechanisms, the promitotic pathways can potentially be exploited therapeutically. With the apparent heterogeneity and distinct molecular aberrations of NPC tumor, the focus has turned into a more personalized treatment in NPC. Herein in this comprehensive review, we depict the current status of screening, diagnosis, treatment, and prevention in NPC. Subsequently, based on the limitations on those aspects, we look at their potential improvements in moving towards the path of precision medicine. The importance of recent advances on the key molecular aberration involved in pathogenesis of NPC for precision medicine progression has also been reported in the present review. Besides, the challenge and future outlook of NPC management will also be highlighted.

Mitigating Radiotoxicity in the Central Nervous System: Role of Proton Therapy

OPINION STATEMENT

Central nervous system (CNS) radiotoxicity remains a challenge in neuro-oncology. Dose distribution advantages of protons over photons have prompted increased use of brain-directed proton therapy. While well-recognized among pediatric populations, the benefit of proton therapy among adults with CNS malignancies remains controversial. We herein discuss the role of protons in mitigating late CNS radiotoxicities in adult patients. Despite limited clinical trials, evidence suggests toxicity profile advantages of protons over conventional radiotherapy, including retention of neurocognitive function and brain volume. Modelling studies predict superior dose conformality of protons versus state-of-the-art photon techniques reduces late radiogenic vasculopathies, endocrinopathies, and malignancies. Conversely, potentially higher brain tissue necrosis rates following proton therapy highlight a need to resolve uncertainties surrounding the impact of variable biological effectiveness of protons on dose distribution. Clinical trials comparing best photon and particle-based therapy are underway to establish whether protons substantially improve long-term treatment-related outcomes in adults with CNS malignancies.

Cause of death during nasopharyngeal carcinoma survivorship: a population-based analysis

Background

Recently, the survival rate of nasopharyngeal carcinoma (NPC) patients has improved greatly due to developments in NPC treatments. But cause-specific mortality in NPC patients remains unclear. This study aims to investigate the common causes of death in NPC patients.

Methods

Eligible patients with NPC were included from the Surveillance, Epidemiology, and End Results (SEER) database. Standardized mortality ratios(SMRs) were calculated to compare death rates in NPC patients with those in the general population.

Results

A total of 3475 patients with NPC were included, of whom 1696 patients died during the follow-up period. 52.83% of deaths were caused by NPC, followed by other cancers (28.13%) and non-cancer causes (18.46%). The proportion of patients who died of NPC decreased over survival time. Moreover, non-cancer causes of death increase from 12.94% to 51.22% over time after 10 years of diagnosis. Heart diseases was the most common non-cancer cause of death in NPC patients.

Conclusions

Although NPC remains the leading cause of death after NPC diagnosis, other non-NPC causes of death represent an increased number of death in NPC patients. These findings support the involvement of multidisciplinary care for follow-up strategy in NPC patients.

Advances and Challenges in Conducting Clinical Trials With Proton Beam Therapy

Advances in proton therapy have garnered much attention and speculation in recent years as the indications for proton therapy have grown beyond pediatric, prostate, spine, and ocular tumors. To achieve and maintain consistent access to this cancer treatment and to ensure the future viability and availability of proton centers in the United States, a call for evidence has been heard and answered by proton radiation oncologists. Answers provided in this review include the evolution of proton therapy research, rationale for proton clinical trial design, challenges in and barriers to the conduct of proton therapy research, and other unique considerations for the study of proton therapy.

Risk of temporal lobe necrosis between proton beam and volumetric modulated arc therapies in patients with different head and neck cancers

BACKGROUND

To investigate the frequency of temporal lobe necrosis (TLN) soon after radiotherapy (RT) and identify differences among patients with various types of head and neck cancer (HNC) and between different RT methods.

METHODS

We retrospectively reviewed 483 patients with HNC who had completed RT in our hospital after January, 2015. These patients were followed-up at the radio-oncology department and received contrast-enhanced magnetic resonance imaging (MRI) or computed tomography (CT) to identify metastases or recurrence of cancer at regular intervals. Meanwhile, the occurrence of TLN, graded according to the Common Terminology Criteria for Adverse Events V5.0, was recorded. We categorized the patients into nasopharyngeal carcinoma (NPC) and non-NPC groups and compared the cumulative occurrence of TLN between the groups using Kaplan-Meier and Cox regression analyses. We further compared the cumulative occurrence of TLN between proton beam therapy (PBT) and volumetric modulated arc therapy (VMAT) in patients with any HNC, NPC, and non-NPC HNC.

RESULTS

Compared with the non-NPC group, the NPC group had a higher frequency of TLN (5.6% vs. 0.4%,  p < 0.01) and were more commonly associated with TLN in the Kaplan-Meier analysis (p < 0.01) and the Cox regression model after covariates were adjusted for (adjusted hazard ratio: 13.35, 95% confidence interval: 1.37-130.61) during the follow-up period. Furthermore, the frequency of TLN was similar between patients receiving PBT and those receiving VMAT (PBT vs. VMAT: 4.7% vs. 6.3%, p = 0.76). Kaplan-Meier analysis revealed that the accumulated risks of TLN were similar between PBT and VMAT in patients with any HNC (p = 0.44), NPC (p = 0.84), and non-NPC HNC (p = 0.70).

CONCLUSION

Our study demonstrated that patients with NPC are susceptible to TLN during the early period after RT. In addition, PBT may be associated with an equivalent risk of TLN when compared with VMAT in patients with NPC or other HNCs.

Vertebral artery sparing volumetric modulated arc therapy in nasopharyngeal carcinoma

Vascular stenosis is a late radiation complication that develops in long-term survivors of nasopharyngeal carcinoma. Vertebral arteries (VAs) are major vessels responsible for posterior circulation. In this study, we evaluated the feasibility of VA-sparing volumetric modulated arc therapy (VMAT) techniques. A total of 20 patients with nasopharyngeal carcinoma treated by a TrueBeam linear accelerator were enrolled in this study. The original VMAT plan was designed without the contouring of VAs as organs at risk (OARs). The same image set of the original VMAT plan was used to contour the VAs for each patient. A new VA-sparing VMAT plan was developed by avoiding VAs as OARs. Finally, a paired t-test was used to compare the dosimetric differences. The VA-sparing VMAT plan had similar target coverage and dose to those of other OARs. The VA-sparing plan yielded a significantly low VA dose from 53 to 40 Gy, with V35Gy changing from 97% to 56%, V50Gy changing from 67% to 35%, and V63Gy changing from 15% to approximately 7%-10% (p < 0.001 for all comparisons). VAs should be correctly identified as OARs. Photon VMAT with VA sparing can help substantially decrease the VA dose.

Radiation therapy for low- and high-risk perineural invasion in head and neck cutaneous squamous cell carcinoma: Clinical outcomes and patterns of failure

BACKGROUND

Perineural invasion (PNI) in head and neck squamous cell carcinoma (HNSCC) portends poor prognosis. Extent of treatment of nerve pathways with varying degrees of PNI and patterns of failure following elective neural radiotherapy (RT) remain unclear.

METHODS

Retrospective review of HNSCC patients with high-risk (clinical/gross, large-nerve, extensive) or low-risk (microscopic/focal) PNI who underwent curative-intent treatment from 2010 to 2021.

RESULTS

Forty-four patients (mean follow-up 22 months; 59% high-risk, 41% low-risk PNI) were included. Recurrence following definitive treatment occurred in 31% high-risk and 17% low-risk PNI patients. Among high-risk patients, 69% underwent surgery with post-operative RT and 46% underwent elective neural RT. Local control (83% low-risk vs. 75% high-risk), disease-free, and overall survival did not differ between groups.

CONCLUSIONS

High local control rates were achieved in high-risk PNI patients treated with adjuvant or primary RT, including treatment of both involved and uninvolved, communicating cranial nerves, with few failures in electively treated regions.

The quality of life in nasopharyngeal carcinoma radiotherapy: A longitudinal study

Objective

This article aims to longitudinally compare nasopharyngeal carcinoma (NPC) patients' quality of life (QoL) during radiotherapy (RT) and identify QoL correlates.

Methods

This study included 98 patients, with 85 completing full follow-up. Data were collected at baseline (T₁), midpoint of RT (T₂), and RT completion (T₃), between October 2021 and November 2022. QoL was assessed using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30). RIOM severity was evaluated by the toxicity criteria of Radiation Therapy Oncology Group (RTOG). The nutritional status was evaluated using the Nutritional Risk Screening 2002 (NRS 2002), body mass index (BMI), and the Patient-Generated Subjective Global Assessment (PG-SGA). The generalized estimating equation described the QoL evolution and correlated it with RIOM, nutritional status, and other influential factors.

Results

Significant deterioration was observed in various subscales of EORTC QLQ-C30 during RT, including global health status (GHS), physical function, role function, emotional function, fatigue, nausea/vomiting, pain, insomnia, appetite loss, and constipation (all P ​< ​0.05). Substantial deterioration was also observed in RIOM, nutritional status, and part of hematological indexes (all P ​< ​0.05). The decline of QoL was associated with gender, age, education level, chemotherapy regimen, Karnofsky performance status (KPS) score, RIOM severity, NRS 2002 score, PG-SGA score, and lymphocyte level (all P ​< ​0.05).

Conclusions

QoL declined during RT and were associated with certain factors. Healthcare professionals should focus on alleviating treatment-related complications and identifying individuals at high risk of malnutrition early to improve outcomes for patients with NPC.

Current Radiotherapy Considerations for Nasopharyngeal Carcinoma

Radiotherapy is the primary treatment modality for nasopharyngeal carcinoma (NPC). Successful curative treatment requires optimal radiotherapy planning and precise beam delivery that maximizes locoregional control while minimizing treatment-related side effects. In this article, we highlight considerations in target delineation, radiation dose, and the adoption of technological advances with the aim of optimizing the benefits of radiotherapy in NPC patients.

Toxicity Profiles and Survival Outcomes Among Patients With Nonmetastatic Oropharyngeal Carcinoma Treated With Intensity-Modulated Proton Therapy vs Intensity-Modulated Radiation Therapy

IMPORTANCE

Patients with oropharyngeal carcinoma (OPC) treated with radiotherapy often experience substantial toxic effects, even with modern techniques such as intensity-modulated radiation therapy (IMRT). Intensity-modulated proton therapy (IMPT) has a potential advantage over IMRT due to reduced dose to the surrounding organs at risk; however, data are scarce given the limited availability and use of IMPT.

OBJECTIVE

To compare toxic effects and oncologic outcomes among patients with newly diagnosed nonmetastatic OPC treated with IMPT vs IMRT with or without chemotherapy.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study included patients aged 18 years or older with newly diagnosed nonmetastatic OPC who received curative-intent radiotherapy with IMPT or IMRT at a single-institution tertiary academic cancer center from January 1, 2018, to December 31, 2021, with follow-up through December 31, 2021.

EXPOSURES

IMPT or IMRT with or without chemotherapy.

MAIN OUTCOMES AND MEASURES

The main outcomes were the incidence of acute and chronic (present after ≥6 months) treatment-related adverse events (AEs) and oncologic outcomes, including locoregional recurrence (LRR), progression-free survival (PFS), and overall survival (OS). Fisher exact tests and χ2 tests were used to evaluate associations between toxic effects and treatment modality (IMPT vs IMRT), and the Kaplan-Meier method was used to compare LRR, PFS, and OS between the 2 groups.

RESULTS

The study included 292 patients with OPC (272 [93%] with human papillomavirus [HPV]-p16-positive tumors); 254 (87%) were men, 38 (13%) were women, and the median age was 64 years (IQR, 58-71 years). Fifty-eight patients (20%) were treated with IMPT, and 234 (80%) were treated with IMRT. Median follow-up was 26 months (IQR, 17-36 months). Most patients (283 [97%]) received a dose to the primary tumor of 70 Gy. Fifty-seven of the patients treated with IMPT (98%) and 215 of those treated with IMRT (92%) had HPV-p16-positive disease. There were no significant differences in 3-year OS (97% IMPT vs 91% IMRT; P = .18), PFS (82% IMPT vs 85% IMRT; P = .62), or LRR (5% IMPT vs 4% IMRT; P = .59). The incidence of acute toxic effects was significantly higher for IMRT compared with IMPT for oral pain of grade 2 or greater (42 [72%] IMPT vs 217 [93%] IMRT; P < .001), xerostomia of grade 2 or greater (12 [21%] IMPT vs 68 [29%] IMRT; P < .001), dysgeusia of grade 2 or greater (16 [28%] IMPT vs 134 [57%] IMRT; P < .001), grade 3 dysphagia (4 [7%] IMPT vs 29 [12%] IMRT; P < .001), mucositis of grade 3 or greater (10 [53%] IMPT vs 13 [70%] IMRT; P = .003), nausea of grade 2 or greater (0 [0%] IMPT vs 18 [8%] IMRT; P = .04), and weight loss of grade 2 or greater (22 [37%] IMPT vs 138 [59%] IMRT; P < .001). There were no significant differences in chronic toxic effects of grade 3 or greater, although there was a significant difference for chronic xerostomia of grade 2 or greater (6 IMPT [11%] vs 22 IMRT [10%]; P < .001). Four patients receiving IMRT (2%) vs 0 receiving IMPT had a percutaneous endoscopic gastrostomy tube for longer than 6 months.

CONCLUSIONS AND RELEVANCE

In this study, curative-intent radiotherapy with IMPT for nonmetastatic OPC was associated with a significantly reduced acute toxicity burden compared with IMRT, with few chronic toxic effects and favorable oncologic outcomes, including locoregional recurrence of only 5% at 2 years. Prospective randomized clinical trials comparing these 2 technologies and of patient-reported outcomes are warranted.

Particle beam therapy for nasopharyngeal cancer: A systematic review and meta-analysis

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Particle beam therapy yields excellent short-term treatment outcomes among NPC patients.

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Particle beam therapy is generally safe in primary and recurrent NPC patients, with ≥G3 late toxicity rates of 20 % or less.

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An approximately 5% mortality rate was reported among recurrent NPC patients.

Background/purpose

A systematic review and meta-analysis were performed to better understand the benefits of particle beam therapy for nasopharyngeal cancer (NPC) treatment. The survival outcomes and toxicity of primary and recurrent NPC patients treated with proton or carbon ion beam therapy were investigated.

Method

PubMed, Scopus, and Embase were searched between 1 January 2007 to 3 November 2021. The inclusion and exclusion criteria included studies with either primary or recurrent NPC patients, sample size of ≥10 patients, and proton or carbon ion beam therapy as interventions. Twenty-six eligible studies with a total of 1502 patients were included. We used a random-effect meta-analysis to examine the impact of particle beam therapy on primary NPC patients and qualitatively described the results among recurrent patients. The primary outcome was overall survival (OS), while secondary outcomes included progression-free survival (PFS), local control (LC) and toxicity.

Results

The pooled OS at 1-year, 2-year and 3-year and 5-year for primary NPC patients who received particle beam therapy were 96 % (95 % confidence interval (CI) = 92 %-98 %), 93 % (95 % CI = 83 %-97 %), 90 % (95 % CI = 73 %-97 %) and 73 % (95 % CI = 52 %-87 %) respectively. The pooled 1-year and 2-year PFS, and LC for these patients were above 90 %. For locally recurrent NPC patients, the 1-year OS rate ranged from 65 % to 92 %, while the 1-year LC rate ranged from 80 % to 88 %. Both proton and carbon ion beam therapy were generally safe among primary and recurrent patients, with ≥G3 late toxicity rates of 20 % or less. Approximately a 5 % mortality rate was reported among recurrent patients.

Conclusions

This systematic review and meta-analysis demonstrated particle beam therapy has great potential in treating NPC, yielding excellent survival outcomes with low toxicity. However, further investigations are needed to assess the long-term outcomes and cost-effectiveness of this newer form of radiotherapy.

Acute radiation dermatitis among patients with nasopharyngeal carcinoma treated with proton beam therapy: Prognostic factors and treatment outcomes

A high incidence of severe acute radiation dermatitis (ARD) has been reported for cancer patients treated by proton beam therapy (PBT). This observational study investigated the prognostic factors and treatment outcomes of ARD among patients with nasopharyngeal carcinoma (NPC) treated with PBT. Fifty-seven patients with newly diagnosed NPC and treated with PBT were enrolled. ARD was recorded weekly based on the criteria of Common Terminology Criteria for Adverse Events version 4.0 at treatment visits (1st to 7th weeks) and 1 week (8th week) and 1 month (11th week) after the completion of PBT. The maximum ARD grade was 1, 2, and 3 in 26 (45.6%), 24 (42.1%), and 7 (12.3%) of the patients, respectively. The peak incidence of grade 2 and 3 ARD was observed during the period of the 6th to 8th weeks. Treatment of ARD included topical corticosteroid alone in 24 (42.1%) patients, topical corticosteroid plus silver sulfadiazine in 33 (57.9%) patients, and non-adhering silicone dressing to cover severe skin wound area in 25 (43.8%) patients. In the 11th week, most grade 2 and 3 ARD had disappeared and 93.0% of the patients had ARD of grade 1 or lower. In the binary logistic regression model, we identified habitual smoking (odds ratio [OR]: 5.2, 95% confidence interval [CI]: 1.3-18.8, P = .012) and N2 to N3 nodal status (OR: 4.9, 95% CI: 1.6-15.4, P = .006) as independent predictors of grade 2 and 3 ARD. The results show ARD is a major concern for patients with NPC treated with PBT, especially those with habitual smoking or advanced nodal status. Topical corticosteroid, silver sulfadiazine, and non-adhering silicone dressing are effective for treating ARD induced by PBT.

Outcomes and Toxicities of Nonmedullary Thyroid Tumors Treated with Proton Beam Radiation Therapy

Purpose

Proton therapy is an emerging therapy for several malignancies owing to its favorable therapeutic ratio. There are very limited data on the use of proton therapy in the management of thyroid carcinoma. Our objective was to review the safety, feasibility, and outcomes of proton therapy for patients with thyroid cancer treated to the head and neck.

Methods

From our institution's proton database from 2012 to 2021, we identified 22 patients with thyroid cancer treated with proton beam therapy. We evaluated outcomes and toxicities.

Results

Median follow-up was 26 months. Of the 22 patients, 50% were female. The mean age was 65 years. Three patients had anaplastic cancer; 13, papillary carcinoma; 2, follicular carcinoma; and 2, poorly differentiated carcinoma. Forty-six percent had T4 disease. Primary targets were the central neck compartment, level VI, and upper mediastinum. Radiation dose was 60 GyRBE adjuvantly, and 70 GyRBE for gross disease (range, 6000-7600 GyRBE). Eight patients underwent upfront adjuvant radiation, and 3 received definitive radiation for unresectable disease upfront. Eleven patients received either salvage or palliative radiation. Fifty-nine percent of patients had extrathyroidal extension, and 64% of patients had gross disease in the neck before treatment. Fifty percent of patients had metastatic disease before treatment. Sixteen patients received concurrent chemotherapy, 63% of these patients received doxorubicin. For all patients, 1-year local regional recurrence (LRR) was 0%, and overall survival (OS) was 90%. Acute grade 3+ toxicities occurred in 27% of patients, the most frequent being dermatitis (27%). Three patients required a percutaneous endoscopic gastrostomy tube after radiation therapy (RT), 2 owing to progression. There were no grade 4+ toxicities.

Conclusions

Proton therapy for thyroid cancer appears feasible and effective with minimal toxicities. Prospective studies comparing proton therapy with intensity-modulated RT, to evaluate the clinical efficacy of using proton therapy to reduce toxicities in patients undergoing radiation for thyroid cancer, are warranted.

Acute toxicity in patients treated with concurrent chemoradiotherapy with proton versus intensity-modulated radiation therapy for nonmetastatic head and neck cancers

BACKGROUND

We evaluated if proton therapy is associated with decreased acute toxicities compared to intensity-modulated radiation therapy (IMRT) in patients receiving concurrent chemoradiotherapy for head and neck cancers.

METHODS

We analyzed 580 patients with nonmetastatic head and neck cancers. Primary endpoint was any 90-day grade ≥3 toxicity, prospectively collected and graded per CTCAEv4. Modified Poisson regression models were used.

RESULTS

Ninety-five patients received proton and 485 IMRT. The proton group had more HPV-positive tumors (65.6 vs. 58.0%, p = 0.049), postoperative treatment (76.8 vs. 62.1%, p = 0.008), unilateral neck treatment (18.9 vs. 6.6%, p < 0.001) and significantly lower doses to organs-at-risk compared to IMRT group. Adjusted for patient and treatment characteristics, the proton group had decreased grade 2 dysgeusia (RR0.67, 95%CI 0.53-0.84, p = 0.004) and a trend toward lower grade ≥3 toxicities (RR0.60, 95%CI 0.41-0.88, p = 0.06).

CONCLUSIONS

Proton therapy was associated with significantly reduced grade 2 dysgeusia and nonstatistically significant decrease in acute grade ≥3 toxicities compared to IMRT.

Dosimetric Parameters Related to Acute Radiation Dermatitis of Patients with Nasopharyngeal Carcinoma Treated by Intensity-Modulated Proton Therapy

Background: Growing patients with nasopharyngeal carcinoma (NPC) were treated with intensity-modulated proton therapy (IMPT). However, a high probability of severe acute radiation dermatitis (ARD) was observed. The objective of the study is to investigate the dosimetric parameters related to ARD for NPC patients treated with IMPT. Methods: Sixty-two patients with newly diagnosed NPC were analyzed. The ARD was recorded based on the criteria of Common Terminology Criteria for Adverse Events version 4.0. Logistic regression model was performed to identify the clinical and dosimetric parameters related to ARD. Receiver operating characteristic (ROC) curve analysis and the area under the curve (AUC) were used to evaluate the performance of the models. Results: The maximum ARD grade was 1, 2, and 3 in 27 (43.5%), 26 (42.0%), and 9 (14.5%) of the patients, respectively. Statistically significant differences (p < 0.01) in average volume to skin 5 mm with the respective doses were observed in the range 54−62 Cobalt Gray Equivalent (CGE) for grade 2 and 3 versus grade 1 ARD. Smoking habit and N2-N3 status were identified as significant predictors to develop grade 2 and 3 ARD in clinical model, and V58CGE to skin 5 mm as an independent predictor in dosimetric model. After adding the variable of V58CGE to the metric incorporating two parameters of smoking habit and N status, the AUC value of the metric increases from 0.78 (0.66−0.90) to 0.82 (0.72−0.93). The most appropriate cut-off value of V58CGE to skin 5 mm as determined by ROC curve was 5.0 cm3, with a predicted probability of 54% to develop grade 2 and 3 ARD. Conclusion: The dosimetric parameter of V58CGE to skin 5 mm < 5.0 cm3 could be used as a constraint in treatment planning for NPC patients treated by IMPT.

Head and Neck Cancer Types and Risks of Cervical-Cranial Vascular Complications within 5 Years after Radiation Therapy

Background and purpose: to investigate the frequency of cervical−cranial vascular complications soon after radiation therapy (RT) and identify differences among patients with various types of head and neck cancer (HNC). Methods: We enrolled 496 patients with HNC who had received their final RT dose in our hospital. These patients underwent carotid duplex ultrasound (CDU) for monitoring significant carotid artery stenosis (CAS). Brain imaging were reviewed to detect vertebral, intracranial artery stenosis, or preexisted CAS before RT. Primary outcome was significant CAS at the internal or common carotid artery within first 5 years after RT. We categorized the patients into nasopharyngeal carcinoma (NPC) and non-NPC groups and compared the cumulative occurrence of significant CAS between the groups using Kaplan−Meier and Cox-regression analyses. Results: Compared to the NPC group, the non-NPC group had a higher frequency of significant CAS (12.7% vs. 2.0%) and were more commonly associated with significant CAS after adjusting the covariates (Adjusted hazard ratio: 0.17, 95% confident interval: 0.05−0.57) during the follow-up period. All the non-NPC subtypes (oral cancer/oropharyngeal, hypopharyngeal, and laryngeal cancers) were associated with higher risks of significant CAS than the NPC group (p < 0.001 respectively). Conclusion: Significant CAS was more frequently noted within 5 years of RT among the patients with non-NPC HNC than among the patients with NPC. Scheduled carotid artery surveillance and vascular risk monitoring should be commenced earlier for patients with non-NPC HNC. By contrast, vascular surveillance could be deferred to 5 years after RT completion in NPC patients.

Proton Therapy for Squamous Cell Carcinoma of the Head and Neck: Early Clinical Experience and Current Challenges

Simple Summary

Proton therapy is a promising type of radiation therapy used to destroy tumor cells. It has the potential to further improve the outcomes for patients with head and neck cancer since it allows to minimize the radiation dose to vital structures around the tumor, leading to less toxicity. This paper describes the current experience worldwide with proton therapy in head and neck cancer.

Abstract

Proton therapy (PT) is a promising development in radiation oncology, with the potential to further improve outcomes for patients with squamous cell carcinoma of the head and neck (HNSCC). By utilizing the finite range of protons, healthy tissue can be spared from beam exit doses that would otherwise be irradiated with photon-based treatments. Current evidence on PT for HNSCC is limited to comparative dosimetric analyses and retrospective single-institution series. As a consequence, the recognized indications for the reimbursement of PT remain scarce in most countries. Nevertheless, approximately 100 PT centers are in operation worldwide, and initial experiences for HNSCC are being reported. This review aims to summarize the results of the early clinical experience with PT for HNSCC and the challenges that are currently faced.

Proton Radiation Therapy for Nasopharyngeal Cancer Patients: Dosimetric and NTCP Evaluation Supporting Clinical Decision

(1) Background: we proposed an integrated strategy to support clinical allocation of nasopharyngeal patients between proton and photon radiotherapy. (2) Methods: intensity-modulated proton therapy (IMPT) plans were optimized for 50 consecutive nasopharyngeal carcinoma (NPC) patients treated with volumetric modulated arc therapy (VMAT), and differences in dose and normal tissue complication probability (ΔNTCPx-p) for 16 models were calculated. Patient eligibility for IMPT was assessed using a model-based selection (MBS) strategy following the results for 7/16 models describing the most clinically relevant endpoints, applying a model-specific ΔNTCPx-p threshold (15% to 5% depending on the severity of the complication) and a composite threshold (35%). In addition, a comprehensive toxicity score (CTS) was defined as the weighted sum of all 16 ΔNTCPx-p, where weights follow a clinical rationale. (3) Results: Dose deviations were in favor of IMPT (ΔD_mean ≥ 14% for cord, esophagus, brainstem, and glottic larynx). The risk of toxicity significantly decreased for xerostomia (-12.5%), brain necrosis (-2.3%), mucositis (-3.2%), tinnitus (-8.6%), hypothyroidism (-9.3%), and trismus (-5.4%). There were 40% of the patients that resulted as eligible for IMPT, with a greater advantage for T3-T4 staging. Significantly different CTS were observed in patients qualifying for IMPT. (4) Conclusions: The MBS strategy successfully drives the clinical identification of NPC patients, who are most likely to benefit from IMPT. CTS summarizes well the expected global gain.

Modern Radiation Oncology: From IMRT to Particle Therapy—Present Status and the Days to Come

There has been tremendous technological development in the field of radiation oncology, mainly during the last few decades. Parallel advancements in imaging and accelerator technologies have contributed significantly to the same. Present-day radiation therapy is aimed at precision, in terms of physical accuracy of both its planning and delivery. This has been made possible by improvements in defining the target (use of various radiological and functional imaging modalities), advanced radiotherapy planning methods (intensity-modulated radiation therapy and recent emergence of particle therapy), and robust verification techniques (image-guided radiation therapy). These developments have enabled delivery of adequate tumoricidal doses conforming to the target, thereby improving disease control with reduced normal tissue toxicity in a wide range of malignancies. Elucidation of molecular pathways determining radioresistance or systemic effects of radiotherapy and strategies for therapeutic manipulation of the same are also being explored. Overall, we look forward to ensuring basic radiotherapy access to all patients, and precision radiation therapy to appropriate candidates (triaged by disease anatomy or biology and associated cost-effectiveness).

Nasopharyngeal Carcinoma: Clinical Achievements and Considerations Among Treatment Options

Nasopharyngeal carcinoma (NPC) is a severe malignancy arising from the nasopharyngeal epithelium and is southern China's third most common cancer. With the advancement of treatment methods, early-stage NPC patients usually have a better prognosis and more prolonged survival period than those with other malignant tumors. Most treatment failures are due to distant metastasis or a locally advanced stage of NPC in the initial diagnosis. In addition, approximately 10% of patients develop local recurrence, and 10%-20% of patients experience distant metastasis after treatment. These patients have a poor prognosis, with a median survival of only approximately 10-15 months. In the rapid development of treatment options, the efficacy and safety of some treatments have been validated and approved for first-line treatment, while those of other treatments remain unclear. The present study aims to provide a comprehensive overview of recent advances in NPC treatment and explain the various therapeutic possibilities in treating locally advanced, recurrent, and metastatic NPC patients.

Physics and biomedical challenges of cancer therapy with accelerated heavy ions

Radiotherapy should have low toxicity in the entrance channel (normal tissue) and be very effective in cell killing in the target region (tumour). In this regard, ions heavier than protons have both physical and radiobiological advantages over conventional X-rays. Carbon ions represent an excellent combination of physical and biological advantages. There are a dozen carbon-ion clinical centres in Europe and Asia, and more under construction or at the planning stage, including the first in the USA. Clinical results from Japan and Germany are promising, but a heated debate on the cost-effectiveness is ongoing in the clinical community, owing to the larger footprint and greater expense of heavy ion facilities compared with proton therapy centres. We review here the physical basis and the clinical data with carbon ions and the use of different ions, such as helium and oxygen. Research towards smaller and cheaper machines with more effective beam delivery is necessary to make particle therapy affordable. The potential of heavy ions has not been fully exploited in clinics and, rather than there being a single 'silver bullet', different particles and their combination can provide a breakthrough in radiotherapy treatments in specific cases.