Treatment Outcome of 227 Patients with Sinonasal Adenoid Cystic Carcinoma (ACC) after Intensity Modulated Radiotherapy and Active Raster-Scanning Carbon Ion Boost: A 10-Year Single-Center Experience

Radioresistant, Rare, Recurrent, and Radioinduced: 4Rs of Hadrontherapy for Patients Selections

Purpose

To describe the role of hadrontherapy (HT) in treating radioresistant, rare, recurrent, and radio-induced tumors, which can be defined, in assonance with the 4Rs of radiobiology, the "4Rs" of HT indications.

Materials and Methods

This is a narrative review written by a multidisciplinary team consisting of radiation oncologists, radiobiologists, and physicists on the current literature on HT, particularly carbon ion radiation therapy. To refine HT indications within the context of the "4Rs" framework, we evaluated tumor histologies across different clinical indication settings and emphasized the radiobiological mechanisms contributing to the effectiveness of HT.

Results

For rare, radioresistant, recurrent, and radio-induced tumors, HT has proven to be effective and safe, achieving high rates of local response with mild toxicity. The current review shows that the biological parameters can assist clinicians in identifying appropriate cases for HT treatment.

Conclusion

Biological characteristics of the tumor support the administration of HT in radioresistant, rare, recurrent, and radio-induced tumors and should be considered during multidisciplinary discussions.

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.

Assessing the Impact of Charged Particle Radiation Therapy for Head and Neck Adenoid Cystic Carcinoma: A Systematic Review and Meta-Analysis

Purpose: Head and neck adenoid cystic carcinoma (HNACC) is a radioresistant tumor. Particle therapy, primarily proton beam therapy and carbon-ion radiation, is a potential radiotherapy treatment for radioresistant malignancies. This study aims to conduct a meta-analysis to evaluate the impact of charged particle radiation therapy on HNACC. Methods: A comprehensive search was conducted in Pubmed, Cochrane Library, Web of Science, Embase, and Medline until December 31, 2022. The primary endpoints were overall survival (OS), local control (LC), and progression-free survival (PFS), while secondary outcomes included treatment-related toxicity. Version 17.0 of STATA was used for all analyses. Results: A total of 14 studies, involving 1297 patients, were included in the analysis. The pooled 5-year OS and PFS rates for primary HNACC were 78% (95% confidence interval [CI] = 66-91%) and 62% (95% CI = 47-77%), respectively. For all patients included, the pooled 2-year and 5-year OS, LC, and PFS rates were as follows: 86.1% (95% CI = 95-100%) and 77% (95% CI = 73-82%), 92% (95% CI = 84-100%) and 73% (95% CI = 61-85%), and 76% (95% CI = 68-84%) and 55% (95% CI = 48-62%), respectively. The rates of grade 3 and above acute toxicity were 22% (95% CI = 13-32%), while late toxicity rates were 8% (95% CI = 3-13%). Conclusions: Particle therapy has the potential to improve treatment outcomes and raise the quality of life for HNACC patients. However, further research and optimization are needed due to the limited availability and cost considerations associated with this treatment modality.

The Role of Carbon Ion Therapy in the Changing Oncology Landscape-A Narrative Review of the Literature and the Decade of Carbon Ion Experience at the Italian National Center for Oncological Hadrontherapy

BACKGROUND

Currently, 13 Asian and European facilities deliver carbon ion radiotherapy (CIRT) for preclinical and clinical activity, and, to date, 55 clinical studies including CIRT for adult and paediatric solid neoplasms have been registered. The National Center for Oncological Hadrontherapy (CNAO) is the only Italian facility able to accelerate both protons and carbon ions for oncological treatment and research.

METHODS

To summarise and critically evaluate state-of-the-art knowledge on the application of carbon ion radiotherapy in oncological settings, the authors conducted a literature search till December 2022 in the following electronic databases: PubMed, Web of Science, MEDLINE, Google Scholar, and Cochrane. The results of 68 studies are reported using a narrative approach, highlighting CNAO's clinical activity over the last 10 years of CIRT.

RESULTS

The ballistic and radiobiological hallmarks of CIRT make it an effective option in several rare, radioresistant, and difficult-to-treat tumours. CNAO has made a significant contribution to the advancement of knowledge on CIRT delivery in selected tumour types.

CONCLUSIONS

After an initial ramp-up period, CNAO has progressively honed its clinical, technical, and dosimetric skills. Growing engagement with national and international networks and research groups for complex cancers has led to increasingly targeted patient selection for CIRT and lowered barriers to facility access.

Planning Strategy to Optimize the Dose-Averaged LET Distribution in Large Pelvic Sarcomas/Chordomas Treated with Carbon-Ion Radiotherapy

To improve outcomes in large sarcomas/chordomas treated with CIRT, there has been recent interest in LET optimization. We evaluated 22 pelvic sarcoma/chordoma patients treated with CIRT [large: HD-CTV ≥ 250 cm3 (n = 9), small: HD-CTV < 250 cm3 (n = 13)], DRBE|LEM-I = 73.6 (70.4-73.6) Gy (RBE)/16 fractions, using the local effect model-I (LEM-I) optimization and modified-microdosimetric kinetic model (mMKM) recomputation. We observed that to improve high-LETd distribution in large tumors, at least 27 cm3 (low-LETd region) of HD-CTV should receive LETd of ≥33 keV/µm (p < 0.05). Hence, LETd optimization using 'distal patching' was explored in a treatment planning setting (not implemented clinically yet). Distal-patching structures were created to stop beams 1-2 cm beyond the HD-PTV-midplane. These plans were reoptimized and DRBE|LEM-I, DRBE|mMKM, and LETd were recomputed. Distal patching increased (a) LETd50% in HD-CTV (from 38 ± 3.4 keV/µm to 47 ± 8.1 keV/µm), (b) LETdmin in low-LETd regions of the HD-CTV (from 32 ± 2.3 keV/µm to 36.2 ± 3.6 keV/µm), (c) the GTV fraction receiving LETd of ≥50 keV/µm, (from <10% to >50%) and (d) the high-LETd component in the central region of the GTV, without significant compromise in DRBE distribution. However, distal patching is sensitive to setup/range uncertainties, and efforts to ascertain robustness are underway, before routine clinical implementation.

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.

Function Preservation in Head and Neck Cancers

The treatment of head and neck cancers can have a significant impact on function and appearance, which results in impairment of quality of life. Various long-term sequelae of treatment include speech and swallowing difficulty, oral incompetence, trismus, xerostomia, dental caries and osteoradionecrosis. Management has evolved from single modality treatment of either surgery or radiation to multimodality treatment to attain acceptable functional outcomes. Brachytherapy, also known as interventional radiotherapy, with its ability to deliver high doses centrally to the target, has been shown to improve local control rates. Due to the rapid fall-off of the dose of brachytherapy there is better organ at risk sparing as compared with that of external beam radiotherapy. In the head and neck region, brachytherapy has been practiced in various sites, including the oral cavity, oropharynx, nasopharynx, nasal vestibule and paranasal sinuses. Additionally, brachytherapy has also been considered for reirradiation as a salvage. Brachytherapy can also be considered as a perioperative technique together with surgery. Close multidisciplinary cooperation is required for a successful brachytherapy programme. In oral cavity cancers, depending on the location of the tumour, brachytherapy has been shown to preserve oral competence, maintain tongue mobility, maintain speech, swallowing and the hard palate. Brachytherapy in oropharyngeal cancers has been shown to reduce xerostomia and also reduce dysphagia and aspiration post-radiation therapy. For the nasopharynx, paranasal sinus and nasal vestibule, brachytherapy preserves the respiratory function of the mucosa. Despite such an incomparable impact on function and organ preservation, brachytherapy is an underutilised technique for head and neck cancers. There is a strong need to improve brachytherapy utilisation in head and neck cancers.

Prognosis of adenoid cystic carcinoma in head and neck region treated with different regimens-A single-centre study

BACKGROUND

No study has evaluated the impact of regimen on recurrence, metastasis and survival in patients with adenoid cystic carcinoma (ACC). The present study aimed to compare the efficacy of radioactive seed implantation and other regimens in treating ACC, so as to investigate the clinical applicability of radioactive seed implantation and determine the indications for this regimen.

METHODS

A total of 188 patients with ACC in oromaxillofacial region were allocated to four groups according to the treatment regimen: group 1 was treated with a combination of surgery and ¹²⁵ I seed therapy, group 2 with a combination of surgery and external radiotherapy, group 3 with surgery, whereas group 4 was untreated. The Kaplan-Meier method was used to assess the survival rates, and the Cox regression analyses were used to identify the associated prognostic factors.

RESULTS

The overall survival rates of 188 patients and groups 1, 2, 3 and 4 were 85.7%, 75%, 68.2% and 37.5%, respectively. Cox regression analysis revealed that age, T stage, N stage and regimen were independent prognostic factors of survival. Amongst patients with primary ACC, the efficacy of radioactive seed implantation was higher in those with perineural invasion than in those without.

CONCLUSION

Patient age, T stage, N stage and regimen are independent prognostic factors of survival in patients with ACC. Patients treated with surgery combined with postoperative ¹²⁵ I seed radiotherapy have a higher overall survival rate, and those with perineural invasion are more suitable for radioactive seed implantation therapy.

Is prophylactic neck irradiation indicated for patients with cN0 Adenoid cystic carcinoma of the paranasal sinuses?

PURPOSE

To study the prevalence of nodal metastases in sinonasal adenoid cystic carcinoma (SNACC) and to evaluate whether prophylactic neck irradiation (PNI) should be performed in patients with clinical N0 (cN0) disease.

PATIENTS AND METHODS

Between April 1992 and November 2020, 166 patients with SNACC who had undergone radiotherapy at our department were retrospectively analyzed. The median follow-up time was 71.3 months.

RESULTS

Among 166 cases of SNACC, a total of 13 (7.8%) had retropharyngeal or cervical nodal metastasis and 93% (12/13) cases occurred in patients with advanced T stage (T3-T4). Levels VIIa, Ib, and IIa were the most common sites of initial nodal involvement. Only 1.2% (2/166) of patients presented late neck recurrence. Lymph node metastasis independently predicted a poor progression-free survival (PFS) (P = 0.017) but had no impact on overall survival (OS) (P = 0.38). PNI was performed on 36% (55/153) of cN0 patients. The OS (P = 0.42), PFS (P = 0.59), nodal recurrence-free survival (NRFS) (P = 0.46) and distant metastasis-free survival (DMFS) (P = 0.63) rates showed no significant difference between cases with and without PNI. Furthermore, cN0 patients with T4b (P = 0.53; P = 0.61), tumor origin from maxillary sinus (P = 0.55; P = 0.53) or nasopharynx involvement (P = 0.56; P = 0.60) showed no extended OS or PFS associated with PNI.

CONCLUSIONS

Regardless of the T stage or the site of origin, prophylactic neck irradiation (PNI) for cN0 patients did not provide any benefit on OS and PFS, suggesting that its application on such patients is not warranted unless there is clinical suspicion.

In Silico Feasibility Study of Carbon Ion Radiotherapy With Simultaneous Integrated Boost for Head and Neck Adenoid Cystic Carcinoma

Purpose

In carbon ion radiotherapy (CIRT), a simultaneous integrated boost (SIB) approach has not been fully exploited so far. The feasibility of a CIRT-SIB strategy for head and neck adenoid cystic carcinoma (ACC) patients was investigated in order to improve treatment planning dose distributions.

Methods and Materials

CIRT plans of 10 ACC patients treated at the National Center for Oncological Hadrontherapy (CNAO, Pavia, Italy) with sequential boost (SEQ) irradiation and prescription doses of 41.0 Gy [relative biological effectiveness (RBE)]/10 fractions to low-risk (LR) clinical target volume (CTV) plus 24.6 Gy(RBE)/6 fractions to the high-risk (HR) CTV were re-planned with two SIB dose levels to the LR-CTV, namely, 48.0 Gy(RBE) and 54.4 Gy(RBE). While planning with SIB, the HR-CTV coverage had higher priority, with fixed organ-at-risk dose constraints among the SIB and SEQ plans. The homogeneity and conformity indexes were selected for CTV coverage comparison. The biologically effective dose (BED) was calculated to compare the different fractionation schemes.

Results

Comparable HR-CTV coverage was achieved with the treatment approaches, while superior conformality and homogeneity were obtained with the SIB technique in both CTVs. With the SEQ, SIB_48.0, and SIB_54.4, the LR-CTV median doses were respectively 50.3%, 11.9%, and 6.0% higher than the prescriptions. Significant reductions of the median and near-maximum BEDs were achieved with both SIB dose levels in the LR-CTV.

Conclusions

The SIB approach resulted in highly conformal dose distributions with the reduction of the unintended dose to the LR-CTV. A prescription dose range for the LR-CTV will be clinically defined to offer tailored personalized treatments, according to the clinical and imaging characteristics of the patients.

Biological Rationale and Clinical Evidence of Carbon Ion Radiation Therapy for Adenoid Cystic Carcinoma: A Narrative Review

Adenoid cystic carcinoma (ACC) is a rare, basaloid, epithelial tumor, arising mostly from salivary glands. Radiation therapy can be employed as a single modality for unresectable tumors, in an adjuvant setting after uncomplete resection, in case of high-risk pathological features, or for recurrent tumors. Due to ACC intrinsic radioresistance, high linear energy transfer (LET) radiotherapy techniques have been evaluated for ACC irradiation: while fast neutron therapy has now been abandoned due to toxicity concerns, charged particle beams such as protons and carbon ions are at present the beams used for hadron therapy. Carbon ion radiation therapy (CIRT) is currently increasingly used for ACC irradiation. The aim of this review is to describe the immunological, molecular and clinicopathological bases that support ACC treatment with CIRT, as well as to expose the current clinical evidence that reveal the advantages of using CIRT for treating ACC.

Omitting elective neck irradiation in clinically N0 sinonasal adenoid cystic carcinoma: A propensity score-matched analysis

OBJECTIVE

To explore the effects of elective neck irradiation (ENI) in clinically node-negative (cN0) sinonasal adenoid cystic carcinoma (SNACC).

MATERIALS AND METHODS

Between January 2000 and December 2016, 60 patients with cN0 sinonasal adenoid cystic carcinoma receiving surgery combined with radiotherapy were analyzed retrospectively, there were 39 received ENI (ENI group) and 21 with no ENI (non-ENI group). Propensity score matching (PSM) was performed to balance clinical factors and match patients. Kaplan-Meier method and Cox proportional hazard model were used to evaluate the impact of ENI on regional relapse risk and survival outcomes.

RESULTS

The median follow-up time for our cohort was 82.0 months (12.4-190.7 months). Four patients (6.7%) developed neck nodal relapses, with a median time to progression of 38.8 months. Among them, two patients in ENI group but failed out-field. After PSM, 21 patients were matched in each group. The 7-year regional relapse-free survival (RRFS), distant metastasis free survival (DMFS), progression-free survival (PFS), and overall survival (OS) between ENI group and non-ENI group were 85.4% vs 73.3% (p = 0.845), 65.2% vs 65.6% (p = 0.548), 68.3% vs 66.2% (p = 0.425), and 87.3% vs 84.0% (p = 0.953). Multivariate Cox analysis showed ENI was not an independent prognostic factor associated with RRFS, DMFS, PFS and OS.

CONCLUSION

Our findings firstly demonstrated the omission of elective neck irradiation in the management of cN0 sinonasal adenoid cystic carcinoma might be safe without compromising disease control and should be further investigated.

The Role of Particle Therapy in Adenoid Cystic Carcinoma and Mucosal Melanoma of the Head and Neck

Particle irradiation is suitable for resistant histologies owing to a combination of improved dose delivery with potential radiobiologic advantages in high linear energy transfer radiation. Within the head and neck, adenoid cystic carcinoma and mucosal melanoma are two such histologies, being radioresistant and lying closely proximal to critical structures. Here, we review the use of particle irradiation for adenoid cystic carcinoma and mucosal melanoma of the head and neck.

Intensity modulated radiation therapy may improve survival for tracheal-bronchial adenoid cystic carcinoma: A retrospective study of 133 cases

PURPOSES

This study aimed to evaluate the role of radiotherapy (RT) and intensity modulated radiation therapy (IMRT) in adjuvant and definitive settings of tracheal-bronchial adenoid cystic carcinoma (TACC) treatment.

MATERIALS/METHODS

TACC patients (n = 133) treated with surgery and/or RT curatively in our institution between January 1^st, 1984 and December 31^st, 2017 were analyzed retrospectively.

RESULTS

Among the 116 patients undergoing surgery, 50 (43.1 %) achieved complete resections and 66 (56.9 %) had positive surgical margins. For patients with positive margins, overall adjuvant RT was correlated with no significantly improved OS (10-year: 58.0 % vs. 47.9 %; P =  0.340) and a slight LRFS benefit (5-year: 81.9 % vs.75.6 %; P =  0.056), but adjuvant IMRT showed significant superiority in both OS (10-year: 82.9 % vs. 47.9 %; P =  0.031) and LRFS (5-year: 100.0 % vs. 75.6 %; P =  0.001) in comparison with no postoperative RT. Multivariate analysis also identified adjuvant IMRT as a significant favorable factor with OS (HR = 0.186, 95 %CI: 0.039-0.883; P =  0.034). For 17 patients receiving definitive RT, IMRT achieved promising 5-year OS of 88.9 % and LRFS of 64.3 %, yet no significant difference from non-IMRT group was reached (P = 0.447 and 0.706). Different therapies presented no significantly different impact on DMFS, whilst DMFS explained more of the OS variances (P < 0.001, R² = 0.480) than LRFS (P < 0.001, R² = 0.323).

CONCLUSION

IMRT could confer greatly improved OS and LRFS in postoperative setting for TACC patients with positive surgical margins. IMRT was also a good therapeutic option for definitive TACC with promising survival and local control.

Therapeutic challenges in radiation-induced salivary gland cancers

PURPOSE OF REVIEW

To give an overview of recent advances in therapeutic approaches of radiation-induced salivary gland cancers (ri-SGCs).

RECENT FINDINGS

Reirradiation with protons and carbon ions demonstrated to be feasible, safe and to offer good local control rates, with the possibility of overcoming radioresistance and dosimetric issues in previously irradiated cancer patients. Chromosomal rearrangements, gene fusions and expression profiles are important to identify specific cancer subtypes and can guide tailored systemic therapy.

SUMMARY

Ri-SGCs are rare and heterogeneous. Patients are often heavily pretreated and at risk of toxicities, and their management remain challenging. A multidisciplinary approach in referral centers is mandatory. Knowledge about SGCs cellular and molecular mechanisms is constantly evolving. In the last years, novel advances in therapeutic approaches, such as carbon ion radiotherapy, are emerging as safe and effective options in active treatment, but further efforts are needed to offer tailored personalized treatments and to improve survival.

Rare Diseases of the Nose, the Paranasal Sinuses, and the Anterior Skull Base

Due to their low incidence and thus resulting limited diagnostic criteria as well as therapeutic options, rare diseases of the nose, the paranasal sinuses, and the anterior skull base are a significant challenge. The value as of which a disease has to be considered as rare amounts to a maximum of 5 patients per 10 000 people. Within these diseases, however, there are extreme differences. Some rare or orphan diseases like for example the inverted papilloma belong to regularly diagnosed and treated diseases of larger departments of oto-rhino-laryngology whereas other rare diseases and malformations have only been described in less than 100 case reports worldwide. This fact emphasizes the necessity of bundling the available experience of diagnostics and therapy. The present article gives an overview about rare diseases of the nose, the paranasal sinuses, and the anterior skull base from the field of diseases/syndromes of the olfactory system, malformations of the nose and paranasal sinuses, ventilation and functional disorders as well as benign and malignant tumors. The classification and data on diagnostic and therapeutic options were established based on the current literature.

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.

The Emerging Potential of Multi-Ion Radiotherapy

Research into high linear energy transfer (LET) radiotherapy now spans over half a century, beginning with helium and deuteron treatment in 1952 and today ranging from fast neutrons to carbon-ions. Owing to pioneering work initially in the United States and thereafter in Germany and Japan, increasing focus is on the carbon-ion beam: 12 centers are in operation, with five under construction and three in planning. While the carbon-ion beam has demonstrated unique and promising suitability in laboratory and clinical trials toward the hypofractionated treatment of hypoxic and/or radioresistant cancer, substantial developmental potential remains. Perhaps most notable is the ability to paint LET in a tumor, theoretically better focusing damage delivery within the most resistant areas. However, the technique may be limited in practice by the physical properties of the beams themselves. A heavy-ion synchrotron may provide irradiation with multiple heavy-ions: carbon, helium, and oxygen are prime candidates. Each ion varies in LET distribution, and so a methodology combining the use of multiple ions into a uniform LET distribution within a tumor may allow for even greater treatment potential in radioresistant cancer.

The 20th Gray lecture 2019: health and heavy ions

OBJECTIVE

Particle radiobiology has contributed new understanding of radiation safety and underlying mechanisms of action to radiation oncology for the treatment of cancer, and to planning of radiation protection for space travel. This manuscript will highlight the significance of precise physical and biologically effective dosimetry to this translational research for the benefit of human health.This review provides a brief snapshot of the evolving scientific basis for, and the complex current global status, and remaining challenges of hadron therapy for the treatment of cancer. The need for particle radiobiology for risk planning in return missions to the Moon, and exploratory deep-space missions to Mars and beyond are also discussed.

METHODS

Key lessons learned are summarized from an impressive collective literature published by an international cadre of multidisciplinary experts in particle physics, radiation chemistry, medical physics of imaging and treatment planning, molecular, cellular, tissue radiobiology, biology of microgravity and other stressors, theoretical modeling of biophysical data, and clinical results with accelerator-produced particle beams.

RESULTS

Research pioneers, many of whom were Nobel laureates, led the world in the discovery of ionizing radiations originating from the Earth and the Cosmos. Six radiation pioneers led the way to hadron therapy and the study of charged particles encountered in outer space travel. Worldwide about 250,000 patients have been treated for cancer, or other lesions such as arteriovenous malformations in the brain between 1954 and 2019 with charged particle radiotherapy, also known as hadron therapy. The majority of these patients (213,000) were treated with proton beams, but approximately 32,000 were treated with carbon ion radiotherapy. There are 3500 patients who have been treated with helium, pions, neon or other ions. There are currently 82 facilities operating to provide ion beam clinical treatments. Of these, only 13 facilities located in Asia and Europe are providing carbon ion beams for preclinical, clinical, and space research. There are also numerous particle physics accelerators worldwide capable of producing ion beams for research, but not currently focused on treating patients with ion beam therapy but are potentially available for preclinical and space research. Approximately, more than 550 individuals have traveled into Lower Earth Orbit (LEO) and beyond and returned to Earth.

CONCLUSION

Charged particle therapy with controlled beams of protons and carbon ions have significantly impacted targeted cancer therapy, eradicated tumors while sparing normal tissue toxicities, and reduced human suffering. These modalities still require further optimization and technical refinements to reduce cost but should be made available to everyone in need worldwide. The exploration of our Universe in space travel poses the potential risk of exposure to uncontrolled charged particles. However, approaches to shield and provide countermeasures to these potential radiation hazards in LEO have allowed an amazing number of discoveries currently without significant life-threatening medical consequences. More basic research with components of the Galactic Cosmic Radiation field are still required to assure safety involving space radiations and combined stressors with microgravity for exploratory deep space travel.

ADVANCES IN KNOWLEDGE

The collective knowledge garnered from the wealth of available published evidence obtained prior to particle radiation therapy, or to space flight, and the additional data gleaned from implementing both endeavors has provided many opportunities for heavy ions to promote human health.

Carbon ion radiation therapy for sinonasal malignancies: Promising results from 2282 cases from the real world

The aim of this study is to compare the effectiveness of carbon ion radiation therapy (CIRT), proton radiation therapy (PRT), and photon‐based intensity‐modulated radiation therapy (IMRT) in the treatment of sinonasal malignancies. We identified studies through systematic review and divided them into three cohorts (CIRT group/PRT group/IMRT group). Primary outcomes of interest were overall survival (OS) and local control (LC). We pooled the outcomes with meta‐analysis and compared the survival difference among groups using Chi² (χ²) test. A representative sample of 2282 patients with sinonasal malignancies (911 in the CIRT group, 599 in the PRT group, and 772 in the IMRT group) from 44 observation studies (7 CIRT, 16 PRT, and 21 IMRT) was included. The pooled 3‐year OS, LC, distant metastasis–free survival, and progression‐free survival rates were 67.0%, 72.8%, 69.4%, and 52.8%, respectively. Through cross‐group analysis, the OS was significantly higher after CIRT (75.1%, 95% CI: 67.1%‐83.2%) than PRT (66.2%, 95% CI: 57.7%‐74.6%; χ² = 13.374, P < .0001) or IMRT (63.8%, 95% CI: 55.3%‐72.3%; χ² = 23.814, P < .0001). LC was significantly higher after CIRT (80.2%, 95% CI: 73.9%‐86.5%) than PRT (72.9%, 95% CI: 63.7%‐82.0%; χ² = 8.955, P = .003) or IMRT (67.8%, 95% CI: 59.4%‐76.2%; χ² = 30.955, P < .0001). However, no significant difference between PRT and IMRT for OS and LC was observed. CIRT appeared to provide better OS and LC for patients with malignancies of nasal cavity and paranasal sinuses. A prospective randomized clinical trial is needed to confirm the superiority of CIRT in the treatment of sinonasal tumors.

Particle Beam Radiation Therapy for Adenoid Cystic Carcinoma of the Nasal Cavity and Paranasal Sinuses

Background: Sinonasal adenoid cystic carcinoma (SNACC) presents a challenge to oncologists due to its complex anatomy and poor prognosis. Although radiation therapy, either definitive or adjuvant to surgery, is an important part of the multidisciplinary management of SNACC, photon-based radiotherapy yielded suboptimal local control. The purpose of this study was to report the clinical results of a large patient cohort treated with particle beam radiation therapy.

Methods: Patients with SNACC that received proton beam therapy (PBT), carbon-ion radiotherapy (CIRT) or a combination of CIRT and PBT between May 2015 and May 2019 were included in the analysis. Three patients were treated with PBT, 17 with CIRT and 18 received PBT and a CIRT boost. Overall survival (OS), progression-free survival (PFS), local control (LC), regional control (RC), and distant metastasis-free (DMF) rates were calculated using the Kaplan-Meier method. Toxicities were reported using the CTCAE (version 4.03).

Results: A total of 38 patients were included in this analysis. Of these patients, 12 had recurrent disease, including 10 whose previous photon-based RT had failed. The most common primary tumor site was the maxillary sinus. Thirty-six patients (94.7%) suffered from locally advanced disease (T3-4). After a median follow-up of 27.2 months, the 3-year OS, PFS, LC, RC, and DMF rates were 96.7, 80.6, 90.0, 100, and 88.7%, respectively. No acute toxicities of grade 3 or above were observed. Two patients experienced grade 3 xerostomia or vision decreased, and one patient died of hemorrhage.

Conclusion: PBT, CIRT or a combination of CIRT and PBT appeared to be a promising treatment option for SNACC and produced satisfactory local control and toxicity profile. Longer follow-up is needed to verify the long-term benefit of particle-beam radiation therapy (PBRT) for patients with SNACC.

Particle therapy in the future of precision therapy

The first hospital-based treatment facilities for particle therapy started operation about thirty years ago. Since then, the clinical experience with protons and carbon ions has grown continuously and more than 200,000 patients have been treated to date. The promising clinical results led to a rapidly increasing number of treatment facilities and many new facilities are planned or under construction all over the world. An inverted depth-dose profile combined with potential radiobiological advantages make charged particles a precious tool for the treatment of tumours that are particularly radioresistant or located nearby sensitive structures. A rising number of trials have already confirmed the benefits of particle therapy in selected clinical situations and further improvements in beam delivery, image guidance and treatment planning are expected. This review summarises some physical and biological characteristics of accelerated charged particles and gives some examples of their clinical application. Furthermore, challenges and future perspectives of particle therapy will be discussed.