Experimental evidence that carbon-ion radiotherapy utilizes cytotoxic T lymphocyte-mediated anti-tumor immunity for shrinking tumors compared to X-ray therapy

The therapeutic efficacy of radiotherapy (RT) is primarily driven by two factors: biophysical DNA damage in cancer cells and radiation-induced anti-tumor immunity. However, Anti-tumor immune responses between X-ray RT (XRT) and carbon-ion RT (CIRT) remain unclear. In this study, we, employed mouse models to assess the immunological contribution, especially cytotoxic T-lymphocyte (CTL)-mediated immunity, to the therapeutic effectiveness of XRT and CIRT in shrinking tumors. We irradiated mouse intradermal tumors of B16F10-ovalbumin (OVA) mouse melanoma cells and 3LL-OVA mouse lung cancer cells with carbon-ion beams or X-rays in the presence or absence of CTLs. CTL removal was performed by administration of anti-CD8 monoclonal antibody (mAb) in mice. Based on tumor growth delay, we determined the tumor growth and regression curves. The enhancement ratio (ER) of the slope of regression lines in the presence of CTLs, relative to the absence of CTLs, indicates the dependency of RT on CTLs for shrinking mouse tumors, and the biological effectiveness (RBE) of CIRT relative to XRT were calculated. Tumor growth curves revealed that the elimination of CD8+ CTLs by administrating anti-CD8 mAb accelerated tumor growth compared to the presence of CTLs in both RTs. The ERs were larger in CIRT compared to XRT in the B16F10-OVA tumor models, but not in the 3LL-OVA models, suggesting a greater contribution of CTL-mediated anti-tumor immunity to tumor reduction in CIRT compared to XRT in the B16F10-OVA tumor model. In addition, the RBE values for both models were larger in the presence of CTLs compared to models without CTLs, suggesting that CIRT may utilize CTL-mediated anti-tumor immunity more than X-ray. The findings from this study suggest that although immunological contribution to therapeutic efficacy may vary depending on the type of tumor cell, CIRT utilizes CTL-mediated immunity to a greater extent compared to XRT.

Inter-fractional error and intra-fractional motion of prostate and dosimetry comparisons of patient position registrations with versus without fiducial markers during treatment with carbon-ion radiotherapy

A few reports have discussed the influence of inter-fractional position error and intra-fractional motion on dose distribution, particularly regarding a spread-out Bragg peak. We investigated inter-fractional and intra-fractional prostate position error by monitoring fiducial marker positions. In 2020, data from 15 patients with prostate cancer who received carbon-ion beam radiotherapy (CIRT) with gold markers were investigated. We checked marker positions before and during irradiation to calculate the inter-fractional positioning and intra-fractional movement and evaluated the CIRT dose distribution by adjusting the planning beam isocenter and clinical target volume (CTV) position. We compared the CTV dose coverages (CTV receiving 95% [V95%] or 98% [V98%] of the prescribed dose) between skeletal and fiducial matching irradiation on the treatment planning system. For inter-fractional error, the mean distance between the marker position in the planning images and that in a patient starting irradiation with skeletal matching was 1.49 ± 1.11 mm (95th percentile = 1.85 mm). The 95th percentile (maximum) values of the intra-fractional movement were 0.79 mm (2.31 mm), 1.17 mm (2.48 mm), 1.88 mm (4.01 mm), 1.23 mm (3.00 mm), and 2.09 mm (8.46 mm) along the lateral, inferior, superior, dorsal, and ventral axes, respectively. The mean V95% and V98% were 98.2% and 96.2% for the skeletal matching plan and 99.5% and 96.8% for the fiducial matching plan, respectively. Fiducial matching irradiation improved the CTV dose coverage compared with skeletal matching irradiation for CIRT for prostate cancer.

Dose-averaged LET optimized carbon-ion radiotherapy for head and neck cancers

This feasibility study confirmed the initial safety and efficacy of a novel carbon-ion radiotherapy (CIRT) using linear energy transfer (LET) painting for head and neck cancer. This study is the first step toward establishing CIRT with LET painting in clinical practice and making it a standard practice in the future.

Prognostic analysis of radiation-induced liver damage following carbon-ion radiotherapy for hepatocellular carcinoma

BACKGROUND

Radiation-induced liver damage (RILD) occasionally occurs following carbon-ion radiotherapy (CIRT) for liver tumors, such as hepatocellular carcinoma (HCC), in patients with impaired liver function disease. However, the associated risk factors remain unknown. The present study aimed to determine the risk factors of RILD after CIRT.

METHODS

We retrospectively analyzed 108 patients with HCC treated with CIRT at the Osaka Heavy Ion Therapy Center between December 2018 and December 2022. RILD was defined as a worsening of two or more points in the Child-Pugh score within 12 months following CIRT. The median age of the patients was 76 years (range 47-95 years), and the median tumor diameter was 41 mm (range 5-160 mm). Based on the pretreatment liver function, 98 and 10 patients were categorized as Child-Pugh class A and B, respectively. We analyzed patients who received a radiation dose of 60 Gy (relative biological effectiveness [RBE]) in four fractions. The median follow-up period was 9.7 months (range 2.3-41.1 months), and RILD was observed in 11 patients (10.1%).

RESULTS

Multivariate analysis showed that pretreatment Child-Pugh score B (p = 0.003, hazard ratio [HR] = 6.90) and normal liver volume spared from < 30 Gy RBE (VS30 < 739 cm3) (p = 0.009, HR = 5.22) were significant risk factors for RILD. The one-year cumulative incidences of RILD stratified by Child-Pugh class A or B and VS30 < 739 cm3 or ≥ 739 cm3 were 10.3% or 51.8% and 39.6% or 9.2%, respectively.

CONCLUSION

In conclusion, the pretreatment Child-Pugh score and VS30 of the liver are significant risk factors for RILD following CIRT for HCC.

Efficacy and toxicity of photon, proton, and carbon ion radiotherapy in the treatment of intracranial solitary fibrous tumor/hemangiopericytoma

BACKGROUND

Solitary fibrous tumors (SFT) of the central nervous system are rare and treatment options are not well established. The aim of this study was to evaluate the clinical outcomes of radiotherapy (RT) and re-radiotherapy (re-RT) for de novo intracranial SFT and recurrent intracranial SFT.

METHODS

This retrospective study analyzed efficacy and toxicity of different RT modalities in patients who received radiotherapy (RT) for intracranial SFT at Heidelberg University Hospital between 2000 and 2020 following initial surgery after de novo diagnosis ("primary group"). We further analyzed the patients of this cohort who suffered from tumor recurrence and received re-RT at our institution ("re-irradiation (re-RT) group"). Median follow-up period was 54.0 months (0-282) in the primary group and 20.5 months (0-72) in the re-RT group. RT modalities included 3D-conformal RT (3D-CRT), intensity-modulated RT (IMRT), stereotactic radiosurgery (SRS), proton RT, and carbon-ion RT (C12-RT). Response rates were analyzed according to RECIST 1.1 criteria.

RESULTS

While the primary group consisted of 34 patients (f: 16; m:18), the re-RT group included 12 patients (f: 9; m: 3). Overall response rate (ORR) for the primary group was 38.3% (N = 11), with 32.4% (N = 11) complete remissions (CR) and 5.9% (N = 2) partial remissions (PR). Stable disease (SD) was confirmed in 5.9% (N = 2), while 41.2% (N = 14) experienced progressive disease (PD). 14% (N = 5) were lost to follow up. The re-RT group had 25.0% CR and 17.0% PR with 58.0% PD. The 1-, 3-, and 5-year progression-free survival rates were 100%, 96%, and 86%, respectively, in the primary group, and 81%, 14%, and 14%, respectively, in the re-RT group. Particle irradiation (N = 11) was associated with a lower likelihood of developing a recurrence in the primary setting than photon therapy (N = 18) (OR = 0.038; p = 0.002), as well as doses ≥ 60.0 Gy (N = 15) versus < 60.0 Gy (N = 14) (OR = 0.145; p = 0.027). Risk for tumor recurrence was higher for women than for men (OR = 8.07; p = 0.014) with men having a median PFS of 136.3 months, compared to women with 66.2 months.

CONCLUSION

The data suggests RT as an effective treatment option for intracranial SFT, with high LPFS and PFS rates. Radiation doses ≥ 60 Gy could be associated with lower tumor recurrence. Particle therapy may be associated with a lower risk of recurrence in the primary setting, likely due to the feasibility of higher RT-dose application.

Five-Year Survival Outcomes After Carbon-Ion Radiotherapy for Operable Stage I NSCLC: A Japanese National Registry Study (J-CROS-LUNG)

INTRODUCTION

The standard therapy for stage I NSCLC is surgery, but some operable patients refuse this option and instead undergo radiotherapy. Carbon-ion radiotherapy (CIRT) is a type of radiotherapy. The Japanese prospective nationwide registry study on CIRT began in 2016. Here, we analyzed real-world clinical outcomes of CIRT for operable patients with stage I NSCLC.

METHODS

All patients with operable stage I NSCLC treated with CIRT in Japan between 2016 and 2018 were enrolled. The dose fractionations for CIRT were selected from several options approved by the Japanese Society for Radiation Oncology. CIRT was delivered to the primary tumor, not to lymph nodes.

RESULTS

The median follow-up period was 56 months. Among 136 patients, 117 (86%) had clinical stage IA NSCLC and 19 (14%) had clinical stage IB NSCLC. There were 50 patients (37%) diagnosed clinically without having been diagnosed histologically. Most tumors (97%) were located in the periphery. The 5-year overall survival, cause-specific survival, progression-free survival, and local control rate were 81.8% (95% confidence interval [CI]: 75.1-89.2), 91.2% (95% CI: 86.0-96.8), 65.9% (95% CI: 58.2-74.6), and 95.8% (95% CI: 92.3-99.5), respectively. Multivariate analysis identified age as a significant factor for overall survival (p = 0.018), whereas age and consolidation/tumor ratio (p = 0.010 and p = 0.004) were significant factors for progression-free survival. There was no grade 4 or higher toxicity. Grade 3 radiation pneumonitis occurred in one patient.

CONCLUSIONS

This study reports the long-term outcomes of CIRT for operable NSCLC in the real world. CIRT for operable patients has been found to have favorable outcomes, with tolerable toxicity.

Nanodosimetric quantity-weighted dose optimization for carbon-ion treatment planning

Dose verification of treatment plans is an essential step in radiotherapy workflows. In this work, we propose a novel method of treatment planning based on nanodosimetric quantity-weighted dose (NQWD), which could realize biological representation using pure physical quantities for biological-oriented carbon ion-beam treatment plans and their direct verification. The relationship between nanodosimetric quantities and relative biological effectiveness (RBE) was studied with the linear least-squares method for carbon-ion radiation fields. Next, under the framework of the matRad treatment planning platform, NQWD was optimized using the existing RBE-weighted dose (RWD) optimization algorithm. The schemes of NQWD-based treatment planning were compared with the RWD treatment plans in term of the microdosimetric kinetic model (MKM). The results showed that the nanodosimetric quantity F3 - 10 had a good correlation with the radiobiological effect reflected by the relationship between RBE and F3 - 10. Moreover, the NQWD-based treatment plans reproduced the RWD plans generally. Therefore, F3 - 10 could be adopted as a radiation quality descriptor for carbon-ion treatment planning. The novel method proposed herein not only might be helpful for rapid physical verification of biological-oriented ion-beam treatment plans with the development of experimental nanodosimetry, but also makes the direct comparison of ion-beam treatment plans in different institutions possible. Thus, our proposed method might be potentially developed to be a new strategy for carbon-ion treatment planning and improve patient safety for carbon-ion radiotherapy.

Conversion surgery for initially unresectable locally advanced pancreatic ductal adenocarcinoma after chemotherapy followed by carbon-ion radiotherapy: a case report

BACKGROUND

Recent advances in chemotherapy and chemoradiotherapy have enabled conversion surgery (CS) to be performed for selected patients with initially unresectable locally advanced (LA) pancreatic ductal adenocarcinoma (PDAC). Many studies indicate CS might extend the survival of patients with initially unresectable LA PDAC. However, several clinical questions concerning CS remain, such as the optimal preoperative treatment. Carbon-ion radiotherapy (CIRT) is a unique radiotherapy that offers higher biological effectiveness than conventional radiotherapy. Here, we report a long-term survival case with initially unresectable LA PDAC who underwent CS after chemotherapy followed by CIRT.

CASE PRESENTATION

The patient was a 72-year-old Japanese woman with unresectable LA pancreatic head cancer with tumor contact to the superior mesenteric artery (SMA). She underwent four courses of chemotherapy (gemcitabine plus nanoparticle albumin-bound paclitaxel). However, the lesion did not shrink and tumor contact with the SMA did not improve after chemotherapy. Because the probability of achieving curative resection was judged to be low, she underwent radical dose CIRT, and chemotherapy was continued. She complained of vomiting 2 months after CIRT. Although imaging studies showed no tumor growth or metastasis, a duodenal obstruction which was speculated to be an adverse effect of CIRT was observed. She could not eat solid food and a trans-nasal feeding tube was inserted. Therapeutic intervention was required to enable enteral nutrition. We proposed several treatment options. She chose resection with the expectation of an anti-tumor effect of chemotherapy and CIRT rather than course observation with tube feeding or bypass surgery. Therefore, subtotal-stomach-preserving pancreatoduodenectomy with portal vein resection was performed as CS. Pathological examination of the resected specimen revealed an R0 resection with a histological response of Evans grade IIA. Postoperatively, she recovered uneventfully. Adjuvant chemotherapy with tegafur/gimeracil/oteracil (S1) was administrated. At the time of this report, 5 years have passed since the initial consultation and she has experienced no tumor recurrence.

CONCLUSIONS

The present case suggests that multidisciplinary treatment consisting of a combination of recent chemotherapy and CIRT may be beneficial for unresectable LA PDAC. However, further studies are required to assess the true efficacy of this treatment strategy.

Five-year outcomes in carbon-ion radiotherapy for postoperative pelvic recurrence of rectal cancer: A prospective clinical trial (GUNMA 0801)

Introduction

Carbon-ion radiotherapy (C-ion RT) is associated with favorable clinical outcomes for the pelvic recurrence of rectal cancer. However, few long-term follow-up studies after C-ion RT have been conducted. Hence, we performed an updated analysis of a prospective clinical trial of C-ion RT for the postoperative pelvic recurrence of rectal cancer.

Materials and methods

The study included 28 patients. Inclusion criteria were patients with confirmed pelvic recurrence of rectal cancer without distant metastasis; those who underwent curative resection of their primary disease and regional lymph nodes without gross or microscopic residual disease; and those who had radiographically measurable tumors. The total dose of C-ion RT for all the patients was 73.6 Gy (relative biological effectiveness) administered in 16 fractions.

Results

The median follow-up duration in all patients and those who survived were 51.2 and 69.2 months, respectively. The follow-up rate at the time of analysis was 96.4%. The 5-year overall survival and local control rates were 50% and 83%, respectively. Four patients had local recurrence, and 17 died of rectal cancer. Regarding late toxicities, two patients developed grade 3 pelvic infection, and nine developed grade 2 peripheral neuropathy.

Conclusion

Our updated analysis of a prospective clinical trial of C-ion RT for postoperative pelvic recurrence of rectal cancer confirmed its long-term efficacy and safety. These results suggest that C-ion RT may be a safe and effective treatment option for the postoperative pelvic recurrence of rectal cancer.

Creation, evolution, and future challenges of ion beam therapy from a medical physicist's viewpoint (Part 3): Chapter 3. Clinical research, Chapter 4. Future challenges, Chapter 5. Discussion, and Conclusion

Clinical studies of ion beam therapy have been performed at the Lawrence Berkeley Laboratory (LBL), National Institute of Radiological Sciences (NIRS), Gesellschaft für Schwerionenforschung (GSI), and Deutsches Krebsforschungszentrum (DKFZ), in addition to the development of equipment, biophysical models, and treatment planning systems. Although cancers, including brain tumors and pancreatic cancer, have been treated with the Bevalac's neon-ion beam at the LBL (where the first clinical research was conducted), insufficient results were obtained owing to the limited availability of neon-ion beams and immaturity of related technologies. However, the 184-Inch Cyclotron's helium-ion beam yielded promising results for chordomas and chondrosarcomas at the base of the skull. Using carbon-ion beams, NIRS has conducted clinical trials for the treatment of common cancers for which radiotherapy is indicated. Because better results than X-ray therapy results have been obtained for lung, liver, pancreas, and prostate cancers, as well as pelvic recurrences of rectal cancer, the Japanese government recently approved the use of public medical insurance for carbon-ion radiotherapy, except for lung cancer. GSI obtained better results than LBL for bone and soft tissue tumors, owing to dose enhancement enabled by scanning irradiation. In addition, DKFZ compared treatment results of proton and carbon-ion radiotherapy for these tumors. This article summarizes a series of articles (Parts 1-3) and describes future issues of immune ion beam therapy and linear energy transfer optimization.

Particle beam radiotherapy in the treatment of WHO grade 2 and 3 meningiomas: an early experience from Shanghai Proton and Heavy Ion Center

PURPOSE

To investigate the efficacy and safety of particle beam radiotherapy (PBRT) in the management of patients with WHO grade 2 and 3 meningiomas.

METHODS

Thirty-six consecutive and non-selected patients with WHO grade 2 (n = 28) and grade 3 (n = 8) meningiomas were treated at the Shanghai Proton and Heavy Ion Center, from May 2015 to March 2022. The median age of the cohort at PBRT was 48 years. There were 25 and 11 patients treated with PBRT in the setting of newly diagnosed diseases and progressive/recurrent diseases, respectively. PBRT was utilized as re-irradiation in 5 patients. Proton radiotherapy (PRT) and carbon-ion radiotherapy (CIRT), with a median dose of 60 Gy-Equivalent (GyE), were provided to 30 and 6 patients, respectively.

RESULTS

With a median follow-up of 23.3 months, the local control rates were 92.0%, 82.0%, and 82.0% at 1, 2, and 3 years for the entire cohort, respectively. Patients with WHO grade 2 meningiomas (100%, 94.1%, 94,1% at 1,2,3 years) had a much better local control than those with WHO grade 3 meningiomas (50%, 25%, 25% at 1,2,3 years; P < 0.001). Three patients, all with WHO grade 3 meningiomas, had deceased at the time of this analysis. Multivariate analyses revealed that WHO grade (grade 2 vs. 3) (p = 0.016) was a significant prognosticator for local control. No severe toxicities (G3 or above) were observed.

CONCLUSIONS

Treatment-induced efficacy and toxicities to PBRT in WHO grade 2 and 3 meningiomas were both highly acceptable. Longer follow-up is needed to evaluate the long-term outcome in terms of disease control, survival, as well as potential late effects.

Dose Distribution Degradation of Carbon-ion Radiotherapy Caused by Tumor Cell-specific Relative Biological Effectiveness of Osteosarcoma: A Simulation Study Using In Vitro Experimental Results

BACKGROUND/AIM

Dose distributions of carbon-ion radiotherapy (C-ion RT) have been created with the relative biological effectiveness (RBE) of human salivary gland cells (HSG). However, no dose distributions have been created using various tumor cell-specific RBE values. Hence, we conducted in vitro experiments to determine the RBE of human osteosarcoma cells (U2OS) and used this RBE value (RBEU2OS) to calculate the dose distribution for C-ion RT.

MATERIALS AND METHODS

To obtain RBE values for various linear energy transfer (LET) levels, we exposed U2OS cells to different doses of X-rays and varying doses and LET levels of C-ion beams (13, 30, 50, and 70 keV/μm). Subsequently, we converted the RBE of HSG (RBEHSG) to RBEU2OS in the treatment planning system and reconstructed the dose distribution for a typical osteosarcoma case. We performed a dose-volume histogram (DVH) analysis, evaluating the percentage of the minimum dose that covered 98%, 50%, and 2% (D98%, D50%, and D2%, respectively), as well as the homogeneity index [HI; calculated as (D2%-D98%)/D50%].

RESULTS

The RBEU2OS values for C-ion beams with LET of 13, 30, 50, and 70 keV/μm were 1.77, 2.25, 2.72, and 4.50, respectively. When comparing DVH parameters with the planning target volume, we observed the following values: D98%, D50%, D2%, and HI for RBEHSG were 64.1, 70.1, 72.4 Gy (RBE), and 0.12, respectively. For RBEU2OS, these values were 86.2, 95.0, 107.9 Gy (RBE), and 0.23, respectively.

CONCLUSION

We utilized RBEU2OS to calculate the dose distribution of carbon ion radiotherapy, revealing potential degradation in dose distribution and particularly worsening of the HI.

Particle radiotherapy in the era of radioimmunotherapy

Radiotherapy (RT) is one of the key modalities for cancer treatment, and more than 70% of tumor patients will receive RT during the course of their disease. Particle radiotherapy, such as proton radiotherapy, carbon-ion radiotherapy (CIRT) and boron neutron capture therapy (BNCT), is currently available for the treatment of patients Immunotherapy combined with photon RT has been successfully used in the clinic. The effect of immunotherapy combined with particle RT is an area of interest. However, the molecular mechanisms underlying the effects of combined immunotherapy and particle RT remain largely unknown. In this review, we summarize the properties of different types of particle RT and the mechanisms underlying their radiobiological effects. Additionally, we compared the main molecular players in photon RT and particle RT and the mechanisms involved the RT-mediated immune response.

Safety of Carbon-ion Radiotherapy for Prostate Cancer After Rectal Cancer Surgery

BACKGROUND/AIM

The safety of carbon-ion radiotherapy (CIRT) for patients with prostate cancer after rectal cancer surgery remains unknown. This is a retrospective analysis of the safety of CIRT in patients with prostate cancer after rectal cancer surgery.

PATIENTS AND METHODS

The subjects were 13 consecutive patients with prostate cancer who underwent CIRT after rectal cancer surgery at the Kanagawa Cancer Center from December 2015 to April 2022. A total dose of 51.6 Gy (relative biological effectiveness) was administered in 12 fractions over 3 weeks. The criteria stated in the Common Terminology Criteria for Adverse Events, version 5.0, were used to assess toxicity. Fisher's exact test was performed to assess the associations between patient clinical factors and rectal toxicity.

RESULTS

The median patient age was 71 years (range=66-83 years). The median observation period was 27.4 months (range=10.6-82.4 months). The median duration from rectal surgery to CIRT was 6.9 years (1.0-16.8 years). Five (38.5%) and six (46.2%) patients had a planning target volume (PTV)-adjacent rectal anastomosis and diabetes mellitus, respectively, and two (15.4%) patients had both. Grades 1 and 2 late gastrointestinal toxicities were observed in one case each. Development of gastrointestinal toxicity was significantly associated with both a PTV adjacent rectal anastomosis and diabetes mellitus (p=0.013).

CONCLUSION

Late gastrointestinal toxicity was tolerable in patients with prostate cancer treated with CIRT after rectal cancer surgery. Patients with both a PTV adjacent rectal anastomosis and diabetes mellitus were more likely to experience late gastrointestinal toxicity.

Carbon-ion Radiotherapy for Inoperable Solitary Fibrous Tumor of the Skull Base: A Case Report

BACKGROUND/AIM

The curative treatment for solitary fibrous tumors (SFTs) consists of surgery. However, surgery for SFTs in the skull base is difficult due to the anatomy and curative surgery may not be possible. Carbon-ion radiotherapy (C-ion RT) might be useful in the treatment of inoperable SFTs in the skull base because of its biological and physical nature. This study presents the clinical outcomes of C-ion RT for an inoperable SFT of the skull base.

CASE REPORT

A 68-year-old female patient experienced hoarseness, deafness on the right side, right facial nerve paralysis, and dysphagia. Magnetic resonance imaging revealed a tumor located in the right cerebello-pontine angle with destruction of the petrous bone, and immunohistochemical studies of the biopsy specimen showed a grade 2 SFT. Firstly, the patient underwent tumor embolization and surgery. However, 5 months after surgery, magnetic resonance imaging revealed regrowth of residual tumor. Subsequently, the patient was referred to our hospital for C-ion RT because curative surgery was unsuitable. The patient received 64 Gy (relative biological effectiveness) of C-ion RT in 16 fractions. Two years after C-ion RT, the tumor showed a partial response. The patient was still alive at the last follow-up without evidence of local recurrence, distant metastasis, or late toxicities.

CONCLUSION

These findings suggest that C-ion RT is a suitable treatment option for inoperable SFTs of the skull base.

Estimation of post-therapeutic liver reserve capacity using 99mTc-GSA scintigraphy prior to carbon-ion radiotherapy for liver tumors

BACKGROUND

There is currently no established imaging method for assessing liver reserve capacity prior to carbon-ion radiotherapy (CIRT) for liver tumors. In order to perform safe CIRT, it is essential to estimate the post-therapeutic residual reserve capacity of the liver.

PURPOSE

To evaluate the ability of pre-treatment 99mTc-galactosyl human serum albumin (99mTc-GSA) scintigraphy to accurately estimate the residual liver reserve capacity in patients treated with CIRT for liver tumors.

MATERIALS AND METHODS

This retrospective study evaluated patients who were performed CIRT for liver tumors between December 2018 and September 2020 and underwent 99mTc-GSA scintigraphy before and 3 months after CIRT, and gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI within 1 month before CIRT were evaluated. The maximal removal rate of 99mTc-GSA (GSA-Rmax) was analyzed for the evaluation of pre-treatment liver reserve capacity. Then, the GSA-Rmax of the estimated residual liver (GSA-RL) was calculated using liver SPECT images fused with the Gd-EOB-DTPA-enhanced MRI. GSA-RL before CIRT and GSA-Rmax at 3 months after CIRT were compared using non-parametric Wilcoxon signed-rank test and linear regression analysis.

RESULTS

Overall, 50 patients were included (mean age ± standard deviation, 73 years ± 11; range, 29-89 years, 35 men). The median GSA-RL was 0.393 [range, 0.057-0.729] mg/min, and the median GSA-Rmax after CIRT was 0.369 [range, 0.037-0.780] mg/min (P = .40). The linear regression equation representing the relationship between the GSA-RL and GSA-Rmax after CIRT was y = 0.05 + 0.84x (R2 = 0.67, P < .0001). There was a linear relationship between the estimated and actual post-treatment values for all patients, as well as in the group with impaired liver reserve capacity (y = - 0.02 + 1.09x (R2 = 0.62, P = .0005)).

CONCLUSIONS

99mTc-GSA scintigraphy has potential clinical utility for estimating the residual liver reserve capacity in patients undergoing carbon-ion radiotherapy for liver tumors.

TRIAL REGISTRATION

UMIN000038328, https://center6.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000043545 .

Carbon-Ion Radiotherapy Using Metal Artifact Reduction Computed Tomography in a Patient with Prostate Cancer with Bilateral Hip Prostheses: A Case Report

Carbon-ion radiotherapy (CIRT) for prostate cancer is both safe and efficacious; beam range calculations use relative stopping power ratio, which is derived from computed tomography (CT) values. However, hip prostheses are made of high atomic number materials and show severe artifacts on CT images. Therefore, it is not possible to accurately calculate dose distribution for CIRT in patients with prostate cancer with hip prostheses. Here, we describe the management of a 77-year-old man with prostate cancer who had previously undergone bilateral hip replacement. CIRT, in combination with androgen deprivation therapy, was recommended as definitive treatment for prostate cancer. Planning CT, magnetic resonance (MRI), and CT images with metal artifact reduction (MAR) were acquired for CIRT planning. MRI and MAR images were superimposed on the planning CT to delineate target volume and organs at risk. The radiation treatment plan consisted of a total dose of 51.6 Gy (relative biological effect) to be delivered in 12 fractions over 3 weeks, and the patient was irradiated in the supine and prone positions with a vertical beam, on alternating days. CIRT was completed as scheduled. No adverse events were observed during treatment or at 3 months after treatment initiation. While we show that CIRT may be a treatment option for patients with prostate cancer with bilateral hip prostheses, further studies are needed to evaluate treatment efficacy and late toxicity and to determine how CIRT can be administered to patients with prostate cancer with bilateral hip prostheses.

Clinical Outcomes of Scanning Carbon-ion Radiotherapy for Soft Tissue Sarcoma of the Extremities

BACKGROUND/AIM

Carbon-ion radiotherapy (CIRT) has been reported to obtain favorable results in the treatment of bone and soft tissue malignancies; however, studies on CIRT for soft tissue sarcomas (STS) of the extremities are limited. Here, we have retrospectively evaluated the therapeutic efficacy and adverse events associated with scanning CIRT (sCIRT) for STS of the extremities at our institution.

PATIENTS AND METHODS

Thirteen consecutive patients with STS who underwent sCIRT between January 2017 and January 2020 were included in the study. The total dose of sCIRT was set at 67.2-70.4 Gy (RBE), which was provided in 16 fractions. Overall survival (OS), progression-free survival (PFS), and local control (LC) were estimated using the Kaplan-Meier method. Toxicity was evaluated using Common Terminology Criteria for Adverse Events v5.0.

RESULTS

The cohort consisted of 10 males and 3 females with a median age of 69 years (range=38-95 years). Median duration of observation was 31.8 months (range=7.4-56.4 months). Tumors were localized to the upper extremity in 2 cases and to the lower extremity in 11 cases. Median maximum tumor diameter was 11.7 cm (range=3.0-36.6 cm), while 3-year OS, PFS, and LC were 61.5%, 44.9%, and 79.1%, respectively. Acute toxicity of grade 3 or higher was not observed. Late toxicity included grade 3 peripheral nerve palsy and decreased range of motion in 1 and 1 patient each. Late toxicity of Grade 4 or higher was not observed.

CONCLUSION

sCIRT for STS of the extremities demonstrates favorable therapeutic results with acceptable toxicity.

Validation and testing of a novel pencil-beam model derived from Monte Carlo simulations in carbon-ion treatment planning for different scenarios

PURPOSE

The calculation ability of the newly-proposed accurate beam model, the double Gaussian-logistic (DG-L) model, was validated in both homogeneous and heterogeneous phantoms to provide helpful information for its future application in clinical carbon-ion treatment planning system (TPS).

METHODS

MatRad was used as the new algorithm test platform. Based on Monte Carlo (MC) method, the basic database in matRad was generated, then comparative dosimetric analyses between the single Gaussian (SG), double Gaussian (DG) and DG-L models against the MC recalculations were performed on the treatment plans of a cubic water phantom, a TG119 phantom and a liver patient scenario. Absolute dose differences, dose-volume histograms (DVHs) and global γ-index analyses derived from the treatment plans were evaluated.

RESULTS

Calculated with the DG-L model, the deviations of the target dose coverage (D₉₅) for the cubic water phantom, the TG119 phantom and the liver patient case against the MC recalculations could be reduced from -2.5%, -4.6% and -6.4% to -0.3%, -2.0% and -4.5% respectively compared to the SG model, while the γ pass rates (3%/3mm) could be enhanced from 98.0%, 90.6% and 90.1% to 99.8%, 95.7% and 91.6%, respectively. The novel beam model also shows improved performance compared with the DG model, without substantially increasing the computation time.

CONCLUSIONS

The DG-L model could effectively improve the dose calculation accuracy and mitigate the delivered dose deficiency in target volumes compared to the SG and DG models. The lateral heterogeneities should be considered for its future implementation in a clinical TPS.

Salvage thoracoscopic esophagectomy after carbon-ion radiotherapy in a patient with esophageal squamous cell carcinoma: a case report

Background

Carbon-ion radiotherapy (CIRT) for esophageal cancer has been receiving significant attention given its high local control rates and minimal damage to normal tissues. However, the efficacy and safety of salvage surgery after CIRT for esophageal cancer remain unclear. We report the case of a patient who underwent salvage thoracoscopic surgery after CIRT.

Case presentation

A 51-year-old woman underwent upper gastrointestinal endoscopy and a type 0-IIa + 0-IIc esophageal squamous cell carcinoma located 27–29 cm from the patient’s incisors, classified as clinical stage I (T1bN0M0), was detected. She received CIRT (50.4 Gy [relative biological effectiveness, RBE]/12 fr) for localized esophageal cancer and achieved complete remission after 4 months. Six years after CIRT, follow-up endoscopic examination demonstrated a type 0-IIa + 0-IIc tumor in the previously treated area. In addition, a type 0-IIa lesion located 20–22 cm from the incisors was found. We diagnosed localized ESCC, classified as clinical stage I (T1bN0M0). Salvage thoracoscopic surgery was performed in the prone position with five access ports. Although the esophagus tightly adhered to the thoracic descending aorta and left main bronchus with severe fibrosis, the esophagus could be separated from the surrounding organs with careful forceps manipulation. The operation time and blood loss were 8 h 45 min and 253 mL, respectively. The patient was discharged from our hospital 17 days after the salvage surgery without any complications. Pathological findings revealed two squamous cell carcinomas. Both tumors were localized in the lamina propria mucosa, and lymph node metastasis was not detected. The tumors were diagnosed as pathological stage IA (pT1aN0M0) according to the TNM criteria. Moreover, pathological examinations showed severe fibrosis of the previously irradiated tissues compared to the normal esophagus located outside of the irradiation field. Following the surgery, the patient had no recurrence for 1 year and 6 months.

Conclusions

Thoracoscopic radical esophagectomy can be performed as salvage surgery. Careful and discreet surgery is integral to perform salvage surgery after CIRT since CIRT may cause severe adhesions and fibrosis in the irradiated field.

Efficacy and Safety of 4 Fractions of Carbon-Ion Radiation Therapy for Hepatocellular Carcinoma: A Prospective Study

INTRODUCTION

Prospective evidence supporting the safety and efficacy of carbon-ion radiotherapy (C-ion RT) for hepatocellular carcinoma (HCC) remains lacking. This prospective study aimed to evaluate the safety and efficacy of hypofractionated C-ion RT in patients with HCC.

METHODS

The inclusion criteria were as follows: (1) pathologically or clinically diagnosed HCC; (2) measurable tumor and tumor size ≤10 cm; (3) absence of major vascular invasion; (4) no extrahepatic metastasis; (5) the alimentary tract was not adjacent to the target lesion (>1 cm); (6) not suitable for or refusal to undergo surgery or local ablative therapies; (7) an interval ≥4 weeks from previous therapy; (8) no other intrahepatic lesion or at least 2 years after the previous curative therapy; (9) performance status score, 0-2; and (10) Child-Pugh score, 5-9. The prescribed C-ion RT dose was 52.8 Gy (relative biological effectiveness [RBE]) or 60.0 Gy (RBE) in 4 fractions.

RESULTS

In total, 35 patients with HCC were enrolled between October 2010 and May 2016. The median follow-up durations in the survivor group (n = 23) and in the whole cohort were 55.1 and 49.0 months, respectively. The 2-, 3-, and 4-year overall survival rates were 82.8%, 76.7%, and 69.4%, respectively. The 2-, 3-, and 4-year local control (LC) rates were 92.6%, 76.5%, and 76.5%, respectively. The median time-to-progression was 25.6 months (95% confidence interval, 13.7-37.5 months). Grade 4 or 5 toxicities were not observed. Grade 3 acute and late toxicities were observed in 2 patients. There was no significant deterioration in serum albumin, bilirubin, prothrombin time-international normalized ratio, platelet count, or Child-Pugh score after C-ion RT.

CONCLUSION

Four fractions of C-ion RT for HCC did not yield serious adverse events and showed promising LC, thus making it a safe and effective modality for this type of malignancy.

Visualisation of Range Shortening in Carbon Ion Beams and Washout of Positron Emitter: First-in-Human Report

BACKGROUND/AIM

Auto-activation positron emission tomography (AAPET) is one of the most promising methods to verify beam range in carbon ion radiotherapy (C-ion RT). We aimed to confirm this for the first time in a clinical setting by performing AAPET in a patient with pancreatic cancer previously receiving coil embolisation of hepatic artery pseudoaneurysm.

MATERIALS AND METHODS

A 70-year-old pancreatic head cancer patient was treated with C-ion RT on a clinical dose of 4.6 Gy (RBE), followed by AAPET, to verify beam ranges in C-ion RT.

RESULTS

Positron emission tomography (PET) revealed low positron emitter concentrations at the distal side of the internal metals and in the aorta compared to the dose distribution of the treatment plan, indicating range shortening by internal metals in C-ion beams and positron emitter transportation by biofluids.

CONCLUSION

AAPET may detect range shortening by internal metals in the trajectory and washout of intravascular positron emitter compared to plan dose distribution.

Who Will Benefit from Charged-Particle Therapy?

Charged-particle therapy (CPT) such as proton beam therapy (PBT) and carbon-ion radiotherapy (CIRT) exhibit substantial physical and biological advantages compared to conventional photon radiotherapy. As it can reduce the amount of radiation irradiated in the normal organ, CPT has been mainly applied to pediatric cancer and radioresistent tumors in the eloquent area. Although there is a possibility of greater benefits, high set-up cost and dearth of high level of clinical evidence hinder wide applications of CPT. This review aims to present recent clinical results of PBT and CIRT in selected diseases focusing on possible indications of CPT. We also discussed how clinical studies are conducted to increase the number of patients who can benefit from CPT despite its high cost.

Technological Advances in Charged-Particle Therapy

Charted-particle therapy (CPT) benefits cancer patients by localizing doses in the tumor volume while minimizing the doses delivered to normal tissue through its unique physical and biological characteristics. The world's first CPT applied on humans was proton beam therapy (PBT), which was performed in the mid-1950s. Among heavy ions, carbon ions showed the most favorable biological characteristics for the treatment of cancer patients. Carbon ions show coincidence between the Bragg peak and maximum value of relative biological effectiveness. In addition, they show low oxygen enhancement ratios. Therefore, carbon-ion radiotherapy (CIRT) has become mainstream in the treatment of cancer patients using heavy ions. CIRT was first performed in 1977 at the Lawrence Berkeley Laboratory. The CPT technology has advanced in the intervening decades, enabling the use of rotating gantry, beam delivery with fast pencil-beam scanning, image-guided particle therapy, and intensity-modulated particle therapy. As a result, as of 2019, a total of 222,425 and 34,138 patients with cancer had been treated globally with PBT and CIRT, respectively. For more effective and efficient CPT, many groups are currently conducting further studies worldwide. This review summarizes recent technological advances that facilitate clinical use of CPT.

Multicenter Study of Carbon-ion Radiotherapy for Oropharyngeal Non-squamous Cell Carcinoma

BACKGROUND/AIM

To evaluate treatment outcomes of carbon-ion radiotherapy for oropharyngeal non-squamous cell carcinoma at four carbon-ion facilities in Japan.

PATIENTS AND METHODS

We retrospectively analyzed the cases of 33 patients with oropharyngeal non-squamous cell carcinoma who were treated with carbon-ion radiotherapy between November 2003 and December 2014.

RESULTS

The histology included adenoid cystic carcinoma (n=25) and mucosal malignant melanoma (n=4). No patients had T1 tumors; 23 had T4 tumors. The most-commonly prescribed dose was 57.6 Gy (RBE) in 16 fractions. The median follow-up period was 34.8 months (range=4.2-122.8 months). The 3-year local control and overall survival rates were 94.7% and 90.7%, respectively. There were no grade ≥4 acute adverse events. Only one patient experienced a grade ≥4 late adverse event. No patients experienced late adverse events related to swallowing or salivary function.

CONCLUSION

Carbon-ion radiotherapy appears to be a promising treatment option for oropharyngeal non-squamous cell carcinoma.

Adaptive planning based on single beam optimization in passive scattering carbon ion radiotherapy for patients with pancreatic cancer

Background

Daily anatomical deviations may distort the dose distribution in carbon ion radiotherapy (CIRT), which may cause treatment failure. Therefore, this study aimed to perform re-planning to maintain the dose coverage in patients with pancreatic cancer with passive scattering CIRT.

Methods

Eight patients with pancreatic cancer and 95 daily computed tomography (CT) sets were examined. Two types of adaptive plans based on new range compensators (RCs) (AP-1) and initial RCs (AP-2) were generated. In AP-2, each beam was optimized by manually adjusting the range shifter thickness and spread-out Bragg peak size to make dose reduction by < 3% of the original plan. Doses of the original plan with bone matching (BM) and tumor matching (TM) were examined for comparison. We calculated the accumulated dose using the contour and intensity-based deformable image registration algorithm. The dosimetric differences in respect to the original plan were compared between methods.

Results

Using TM and BM, mean ± standard deviations of daily CTV V95 (%) difference from the original plan was − 5.1 ± 6.2 and − 8.8 ± 8.8, respectively, but 1.2 ± 3.4 in AP-1 and − 0.5 ± 2.1 in AP-2 (P < 0.001). AP-1 and AP-2 enabled to maintain a satisfactory accumulated dose in all patients. The dose difference was 1.2 ± 2.8, − 2,1 ± 1.7, − 7.1 ± 5.2, and − 16.5 ± 15.0 for AP-1, AP-2, TM, and BM, respectively. However, AP-2 caused a dose increase in the duodenum, especially in the left–right beam.

Conclusions

The possible dose deterioration should be considered when performing the BM, even TM. Re-planning based on single beam optimization in passive scattering CIRT seems an effective and safe method of ensuring the treatment robustness in pancreatic cancer. Further study is necessary to spare healthy tissues, especially the duodenum.

Dosimetric Comparison Between Carbon-ion Radiotherapy and Photon Radiotherapy for Stage I Esophageal Cancer

BACKGROUND/AIM

The present study aimed to compare the radiation dose distribution of carbon-ion radiotherapy (CIRT) for stage I esophageal cancer with three-dimensional conformal radiotherapy (3DCRT) and volumetric modulated arc therapy (VMAT).

PATIENTS AND METHODS

Fifteen patients with cT1bN0M0 esophageal cancer who received 3DCRT at Kanagawa Cancer Center between January 2014 and April 2019 were enrolled. The dose-volume histogram parameters of the target volume and normal organs planned with CIRT, 3DCRT, and VMAT were evaluated.

RESULTS

The homogeneity index for the target volume of CIRT was significantly lower than that of 3DCRT and VMAT. In addition, the radiation dose of CIRT to the heart, lungs, spinal cord, and skin was significantly lower than that of 3DCRT and VMAT.

CONCLUSION

Favorable dose distributions with CIRT were demonstrated compared with 3DCRT and VMAT for esophageal cancer.

Carbon-ion Radiotherapy for Oligometastatic Colorectal Cancer in the Liver or Lung

BACKGROUND/AIM

We aimed to evaluate the clinical outcomes of oligometastatic colorectal cancer in the liver and lung treated with carbon-ion radiotherapy (C-ion RT).

PATIENTS AND METHODS

Nineteen consecutive patients with oligometastatic colorectal cancer in the liver or lung who received C-ion RT were analyzed. The doses of C-ion RT were 60.0 Gy [relative biological effectiveness (RBE)] in 4 fractions, 60.0 Gy (RBE) in 12 fractions, or 64.8 Gy (BRE) in 12 fractions.

RESULTS

The median follow-up duration was 19 months. There were 23 tumors in 19 patients. The 2-year overall survival and local control rates for the whole patient cohort were 100% and 67%, respectively. None of the patients developed grade 2 or higher acute or late toxicities.

CONCLUSION

C-ion RT for oligometastatic colorectal cancer in liver and lung provides favorable clinical outcomes. These outcomes suggest C-ion RT is a treatment option for oligometastatic colorectal cancer in liver and lung.

Carbon-ion radiotherapy subsequent to balloon-occluded retrograde transvenous obliteration for hepatocellular carcinoma with hepatic encephalopathy: a multidisciplinary approach

Radical treatments of hepatocellular carcinoma (HCC) with hepatic encephalopathy (HE) can be often difficult due to poor liver function or disturbance of consciousness. An effective treatment requires a combinatorial approach incorporating a treatment for HE and radical therapy for HCC that does not compromise liver function. Here, we report a case of a 78-year-old Japanese male with HCC and HE caused by splenorenal shunt. Serum ammonia levels were high. He was not suitable for surgery, percutaneous radiofrequency ablation, or transarterial chemoembolization due to the location of the tumor and poor liver function, which included HE. Thus, he underwent BRTO, with an immediate improvement in both HE and serum ammonia levels. After BRTO, he received C-ion RT as a radical treatment for HCC. After treatment, HCC was well controlled; however, at 35 months post-initiation of C-ion RT, he developed local recurrence without a further reduction in liver function status. Therefore, we repeated C-ion RT. The patient remains alive at 3 months post-treatment, with no evidence of local recurrence, distant metastasis, or toxicity. Although this is a single case report, it suggests that a combinatorial treatment consisting of BRTO and C-ion RT may increase survival rates of patients with HCC and HE.

Carbon-ion radiotherapy for octogenarians with locally advanced non-small-cell lung cancer

PURPOSE

The clinical significance of carbon-ion radiotherapy (CIRT) for octogenarians with locally advanced non-small-cell lung cancer (LA-NSCLC) remains unclear. We aimed to evaluate the clinical outcomes of CIRT alone for octogenarians with LA-NSCLC.

MATERIALS AND METHODS

We evaluated 32 patients who underwent CIRT alone between 1997 and 2015. The median age was 82.0 years (range, 80-88 years). In terms of clinical stage (UICC 7th edition), 7 (21.9%), 10 (31.3%), 11 (34.4%), and 4 (12.5%) patients had stage IIA, IIB, IIIA, and ΙΙΙB disease, respectively. The median CIRT dose was 72.0 Gy (relative biological effectiveness), and the median follow-up period was 33.1 months.

RESULTS

All patients successfully completed CIRT. Regarding grade ≥ 2 toxicities, 1 (3.1%), 3 (9.4%), and 4 (0.7%) patients developed grade 3 radiation pneumonitis, grade 2 radiation pneumonitis, and grade 2 dermatitis, respectively. No grade ≥ 4 toxicities were observed. The 2 year LC, PFS, and OS rates were 83.5%, 46.7%, and 68.0%, respectively.

CONCLUSION

CIRT alone is safe and effective for octogenarians with LA-NSCLC.

Robustness of daily dose for each beam angle and accumulated dose for inter-fractional anatomical changes in passive carbon-ion radiotherapy for pancreatic cancer: Bone matching versus tumor matching

PURPOSE

We aimed to assess the robustness of accumulated dose distributions for inter-fractional changes in passive carbon-ion radiotherapy for pancreatic cancer.

METHODS

Ninety-five daily CT image sets acquired after the treatment of eight patients with pancreatic cancer were used in this prospective study. Dose distributions with treatment beam fields were recalculated for bone matching (BM) and tumor matching (TM) positions on all daily CT images, the accumulated doses being calculated using deformable image registration methods. The prescribed dose was 55.2 Gy (relative biological effectiveness [RBE]) in 12 fractions. Dose volume parameters of V95 (%) for CTV and GTV, and D2cc (Gy(RBE)) for the stomach and duodenum were evaluated.

RESULTS

The medians (range) of CTV V95 (%) were 91.9 (86.1-100.0), 80.5 (56.1-90.6), and 86.4 (72.5-96.5) for the Plan, accumulated with BM and TM, respectively; GTV values (%) were 98.0 (85.7-100.0), 93.3 (65.7-99.9), and 96.2 (84.8-100.0), respectively. There were significant differences between all combinations apart from the Plan and TM for both targets. The values of stomach D2cc (Gy(RBE)) were 36.0 (16.9-43.4), 36.7 (17.9-45.0), and 35.2 (16.8-43.5), respectively; duodenum values (Gy(RBE)) were 25.2 (21.3-40.3), 30.1 (23.3-48.6), and 28.3 (20.4-50.6), respectively. There was a significant difference between the Plan and BM for duodenum only.

CONCLUSIONS

TM is recommended over BM because it can achieve higher target dose coverage than BM. Nevertheless, it is not enough in some cases. Further technical improvements are necessary to improve the target dose coverage.

Four-dimensional carbon-ion pencil beam treatment planning comparison between robust optimization and range-adapted internal target volume for respiratory-gated liver and lung treatment

We investigated the dose differences between robust optimization-based treatment planning (4DRO) and range-adapted internal target volume (rITV). We used 4DCT dataset of 20 lung cancer and 20 liver cancer patients, respectively, who had been treated with respiratory-gated carbon-ion pencil beam scanning therapy. 4DRO and rITV plans were created with the same clinical target volume (CTV) and organs at risk (OAR) contours. Four-dimensional dose distribution was calculated using deformable image registration. Dose metrics (e.g. D95, V20) were analyzed. Statistical significance was assessed by the Wilcoxon signed-rank test. For the lung cases, the mean CTV-D95 value for the rITV plan (=98.5%) was same as that for the 4DRO plan (=98.5%, P = 0.106), while the mean D95 value for the CTV + setup margin contour for the rITV plan (=98.2%) was higher than that for the 4DRO plan (95.2%, P < 0.001). For the liver cases, the mean CTV-D95 value for the rITV plan (=98.1%) was slightly lower than that for the 4DRO plan (=98.5%, P < 0.01), while the mean D95 value for the CTV + setup margin contour for the rITV plan (=98.0%) was higher than that for the 4DRO plan (94.1%, P < 0.001). For the doses to the organs at risk (OARs), the ipsilateral lung-V20/liver-V20 values for the rITV plan (=10.1%/19.7%) was significantly higher than that for the 4DRO plan (=8.6%/17.6, P < 0.001). Although the target coverage for 4DRO plan may be worse than that for rITV plan in the presence of the setup error, the 4DRO plan can improve OAR dose while preserving acceptable target dose coverage.

Efficacy and feasibility of re-irradiation using carbon ions for pancreatic cancer that recurs after carbon-ion radiotherapy

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Carbon-ion re-irradiation for pancreatic cancer; feasibility and efficacy.

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Adjuvant chemotherapy improve local control of re-irradiation using carbon ions.

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Carbon-ion radiotherapy for recurrent pancreatic cancer; reasonable option.

Background and purpose

Patients who receive carbon-ion radiotherapy (C-ion RT) for primary pancreatic cancer may experience locoregional recurrence; however, the treatment options for such patients are limited. We aimed to investigate the feasibility and efficacy of carbon-ion re-irradiation for patients with pancreatic cancer who experienced recurrence after initial C-ion RT.

Materials and methods

Twenty-one patients with recurrent pancreatic cancer who underwent repeat C-ion RT between December 2010 and November 2016 at our institute were retrospectively evaluated. The sites of post-initial C-ion RT failure were in-field central in 16 patients (76.2%) and marginal in 5 (23.8%). The median doses of initial and repeat C-ion RT were both 52.8 Gy (relative biological effectiveness [RBE]). Thirteen patients (61.9%) received concurrent chemotherapy with re-irradiation, while 11 (52.4%) received adjuvant chemotherapy.

Results

The median follow-up period after re-irradiation was 11 months. The 1-year local control, progression-free survival, and overall survival rates were 53.5%, 24.5%, and 48.7%, respectively. Toxicity data was obtained from the patients’ charts. Only 1 patient (4.8%) developed grade 3 acute toxicities and none developed grade ≥3 late toxicities. Univariate analysis indicated that patients who received adjuvant chemotherapy had significantly improved local control rates compared with those who did not; the 1-year local control rates were 80.0% and 0.0%, respectively (P = 0.0469).

Conclusion

Repeating C-ion RT may be a reasonable option with tolerable toxicity for patients with recurrent pancreatic cancers. Adjuvant chemotherapy appears to improve the local control rate. This is the first study to examine re-irradiation using C-ion for recurrent pancreatic cancer after initial C-ion RT.

Primary spindle cell sarcoma of the heart treated with carbon-ion radiotherapy: Case report

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Primary cardiac tumors are rare. Seventy-five percent of the tumors are benign and 25 % are malignant.

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Primary cardiac sarcoma is a rare malignant cardiac neoplasm with a poor prognosis.

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No evidence-based guidelines exist regarding optimal surgical treatment of primary cardiac sarcomas.

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Systemic chemotherapy is indicated for patients with widespread or unresectable malignancies.

Introduction

Primary cardiac sarcoma is a rare malignant cardiac neoplasm with a poor prognosis. No evidence-based guidelines exist regarding surgical treatment management, although some case reports have been published. We report the outcome of a patient with spindle cell sarcoma of the heart treated postoperatively with carbon-ion radiotherapy and chemotherapy.

Presentation of case

A 16-year-old female patient was noted to have abnormal electrocardiogram results for 2 consecutive years at a high school medical check. She was referred to our hospital and a cardiac tumor in the left atrium was suspected. The preoperative diagnosis was myxoma, but abnormalities were also observed macroscopically during surgery, and a diagnosis of spindle cell sarcoma was made by rapid intraoperative pathological analysis. We resected the tumor as much as possible with surgery, but the tumor in the left lower pulmonary vein could not be respected. We performed carbon-ion radiotherapy postoperatively. She experienced recurrence 1 year later and tumor growth 2 years later. We considered additional surgical treatment, but eventually selected chemotherapy. She died 4 years and 7 months after initial surgery.

Conclusion

Spindle cell sarcoma is a rare disease with a poor prognosis. Although no optimal treatment method has been established, in the present case, incomplete surgical resection and postoperative carbon-ion radiotherapy were performed, yielding a relatively long survival period.

Phase I dose-escalation trial of S-1 combined with carbon-ion radiotherapy for sinonasal squamous cell carcinoma

This study aimed to determine the maximum tolerance dose (MTD) and to estimate the recommended dose (RD) of concomitant S-1 with carbon-ion radiotherapy (RT) for sinonasal squamous cell carcinoma (SCC). Nine patients with sinonasal SCC received carbon-ion RT with escalating doses of S-1 according to phase I methods. Doses of 40, 60 and 80 mg/m2/day were administered twice daily in dose levels 1, 2 and 3, respectively, from days 1 to 14 and 22 to 35. Carbon-ion RT was administered at a dose of 70.4 Gy (relative biological effectiveness) in 32 fractions, 5 days a week. Two patients developed grade 3 acute dermatitis. However, none developed dose-limiting toxicities. Therefore, the MTD of S-1 could not be determined; the RD was estimated to be 80 mg/m2/day with concurrent carbon-ion RT. Partial response and stable disease were noted in 5 and 4 patients, respectively. The 2-year overall survival and local control rates were 56 and 74%, respectively. Overall, 2 patients developed ≥grade 3 late toxicities; among them, 1 patient developed grade 3 cataract and the other developed grade 4 cataract, optic nerve disorder and hearing impairment. To the best of our knowledge, this phase I study is the first clinical trial to evaluate concomitant S-1 with carbon-ion RT for sinonasal SCC. The MTD of S-1 could not be determined, and the RD was estimated to be 80 mg/m2/day. This study demonstrated a manageable safety profile for this combination. The observed outcomes may facilitate further evaluation of this novel therapy.

Dose-averaged linear energy transfer per se does not correlate with late rectal complications in carbon-ion radiotherapy

BACKGROUND AND PURPOSE

Several studies have focused on increasing the linear energy transfer (LET) within tumours to achieve higher biological effects in carbon-ion radiotherapy (C-ion RT). However, it remains unclear whether LET affects late complications. We assessed whether physical dose and LET distribution can be specific factors for late rectal complications in C-ion RT.

MATERIALS AND METHODS

Overall, 134 patients with uterine carcinomas were registered and retrospectively analysed. Of 134 patients, 132 who were followed up for >6 months were enrolled. The correlations between the relative biological effectiveness (RBE)-weighted dose based on the Kanai model (the ostensible "clinical dose"), dose-averaged LET (LETd), or physical dose and rectal complications were evaluated. Rectal complications were graded according to the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer criteria.

RESULTS

Nine patients developed grade 3 or 4 late rectal complications. Linear regression analysis found that D_2cc in clinical dose was the sole risk factor for ≥grade 3 late rectal complications (p = 0.012). The receiver operating characteristic analysis found that D_2cc of 60.2 Gy (RBE) was a suitable cut-off value for predicting ≥grade 3 late rectal complications. Among 35 patients whose rectal D_2cc was ≥60.2 Gy (RBE), no correlations were found between severe rectal toxicities and LETd alone or physical dose per se.

CONCLUSION

We demonstrated that severe rectal toxicities were related to the rectal D_2cc of the clinical dose in C-ion RT. However, no correlations were found between severe rectal toxicities and LETd alone or physical dose per se.

Mixed-beam approach for high-risk prostate cancer: Carbon-ion boost followed by photon intensity-modulated radiotherapy. Dosimetric and geometric evaluations (AIRC IG-14300)

BACKGROUND AND PURPOSE

The aim was to evaluate dosimetric uncertainties of a mixed beam approach for patients with high-risk prostate cancer (PCa). The treatment consists of a carbon ion radiotherapy (CIRT) boost followed by whole-pelvis intensity-modulated RT (IMRT).

MATERIALS AND METHODS

Patients were treated with a CIRT boost of 16.6 Gy/4 fractions followed by whole-pelvis IMRT of 50 Gy/25 fractions, with consequent long term androgen deprivation therapy. Deformable computed tomography image registration (DIR) was performed and corresponding doses were used for plan sum. A comparative IMRT photon plan was obtained as whole-pelvis IMRT of 50 Gy/25 fractions followed by a boost of 28 Gy/14 fractions. DIR performances were evaluated through structure-related and image characteristics parameters.

RESULTS

Until now, five patients out of ten total enrolled ended the treatment. Dosimetric parameters were lower in CIRT + IMRT than IMRT-only plans for all organs at risk (OARs) except femoral heads. Regarding DIR evaluation, femoral heads were the less deformed OAR. Penile bulb, bladder and anal canal showed intermediate deformation. Rectum was the most deformed. DIR algorithms were patient (P)-dependent, as performances were the highest for P3 and P4, intermediate for P2 and P5, and the lowest for P1.

CONCLUSIONS

CIRT allows better OARs sparing while increasing the efficacy due to the higher radio-biological effect of carbon ions. However, a mixed beam approach could introduce DIR problems in multi-centric treatments with different operative protocols. The development of this prospective trial will lead to more mature data concerning the clinical impact of implementing DIR procedures in dose accumulation applications for high-risk PCa treatments.

Organ motion quantification and margins evaluation in carbon ion therapy of abdominal lesions

PURPOSE

In image-guided particle radiotherapy of abdominal lesions, respiratory motion hinders treatment accuracy. In this study, 2D cineMRI data were used to quantify the tumor (GTV) motion and to evaluate the clinical approach based on deriving an internal target volume (ITV) from a planning 4DCT for gating treatments.

METHODS

Seven patients with abdominal lesions were treated with carbon-ion therapy at the National Centre of Oncological Hadron-therapy (Italy). The MR scan was performed on the same day of the 4DCT acquisition. For four patients, an additional MR was acquired approximately after 1 week. The cineMRI combined with deformable image registration algorithm was used to quantify tumor motion. Afterwards, two ITVs were defined considering (1) all phases (ITVFB) and (2) only phases within the gating window (ITVG), and then compared with the clinical (4DCT-derived) ITVs (ITVCG and ITVCFB).

RESULTS

Tumor residual motion estimated by cineMRI data in the two MRI sessions resulted not significantly different from 4DCT, although cineMRI accounted for cycle-to-cycle variations. The ITV normalized for the GTV median values were higher for ITVFB with respect to ITVG, ITVCFB and ITVCG. The Hausdorff distances with respect to the GTV were up to 10.55 mm, 3.13 mm, 5.56 mm and 2.51 mm, for ITVFB, ITVG, ITVCFB and ITVCG, respectively. According to both metrics, ITVCG and ITVG were not found significantly different.

CONCLUSIONS

CineMRI acquisitions allowed to quantify organ motion without delivering additional dose to the patient and to verify treatment margins in gated carbon-ion therapy of abdominal lesions.

Preliminary result of carbon-ion radiotherapy using the spot scanning method for prostate cancer

BACKGROUND

Carbon-ion radiotherapy (CIRT) for prostate cancer was initiated at Kanagawa Cancer Center in 2015. The present study analyzed the preliminary clinical outcomes of CIRT for prostate cancer.

METHODS

The clinical outcomes of 253 patients with prostate cancer who were treated with CIRT delivered using the spot scanning method between December 2015 and December 2017 were retrospectively analyzed. The irradiation dose was set at 51.6 Gy (relative biological effectiveness) delivered in 12 fractions over 3 weeks. Biochemical relapse was defined using the Phoenix definition. Toxicities were assessed according to CTCAE version 4.0.

RESULTS

The median patient age was 70 (47-86) years. The median follow-up duration was 35.3 (4.1-52.9) months. According to the D'Amico classification system, 8, 88, and 157 patients were classified as having low, intermediate, and high risks, respectively. Androgen deprivation therapy was administered in 244 patients. The biochemical relapse-free rate in the low-, intermediate-, and high-risk groups at 3 years was 87.5, 88.0, and 97.5%, respectively (P = 0.036). Grade 2 acute urinary toxicity was observed in 12 (4.7%) patients. Grade 2 acute rectal toxicity was not observed. Grade 2 late urinary toxicity and grade 2 late rectal toxicity were observed in 17 (6.7%) and 3 patients (1.2%), respectively. Previous transurethral resection of the prostate was significantly associated with late grade 2 toxicity in univariate analysis. The predictive factor for late rectal toxicity was not detected.

CONCLUSION

The present study demonstrated that CIRT using the spot scanning method for prostate cancer produces favorable outcomes.

Perturbation analysis of 4D dose distribution for scanned carbon-ion beam radiotherapy

PURPOSE

To evaluate the patients' set-up error-induced perturbation effects on 4D dose distributions (4DDD) of range-adapted internal target volume-based (raITV) treatment plan using lung and liver 4DCT data sets.

METHODS

We enrolled 20 patients with lung and liver cancer treated with respiratory-gated carbon-ion beam scanning therapy. PTVs were generated by adding a 2 mm range-adapted set-up margin on the raITVs. Set-up errors were simulated by shifting the beam isocenter in three translational directions of ±2 mm, ±4 mm, and ±6 mm. 4DDDs were calculated for both nominal and isocenter-shifted situations. Dose metrics of CTV dose coverage (D95) and normal tissue sparing were evaluated. Statistical significance with p < 0.01 was considered by Wilcoxon signed rank test.

RESULTS

The CTV dose coverage was more sensitive to set-up errors for lung cases than for liver cases, and more serious in superior-inferior direction. The sufficient CTV-D95 > 98% could be achieved with set-up errors less than ±2 mm in all shift directions both for lung and liver cases. With the increase of set-up error, the CTV dose coverage decreased gradually. The clinical criterial of CTV-D95 > 95% could not be fulfilled with set-up error reached to ±4 mm for lung cases, and ±6 mm for liver cases. OAR doses did not have a significant difference with each set-up error for both lung and liver cases.

CONCLUSIONS

The range-adapted set-up margin successfully prevented dose degradation of 4DDDs in the presence of the same magnitude of set-up error for raITV-based carbon-ion beam scanning therapy.

Dose assessment for patients with stage I non-small cell lung cancer receiving passive scattering carbon-ion radiotherapy using daily computed tomographic images: A prospective study

BACKGROUND AND PURPOSE

This study aimed to assess dose distributions for stage I non-small cell lung cancer (NSCLC) with passive scattering carbon-ion radiotherapy (C-ion RT) using daily computed tomography (CT) images.

MATERIALS AND METHODS

We enrolled 10 patients with stage I NSCLC and acquired a total of 40 pre-fractional CT image series under the same settings as the planning CT images. These CT images were registered with planning CT images for dose evaluation using both bone matching (BM) and tumor matching (TM). Using deformable image registration, we generated accumulated doses. Moreover, the volumetric dose parameters were compared in terms of tumor coverage and lung exposure and statistical analyses were performed.

RESULTS

Overall, 25% of 40 fractional dose distributions were unacceptable with BM, compared with 2.5% with TM (P < 0.001). Using BM, three patients' accumulated dose distributions were unacceptable; however, all were satisfactory with TM (P < 0.001). No differences were observed in water-equivalent path length (WEL). The required margins in patients with poor dose distribution were 5.9 and 4.4 mm for BM and TM, respectively.

CONCLUSIONS

This study establishes that CT image-based TM is robust compared with conventional BM for both daily and accumulated dose distributions. The effects of changes in WEL seem to be limited. Hence, daily CT alignment is recommended for patients with stage I NSCLC receiving C-ion RT.

Safety and Efficacy of Carbon-ion Radiotherapy Alone for Stage III Non-small Cell Lung Cancer

BACKGROUND/AIM

We evaluated the efficacy and safety of carbon-ion radiotherapy (CIRT) alone for Stage III non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Data of 65 patients (median age=73 years) with Stage III NSCLC who underwent CIRT alone in the QST Hospital, Chiba, Japan, between 1997 and 2015 were retrospectively analysed. The median dose was 72.0 Gy (relative biological effectiveness).

RESULTS

The median follow-up was 27.6 months (range=1.6-207.7 months). Two-year local control, progression-free survival (PFS), and overall survival (OS) rates were 73.9%, 38.6%, and 54.9%, respectively. Overall, 1 (2%), 4 (6%), and 1 (2%) patient developed Grade 4 (mediastinal haemorrhage), Grade 3 (radiation pneumonitis), and Grade 3 (bronchial fistula) toxicities, respectively. On univariate analysis, clinical T and N stage and CIRT timing were significant predictors of PFS and OS; clinical target volume was a significant predictor of PFS.

CONCLUSION

CIRT alone is effective with acceptable toxicity for Stage III NSCLC.

Assessment of risk factors associated with development of oronasal fistula as a late complication after carbon-ion radiotherapy for head and neck cancer

BACKGROUND

Oronasal fistulae (ONF) are one of the rare but serious complications of conventional photon radiotherapy. This study aimed to identify the risk factors for the development of ONF after carbon-ion radiotherapy (C-ion RT).

MATERIALS AND METHODS

The data of 62 cases of sinonasal and oral cavity cancers treated with C-ion RT and followed-up in excess of 5 years were retrospectively reviewed. The correlation between the clinical and dosimetric parameters and the development of ONF was analysed.

RESULTS

A total of 80.6% cases had sinonasal malignancies, and most tumours had advanced T stages (96.8%). Maxillary invasion was observed in 16 cases (25.8%), and malignant melanoma was the most common histology (46.8 %). All the cases received a dose of between 57.6 Gy (RBE) and 64 Gy (RBE) in 16 fractions over 4 weeks. At a median follow up of 88.8 months, 23 cases (37.1%) developed small localised ONF; however, none were of grade III severity. On separate multivariate analyses of clinical parameters in the entire cohort and in cases without maxillary invasion, the number of teeth irradiated with more than 50 Gy (RBE) was found to be the common significant independent risk factor for development of ONF.

CONCLUSION

The number of teeth irradiated with more than 50 Gy (RBE) is a significant independent risk factor for the development of ONF, which is a late complication of C-ion RT delivered in 16 fractions.

Post-carbon-ion radiotherapy vertebral pathological fractures in upper cervical primary malignant spinal tumors treated by occipito-cervical fusion

PURPOSE

To describe the characteristic features of post-carbon-ion radiotherapy (CIRT) vertebral pathological fractures (VPFs) in upper cervical primary malignant spinal tumors (PMSTs) treated by occipito-cervical (OC) fusion.

METHODS

OC fusion was performed for three consecutive patients with post-CIRT VPFs. The clinical results and imaging findings, including bone single-photon emission computed tomography (SPECT)/CT were prospectively collected.

RESULTS

No surgery-related wound complication and surgical site infection were noted. One patient experienced re-fracture and displacement of dens with the loosening of occipital screws and was treated by posterior revision surgery. At the final follow-up, all patients were alive without evidence of disease, and the solid OC fusion was confirmed. Bone SPECT/CT clearly revealed the effect of CIRT on bone turnover in the irradiated field.

CONCLUSION

The OC fusion with autologous bone grafts was a reliable option for the treatment of post-CIRT VPCs in the patients with upper cervical PMSTs. In addition, evaluation of the bone turnover at the irradiated field by bone SPECT/CT would help surgeons select an effective plan of care, such as fusion level and postoperative care.

Dosimetric parameters predictive of nasolacrimal duct obstruction after carbon-ion radiotherapy for head and neck carcinoma

BACKGROUND AND PURPOSE

Little information is available on the risk factors for nasolacrimal duct obstruction after radiotherapy for head and neck tumors. We investigated the incidence and predictive dosimetric parameters for nasolacrimal duct obstruction following carbon-ion radiotherapy for head and neck tumors.

MATERIALS AND METHODS

Twenty-eight patients with head and neck non-squamous cell carcinoma were analyzed in this single-institution prospective study. More than half of the tumors were located in the nasal cavity and maxillary sinus. Carbon-ion radiotherapy consisting of 57.6 or 64.0 Gy(relative biological effectiveness; RBE) in 16 fractions was administered. Nasolacrimal duct obstruction was recorded according to Common Terminology Criteria for Adverse Events version 4.0. Cutoff values were determined using receiver operating characteristic (ROC) curve analysis. VX indicates the volume irradiated with X Gy(RBE).

RESULTS

The median follow-up period was 60.3 months. Incidences of Grade 1 and 2 nasolacrimal duct obstructions were 46% (13/28) and 7% (2/28), respectively; no Grade 3 or greater toxicities were recorded. Throughout the dose range, the volumes of the irradiated nasolacrimal ducts were significantly higher in the obstruction-positive patients than in the obstruction-negative patients (p < 0.001 for V10, V20, V30, V40, V50, and V60). Cutoff values determined by the ROC curve analysis classified the obstruction-positive patients with an accuracy of >96% over the entire range of V10-V60.

CONCLUSION

The incidence and predictive dosimetric parameters for nasolacrimal duct obstruction after carbon-ion radiotherapy were demonstrated in a prospective cohort. These data should help optimize carbon-ion radiotherapy treatments for patients with head and neck tumors.

Clinical results of carbon-ion radiotherapy with separation surgery for primary spine/paraspinal sarcomas

PURPOSE

To evaluate the clinical outcome of combination of carbon-ion radiotherapy with separation surgery (CIRT-SS) in patients with primary spinal/paraspinal sarcoma (PSPS) and epidural spinal cord compression (ESCC).

METHODS

CIRT-SS was performed in 11 consecutive patients. Patients treated in the primary and salvage settings were categorized into Group A (n = 8) and Group B (n  = 3), respectively. Clinical results and imaging findings were collected, with a particular focus on ESCC grade, treatment-associated adverse events (AEs), and the locoregional control (LRC) rate and overall survival (OS).

RESULTS

The median follow-up period from the start of CIRT-SS was 25 months (7-57 months). ESCC was improved by SS in all cases. No patients exhibited radiation-induced myelopathy (RIM), but three developed Grade 3 vertebral compression fracture (VCF) during follow-up. Locoregional recurrences were observed in four patients [Group A: 1 (12.5%), Group B: 3 (100%)]. Over the entire follow-up period, three patients developed distant metastases and two patients died. The 2-year LRC rate and OS were 70% and 80%, respectively.

CONCLUSION

CIRT-SS in the primary setting achieved acceptable LRC and OS without RIM in patients with PSPS and with ESCC. VCF was the most frequent AE associated with CIRT-SS.

Health Technology Assessment of Carbon-ion Beam Radiotherapy: A Systematic Review of Clinical Effectiveness and Safety for 54 Oncological Indications in 12 Tumour Regions

BACKGROUND/AIM

Due to the unique physical dose distribution of carbon-ion radiotherapy (CIRT), CIRT can be regarded as a novel tumour irradiation technique - potentially advantageous for various tumour types. Yet it is unclear in how far, superiority or inferiority can be claimed when comparing CIRT to standard irradiation. This study aimed to assess the scientific evidence regarding the effectiveness and safety of CIRT.

MATERIALS AND METHODS

A systematic literature review was performed using the European Network for Health Technology Assessment (EUnetHTA) Core Model® for rapid relative effectiveness assessment. The literature search for clinical outcome studies on CIRT was performed using four databases [Cochrane (Central), Centre for Research and Dissemination (CRD), Embase and OVID MEDLINE]. The Cochrane Risk of Bias Tool (for randomised controlled trials) and the Institute of Health Economics (IHE-18) Checklist (for observational studies) were used to assess the risk of bias of the included studies. The evidence synthesis was restricted to 54 oncological indications in 12 broad tumour regions and studies with a low or moderate risk of bias, published between 2005 and 2017.

RESULTS

Twenty-seven studies were eligible for the qualitative synthesis of the evidence regarding the effectiveness and safety of CIRT: One randomised controlled trial that primarily focused on the feasibility of CIRT, three case-control studies, three before- and after- studies with a focus on quality of life, and 20 further studies of case series. Overall, insufficient scientific evidence was found for superiority or inferiority of CIRT when compared to standard irradiation for 13/54 oncologicaI indications in 7/12 tumour regions (skull base tumours, brain cancer, cancer in the ear-nose-throat region, bone and soft-tissue tumours, lung cancer, prostate cancer, gastrointestinal tumours). No scientific evidence was found for the remaining 41/54 oncological indications.

CONCLUSION

CIRT is undoubtedly, theoretically, a promising cancer treatment. To date, however, it lacks randomised controlled trials assessing the long-term effectiveness and harms associated with the use of CIRT. CIRT must be considered as an experimental treatment due to the lack of high-quality clinical research.

Feasibility of Re-irradiation using carbon ions for recurrent head and neck malignancies after carbon-ion radiotherapy

BACKGROUND AND PURPOSE

Locoregional recurrence after carbon-ion radiotherapy (CIRT) for primary head and neck malignancies, such as malignant mucosal melanoma, adenoid cystic carcinoma, and sarcoma, occurs occasionally. However, the treatment options are limited. We report on the toxicity and efficacy of re-irradiation using carbon ions for recurrent head and neck malignancies after CIRT.

MATERIALS AND METHODS

Data of 48 patients with recurrent head and neck malignancies treated with re-irradiation with CIRT at our institution (2007-2016) were retrospectively analyzed. Twenty-one patients (43.8%) had malignant mucosal melanoma, 17 (35.4%) had adenoid cystic carcinoma, six (12.5%) had bone and soft tissue sarcomas, and four patients (8.3%) had other disease types. Tumor recurrences at re-irradiation were located in the paranasal cavity (n = 18, 37.5%), nasal cavity (n = 9, 18.8%), nasopharynx (n = 4, 8.3%), orbit (n = 3, 6.3%), cavernous sinus (n = 3, 6.3%), and at other sites (n = 11, 22.9%). The median dose of initial CIRT and that at re-irradiation were 57.6 Gy and 54.0 Gy (relative biological effectiveness [RBE]), respectively. None of the patients received concurrent chemotherapy.

RESULTS

The median follow-up period after re-irradiation was 27.1 months. Five patients (10.4%) developed Grade 3 acute toxicities and 18 (37.5%) developed Grade ≥3 late toxicities, including Grade 5 central nervous system necrosis in one patient. The 2-year local control, locoregional control, progression-free survival, and overall survival rates were 40.5, 33.5%, 29.4%, and 59.6%, respectively.

CONCLUSION

Re-irradiation using carbon ions may be a reasonable treatment option with tolerable toxicity for patients with recurrent head and neck malignancies after CIRT.

Carbon-ion radiotherapy for lymph node oligo-recurrence: a multi-institutional study by the Japan Carbon-Ion Radiation Oncology Study Group (J-CROS)

Background

The efficacy of carbon-ion radiotherapy (C-ion RT) for lymph node (LN) oligo-recurrence has only been evaluated in limited single-center studies. We aimed to investigate the benefit of C-ion RT for LN oligo-recurrence in a large multi-center study.

Methods

Patients who received C-ion RT between December 1996 and December 2015 at 4 participating facilities and who met the following eligibility criteria were included: (i) histological or clinical diagnosis of LN recurrence; (ii) controlled primary lesion; (iii) no recurrence other than LN; (iv) LN recurrence involved in a single lymphatic site; and (v) age ≥ 20 years.

Results

A total of 323 patients were enrolled. Median follow-up period was 34 months for surviving patients. The most common dose fractionation of C-ion RT was 48.0 Gy (relative biological effectiveness) in 12 fractions. Forty-seven patients had a history of RT at the recurrent site. The 2-year local control (LC) and overall survival (OS) rates after C-ion RT were 85% and 63%, respectively. Only 1 patient developed grade-3 toxicity. Factors such as LN diameter, histology, and history of previous RT did not correlate with LC. Smaller diameters (< 30 mm) and numbers (≤ 3) of LN metastases as well as longer disease-free intervals post-primary therapy (≥ 16 months) were associated with significantly better OS.

Conclusions

C-ion RT for LN oligo-recurrence appeared to be effective and safe. C-ion RT may provide a survival benefit to patients with LN oligo-recurrence, particularly to those with few LN metastases, smaller LN diameters, and longer disease-free intervals.

Electronic supplementary material

The online version of this article (10.1007/s10147-019-01440-y) contains supplementary material, which is available to authorized users.

Fusion surgery with instrumentation following carbon ion radiotherapy for primary lumbar tumors: A case series

Carbon-ion radiotherapy (CIRT) is a useful modality for treatment of primary spinal sarcoma, but osteonecrosis after CIRT may cause pseudoarthrosis that can make subsequent reconstruction surgery difficult. The patients were a 68-year-old man (case 1), a 30-year-old woman (case 2), and a 49-year-old man (case 3) with lumbar lesions. After CIRT, cases 1 and 3 were treated with instrumented spondylectomy and case 2 underwent posterior decompression and instrumentation surgery. Cases 1 and 2 required several salvage procedures because of failure of instrumentation (rod breakage) before bone union was achieved. After multiple revision surgeries, these cases did achieve bone union without tumor recurrence. In contrast, in case 3, only spondylectomy using a pedicle screw system at 20 months after CIRT was required for fusion. At follow-up 11 years postoperatively, CT showed bone union with invasion of autograft bone from the iliac crest into adjacent vertebra. Collapse or a finding of viable tumor cells after CIRT requires surgery such as spondylectomy with reconstruction. Instrumented fixation following CIRT for a lumbar primary tumor should be performed with multilevel anterior support using a sufficient amount of bone graft in posterior fusion levels.