Intensity-modulated radiotherapy for paranasal sinuses and base of skull tumors

Long-Term Follow-Up of Post Radiation Complete Sinus Opacification in Sinonasal Cancer Patients

OBJECTIVE

Treatment of sinonasal malignancies most often requires primary or postoperative radiation treatment. Post radiation sinonasal morbidity has been previously described; however, none addressed post-radiation sinus obstruction. Our objective was to investigate the long-term outcomes of post radiation complete isolated sinus opacification (CISO).

METHODS

A retrospective analysis of sinonasal cancer patients treated with radiation therapy during the years 2002 to 2022. Clinical, imaging and treatment data were collected from patients' medical records. Only patients with at least 12 months of follow-up and available imaging for review were included.

RESULTS

Out of 109 patients, 37 patients were identified to meet the inclusion criteria. Mean follow-up was 58 months. 35% of patients were diagnosed with persistent post radiation CISO with a mean onset of 4 months. All these patients remained asymptomatic, and their imaging remained stable during follow-up with none developing an expanding mucocele. Ethmoid sinus tumor involvement was found to be more prevalent in the CISO group (62% vs. 25%, p-value = 0.048) as well as chemotherapy/immunotherapy (54% vs. 38%, p-value = 0.046). Multivariant analysis revealed that ethmoid sinus involvement (OR = 9.516, p-value = 0.047) and adjuvant therapy, either chemotherapy/immunotherapy (OR = 10.75, p-value = 0.036) were found to be a predictive factor for complete opacification.

CONCLUSION

Our study revealed that a substantial number of post-radiation patients develop a stable and persistent CISO, often in the frontal and sphenoid sinuses. These patients remained asymptomatic, and none required surgical intervention during nearly 5 years of follow-up.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:4232-4238, 2024.

Treatment and related morbidity of nasal cavity and paranasal sinus cancers

Introduction

Sinonasal malignancies are rare and histologically heterogeneous cancers of the nasal cavity and sinuses. The treatment of choice is usually surgery and, if necessary, adjuvant radiotherapy. In this study, we aimed to investigate treatment modalities and associated morbidity.

Methods

A consecutive case series of solid sinonasal cancer treated at our tertiary referral center was analyzed. We performed a retrospective chart review and statistical analysis.

Results

A total of 156 patients with sinonasal cancer were enrolled in the present study. Male patients were more frequently affected (62%) and the median age was 64 years. Squamous cell carcinoma, adenocarcinoma and malignant melanoma (MM) were the most common histopathological entities. Surgery was the primary treatment modality for 73% of curatively treated patients. Primary radiotherapy alone or in combination with systemic treatment was less frequent. Median overall (OS) and recurrence-free survival (RFS) was 164 months and 71.3 months, respectively. Multivariate analysis revealed negative associations of histology (MM) and skull base involvement on RFS and age, skull base involvement and the type of primary therapy (radiochemotherapy) on OS. Postoperative 30-day morbidity was low, with most patients (84%) experiencing no reported events. Radiotherapy was generally well-tolerated, despite most of patients experienced acute toxicity such as dermatitis (80.6%) or mucositis (72.1%). However, only one event of acute toxicity > grade 3 was reported. Long term morbidity was most frequently reported as pain (23%), dry mucosa (19%) and anosmia (14%).

Conclusion

We observed negative associations of histology (MM) and skull base involvement on RFS and age, skull base involvement and the type of primary therapy (radiochemotherapy) on OS. Acute treatment-related morbidity was generally low for surgical patients and considerable for irradiated patients. Moreover, a consistent part of the cohort displayed long term morbidity.

Combined Photon and Carbon Ion Radiation Therapy for Sinonasal Malignancies: Results of the HIT-SNT Prospective Phase 2 Trial

PURPOSE

Radiation treatment of sinonasal malignancies is a challenging task due to proximity to critical structures of the head and neck and skull base. Local tumor control is highly dose-dependent, but dose application is limited due to accompanying toxicity and dose constraints. To evaluate the toxicity and efficacy of combined radiation treatment with intensity-modulated radiation therapy (IMRT) and carbon ion boost, we conducted a prospective phase 2 IMRT-Heidelberg Ion-Beam Therapy Sinonasal Tumors (HIT-SNT) trial.

METHODS AND MATERIALS

Between 2011 and 2019, we treated 35 patients with histologically proven, incompletely resected or inoperable adeno- (51%) or squamous cell carcinoma (49%) of the paranasal sinuses with combined IMRT (50 Gy) and carbon ion boost (24 Gy relative biologic effectiveness) to a total dose of 74 Gy.

RESULTS

Acute mucositis Common Terminology Criteria for Adverse Events (CTCAE) grade 3 occurred in 12% of patients (n = 4) and was accompanied by odynophagia CTCAE grade 3. Except for 1 case of grade 3 weight loss, no other acute high-grade toxicity (grade 3-4) was observed. In a small patient cohort of 15 patients eligible for long-term follow-up we have seen no high-grade (grade ≥3) long-term side effects 2 years after radiation therapy. None of these patients suffered from therapy-associated vision or hearing loss. Secondary endpoints were 2-year overall survival, 2-year local progression-free survival, 2-year progression-free survival, and 2-year metastases-free survival with 79.4%, 61.8%, 61.8%, and 64.8%, respectively.

CONCLUSIONS

To our knowledge, this is the first prospective data on toxicity and outcome of bimodal radiation therapy for the rare entity of sinonasal malignancies. Our study shows a low rate of CTCAE-reported acute toxicity with reasonable tumor control and survival rates after bimodal radiation therapy, which therefore remains a therapy approach to be further evaluated.

[Proposal for the delineation of postoperative primary clinical target volumes in maxillary sinus and nasal cavity cancers]

In this article, we propose a consensus delineation of postoperative clinical target volumes for the primary tumour in maxillary sinus and nasal cavity cancers. These guidelines are developed based on radioanatomy and the natural history of those cancers. They require the fusion of the planning CT with preoperative imaging for accurate positioning of the initial GTV and the combined use of the geometric and anatomical concepts for the delineation of clinical target volume for the primary tumour. This article does not discuss the indications of external radiotherapy (nor concurrent systemic treatment) but focuses on target volumes when there is an indication for radiotherapy.

Salvage skull base surgery after proton beam therapy for recurrent sinonasal malignancies: A retrospective study

BACKGROUND

This study aimed to examine treatment outcomes and postoperative complications associated with salvage skull base surgery following radical proton beam therapy (PBT).

METHODS

Nine patients who underwent salvage skull base surgery following curative PBT as the initial treatment at our institution between September 2002 and May 2023 were retrospectively reviewed.

RESULTS

The cohort comprised four males and five females with a mean age of 48.1 years. The average proton dose administered during initial therapy was 68.5 Gy (relative biological effectiveness). Among the salvage surgeries, eight were anterior skull base surgeries, and one was an anterior middle skull base surgery. No local recurrences or perioperative deaths were observed. Postoperative complications occurred in three patients (33.3%), all experiencing surgical site infections, with one also having cerebrospinal fluid leakage.

CONCLUSION

The study demonstrates that salvage skull base surgery after PBT effectively achieves local control and safety in patients with recurrent sinonasal malignancies.

International Consensus Statement on Allergy and Rhinology: Sinonasal Tumors

BACKGROUND

Sinonasal neoplasms, whether benign and malignant, pose a significant challenge to clinicians and represent a model area for multidisciplinary collaboration in order to optimize patient care. The International Consensus Statement on Allergy and Rhinology: Sinonasal Tumors (ICSNT) aims to summarize the best available evidence and presents 48 thematic and histopathology-based topics spanning the field.

METHODS

In accordance with prior International Consensus Statement on Allergy and Rhinology documents, ICSNT assigned each topic as an Evidence-Based Review with Recommendations, Evidence-Based Review, and Literature Review based on the level of evidence. An international group of multidisciplinary author teams were assembled for the topic reviews using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses format, and completed sections underwent a thorough and iterative consensus-building process. The final document underwent rigorous synthesis and review prior to publication.

RESULTS

The ICSNT document consists of four major sections: general principles, benign neoplasms and lesions, malignant neoplasms, and quality of life and surveillance. It covers 48 conceptual and/or histopathology-based topics relevant to sinonasal neoplasms and masses. Topics with a high level of evidence provided specific recommendations, while other areas summarized the current state of evidence. A final section highlights research opportunities and future directions, contributing to advancing knowledge and community intervention.

CONCLUSION

As an embodiment of the multidisciplinary and collaborative model of care in sinonasal neoplasms and masses, ICSNT was designed as a comprehensive, international, and multidisciplinary collaborative endeavor. Its primary objective is to summarize the existing evidence in the field of sinonasal neoplasms and masses.

Current management and future challenges in salivary glands cancer

Salivary gland cancers (SGCs) are rare, accounting for less than 5% of all malignancies of the head and neck region, and are morphologically heterogeneous. The diagnosis is mainly based on histology, with the complementary aid of molecular profiling, which is helpful in recognizing some poorly differentiated, borderline, or atypical lesions. Instrumental imaging defines the diagnosis, representing a remarkable tool in the treatment plan. Ultrasound and magnetic resonance are the most common procedures used to describe the primary tumour. The treatment of SGCs is multimodal and consists of surgery, radiotherapy, and systemic therapy; each treatment plan is, however, featured on the patient and disease's characteristics. On 24 June 2022, in the meeting "Current management and future challenges in salivary gland cancers" many experts in this field discussed the state of the art of SGCs research, the future challenges and developments. After the meeting, the same pool of experts maintained close contact to keep these data further updated in the conference proceedings presented here. This review collects the insights and suggestions that emerged from the discussion during and after the meeting per se.

The SINTART 2 Study. A phase II non-randomised controlled trial of induction chemotherapy, photon-, proton- and carbon-ion-based radiotherapy integration in patients with locally advanced unresectable sinonasal tumours

PURPOSE

Unresectable, locally advanced sinonasal epithelial tumours are rare diseases with poor prognosis. Multimodal approach is widely used, although no standard therapy has been established in prospective trials. This study assessed activity and safety of an innovative integration of multimodality treatment-induction chemotherapy (ICT), surgery and radiotherapy (RT)-modulated by histology and response to ICT.

METHODS

Patients with untreated, unresectable sinonasal epithelial tumours with selected histotypes (squamous cell carcinoma, intestinal-type adenocarcinoma, sinonasal undifferentiated and neuroendocrine carcinoma, olfactory neuroblastoma) were enroled in a single-arm, open-label, phase II, multicentre clinical trial. Patients were treated with up to 5 ICT cycles, whose regimen was selected according to histotype. Photon and/or proton/carbon-ion-based RT was employed according to disease site, stage and ICT response. Primary end-point was 5-years progression-free survival (PFS), secondary end-points were overall survival (OS), ICT objective response rate per RECIST 1.1 and safety.

RESULTS

Twenty-five patients were evaluable for primary end-point. Five-year PFS was 26.8% (95% confidence interval [CI]: 12.6-57.1), with a median PFS of 18 months. Five-year OS was 23.8% (95% CI: 9.5-59.3), with a median OS of 27 months. The overall response rate to ICT was 40%. Three-year PFS for patients achieving major volumetric partial response (mPRv) versus non-mPRv was 40% (95% CI: 13.7-100%) versus 23.1% (95% CI: 8.3-64.7%) (P = 0.318) and 3-year OS was 53.3% (95% CI: 21.4-100%) versus 37.7% (95% CI: 20.0-71.0%) (P = 0.114).

CONCLUSION

Multimodal combination of ICT and innovative RT did not provide a significant improvement in survival rates with respect to previous experiences. This finding underscores the need for future research in this rare disease, still characterised by a heavy burden and poor prognosis. We observed longer survival in subjects achieving response to ICT. The overall treatment safety is acceptable.

The contemporary management of cancers of the sinonasal tract in adults

Sinonasal malignancies make up <5% of all head and neck neoplasms, with an incidence of 0.5-1.0 per 100,000. The outcome of these rare malignancies has been poor, whereas significant progress has been made in the management of other cancers. The objective of the current review was to describe the incidence, causes, presentation, diagnosis, treatment, and recent developments of malignancies of the sinonasal tract. The diagnoses covered in this review included sinonasal undifferentiated carcinoma, sinonasal adenocarcinoma, sinonasal squamous cell carcinoma, and esthesioneuroblastoma, which are exclusive to the sinonasal tract. In addition, the authors covered malignances that are likely to be encountered in the sinonasal tract-primary mucosal melanoma, NUT (nuclear protein of the testis) carcinoma, and extranodal natural killer cell/T-cell lymphoma. For the purpose of keeping this review as concise and focused as possible, sarcomas and malignancies that can be classified as salivary gland neoplasms were excluded.

Research Value of Intensity Modulated Radiation Therapy in Alleviating Parotid Gland Function Injury in Patients with Stage N0 Nasopharyngeal Carcinoma from Physical and Dosimetric Aspects

Objective

To study the feasibility of intensity modulated radiation therapy (IMRT) for stage N₀ nasopharyngeal carcinoma (NPC) and its parotid gland (PG) function preservation from physical and dosimetric aspects.

Methods

All the clinical data of 77 patients with pathologically confirmed T_1-4N₀M₀ NPC who received radiotherapy between July 2017 and October 2019 in the Radiotherapy Center of Taizhou Hospital of Zhejiang Province affiliated to Wenzhou Medical University were analyzed retrospectively. Three-dimensional conformal radiotherapy (3D-CRT) and IMRT were used in 35 and 42 cases, respectively. The treatment efficiency and the dosimetry differences of the PG in the intensity modulation plan were compared between groups. Quantitative monitoring of 99mTc radionuclide imaging of PG was performed before, at the end of, and 3, 6, and 12 months after radiotherapy. The degree of PG function injury and xerostomia was compared between groups at the end of radiotherapy and 12 months later.

Results

Higher minimal, maximal, and average irradiation doses of PG were determined in 3D-CRT-treated patients compared with IMRT-treated cases (P < 0.05). Compared with before radiotherapy, the PG uptake index (UI) and excretion index (EI) of both cohorts of patients decreased to varying degrees at the end of radiotherapy, with PG function injury and xerostomia symptoms observed in all cases but with no obvious difference between groups (P > 0.05). To a certain extent, the PG function recovered and the xerostomia symptoms relieved in both groups 12 months after radiotherapy, with better improvements in IMRT group versus 3D-CRT group.

Conclusion

IMRT has similar short-term efficacy to 3D-CRT in treating patients with stage N₀ NPC, but it can effectively reduce the dose of PG radiotherapy and protect the PG function on the premise of ensuring sufficient tumor coverage and dose, showing certain dosimetry advantages.

Management of sinonasal cancers: Survey of UK practice and literature overview

INTRODUCTION

Sinonasal malignancy is a rare and heterogenous disease, with limited evidence to guide management. This report summarises the findings of a UK survey and expert workshop discussion which took place to inform design of a proposed UK trial to assess proton beam therapy versus intensity-modulated radiation therapy.

METHOD

A multidisciplinary working group constructed an online survey to assess current approaches within the UK to surgical and non-surgical practice. Head and neck clinical oncologists, ear nose and throat (ENT) and oral-maxillofacial (OMF) surgeons were invited to participate in the 42-question survey in September 2020. The Royal College of Radiologists Consensus model was adopted in establishing categories to indicate strength of response. An expert panel conducted a virtual workshop in November 2020 to discuss areas of disagreement.

RESULTS

A survey was sent to 140 UK-based clinicians with 63 responses (45% response rate) from 30 centres, representing a broad geographical spread. Participants comprised 35 clinical oncologists (56%) and 29 surgeons (44%; 20 ENT and 9 OMF surgeons). There were variations in preferred sequence and combination of treatment modalities for locally advanced maxillary squamous cell carcinoma and sinonasal undifferentiated carcinoma. There was discordant surgical management of the orbit, dura, and neck. There was lack of consensus for radiotherapy in post-operative dose fractionation, target volume delineation, use of multiple dose levels and treatment planning approach to organs-at-risk.

CONCLUSION

There was wide variation across UK centres in the management of sinonasal carcinomas. There is need to standardise UK practice and develop an evidence base for treatment.

Outcomes of osteosarcoma, chondrosarcoma and chordoma treated with image guided-intensity modulated radiation therapy

BACKGROUND & PURPOSE

To evaluate the efficacy and toxicity of dose-escalated image guided-intensity modulated radiation therapy (IG-IMRT) in osteosarcoma (OGS), chondrosarcoma (CS) and chordoma (CH) of head and neck (H&N) and pelvis.

METHODS AND MATERIALS

In this prospective non-randomized study, 65 patients of H&N or pelvic OGS (24), CS (7) and CH (34) mandating definitive or post-operative radiotherapy from May 2013 to December 2018 were included. Radiotherapy doses in definitive setting were 72.0 Gy for CH and 70.2 Gy for OGS and CS; while in post-operative setting it was 66.6 Gy and 64.8 Gy respectively (at 1.8 Gy per fraction).

RESULTS

Planned doses of radiotherapy could be completed in 61 (93.8%) patients; with grade III or higher acute and late toxicities of 3% and 0% respectively. With a median follow-up of 52 (range 6-92) months, the five-year actuarial local control (LC) rates were 66% in OGS, 38.1% in CS and 75.9% in CH; while cause-specific survival (CSS) rates were 54.7%, 64.3% and 92.2% respectively. There was no statistically significant difference in outcomes for patients receiving definitive and post-operative radiotherapy. Locally controlled disease at first follow-up after radiotherapy was associated with improved CSS and OS in CS (p = 0.014) and CH (p < 0.001). Radiotherapy resulted in significant and sustained improvement in Musculoskeletal tumour society (MSTS) score and reduction in pain score. Salvage re-irradiation was feasible in local progression after radiotherapy, with good outcomes and tolerability.

CONCLUSION

Dose-escalated IG-IMRT results in good LC & functional improvement with minimal toxicity in OGS, CS and CH.

Precision Postoperative Radiotherapy in Sinonasal Carcinomas after Endonasal Endoscopic Surgery

Simple Summary

Sinonasal cancers are rare and heterogeneous tumors, mainly carcinomas, with essentially local evolution and a severe vital and functional prognosis. These tumors are more and more being treated in first intent by a mini-morbid endoscopic approach rather than open surgery as the cornerstone of curative treatment. Adjuvant radiotherapy remains necessary owing to non-optimal local control. This article describes the requirements of radiotherapy to ensure adequate delays, the potential of postoperative radiotherapy to increase local and distant disease control and to decrease morbidity further after mini morbid surgery and dose painting techniques, and reviews the criteria that lead to the choice of one technique over another.

Abstract

Radiotherapy plays an important role in the treatment of sinonasal cancer, mainly in the adjuvant setting after surgical resection. Many technological approaches have been described, including intensity-modulated radiotherapy, concomitant chemoradiotherapy, charged particle therapy or combined approaches. The choice is based on general criteria related to the oncological results and morbidity of each technique and their availability, as well as specific criteria related to the tumor (tumor extensions, pathology and quality of margins). The aims of this review are: (i) to provide an overview of the radiotherapy techniques available for the management of sinonasal malignant tumors and (ii) to describe the constraints and opportunities of radiotherapy owing to the recent developments of endonasal endoscopic surgery. The indication and morbidity of the different techniques will be discussed based on a critical literature review.

The effect of prior radiation on the success of ventral skull base reconstruction: A systematic review and meta-analysis

The incidence of cerebrospinal fluid leak after ventral skull base reconstruction is a primary outcome of interest to skull base surgeons. Exposure to pre-operative radiation may put patients at an increased risk of skull base reconstructive failure. A systematic search identified studies which included patients receiving ventral skull base reconstruction in the setting of pre-operative radiation. A meta-analysis using a random effects model was conducted to estimate an odds ratio of cerebrospinal fluid (CSF) leak in patients exposed to pre-operative radiation. A meta-analysis of 13 studies demonstrated that the odds ratio of CSF leak was 1.73 (95% CI 0.98-3.05). The majority of studies (77%) used vascularized tissue grafts for reconstruction. We identified an increased incidence of CSF leak among patients undergoing ventral skull base reconstruction after prior radiation therapy, although not of statistical significance. Skull base surgeons should exercise caution when planning reconstruction in this population.

Sinonasal cancers treatments: state of the art

PURPOSE OF REVIEW

The present review provides the reader with the state-of-the-art concepts of sinonasal oncology in view of the latest literature data.

RECENT FINDINGS

Most recent publications in sinonasal oncology assessed treatment timing, centralization, surgical approach, margin status, orbit/neck management, salvage strategies, emerging surgical technologies, intensity-modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT), particle radiotherapy, and neoadjuvant chemotherapy.

SUMMARY

Indications to endoscopic surgery for sinonasal cancer have plateaued and are unlikely to further expand. Endoscopic surgery provides noninferior results compared to open surgery and best suits timing constraints imposed by multimodal treatment. Management of orbit-encroaching sinonasal cancer is remarkably improving mostly owing to optimal use of nonsurgical strategies. Prognostic value of the margin status and management of the nodal basin and recurrent sinonasal tumors are far from being fully elucidated. Most promising surgical technologies are surgical navigation, optical imaging, and radiofrequency-aided ablation. IMRT and VMAT have theoretical technical advantages that are in the process of being clinically demonstrated. Pieces of evidence are progressively confirming the physical and radiobiological advantages offered by particle radiotherapy. Systemic therapy is being tested mostly in the neoadjuvant setting with the aim of improving outcomes in locally advanced sinonasal cancers; response to induction chemotherapy could better select a further locoregional approach.

Gamma Knife Stereotactic Radiosurgery for Conjunctival Squamous Cell Carcinoma Invading the Anterior Orbit: A Case Series

Introduction

The aim of the study was to report our experience in the use of Gamma Knife Stereotactic Radiosurgery (GKSTRS) for conjunctival squamous cell carcinoma (SCC) invading the orbit, as an alternative to exenteration surgery.

Patients and Methods

Patients who had GKSTRS for conjunctival SCC invading the orbit but sparing the bone (AJCC eighth ed. T4a) with a minimum of 1-year follow-up were included. Treatment failure was defined as no decrease in tumour size 3 months post-treatment, or further growth during the follow-up period. Patients were followed up 3-monthly for 2 years and 6-monthly afterwards with a minimum of yearly MR Imaging of orbit.

Results

Six patients met the inclusion criteria. MR imaging was used to identify the extent of orbital involvement of SCC. Stereotactic radiosurgery utilizing the Leksell Gamma Knife® Perfexion was delivered in a single session in which patients received 18-20 Gy to the 45-50% isodose. The median follow-up was 29 months. Four patients responded to the treatment and had no evidence of recurrence at their most recent follow-up. The treatment failed in 2 patients, in 1 of whom the tumour was larger and extended deeper into the orbit. The other patient developed a recurrence away from the treated area at 9 months, suggesting a multifocal disease. Both patients had poorly differentiated SCC.

Conclusion

GKSTRS is a potential alternative to orbital exenteration surgery for conjunctival SCC extending into the anterior orbit in a selected group of patients refusing orbital exenteration or has a second blind eye. Nevertheless, the disease is more likely to recur than with exenteration surgery, hence lifelong monitoring and low threshold for surgical intervention or retreatment is prudent.

Intensity-modulated radiation therapy for nasal cavity and paranasal sinus tumors: Experience from a single institute

BACKGROUND

To assess the efficacy of intensity-modulated radiation therapy (IMRT) for tumors of the nasal cavity and paranasal sinus (PNS) region.

MATERIALS AND METHODS

Two hundred fourteen patients with tumors of the nasal cavity and PNS region treated with curative intent IMRT between 2007 and 2019 were included in this retrospective analysis.

RESULTS

Fifty-one (24.1%) received definitive RT/CTRT and 163 (75.9%) received adjuvant RT. Most common histology was squamous cell carcinoma (26.1%) followed by adenoid cystic carcinoma (21.5%). The median follow-up was 43.5 months. The 5-year local control (LC), event-free survival (EFS), and overall survival (OS) for the entire cohort was 66.9%, 59%, and 73.9%, respectively. On univariate analysis treatment with nonsurgical modality, T classification and undifferentiated/poorly differentiated histology were associated with inferior 5-year LC, EFS, and OS. Four patients had late Grade 3/Grade 4 ocular toxicity.

CONCLUSIONS

IMRT should be the standard of care for tumors of PNS region across all histologies and treatment setting.

[Proposal for the delineation of postoperative primary clinical target volumes in ethmoid cancers]

It is proposed to delineate the anatomo-clinical target volumes of primary tumor (CTV-P) in ethmoid cancers treated with post-operative radiotherapy. This concept is based on the use of radioanatomy and the natural history of cancer. It is supported by the repositioning of the planning scanner with preoperative imaging for the replacement of the initial GTV and the creation of margins around it extended to the microscopic risk zones according to the anatomical concept. This article does not discuss the indications of external radiotherapy but specifies the volumes to be delineated if radiotherapy is considered.

Particle Beam Radiation Therapy for Skull Base Sarcomas

Background: To report the clinical experience of carbon-ion and proton radiation therapy for skull base sarcomas.

Methods: An analysis of the retrospective data registry from the Shanghai Proton and Heavy Ion Center for patients with skull base sarcomas was conducted. The 1-/2-year local relapse-free, distant metastasis-free, progression-free, and overall survival (LRFS, DMFS, PFS, OS) rates as well as associated prognostic indicators were analyzed. Radiotherapy-induced acute and late toxicities were summarized.

Results: Between 7/2014 and 5/2019, 62 patients with skull base sarcomas of various subtypes received carbon-ion radiation therapy (53), proton radiation therapy (5), or proton radiation therapy + carbon-ion boost (4). With a median follow-up of 20.4 (range 2.73–91.67) months, the 1-/2-year OS, LRFS, DMFS, and PFS rates were 91.2%/80.2%, 89.2%/80.2%, 86.0%/81.1%, and 75.8%/62.9%, respectively. Grade 3 mucositis and grade 4 hemorrhage were observed in 1 patient for each. Only grade 1 and grade 2 toxicities were observed except for the same patient with grade 4 acute toxicity died of severe hemorrhage (grade 5). Multivariate analyses revealed the lack of prior RT was an independent favorable prognostic factor for OS, PFS, and LRFS, age under 40 was associated with improved OS, early T-disease (T1/2) showed a significant association with better PFS.

Conclusion: With few observed acute and late toxicities, particle beam radiation therapy provided effective tumor control and overall survival for patients with skull base sarcomas.