Dose escalation study of carbon ion radiotherapy for locally advanced head-and-neck cancer

Carbon-ion radiotherapy for clear cell odontogenic carcinomas

BACKGROUND

Clear cell odontogenic carcinoma (CCOC) is a rare odontogenic malignant tumor. The standard treatment for CCOC is surgical resection and adjuvant radiotherapy (RT). Radiotherapy is generally considered in inoperable cases. However, there are no reports on definitive RT for CCOC, and the role of RT in patients with inoperable CCOC remains unknown. Therefore, in this report, we present two cases of carbon-ion (C-ion) RT for CCOC.

CASE PRESENTATION

In case 1, a 73-year-old man with mandibular CCOC presented with recurrence in the inferior temporal fossa after two tumor resections. The tumor was considered inoperable, and C-ion RT (57.6 Gy in 16 fractions) was administered. The tumor remained controlled even after 20 months of C-ion RT; however, the patient died of other causes. In case 2, a 34-year-old man with maxillary CCOC presented with recurrence in the left sinonasal region after two tumor resections. The tumor was considered inoperable, and C-ion RT (64 Gy in 16 fractions) was administered. However, recurrence was observed in the irradiated field 19 months after the treatment. Subsequently, C-ion RT (64 Gy in 16 fractions) was repeated for the recurrent tumors. Seven years and 6 months after the initial irradiation, the tumor remains controlled, and the patient is alive without any unexpected serious adverse events.

CONCLUSION

C-ion RT may be an effective treatment option for patients with inoperable CCOC.

Investigation of intra-fractionated range guided adaptive proton therapy: I. On-line PET imaging and range measurement

Objective.Develop a prototype on-line positron emission tomography (PET) scanner and evaluate its capability of on-line imaging and intra-fractionated proton-induced radioactivity range measurement.Approach.Each detector consists of 32 × 32 array of 2 × 2 × 30 mm3Lutetium-Yttrium Oxyorthosilicate scintillators with single-scintillator-end readout through a 20 × 20 array of 3 × 3 mm2Silicon Photomultipliers. The PET can be configurated with a full-ring of 20 detectors for conventional PET imaging or a partial-ring of 18 detectors for on-line imaging and range measurement. All detector-level readout and processing electronics are attached to the backside of the system gantry and their output signals are transferred to a field-programable-gate-array based system electronics and data acquisition that can be placed 2 m away from the gantry. The PET imaging performance and radioactivity range measurement capability were evaluated by both the offline study that placed a radioactive source with known intensity and distribution within a phantom and the online study that irradiated a phantom with proton beams under different radiation and imaging conditions.Main results.The PET has 32 cm diameter and 6.5 cm axial length field-of-view (FOV), ∼2.3-5.0 mm spatial resolution within FOV, 3% sensitivity at the FOV center, 18%-30% energy resolution, and ∼9 ns coincidence time resolution. The offline study shows the PET can determine the shift of distal falloff edge position of a known radioactivity distribution with the accuracy of 0.3 ± 0.3 mm even without attenuation and scatter corrections, and online study shows the PET can measure the shift of proton-induced positron radioactive range with the accuracy of 0.6 ± 0.3 mm from the data acquired with a short-acquisition (60 s) and low-dose (5 MU) proton radiation to a human head phantom.Significance.This study demonstrated the capability of intra-fractionated PET imaging and radioactivity range measurement and will enable the investigation on the feasibility of intra-fractionated, range-shift compensated adaptive proton therapy.

Long-Term Outcomes Following Definitive or Adjuvant Proton Radiotherapy for Adenoid Cystic Carcinoma

Purpose

Adenoid cystic carcinoma (ACC) is a rare malignancy accounting for 1% of all head and neck cancers. Treatment for ACC has its challenges and risks, yet few outcomes studies exist. We present long-term outcomes of patients with ACC of the head and neck treated with proton therapy (PT).

Materials and Methods

Under an institutional review board-approved, single-institutional prospective outcomes registry, we reviewed the records of 56 patients with de novo, nonmetastatic ACC of the head and neck treated with PT with definitive (n = 9) or adjuvant PT (n = 47) from June 2007 to December 2021. The median dose to the primary site was 72.6 gray relative biological equivalent (range, 64-74.4) delivered as either once (n = 19) or twice (n = 37) daily treatments. Thirty patients received concurrent chemotherapy. Thirty-one patients received nodal radiation, 30 electively and 1 for nodal involvement.

Results

With a median follow-up of 6.2 years (range, 0.9-14.7), the 5-year local-regional control (LRC), disease-free survival, cause-specific survival, and overall survival rates were 88%, 85%, 89%, and 89%, respectively. Intracranial extension (P = .003) and gross residual tumor (P = .0388) were factors associated with LRC rates. While the LRC rate for those with a gross total resection was 96%, those with subtotal resection or biopsy alone were 81% and 76%, respectively. The 5-year cumulative incidence of clinically significant grade ≥3 toxicity was 15%, and the crude incidence at the most recent follow-up was 23% (n = 13).

Conclusion

This is the largest sample size with the longest median follow-up to date of patients with ACC treated with PT. PT can provide excellent disease control for ACC of the head and neck with acceptable toxicity. T4 disease, intracranial involvement, and gross residual disease at the time of PT following either biopsy or subtotal resection were significant prognostic features for worse outcomes.

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.

Carbon Ions Suppress Angiogenesis and Lung Metastases in Melanoma by Targeting CXCL10

Carbon-ion radiotherapy (CIRT) enhanced local control in patients with malignant melanoma. In several in vitro studies, carbon ions (C ions) have been also shown to decrease the metastatic potential of melanoma cells. CXC motif 10 (CXCL10) has been shown to play a crucial role in regulating tumor metastasis and it significantly increase in human embryonic kidney cells after heavy ion irradiations. This study sought to explore the regulatory effect of C ions on melanoma metastasis, emphasizing the role of CXCL10 in this process. To explore the potential regulatory effect of C ions on tumor metastasis in vivo, we developed a lung metastasis mouse model by injecting B16F10 cells into the footpad and subjected all mice to treatment with X rays and C ions. Subsequently, a series of assays, including histopathological analysis, enzyme-linked immunosorbent assay, real-time PCR, and western blotting, were conducted to assess the regulatory effects of C ions on melanoma. Our results showed that mice treated with C ions exhibited significantly less tumor vascularity, enhanced tumor necrosis, alleviated lung metastasis, and experienced longer survival than X-ray irradiated mice. Moreover, VEGF expression in B16F10 cells was significantly reduced by C-ion treatment, which could be alleviated by CXCL10 knockdown in vitro. Further investigations revealed that co-culturing with HUVECs resulted in a significant inhibition of proliferation, migration, and tube formation ability in the C-ion treated group, while the opposite effect was observed in the C-ion treated with si-CXCL10 group. In conclusion, our findings demonstrate that treatment with carbon-ion radiation can suppress angiogenesis and lung metastases in melanoma by specifically targeting CXCL10. These results suggest the potential utility of carbon ions in treating melanoma.

Future Perspective: Carbon Ion Radiotherapy for Head and Neck and Skull Base Malignancies

Head and neck and base of skull malignancies are challenging for surgical and radiotherapy treatment due to the density of sensitive tissues. Carbon ion radiotherapy (CIRT) is a form of heavy particle therapy that uses accelerated carbon ions to treat malignancies that may be radioresistant or in challenging anatomic locations. CIRT has an increased biological effectiveness (ie, increased cell killing) at the end of the range of the carbon beam (ie, within the target tissue) but not in the entrance dose. This increased biological effectiveness can overcome the effects of radioresistant tumors, tissue hypoxia, and the need for radiotherapy fractionation.

Real-time deep neural network-based automatic bowel gas segmentation on X-ray images for particle beam treatment

Since particle beam distribution is vulnerable to change in bowel gas because of its low density, we developed a deep neural network (DNN) for bowel gas segmentation on X-ray images. We used 6688 image datasets from 209 cases as training data, 736 image datasets from 23 cases as validation data and 102 image datasets from 51 cases as test data (total 283 cases). For the training data, we prepared three types of digitally reconstructed radiographic (DRR) images (all-density, bone and gas) by projecting the treatment planning CT image data. However, the real X-ray images acquired in the treatment room showed low contrast that interfered with manual delineation of bowel gas. Therefore, we used synthetic X-ray images converted from DRR images in addition to real X-ray images.We evaluated DNN segmentation accuracy for the synthetic X-ray images using Intersection over Union, recall, precision, and the Dice coefficient, which measured 0.708 ± 0.208, 0.832 ± 0.170, 0.799 ± 0.191, and 0.807 ± 0.178, respectively. The evaluation metrics for the real X-images were less accurate than those for the synthetic X-ray images (0.408 ± 0237, 0.685 ± 0.326, 0.490 ± 0272, and 0.534 ± 0.271, respectively). Computation time was 29.7 ± 1.3 ms/image. Our DNN appears useful in increasing treatment accuracy in particle beam therapy.

Comparison of dosimetries of carbon-ion pencil beam scanning, proton pencil beam scanning and volumetric modulated arc therapy for locally recurrent rectal cancer

We compared the dose distributions of carbon-ion pencil beam scanning (C-PBS), proton pencil beam scanning (P-PBS) and Volumetric Modulated Arc Therapy (VMAT) for locally recurrent rectal cancer. The C-PBS treatment planning computed tomography (CT) data sets of 10 locally recurrent rectal cancer cases were randomly selected. Three treatment plans were created using identical prescribed doses. The beam angles for C-PBS and P-PBS were identical. Dosimetry, including the dose received by 95% of the planning target volume (PTV) (D95%), dose to the 2 cc receiving the maximum dose (D2cc), organ at risk (OAR) volume receiving > 15Gy (V15) and > 30Gy (V30), was evaluated. Statistical significance was assessed using the Wilcoxon signed-rank test. Mean PTV-D95% values were > 95% of the volume for P-PBS and C-PBS, whereas that for VMAT was 94.3%. However, PTV-D95% values in P-PBS and VMAT were < 95% in five and two cases, respectively, due to the OAR dose reduction. V30 and V15 to the rectum/intestine for C-PBS (V30 = 4.2 ± 3.2 cc, V15 = 13.8 ± 10.6 cc) and P-PBS (V30 = 7.3 ± 5.6 cc, V15 = 21.3 ± 13.5 cc) were significantly lower than those for VMAT (V30 = 17.1 ± 10.6 cc, V15 = 55.2 ± 28.6 cc). Bladder-V30 values with P-PBS/C-PBS (3.9 ± 4.8 Gy(RBE)/3.0 ± 4.0 Gy(RBE)) were significantly lower than those with VMAT (7.9 ± 8.1 Gy). C-PBS provided superior dose conformation and lower OAR doses compared with P-PBS and VMAT. C-PBS may be the best choice for cases in which VMAT and P-PBS cannot satisfy dose constraints. C-PBS could be another choice for cases in which VMAT and P-PBS cannot satisfy dose constraints, thereby avoiding surgical resection.

Salivary gland cancers in elderly patients: challenges and therapeutic strategies

Salivary gland carcinomas (SGCs) are the most heterogeneous subgroup of head and neck malignant tumors, accounting for more than 20 subtypes. The median age of SGC diagnosis is expected to rise in the following decades, leading to crucial clinical challenges in geriatric oncology. Elderly patients, in comparison with patients aged below 65 years, are generally considered less amenable to receiving state-of-the-art curative treatments for localized disease, such as surgery and radiation/particle therapy. In the advanced setting, chemotherapy regimens are often dampened by the consideration of cardiovascular and renal comorbidities. Nevertheless, the elderly population encompasses a broad spectrum of functionalities. In the last decades, some screening tools (e.g. the G8 questionnaire) have been developed to identify those subjects who should receive a multidimensional geriatric assessment, to answer the question about the feasibility of complex treatments. In the present article, we discuss the most frequent SGC histologies diagnosed in the elderly population and the relative 5-years survival outcomes based on the most recent data from the Surveillance, Epidemiology, and End Results (SEER) Program. Moreover, we review the therapeutic strategies currently available for locoregionally advanced and metastatic disease, taking into account the recent advances in precision oncology. The synergy between the Multidisciplinary Tumor Board and the Geriatrician aims to shape the most appropriate treatment pathway for each elderly patient, focusing on global functionality instead of the sole chronological age.

A randomized controlled phase III study comparing hadrontherapy with carbon ions versus conventional radiotherapy - including photon and proton therapy - for the treatment of radioresistant tumors: the ETOILE trial

BACKGROUND

Some cancers such as sarcomas (bone and soft tissue sarcomas) and adenoid cystic carcinomas are considered as radioresistant to low linear energy transfer radiation (including photons and protons) and may therefore beneficiate from a carbon ion therapy. Despite encouraging results obtained in phase I/II trials compared to historical data with photons, the spread of carbon ions has been limited mainly because of the absence of randomized medical data. The French health authorities stressed the importance of having randomized data for carbon ion therapy.

METHODS

The ETOILE study is a multicenter prospective randomized phase III trial comparing carbon ion therapy to either advanced photon or proton radiotherapy for inoperable or macroscopically incompletely resected (R2) radioresistant cancers including sarcomas and adenoid cystic carcinomas. In the experimental arm, carbon ion therapy will be performed at the National Center for Oncological Hadrontherapy (CNAO) in Pavia, Italy. In the control arm, photon or proton radiotherapy will be carried out in referent centers in France. The primary endpoint is progression-free survival (PFS). Secondary endpoints are overall survival and local control, toxicity profile, and quality of life. In addition, a prospective health-economic study and a radiobiological analysis will be conducted. To demonstrate an absolute improvement in the 5-year PFS rate of 20% in favor of carbon ion therapy, 250 patients have to be included in the study.

DISCUSSION

So far, no clinical study of phase III has demonstrated the superiority of carbon ion therapy compared to conventional radiotherapy, including proton therapy, for the treatment of radioresistant tumors.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02838602 . Date of registration: July 20, 2016. The posted information will be updated as needed to reflect protocol amendments and study progress.

Evaluation of the Response of HNSCC Cell Lines to γ-Rays and 12C Ions: Can Radioresistant Tumors Be Identified and Selected for 12C Ion Radiotherapy?

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignancy worldwide. Thirty percent of patients will experience locoregional recurrence for which median survival is less than 1 year. Factors contributing to treatment failure include inherent resistance to X-rays and chemotherapy, hypoxia, epithelial to mesenchymal transition, and immune suppression. The unique properties of ¹²C radiotherapy including enhanced cell killing, a decreased oxygen enhancement ratio, generation of complex DNA damage, and the potential to overcome immune suppression make its application well suited to the treatment of HNSCC. We examined the ¹²C radioresponse of five HNSCC cell lines, whose surviving fraction at 3.5 Gy ranged from average to resistant when compared with a larger panel of 38 cell lines to determine if ¹²C irradiation can overcome X-ray radioresistance and to identify biomarkers predictive of ¹²C radioresponse. Cells were irradiated with ¹²C using a SOBP with an average LET of 80 keV/μm (CNAO: Pavia, Italy). RBE values varied depending upon endpoint used. A 37 gene signature was able to place cells in their respective radiosensitivity cohort with an accuracy of 86%. Radioresistant cells were characterized by an enrichment of genes associated with radioresistance and survival mechanisms including but not limited to G2/M Checkpoint MTORC1, HIF1α, and PI3K/AKT/MTOR signaling. These data were used in conjunction with an in silico-based modeling approach to evaluate tumor control probability after ¹²C irradiation that compared clinically used treatment schedules with fixed RBE values vs. the RBEs determined for each cell line. Based on the above analysis, we present the framework of a strategy to utilize biological markers to predict which HNSCC patients would benefit the most from ¹²C radiotherapy.

Flourish of Proton and Carbon Ion Radiotherapy in China

Proton and heavy ion therapy offer superior relative biological effectiveness (RBE) in the treatment of deep-seated tumors compared with conventional photon radiotherapy due to its Bragg-peak feature of energy deposition in organs. Many proton and carbon ion therapy centers are active all over the world. At present, five particle radiotherapy institutes have been built and are receiving patient in China, mainly including Wanjie Proton Therapy Center (WPTC), Shanghai Proton Heavy Ion Center (SPHIC), Heavy Ion Cancer Treatment Center (HIMM), Chang Gung Memorial Hospital (CGMH), and Ruijin Hospital affiliated with Jiao Tong University. Many cancer patients have benefited from ion therapy, showing unique advantages over surgery and chemotherapy. By the end of 2020, nearly 8,000 patients had been treated with proton, carbon ion or carbon ion combined with proton therapy. So far, there is no systemic review for proton and carbon ion therapy facility and clinical outcome in China. We reviewed the development of proton and heavy ion therapy, as well as providing the representative clinical data and future directions for particle therapy in China. It has important guiding significance for the design and construction of new particle therapy center and patients’ choice of treatment equipment.

Nuclear Fragmentation Imaging for Carbon-Ion Radiation Therapy Monitoring: an In Silico Study

Purpose

This article presents an in vivo imaging technique based on nuclear fragmentation of carbon ions in irradiated tissues for potential real-time monitoring of carbon-ion radiation therapy (CIRT) treatment delivery and quality assurance purposes in clinical settings.

Materials and Methods

A proof-of-concept imaging and monitoring system (IMS) was devised to implement the technique. Monte Carlo simulations were performed for a prospective pencil-beam scanning CIRT nozzle. The development IMS benchmark considered a 5×5-cm² pixelated charged-particle detector stack positioned downstream from a target phantom and list-mode data acquisition. The abundance and production origins, that is, vertices, of the detected fragments were studied. Fragment trajectories were approximated by straight lines and a beam back-projection algorithm was built to reconstruct the vertices. The spatial distribution of the vertices was then used to determine plan relevant markers.

Results

The IMS technique was applied for a simulated CIRT case, a primary brain tumor. Four treatment plan monitoring markers were conclusively recovered: a depth dose distribution correlated profile, ion beam range, treatment target boundaries, and the beam spot position. Promising millimeter-scale (3-mm, ≤10% uncertainty) beam range and submillimeter (≤0.6-mm precision for shifts <3 cm) beam spot position verification accuracies were obtained for typical therapeutic energies between 150 and 290 MeV/u.

Conclusions

This work demonstrated a viable online monitoring technique for CIRT treatment delivery. The method's strong advantage is that it requires few signal inputs (position and timing), which can be simultaneously acquired with readily available technology. Future investigations will probe the technique's applicability to motion-sensitive organ sites and patient tissue heterogeneities. In-beam measurements with candidate detector-acquisition systems are ultimately essential to validate the IMS benchmark performance and subsequent deployment in the clinic.

Adenoid cystic Carcinoma and Carbon ion Only irradiation (ACCO): Study protocol for a prospective, open, randomized, two-armed, phase II study

Background

Adenoid cystic carcinoma is a rare form of head and neck cancer with a slow, but aggressive growth pattern which remains a challenge for local tumor control. Based on phase II data, radiation treatment using partially high LET radiation results in a prolonged PFS and OS. There is a paucity of randomized clinical data examining the role of the use of high LET radiation only. Therefore, the purpose of this prospective clinical trial is to analyze local control rates in patients with node negative ACC treated with carbon ion radiotherapy alone compared to a combined modality approach.

Methods

This trial is conducted as a prospective, open-label, phase II, two-armed, investigator-initiated study comparing the local control rates in node negative ACCs of the head and neck treated either with sole carbon ion radiotherapy or a combination of carbon ions and photons. Secondary outcomes investigated are progression-free survival, overall survival, acute and late toxicity, and quality of life. A total of 314 patients will be randomly assigned to C12 treatment alone or bimodal treatment: Patients in the experimental group will receive a dose of 51 Gy (RBE) in 17 fractions and a boost of 15 Gy (RBE) in 5 fractions. Patients in the control group will receive 25 fractions photon IMRT 50Gy and a boost using 8 × 3 Gy (RBE) carbon ions. Local control will be assessed in regular follow up examinations until 5 years after the completion of treatment.

Discussion

The present trial aims to evaluate local control rates to compare sole carbon ion radiotherapy to bimodal radiotherapy with carbon ions and photons in patients with node negative ACCs of the head and neck region. Local control is selected as the primary endpoint due to its major clinical relevance because of slow but aggressive growth patterns.

Trial registration

The study was prospectively registered on 2nd January 2020: ClinicalTrials.gov, NCT04214366. “Adenoid Cystic Carcinoma and Carbon Ion Only Irradiation (ACCO)”.

Study status

Under recruitment, participant recruitment is not completed. Start of recruitment was January 2020. There are no results been published or submitted to any journal.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08473-5.

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.

Novel On-line PET Imaging for Intra-Beam Range Verification and Delivery Optimization: A Simulation Feasibility Study

On-line PET image-based method uses an initial particle beam to measure the particle beam range (BR) within the same fraction so that any measured range-shift with respect to the predicted BR can be compensated before the rest therapeutic beam deliveries. However, the method requires to use a low-dose initial beam to minimize the risk of beam overshooting, which leads to low image count and inaccurate BR measurement. In this in-silico study, we evaluated the feasibility of a new on-line PET imaging method that measures BR at the mid-plane of a target volume with part of the high-dose therapy beams to verify BR and guide adaptive treatment re-planning. Simulations included various processes of proton beam radiations to a tumor inside a human brain phantom, positron and PET image generation at the mid-plane with initial beams, activity range measurement, and range-shift compensated beam delivery. The results demonstrated that the new method, under the simulated conditions, can achieve ~1.1 mm mid-plane BR measurement accuracy and closely match the delivered range-shift compensated dose distribution with the planned one. Overall, it is promising that this new method may significantly improve particle therapy accuracy.

Efficacy and safety of carbon-ion radiotherapy for the malignant melanoma: A systematic review

Malignant melanomas (MMs) were the fifth most common cancer in men and the sixth most common cancer in women in 2018, respectively. These are characterized by high metastatic rates and poor prognoses. We systematically reviewed safety and efficacy of carbon-ion radiotherapy (CIRT) for treating MMs. Eleven studies were eligible for review, and the data showed that MM patients showed better local control with low recurrence and mild toxicities after CIRT. Survival rates were slightly higher in patients with cutaneous or uveal MMs than in those with mucosal MMs. CIRT in combination with chemotherapy produced higher progression-free survival rates than CIRT only. In younger patients, higher rates of distant metastases of gynecological MMs were observed. The data indicated that CIRT is effective and safe for treating MMs; however, a combination with systemic therapy is recommended to ensure the best possible prognosis for MMs.

Adenoid Cystic Carcinoma of Bartholin's Gland: What Is the Best Approach?

Background and summary: Among all vulvar cancers, primary adenoid cystic carcinoma (ACC) of Bartholin's gland is a very rare tumor characterized by a slow growth, a high local aggressiveness, and a remarkable recurrence rate. Due to its rarity, treatment remains a challenge for oncologists and gynecological surgeons. Key message: The present paper reports clinical, radiological, and histological features of ACC of Bartholin's gland and reviews the literature data on the treatment options with a particular focus on the potential role of particle radiation therapy.

Reirradiation of salivary gland tumors with carbon ion radiotherapy at CNAO

AIMS

To report oncologic and functional outcomes in terms of tumor control and toxicity of carbon ion radiotherapy (CIRT) in reirradiation setting for recurrent salivary gland tumors at CNAO.

METHODS

From November 2013 to September 2016, 51 consecutive patients with inoperable recurrent salivary gland tumors were retreated with CIRT in the frame of the phase II protocol CNAO S14/2012C for recurrent head and neck tumors.

RESULTS

Majority of pts (74.5%) had adenoid cystic carcinoma, mainly rcT4a (51%) and rcT4b (37%). Median dose of prior photon based radiotherapy was 60 Gy. Median dose of CIRT was 60 Gy [RBE] at a mean of 3 Gy [RBE] per fraction. During reirradiation, 19 patients (37.3%) experienced grade G1 toxicity, 19 pts (37.3%) had G2 and 2 pts (3.9%) had G3. Median follow up time was 19 months. Twenty one (41.2%) patients had stable disease and 30 (58.8%) tumor progression at the time of last follow up. Furthermore, 9 (18%) patients had G1 late toxicity, 19 (37%) had G2 and 9 (17. 5%) had G3. Using the Kaplan Meier method, progression free survival (actuarial) at one and two years were 71.7% and 52.2% respectively. Estimated overall survival (actuarial) at one and two years were 90.2% and 64%, respectively.

CONCLUSIONS

CIRT is a good option for retreatment of inoperable recurrent salivary gland tumors with acceptable rates of acute and late toxicity. Longer follow up time is needed to assess the effectiveness of CIRT in reirradiation setting of salivary gland tumors.

Cost-effectiveness analysis (CEA) of IMRT plus C12 boost vs IMRT only in adenoid cystic carcinoma (ACC) of the head and neck

Background

Particle therapy provides steep dose gradients to facilitate dose escalation in challenging anatomical sites which has been shown not only to improve local control but also overall survival in patients with ACC. Cost-effectiveness of intensity-modulated radiotherapy (IMRT) plus carbon ion (C12) boost vs IMRT alone was performed in order to objectivise and substantiate more widespread use of this technology in ACC.

Methods

Patients with pathologically confirmed ACC received a combination regimen of IMRT plus C12 boost. Patients presenting outside C12 treatment slots received IMRT only. Clinical results were published; economic analysis on patient-level data was carried out from a healthcare purchaser’s perspective based on costs of healthcare utilization. Cost histories were generated from resource use recorded in individual patient charts and adjusted for censoring using the Lin I method. Cost-effectiveness was measured as incremental cost-effectiveness ratio (ICER). Sensitivity analysis was performed regarding potentially differing management of recurrent disease.

Results

The experimental treatment increased overall costs by € 18,076 (€13,416 – €22,922) at a mean survival benefit of 0.86 years. Despite improved local control, following costs were also increased in the experimental treatment. The ICER was estimated to 26,863 €/LY. After accounting for different management of recurrent disease in the two cohorts, the ICER was calculated to 20,638 €/LY.

Conclusion

The combined treatment (IMRT+C12 boost) substantially increased initial and overall treatment cost. In view of limited treatment options in ACC, costs may be acceptable though. Investigations into quality of life measures may support further decisions in the future.

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

We aimed to evaluate the treatment outcome of primary and postoperative bimodal radiotherapy (RT) including intensity modulated photon radiotherapy (IMRT) and carbon ion radiotherapy (CIRT) for sinonasal adenoid cystic carcinoma (ACC) patients. Medical records of 227 consecutive patients who received either a primary (n = 90, 40%) or postoperative (n = 137, 60%; R2, n = 86, 63%) IMRT with doses between 48 and 56 Gy in 1.8 or 2 Gy fractions and active raster-scanning carbon ion boost with 18 to 24 Gy (RBE, relative biological effectiveness) in 3 Gy (RBE) fractions between 2009 and 2019 up to a median total dose of 80 Gy (EQD2, equivalent dose in 2 Gy single dose fractions, range 71–80 Gy) were reviewed. Results: Median follow-up was 50 months. In univariate and multivariate analysis, no significant difference in local control (LC) could be shown between the two treatment groups (p = 0.33). Corresponding 3-year LC rates were 79% for primary bimodal RT and 82% for postoperative bimodal RT, respectively. T4 stage (p = 0.002) and solid histology (p = 0.005) were identified as independent prognostic factors for decreased LC. Significant worse long-term treatment tolerance was observed for postoperatively irradiated patients with 17% vs. 6% late grade 3 toxicity (p < 0.001). Primary radiotherapy including IMRT and carbon ion boost for dose-escalation results in adequate LC with less long-term grade 3 toxicity compared to postoperative bimodal radiotherapy in sinonasal ACC patients. The high rate of macroscopic tumor disease in the postoperative group makes the interpretation of the beneficial results in LC for primary RT difficult.

Carbon-ion radiotherapy in accelerated hypofractionated active raster-scanning technique for malignant lacrimal gland tumors: feasibility and safety

Introduction

We evaluated treatment outcomes of CIRT in an active raster-scanning technique alone or in combination with IMRT for lacrimal gland tumors.

Methods

A total of 24 patients who received CIRT for a malignant lacrimal gland tumor at the HIT between 2009 and 2018 were analyzed retrospectively for LC, OS, and distant progression-free survival (DPFS) using Kaplan-Meier estimates. Toxicity was assessed according to the CTCAE version 5.

Results

Median follow-up was 30 months and overall median LC, OS, and DPFS 24 months, 36 months, and 31 months, respectively. Two-year LC, OS, and DPFS of 93%, 96%, and 87% with CIRT was achieved for all patients. Local failure occurred only in patients with ACC and after a median follow-up of 30 months after the completion of RT (n=5, 21%; P=0.09). We identified a significant negative impact of a macroscopic tumor disease, which was diagnosed on planning CT or MRI before RT, on LC (P=0.026). In contrast, perineural spread (P=0.661), T stage (P=0.552), and resection margins in operated patients (P=0.069) had no significant impact on LC. No grade ≥3 acute or grade >3 chronic toxicity occurred. Late grade 3 side effects were identified in form of a wound-healing disorder 3 months after RT in one patient and temporal lobe necrosis 6 months after RT in another (n=2, 8%).

Conclusion

Accelerated hypofractionated active raster-scanning CIRT for relative radio-resistant malignant lacrimal gland tumors results in adequate LC rates and moderate acute and late toxicity. Nevertheless, LC for ACC histology remains challenging and risk factors for local recurrence are still unclear. Further follow-up is necessary to evaluate long-term clinical outcome.

Postoperative radiotherapy for T1/2N0M0 mucoepidermoid carcinoma positive for CRTC1/3-MAML2 fusions

BACKGROUND

The National Comprehensive Cancer Network (NCCN) guidelines recommend considering postoperative radiotherapy (PORT) for completely resected T1/2N0M0 salivary mucoepidermoid carcinomas when they show tumor spillage, perineural invasion, or intermediate/high-grade histology. CRTC1/3-MAML2 fusions have been associated with a favorable clinical outcome.

METHODS

Forty-seven T1/2N0M0 mucoepidermoid carcinoma cases positive for CRTC1/3-MAML2 fusions were completely resected and were not treated with PORT.

RESULTS

Pathologically, none of the cases showed tumor spillage or perineural invasion. Cases with intermediate/high-grade histology numbered 9 (19%) to 26 (55%) with the currently used 3 different grading systems. During the follow-up (median 60 months), locoregional tumor recurrence occurred in 4 cases, which were treated with surgery alone. At the last follow-up (median 60 months; 7-160), all patients were alive with no evidence of disease.

CONCLUSION

An excellent prognosis may be achieved without PORT in T1/2N0M0 mucoepidermoid carcinoma patients positive for CRTC1/3-MAML2 fusions when the tumors are completely resected without tumor spillage.

Efficacy and safety of carbon-ion radiotherapy for lacrimal gland carcinomas with extraorbital extension: a retrospective cohort study

Purpose

To evaluate the efficacy and safety of carbon-ion radiotherapy (CIRT) for patients with lacrimal gland carcinomas (LGCs) with extraorbital extension.

Results

The median follow-up period was 53.7 months. The 5-year local control and overall survival rates were 62% and 65%, respectively. Regarding late toxicities, 12 patients (36.4%) developed Grade 4 optic nerve disorders, including visual losses of the diseased side (N = 8; 66.7%), and 1 patient (3.0%) developed a Grade 3 optic nerve disorder. Three patients (9.0%) developed Grade 3 cataracts, 3 (9.0%) developed glaucoma, and 1 (3.0%) developed retinopathy. Two patients (6.1%) had Grade 4 central nervous system necrosis. No Grade 5 late toxicities were observed. The 5-year preservation rate of the ipsilateral eyeball was 86%.

Conclusion

Definitive CIRT is effective for LGCs with extraorbital extension with acceptable toxicity.

Methods

Thirty-three patients treated with CIRT at our institution were analyzed. Sixteen patients (48.5%) had adenoid cystic carcinoma, 8 (24.2%) had adenocarcinoma not otherwise specified, and 9 (27.3%) had other types of the disease. Thirty patients (90.9%) had T4c tumors. The prescribed doses were 57.6 Gy (relative biological effectiveness [RBE]) (N = 18; 54.5%) and 64.0 Gy (RBE) (N = 15; 45.5%) in 16 fractions.

Prospective observational study of carbon-ion radiotherapy for non-squamous cell carcinoma of the head and neck

To evaluate the efficacy and safety of carbon-ion radiotherapy for non-squamous cell carcinoma of the head and neck, 35 patients were enrolled in this prospective study. The primary end-point was the 3-year local control rate, and the secondary end-points included the 3-year overall survival rate and adverse events. Acute and late adverse events were evaluated according to the Common Terminology Criteria for Adverse Events, version 4.0. The median follow-up time for all patients was 39 months. Thirty-two and three patients received 64.0 Gy (relative biological effectiveness) and 57.6 Gy (relative biological effectiveness) in 16 fractions, respectively. Adenoid cystic carcinoma was dominant (60%). Four patients had local recurrence and five patients died. The 3-year local control and overall survival rates were 93% and 88%, respectively. Acute grade 2-3 radiation mucositis (65%) and dermatitis (31%) was common, which improved immediately with conservative therapy. Late mucositis of grade 2, grade 3, and grade 4 were observed in 11, one, and no patients, respectively. There were no adverse events of grade 5. Carbon-ion radiotherapy achieved excellent local control and overall survival rates for non-squamous cell carcinoma. However, the late mucosal adverse events were not rare, and meticulous treatment planning is required. Trial registration no. UMIN000007886.

Prognostic factors of adenoid cystic carcinoma of the head and neck in carbon-ion radiotherapy: The impact of histological subtypes

PURPOSE

The aim of this study was to evaluate the effect of histological subtypes of head and neck adenoid cystic carcinoma (ACC) on the results of carbon-ion radiotherapy (CIRT).

MATERIAL AND METHODS

Of the 113 patients with ACC who were treated with CIRT between December 2006 and July 2013, 100 patients with identified histological subtypes were enrolled in this study. CIRT at a total dose of 57.6 or 64.0Gy (RBE) was administered in 16 fractions. Histological grading was defined as the presence or absence of a solid growth pattern.

RESULTS

Median follow-up was 60 months. 5-Year local control (LC), overall survival (OS) and distant metastasis free survival (DMFS) of all patients were 68.6%, 74.8% and 65.7%, respectively. On multivariate analysis, the prescribed dose (p=0.001) and gross tumor volume (p=0.002) were significant independent risk factors for LC. No significant difference for local control of solid/non-solid growth patterns was found (p=0.093). Solid growth pattern was an independent risk factor for both OS (p=0.033) and DMFS (p=0.024).

CONCLUSIONS

CIRT appears able to locally control solid growth pattern ACC in the head and neck. Improved intervention is needed to extend DMFS and OS.

Outcomes after primary or adjuvant radiotherapy for salivary gland carcinoma

BACKGROUND

We report long-term outcomes of patients treated with primary radiotherapy (RT) or surgery and adjuvant RT for salivary gland malignancies.

MATERIALS AND METHODS

From 1964 to 2012, 291 patients received primary RT (n = 67) or RT combined with surgery (n = 224).

RESULTS

The 5-, 10-, and 15-year local control, local-regional control, distant metastasis-free survival, cause-specific survival and overall survival rates were 82%, 77% and 73%; 77%, 72% and 67%; 74%, 70% and 70%; 70%, 59% and 54%; and 63%, 47% and 38%, respectively. Per multivariate analysis, combined surgery and RT and T stage impacted local control; overall stage and combined surgery and RT impacted local-regional control; overall stage impacted distant metastasis-free survival; and overall stage, node positivity, clinical nerve invasion, and surgery and RT impacted cause-specific and overall survival. Five percent of patients experienced grade 3 or worse toxicity.

CONCLUSION

Combined surgery and RT improves local control, local-regional control, and cause-specific survival compared with primary RT for salivary tumors.

Salivary Gland. Photon beam and particle radiotherapy: Present and future

Salivary gland cancers (SGCs) are rare diseases and their treatment depends upon histology, stage and site of origin. Radical surgery is the mainstay of treatment but radiotherapy (RT) plays a key role in both the postoperative and the inoperable setting, as well as in recurrent disease. In the absence of prospective randomized trials, a wide retrospective literature suggests postoperative RT (PORT) in patients with high risk pathological features. SGCs, and adenoid cystic carcinoma (ACC) in particular, are known to be radio-resistant tumors and should therefore respond well to particle beam therapy. Recently, excellent outcome has been reported with radical carbon ion RT (CIRT) in particular for ACC. Both modern photon- and hadron-based treatments are effective and are characterized by a favourable toxicity profile. But it is not clear whether one modality is superior to the other for disease control, due to the differences in patients' selection, techniques, fractionation schedules and outcome measurements among clinical experiences. In this paper, we review the role of photon and particle RT for malignant SGCs, discussing the difference between modalities in terms of biological and technical characteristics. RT dose and target volumes for different histologies (ACC versus non-ACC) have also been taken into consideration.

Treatment outcome of ion beam therapy in eight patients with head and neck cancers

Ion beam therapy has enabled us to treat formerly untreatable malignant tumors. The aim of the present study was to investigate the long-term follow-up course of patients with head and neck cancers who received ion beam therapy. The subjects were 8 patients (3 men and 5 women aged 43-78 years) with head and neck cancers who visited our department from 2006 to 2015 and received ion beam therapy. Six patients received carbon ion beam therapy, and the other two patients received proton beam therapy. The medical records of the patients were retrospectively analyzed. The primary site was the nasal and paranasal sinuses in six cases, nasopharynx in one case, and external auditory canal in one case. The histological type was olfactory neuroblastoma, malignant melanoma, and adenoid cystic carcinoma in two cases each, and chondrosarcoma and squamous cell carcinoma in one case each. The exposure dose ranged from 64 to 70.4 GyE. The average follow-up period was 42.0 months. Early adverse events were generally mild, and complete therapeutic response was obtained in all cases. However, five patients developed severe late complications including craniospinal dissemination, osteoradionecrosis of the maxilla and skull base, brain necrosis, and loss of eyesight. Three patients died of distant metastasis, local recurrence and/or brain necrosis within 2 years, and four patients have been surviving with distant metastasis or severe late complications. Ion beam therapy exhibits outstanding antitumor effects, but the severe late complications of the therapy must also be recognized.

Carbon-Ion Radiation Therapy for Pelvic Recurrence of Rectal Cancer

PURPOSE

Investigation of the treatment potential of carbon-ion radiation therapy in pelvic recurrence of rectal cancer.

METHODS AND MATERIALS

A phase 1/2 dose escalation study was performed. One hundred eighty patients (186 lesions) with locally recurrent rectal cancer were treated with carbon-ion radiation therapy (CIRT) (phase 1/2: 37 and 143 patients, respectively). The relapse locations were 71 in the presacral region, 82 in the pelvic sidewalls, 28 in the perineum, and 5 near the colorectal anastomosis. A 16-fraction in 4 weeks dose regimen was used, with total dose ranging from 67.2 to 73.6 Gy(RBE); RBE-weighted absorbed dose: 4.2 to 4.6 Gy(RBE)/fraction.

RESULTS

During phase 1, the highest total dose, 73.6 Gy(RBE), resulted in no grade >3 acute reactions in the 13 patients treated at that dose. Dose escalation was halted at this level, and this dose was used for phase 2, with no other grade >3 acute reactions observed. At 5 years, the local control and survival rates at 73.6 Gy(RBE) were 88% (95% confidence interval [CI], 80%-93%) and 59% (95% CI, 50%-68%), respectively.

CONCLUSION

Carbon-ion radiation therapy may be a safe and effective treatment option for locally recurrent rectal cancer and may serve as an alternative to surgery.

Unexpected radiation laryngeal necrosis after carbon ion therapy using conventional dose fractionation for laryngeal cancer

Carbon ion therapy is a type of radiotherapy that can deliver high-dose radiation to a tumor while minimizing the dose delivered to organs at risk. Moreover, carbon ions are classified as high linear energy transfer radiation and are expected to be effective for even photon-resistant tumors. A 73-year-old man with glottic squamous cell carcinoma, T3N0M0, refused laryngectomy and received carbon ion therapy of 70 Gy (relative biological effectiveness) in 35 fractions. Three months after the therapy, the patient had an upper airway inflammation, and then laryngeal edema and pain occurred. Five months after the therapy, the airway stenosis was severe and computed tomography showed lack of the left arytenoid cartilage and exacerbation of laryngeal necrosis. Despite the treatment, 5 and a half months after the therapy, the laryngeal edema and necrosis had become even worse and the surrounding mucosa was edematous and pale. Six months after the therapy, pharyngolaryngoesophagectomy and reconstruction with free jejunal autograft were performed. The surgical specimen pathologically showed massive necrosis and no residual tumor. Three years after the carbon ion therapy, he is alive without recurrence. The first reported laryngeal squamous cell carcinoma case treated with carbon ion therapy resulted in an unexpected radiation laryngeal necrosis. Tissue damage caused by carbon ion therapy may be difficult to repair even for radioresistant cartilage; therefore, hollow organs reinforced by cartilage, such as the larynx, may be vulnerable to carbon ion therapy. Caution should be exercised when treating tumors in or adjacent to such organs with carbon ion therapy.

Induction of Non-Targeted Stress Responses in Mammary Tissues by Heavy Ions

Purpose

Side effects related to radiation exposures are based primarily on the assumption that the detrimental effects of radiation occur in directly irradiated cells. However, several studies have reported over the years of radiation-induced non-targeted/ abscopal effects in vivo that challenge this paradigm. There is evidence that Cyclooxygenase-2 (COX2) plays an important role in modulating non-targeted effects, including DNA damages in vitro and mutagenesis in vivo. While most reports on radiation-induced non-targeted response utilize x-rays, there is little information available for heavy ions.

Methods and Materials

Adult female transgenic gpt delta mice were exposed to an equitoxic dose of either carbon or argon particles using the Heavy Ion Medical Accelerator in Chiba (HIMAC) at the National Institute of Radiological Sciences (NIRS) in Japan. The mice were stratified into 4 groups of 5 animals each: Control; animals irradiated under full shielding (Sham-irradiated); animals receiving whole body irradiation (WBIR); and animals receiving partial body irradiation (PBIR) to the lower abdomen with a 1 x 1 cm² field. The doses used in the carbon ion group (4.5 Gy) and in argon particle group (1.5 Gy) have a relative biological effectiveness equivalent to a 5 Gy dose of x-rays. 24 hours after irradiation, breast tissues in and out of the irradiated field were harvested for analysis. Induction of COX2, 8-hydroxydeoxyguanosine (8-OHdG), phosphorylated histone H2AX (γ-H2AX), and apoptosis-related cysteine protease-3 (Caspase-3) antibodies were examined in the four categories of breast tissues using immunohistochemical techniques. Analysis was performed by measuring the intensity of more than 20 individual microscopic fields and comparing the relative fold difference.

Results

In the carbon ion group, the relative fold increase in COX2 expression was 1.01 in sham-irradiated group (p > 0.05), 3.07 in PBIR (p < 0.05) and 2.50 in WBIR (p < 0.05), respectively, when compared with controls. The relative fold increase in 8-OHdG expression was 1.29 in sham-irradiated (p > 0.05), 11.31 in PBIR (p < 0.05) and 11.79 in WBIR (p < 0.05), respectively, when compared with controls. A similar increase in γ-H2AX expression was found in that, compared to controls, the increase was 1.41 fold in sham-irradiated (p > 0.05), 8.41 in PBIR (p < 0.05) and 10.59 in WBIR (p < 0.05). Results for the argon particle therapy group showed a similar magnitude of changes in the various biological endpoints examined. There was no statistical significance observed in Caspase-3 expression among the 4 groups.

Conclusions

Our data show that both carbon and argon ions induced non-targeted, out of field induction of COX2 and DNA damages in breast tissues. These effects may pose new challenges to evaluate the risks associated with radiation exposure and understanding radiation-induced side effects.

Head and Neck Cancers, Version 1.2015

These NCCN Guidelines Insights focus on recent updates to the 2015 NCCN Guidelines for Head and Neck (H&N) Cancers. These Insights describe the different types of particle therapy that may be used to treat H&N cancers, in contrast to traditional radiation therapy (RT) with photons (x-ray). Research is ongoing regarding the different types of particle therapy, including protons and carbon ions, with the goals of reducing the long-term side effects from RT and improving the therapeutic index. For the 2015 update, the NCCN H&N Cancers Panel agreed to delete recommendations for neutron therapy for salivary gland cancers, because of its limited availability, which has decreased over the past 2 decades; the small number of patients in the United States who currently receive this treatment; and concerns that the toxicity of neutron therapy may offset potential disease control advantages.

Targeting head and neck cancer stem cells to overcome resistance to photon and carbon ion radiation

Although promising new radiation therapy techniques such as hadrontherapy are currently being evaluated in the treatment of head and neck malignancies, local control of head and neck squamous cell carcinoma (HNSCC) remains low. Here, we investigated the involvement of cancer stem-like cells (CSCs) in a radioresistant HNSCC cell line (SQ20B). Stem-like cells SQ20B/SidePopulation(SP)/CD44(+)/ALDH(high) were more resistant to both photon and carbon ion irradiation compared with non-CSCs. This was confirmed by a BrdU labeling experiment, which suggests that CSCs were able to proliferate and to induce tumorigenicity after irradiation. SQ20B/SP/CD44(+)/ALDH(high) were capable of an extended G2/M arrest phase in response to photon or carbon ion irradiation compared with non-CSCs. Moreover, our data strongly suggest that resistance of CSCs may result from an imbalance between exacerbated self-renewal and proliferative capacities and the decrease in apoptotic cell death triggering. In order to modulate these processes, two targeted pharmacological strategies were tested. Firstly, UCN-01, a checkpoint kinase (Chk1) inhibitor, induced the relapse of G2/M arrest and radiosensitization of SQ20B-CSCs. Secondly, all-trans retinoic acid (ATRA) resulted in an inhibition of ALDH activity, and induction of the differentiation and radiosensitization of SQ20B/SP/CD44(+)/ALDH(high) cells. The combination of ATRA and UCN-01 treatments with irradiation drastically decreased the surviving fraction at 2Gy of SQ20B-CSCs from 0.85 to 0.38 after photon irradiation, and from 0.45 to 0.21 in response to carbon ions. Taken together, our results suggest that the combination of UCN-01 and ATRA represent a promising pharmacological-targeted strategy that significantly sensitizes CSCs to photon or carbon ion radiation.

ICRP Publication 127: Radiological Protection in Ion Beam Radiotherapy

The goal of external-beam radiotherapy is to provide precise dose localisation in the treatment volume of the target with minimal damage to the surrounding normal tissue. Ion beams, such as protons and carbon ions, provide excellent dose distributions due primarily to their finite range, allowing a significant reduction of undesired exposure of normal tissue. Careful treatment planning is required for the given type and localisation of the tumour to be treated in order to maximise treatment efficiency and minimise the dose to normal tissue. Radiation exposure in out-of-field volumes arises from secondary neutrons and photons, particle fragments, and photons from activated materials. These unavoidable doses should be considered from the standpoint of radiological protection of the patient. Radiological protection of medical staff at ion beam radiotherapy facilities requires special attention. Appropriate management and control are required for the therapeutic equipment and the air in the treatment room that can be activated by the particle beam and its secondaries. Radiological protection and safety management should always conform with regulatory requirements. The current regulations for occupational exposures in photon radiotherapy are applicable to ion beam radiotherapy with protons or carbon ions. However, ion beam radiotherapy requires a more complex treatment system than conventional radiotherapy, and appropriate training of staff and suitable quality assurance programmes are recommended to avoid possible accidental exposure of patients, to minimise unnecessary doses to normal tissue, and to minimise radiation exposure of staff.

IMRT with Stereotactic Body Radiotherapy Boost for High Risk Malignant Salivary Gland Malignancies: A Case Series

Patients with high risk salivary gland malignancies are at increased risk of local failure. We present our institutional experience with dose escalation using hypofractionated stereotactic body radiotherapy (SBRT) in a subset of this rare disease. Over the course of 9 years, 10 patients presenting with skull base invasion, gross disease with one or more adverse features, or those treated with adjuvant radiation with three or more pathologic features were treated with intensity-modulated radiation therapy followed by hypofractionated SBRT boost. Patients presented with variable tumor histologies, and in all but one, the tumors were classified as poorly differentiated high grade. Four patients had gross disease, three had gross residual disease, three had skull base invasion, and two patients had rapidly recurrent disease (≤6 months) that had been previously treated with surgical resection. The median stereotactic radiosurgery boost dose was 17.5 Gy (range 10–30 Gy) given in a median of five fractions (range 3–6 fractions) for a total median cumulative dose of 81.2 Gy (range 73.2–95.6 Gy). The majority of the patients received platinum based concurrent chemotherapy with their radiation. At a median follow-up of 32 months (range 12–120) for all patients and 43 months for surviving patients (range 12–120), actuarial 3-year locoregional control, distant control, progression-free survival, and overall survival were 88, 81, 68, and 79%, respectively. Only one patient failed locally and two failed distantly. Serious late toxicity included graft ulceration in one patient and osteoradionecrosis in another patient, both of which underwent surgical reconstruction. Six patients developed fibrosis. In a subset of patients with salivary gland malignancies with skull base invasion, gross disease, or those treated adjuvantly with three or more adverse pathologic features, hypofractionated SBRT boost to intensity-modulated radiotherapy yields good local control rates and acceptable toxicity.

Effects of the dose-volume relationship on and risk factors for maxillary osteoradionecrosis after carbon ion radiotherapy

Background

Osteoradionecrosis (ORN) is a critical complication after carbon ion (C-ion) or photon radiotherapy (RT) for head and neck tumors. However, the risk factors for ORN after C-ion RT remain unclear. Therefore, the present study aimed to investigate the effects of the dose-volume relationship on and risk factors for ORN development after C-ion RT. We, however, focused on the maxillary bone because most tumors treated with C-ion RT were primarily located in the sinonasal cavity.

Methods

The patients enrolled in this study received more than 10% of the prescribed total dose of 57.6 Gy equivalent (GyE) in 16 fractions to their maxilla. All patients were followed up for more than 2 years after C-ion RT. Those with tumor invasion to the maxilla before C-ion RT or local recurrence after the treatment were excluded from the study to accurately evaluate the effects of irradiation on the bone. Sixty-three patients were finally selected. The severity of ORN was assessed according to the Common Terminology Criteria for Adverse Events version 4.0. The correlation between clinical and dosimetric parameters and ORN incidence was retrospectively analyzed.

Results

The median follow-up period was 79 months. Of the 63 enrolled patients, 26 developed ORN of grade ≥1. Multivariate analysis revealed that the maxilla volume receiving more than 50 GyE (V50) and the presence of teeth within the planning target volume were significant risk factors for ORN. Dose-volume histogram analysis revealed that V10 to V50 parameters were significantly higher in patients with ORN than in those without ORN.

Conclusions

V50 and the presence of teeth within the planning target volume were independent risk factors for the development of ORN after C-ion RT using a 16-fraction protocol.

Particle radiotherapy using protons or carbon ions for unresectable locally advanced head and neck cancers with skull base invasion

OBJECTIVE

To study the oncological outcome of the patients with unresectable locally advanced primary head and neck cancers invading the skull base, treated with particle radiotherapy.

METHODS

Fifty-seven patients with unresectable primary head and neck cancers invading the skull base received proton or carbon ion radiotherapy as definitive treatment at Hyogo Ion Beam Medical Center between 2003 and 2009. Forty-seven patients were treated with proton radiotherapy and 10 patients were treated with carbon ion radiotherapy. A retrospective review was performed with clinical charts and recorded imagings.

RESULTS

With a median follow-up of 32 months, the 3-year actual survival and local progression-free rates of all the patients were 61 and 56%, respectively. The 3-year actual survival rates of adenoid cystic carcinoma, squamous cell carcinoma, olfactory neuroblastoma, adenocarcinoma and malignant melanoma were 83, 44, 75, 0 and 38%, respectively. The 3-year actual local control rates of adenoid cystic carcinoma, squamous cell carcinoma, olfactory neuroblastoma, adenocarcinoma and malignant melanoma were 63, 31, 83, 50 and 0%, respectively. Distant metastasis was observed in 13 of 25 patients in adenoid cystic carcinoma, two of 14 patients in squamous cell carcinoma, one of six patients with olfactory neuroblastoma, two of four patients with adenocarcinoma, three of four patients with malignant melanoma and two of three patients with undifferentiated carcinoma. Mucositis and dermatitis were seen as acute toxicities. The most common late toxicity was visual disorder. Grades 2, 3 and 4 visual disorders were observed in seven, five and two patients, respectively.

CONCLUSIONS

Proton and carbon ion radiotherapy resulted in satisfactory local control in patients with locally advanced unresectable primary head and neck cancers invading the skull base.