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.

Biological dose optimization incorporating intra-tumoural cellular radiosensitivity heterogeneity in ion-beam therapy treatment planning

OBJECTIVE

Treatment plans of charged-particle therapy have been made under an assumption that all cancer cells within a tumour equally respond to a given radiation. However, an intra-tumoural cellular radiosensitivity heterogeneity clearly exists, and it may lead to an overestimation of therapeutic effects of the radiation. The purpose of this study was to develop a biological model that can incorporate the radiosensitivity heterogeneity into biological optimization for charged-particle therapy treatment planning. Approach. The radiosensitivity heterogeneity was modeled as the variability of a cell-line specific parameter in the microdosimetric kinetic model following the gamma distribution. To validate the developed intra-tumoural-radiosensitivity-heterogeneity-incorporated microdosimetric kinetic (HMK) model, a treatment plan with H-ion beams was made for a chordoma case assuming a radiosensitivity heterogeneous region within the tumour. To investigate the effects of the radiosensitivity heterogeneity on the biological effectiveness of H-, He-, C-, O-, and Ne-ion beams, the relative biological effectiveness (RBE)-weighted dose distributions were planned to a cuboid target with the stated ion beams without considering the heterogeneity. The planned dose distributions were then recalculated by taking the heterogeneity into account. Main results: The cell survival fraction and corresponding RBE weighted dose w- ere formulated basedon the HMK model. The first derivative of the RBE-weighted dose distribution was also derived,which is needed for fast biological optimization. For the patient plan, the biological optimization increasedthe dose to the radiosensitivity heterogeneous region to compensate for the heterogeneity-inducedreduction in biological effectiveness of the H-ion beams. The reduction in biological effectiveness dueto the heterogeneity waspronouncedfor low-LET beams but moderate for high-LET beams. The RBE-weighted dose in the cuboid target decreased by 7.6% for the H-ion beam, while it decreased by just 1.4% for the Ne-ion beam. Significance. The optimal treatment plans that consider the intra-tumoural cellular radiosensitivity heterogeneity can be devised using the HMK model. .

Carbon-Ion Radiation Therapy for Unresectable Locally Recurrent Colorectal Cancer: A Promising Curative Treatment for Both Radiation Therapy: Naïve Cases and Reirradiation Cases

PURPOSE

It is difficult to effectively cure patients with unresectable locally recurrent colorectal cancers (LRCRCs) using conventional chemotherapy or chemoradiation therapy. Furthermore, treatment options vary depending on the patient's history of radiation therapy. Carbon-ion radiation therapy (CIRT) is a potentially curative treatment for these patients. Here, we compare the treatment outcomes of radiation therapy-naïve cases (nRT) and re-irradiation cases (reRT).

METHODS AND MATERIALS

Patients with LRCRC treated with CIRT at QST Hospital between 2003 and 2019 were eligible. CIRT was administered daily 4 d/wk for 16 fractions. The total irradiated dose was set at 73.6 Gy (relative biologic effectiveness-weighted dose [RBE]) for nRT and 70.4 Gy (RBE) for reRT patients.

RESULTS

We included 390 nRT cases and 83 reRT cases. The median follow-up period from the initiation of CIRT was 48 (5-208) months. The 3-year overall survival (OS) rates for nRT and reRT were 73% (95% CI, 68%-77%) and 76% (65%-84%), respectively. The 5-year OS rates were 50% (45%-55%) and 50% (38%-61%), respectively. These rates did not differ significantly (P = .55). The 3-year local control (LC) rates for nRT (73.6 Gy) and reRT (70.4 Gy) cases were 80% (75%-84%) and 80% (68%-88%), respectively. The 5-year LC rates were 72% (67%-78%) and 69% (55%-81%), respectively, without a significant difference (P = .56).

CONCLUSIONS

Our results suggest that CIRT for LRCRC is a very effective and promising treatment for both nRT and reRT cases.

High-Linear Energy Transfer Irradiation in Clinical Carbon-Ion Beam With the Linear Energy Transfer Painting Technique for Patients With Head and Neck Cancer

Purpose

Dose-averaged linear energy transfer (LETd) is one of the important factors in determining clinical outcomes for carbon-ion radiation therapy. Innovative LET painting (LP) has been developed as an advanced form of conventional intensity modulated carbon-ion radiation therapy (IMIT) at the QST Hospital. The study had 2 motivations: to increase the minimum LETd (LETdmin) and to improve uniformity of the LETd distribution within the gross tumor volume (GTV) by using LP treatment plans for patients with head and neck cancer while maintaining the relative biologic effectiveness (RBE)-weighted dose coverage within the planning tumor volume (PTV) the same as in the conventional IMIT plan.

Methods and Materials

The LP treatment plans were designed with the in-house treatment planning system. For the plans, LETd constraints and LETdmin, goal-LETd, and maximum-LETd (LETdmax) constraints for the GTV were added to the conventional dose constraints in the IMIT prescription. For 13 patients with head and neck cancer, the RBE-weighted dose to 90% (D90) and 50% (D50) of the PTV and the LETdmin, mean (LETdmean), and LETdmax values within the GTV in the LP plans were evaluated by comparing them with those in the conventional IMIT plans.

Results

The LP for 13 patients with head and neck cancer could keep D90s and D50s for the PTV within 1.0% of those by the conventional IMIT. Among the 13 patients, the mean LETdmin of the LP plans for the GTV was 59.2 ± 7.9 keV/μm, whereas that of the IMIT plans was 45.9 ± 6.0 keV/μm. The LP increased the LETdmin to 8 to 24 keV/μm for the GTV compared with IMIT.

Conclusions

While maintaining the dose coverage to the PTV as comparable to that for IMIT, the LP increased the mean LETdmin to 13.2 keV/μm for the GTV. For a GTV up to 170 cm3, LETd > 44 keV/μm could be achieved using LP, which according to previous studies was associated with lower recurrence. In addition, the LP method delivered more uniform LETd distributions compared with IMIT.

Shortening image registration time using a deep neural network for patient positional verification in radiotherapy

We sought to accelerate 2D/3D image registration computation time using image synthesis with a deep neural network (DNN) to generate digitally reconstructed radiographic (DRR) images from X-ray flat panel detector (FPD) images. And we explored the feasibility of using our DNN in the patient setup verification application. Images of the prostate and of the head and neck (H&N) regions were acquired by two oblique X-ray fluoroscopic units and the treatment planning CT. DNN was designed to generate DRR images from the FPD image data. We evaluated the quality of the synthesized DRR images to compare the ground-truth DRR images using the peak signal-to-noise ratio (PSNR) and structural similarity index measure (SSIM). Image registration accuracy and computation time were evaluated by comparing the 2D-3D image registration algorithm using DRR and FPD image data with DRR and synthesized DRR images. Mean PSNR values were 23.4 ± 3.7 dB and 24.1 ± 3.9 dB for the pelvic and H&N regions, respectively. Mean SSIM values for both cases were also similar (= 0.90). Image registration accuracy was degraded by a mean of 0.43 mm and 0.30°, it was clinically acceptable. Computation time was accelerated by a factor of 0.69. Our DNN successfully generated DRR images from FPD image data, and improved 2D-3D image registration computation time up to 37% in average.

Carbon Ion Radiotherapy: An Evidence-Based Review and Summary Recommendations of Clinical Outcomes for Skull-Base Chordomas and Chondrosarcomas

Skull-base chordoma and chondrosarcoma are rare radioresistant tumors treated with surgical resection and/or radiotherapy. Because of the established dosimetric and biological benefits of heavy particle therapy, we performed a systematic and evidence-based review of the clinical outcomes of patients with skull-base chordoma and chondrosarcoma treated with carbon ion radiotherapy (CIRT). A literature review was performed using a MEDLINE search of all articles to date. We identified 227 studies as appropriate for review, and 24 were ultimately included. The published data illustrate that CIRT provides benchmark disease control outcomes for skull-base chordoma and chondrosarcoma, respectively, with acceptable toxicity. CIRT is an advanced treatment technique that may provide not only dosimetric benefits over conventional photon therapy but also biologic intensification to overcome mechanisms of radioresistance. Ongoing research is needed to define the magnitude of benefit, patient selection, and cost-effectiveness of CIRT compared to other forms of radiotherapy.

Simulation study of comparative dosimetric analysis of coplanar horizontal-port scanned carbon-ion beam therapy in the head and neck

OBJECTIVE

Carbon-ion radiotherapy (CIRT) has demonstrated success in treating radioresistant disease within the head and neck, owing to its unique physical and radiobiological properties. Construction cost remains prohibitive; a center offering only a horizontal port may bridge this difficulty, but removal of the vertical port may prohibit treatment of disease near critical organs-at-risk. Building a center only containing a horizontal treatment port has been proposed as one method for cost savings.

METHODS

20 complex cases of head and neck cancer previously treated with conventional CIRT were retrospectively planned using horizontal-port-only treatment incorporating non-coplanar treatment angles to achieve greater degrees of freedom. These were dosimetrically compared with the previous plans.

RESULTS

Comparable D95 coverage of both planning target volume and gross tumor volume with ability to meet organ-at-risk constraints were feasible with horizontal-port-only treatment. Collectively differences were noted in PTV D95, brain stem Dmax, contralateral eye Dmax and V10 Gy (RBE); further qualitative differences were noted on a plan-by-plan basis dependent on disease location.

CONCLUSION

Horizontal-port-only treatment employing non-coplanar angles was feasible for complicated head and neck disease typically treated with CIRT, though careful consideration is necessary on a plan-by-plan basis.

ADVANCES IN KNOWLEDGE

It is worth noting that non-coplanar approaches are not typically used with the current treatment gantry and may extend further the difference between horizontal port planning and a gantry-based gold-standard.

Deep neural network-based synthetic image digital fluoroscopy using digitally reconstructed tomography

We developed a deep neural network (DNN) to generate X-ray flat panel detector (FPD) images from digitally reconstructed radiographic (DRR) images. FPD and treatment planning CT images were acquired from patients with prostate and head and neck (H&N) malignancies. The DNN parameters were optimized for FPD image synthesis. The synthetic FPD images' features were evaluated to compare to the corresponding ground-truth FPD images using mean absolute error (MAE), peak signal-to-noise ratio (PSNR), and structural similarity index measure (SSIM). The image quality of the synthetic FPD image was also compared with that of the DRR image to understand the performance of our DNN. For the prostate cases, the MAE of the synthetic FPD image was improved (= 0.12 ± 0.02) from that of the input DRR image (= 0.35 ± 0.08). The synthetic FPD image showed higher PSNRs (= 16.81 ± 1.54 dB) than those of the DRR image (= 8.74 ± 1.56 dB), while SSIMs for both images (= 0.69) were almost the same. All metrics for the synthetic FPD images of the H&N cases were improved (MAE 0.08 ± 0.03, PSNR 19.40 ± 2.83 dB, and SSIM 0.80 ± 0.04) compared to those for the DRR image (MAE 0.48 ± 0.11, PSNR 5.74 ± 1.63 dB, and SSIM 0.52 ± 0.09). Our DNN successfully generated FPD images from DRR images. This technique would be useful to increase throughput when images from two different modalities are compared by visual inspection.

A Phase Ib Study of Durvalumab (MEDI4736) in Combination with Carbon-Ion Radiotherapy and Weekly Cisplatin for Patients with Locally Advanced Cervical Cancer (DECISION Study): The Early Safety and Efficacy Results

We conducted a phase Ib study to examine the safety of a combination of carbon-ion RT (CIRT) with durvalumab (MEDI4736; AstraZeneca) in patients with locally advanced cervical cancer. This was an open-label, single-arm study with a modified 3 + 3 design. Patients with newly diagnosed histologically proven locally advanced cervical cancer were enrolled. All patients received 74.4 Gy of CIRT in 20 fractions and concurrent weekly cisplatin (chemo-CIRT) at a dose of 40 mg/m². Durvalumab was administered (1500 mg/body) at weeks two and six. The primary endpoint was the incidence of adverse events (AEs) and serious AEs (SAEs), including dose-limiting toxicity (DLT). All three enrolled patients completed the treatment without interruption. One patient developed hypothyroidism after treatment and was determined to be an SAE. No other SAEs were observed. The patient recovered after levothyroxine sodium hydrate treatment. None of the AEs, including hypothyroidism, were associated with DLT in the present study. All three patients achieved complete responses within the CIRT region concerning treatment efficacy. This phase 1b trial demonstrates the safety of combining chemo-CIRT and durvalumab for locally advanced cervical cancer in the early phase. Further research is required as only three patients were included in this study.

Basic and translational research on carbon-ion radiobiology

Carbon-ion beam irradiation (IR) has evident advantages over the conventional photon beams in treating tumors. It releases enormous amount of energy in a well-defined range with insignificant scatter in surrounding tissues based on well-localized energy deposition. Over the past 28 years, more than 14,000 patients with various types of cancer have been treated by carbon ion radiotherapy (CIRT) with promising results at QST. I have provided an overview of the basic and translational research on carbon-ion radiobiology including mechanisms underlying high linear energy transfer (LET) carbon-ion IR-induced cell death (apoptosis, autophagy, senescence, mitotic catastrophe etc.) and high radiocurability produced by carbon-ion beams in combination with DNA damaging drugs or with molecular-targeted drugs, micro-RNA therapeutics and immunotherapy. Additionally, I have focused on the application of these treatment in human cancer cells, especially cancer stem cells (CSCs). Finally, I have summarized the current studies on the application of basic carbon-ion beam IR according to the cancer types and clinical outcomes.

Carbon-ion beam irradiation in combination with cisplatin effectively suppresses xenografted malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a rare aggressive cancer. This study investigated the growth-inhibitory effects of the combination of carbon ion beam irradiation (IR) and cisplatin (CDDP) on MPM xenografts. Carbon-ion beam IR at 15 Gy effectively inhibited tumor growth and decreased the tumor volume more than 90% after 9 weeks. However, tumor regrowth was observed after 17 weeks. The combination of carbon-ion beam IR (15 Gy) and CDDP significantly suppressed tumor growth after 9 weeks, with tumor regression being observed for more than 18 weeks. In contrast, X-ray IR (30 Gy) alone or in combination with CDDP effectively suppressed tumor growth and decreased the tumor volume after 11 weeks, but tumor growth was observed after 15 weeks. Carbon-ion beam IR at 25 Gy resulted in complete tumor regression without tumor regrowth in the 20-week follow-up period. Histopathological analysis revealed that combination of carbon-ion beam IR and CDDP exerted effective cytotoxic effects on MPM xenograft tumor cells and significantly promoted tumor cell necrosis, cavitation, and fibrosis when compared with individual treatment with carbon-ion beam, X-ray IR, or CDDP. Immunohistochemical analysis revealed that the expression levels of tumor cell migration and invasion-related proteins such as CXCL12, MMP2 and MMP9 were not significantly affected upon low dose (15 Gy) carbon-ion beam IR alone or in combination with CDDP but were markedly upregulated upon treatment with CDDP alone relative to control. However, IR with a high dose (25 Gy) carbon-ion beam inhibited tumor growth without upregulating these proteins. In conclusion, the combination of IR with a low dose (15 Gy) carbon ion beam and CDDP effectively suppressed MPM tumor in vivo without significantly upregulating CXCL12, MMP2 and MMP9, suggesting that combination therapy of carbon ion beam IR and chemotherapy is a promising therapeutic strategy for MPM.

Effects of dose and dose-averaged linear energy transfer on pelvic insufficiency fractures after carbon-ion radiotherapy for uterine carcinoma

BACKGROUND AND PURPOSE

The correlation between dose-averaged linear energy transfer (LETd) and its therapeutic or adverse effects, especially in carbon-ion radiotherapy (CIRT), remains controversial. This study aimed to investigate the effects of LETd and dose on pelvic insufficiency fractures after CIRT.

MATERIAL AND METHODS

Among patients who underwent CIRT for uterine carcinoma, 101 who were followed up for > 6 months without any other therapy were retrospectively analyzed. The sacrum insufficiency fractures (SIFs) were graded according to the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer toxicity criteria. The correlations between the relative biological effectiveness (RBE)-weighted dose, LETd, physical dose, clinical factors, and SIFs were evaluated. In addition, we analyzed the association of SIF with LETd, physical dose, and clinical factors in cases where the sacrum D50% RBE-weighted dose was above the median dose.

RESULTS

At the last follow-up, 19 patients developed SIFs. Receiver operating characteristic curve analysis revealed that the sacrum D50% RBE-weighted dose was a valuable predictor of SIF. Univariate analyses suggested that LETd V10 keV/µm, physical dose V5 Gy, and smoking status were associated with SIF. Cox regression analysis in patients over 50 years of age validated that current smoking habit was the sole risk factor for SIF. Therefore, LETd or physical dose parameters were not associated with SIF prediction.

CONCLUSION

The sacrum D50% RBE-weighted dose was identified as a risk factor for SIF. Additionally, neither LETd nor physical dose parameters were associated with SIF prediction.

Long-term outcomes of high dose carbon-ion radiation therapy for unresectable upper cervical (C1-2) chordoma

Background

Chordoma is a rare, locally invasive neoplasm of the axial skeleton. Complete resection is often difficult, especially for the upper‐cervical (C1‐2) spine. We evaluated the efficacy and safety of carbon‐ion radiotherapy (CIRT) for unresectable C1‐2 chordoma.

Methods

Patients with C1‐2 chordoma treated with definitive CIRT (60.8 Gy [RBE] in 16 fractions) were retrospectively analyzed. We evaluated OS, LC, PFS, and toxicity.

Results

Nineteen eligible patients all completed the planned course of CIRT. With the median follow‐up 68 months (range: 29–144), median OS was 126 months (range: 36‐NA). Five‐year OS, LC, and PFS were 68.4% (95% CI, 42.8%–84.4%), 75.2% (46.1%–90.0%), and 64.1% (36.3%–82.3%), respectively. Regarding acute toxicity of grade ≥3, there was only one grade 3 mucositis. Late toxicity included radiation‐induced myelitis (grade 3 in 1 patient; 5.3%), and compression fractures (n = 5; 26.3%).

Conclusions

High‐dose CIRT is a promising treatment option for unresectable upper cervical chordoma.

Emerging Role of Carbon Ion Radiotherapy in Reirradiation of Recurrent Head and Neck Cancers: What Have We Achieved So Far?

Administering reirradiation for the treatment of recurrent head and neck cancers is extremely challenging. These tumors are hypoxic and radioresistant and require escalated radiation doses for adequate control. The obstacle to delivering this escalated dose of radiation to the target is its proximity to critical organs at risk (OARs) and possible development of consequent severe late toxicities. With the emergence of highly sophisticated technologies, intensity-modulated radiotherapy (IMRT) and stereotactic body radiotherapy have shown promising outcomes. Proton beam radiotherapy has been used for locally recurrent head and neck cancers because of its excellent physical dose distribution, exploring sharp Bragg peak properties with negligible entrance and exit doses. To further improve these results, carbon ion radiotherapy (CIRT) has been explored in several countries across Europe and Asia because of its favorable physical properties with minimal entrance and exit doses, sharper lateral penumbra, and much higher and variable relative biological efficacy, which cannot be currently achieved with any other form of radiation. Few studies have described the role of CIRT in recurrent head and neck cancers. In this article, we have discussed the different aspects of carbon ions in reirradiation of recurrent head and neck cancers, including European and Asian experiences, different dose schedules, dose constraints of OARs, outcomes, and toxicities, and a brief comparison with proton beam radiotherapy and IMRT.

Multicenter study of re-irradiation using carbon-ions for head and neck malignancies after photon radiotherapy

Purpose

The goal of this multicenter retrospective study of patients with head and neck malignancies was to evaluate the efficacy and safety of carbon‐ion (C‐ion) radiotherapy (RT) after photon RT.

Methods

We enrolled 56 patients with head and neck malignancies who underwent re‐irradiation (re‐RT) using C‐ions between November 2003 and March 2019, treated previously with photon RT. The tumors at re‐RT were located in the sinonasal cavities (n = 20, 35.7%), skull base (n = 12, 21.4%), and orbit (n = 7, 12.5%). The tumors at the initial RT were located in the sinonasal cavities (n = 13, 23.2%), skull base (n = 9, 16.1%), and orbit (n = 9, 16.1%). The median period between the initial RT and re‐RT was 41 (4–568) months. The most common histology of re‐RT was squamous cell carcinoma (n = 11, 19.6%). The most commonly used protocol was 57.6 Gy (relative biological effectiveness) in 16 fractions (n = 23, 41.1%). Surgery preceded re‐RT in three patients (5.4%). One patient with malignant melanoma received concurrent chemotherapy.

Results

The 2‐year local control, progression‐free survival, and overall survival rates were 66.5%, 36.9%, and 67.9%, respectively. The median follow‐up time was 28 months. Two patients (3.6%) developed grade ≥ 3 acute toxicities, and 14 (25.0%) developed grade ≥ 3 late toxicities. A single patient had confirmed grade 5 dermatitis with infection.

Conclusion

Re‐RT using C‐ions for head and neck malignancies after photon RT is an effective treatment with tolerable toxicity.

Long-term outcomes of octogenarian pancreatic cancer patients treated with carbon ion radiotherapy

BACKGROUND

Pancreatic cancer is a disease of the elderly; patients >65 years are 60% of the cases. Due to multiple comorbidities, treating these patients is challenging. We report the efficacy and safety of carbon ion radiotherapy (C-ion RT) in octogenarians.

METHODS

We retrospectively analyzed the cases of 46 pancreatic cancer patients aged ≥80 years (median 83, range 80-97) treated with definitive C-ion RT in 2007-2018 at our institute.

RESULTS

Twenty-five patients (54%) had resectable or borderline-resectable disease; none underwent surgery (because of medical reasons, e.g., age, multiple comorbidities). C-ion RT was delivered with a median dose of 55.2 Gy (RBE) in 12 fractions. The survivors' median follow-up period was 43 (range 19-76) months. The entire cohort's median overall survival (OS) was 15 (95%CI: 14-22) months with a 3-year OS of 20% (95%CI: 11%-35%). On both univariate and multivariate analyses, baseline CA19-9 remained the significant independent OS prognostic factor (p = 0.032). The 3-year local control rate for all patients was 34% (95%CI: 19%-53%). Local failure (n = 25, 54%) was as common as distant relapse (n = 26, 57%); 33% of the patients experienced both local and systemic failure. About 15% underwent re-C-ion RT for infield recurrence; they achieved a median 22-month OS. No patients exhibited grade ≥3 severe acute or late toxicities (including those who received re-C-ion RT).

CONCLUSIONS

C-ion RT in octogenarians with pancreatic cancer showed promising outcomes with acceptable acute and late toxicities and can be considered a reasonable alternative to radical surgery.

Accurate delineation of mucosal lesions in treatment planning computed tomography using iodine paste markers for oral mucosal melanoma

We introduce the utility of iodine paste markers using endodontic materials for the accurate contouring of mucosal lesions of oral mucosal melanoma (OMM), which are difficult to delineate on imaging during the planning of carbon-ion radiation therapy (CIRT). The patient had a primary OMM located in the palatal mucosa without palatal or maxillary bone invasion. A dental root canal filling material, which is a calcium hydroxide/iodoform non-hardenable paste, was used as a marker. We first performed treatment planning computed tomography (CT) without an iodine paste marker for mucosal lesions. Subsequently, we placed an iodine paste marker on the palatal mucosal lesion to accurately delineate the mucosal lesions of the palate. Finally, we took reference CT with an iodine paste marker. CT without the marker was fused to the reference CT with markers during treatment planning, and the gross tumor volume (GTV) was contoured. Thereafter, CIRT was delivered without markers. During CIRT, expected acute mucositis was observed in the area of the planning target volume (PTV), including melanosis, in accordance with the dose distribution. The use of iodine paste markers for localized mucosal lesions, which are difficult to delineate on CT and MRI, may be useful for contouring GTVs on treatment planning CT accurately.

Carbon Ion Radiotherapy for Locally Recurrent Rectal Cancer of Patients with Prior Pelvic Irradiation

BACKGROUND

This study aimed to assess the safety and efficacy of carbon-ion radiotherapy (CIRT) for salvage of previously X-ray-irradiated (XRT) locally recurrent rectal cancer (LRRC).

METHODS

Between September 2005 and December 2017, 77 patients with LRRC were treated with CIRT re-irradiation. All the patients had received prior XRT with a median dose of 50.0 Gy (range 20-74 Gy), principally for neoadjuvant or adjuvant recurrence prophylaxis in 34 patients and for recurrence in 43 patients. The total CIRT dose of 70.4 Gy (RBE) (gray relative biologic effectiveness) was administered in 16 fixed fractions during 4 weeks (4.4 Gy [RBE] per fraction).

RESULTS

All the patients completed the scheduled treatment course. None of the patients received resection after CIRT. Acute grade 3 toxicities occurred for eight patients (10 %), including five grade 3 pelvic infections (2 involving pain and 1 involving neuropathy). Late grade 3 toxicities occurred for 16 patients (21 %): 13 with late grade 3 pelvic infections, 9 with gastrointestinal toxicity, 1 with skin toxicity, 2 with pain, and 4 with neuropathy. No grade 4+ toxicity was noted. The overall local control rates (infield + out-of-field recurrence) were 69 % at 3 years and 62 % at 5 years. In the planning target volume (PTV), the infield recurrence rates were 90 % and 87 % respectively. The control rates for regional recurrence were 85 % at 3 years and 81 % at 5 years. The median overall survival time was 47 months. The survival rates were 61 % at 3 years and 38 % at 5 years.

CONCLUSION

Carbon-ion re-irradiation of previously X-ray-irradiated locally recurrent rectal cancer appears to be safe and effective, providing good local control and survival advantage without unacceptable morbidity.

Adaptation of stochastic microdosimetric kinetic model to hypoxia for hypo-fractionated multi-ion therapy treatment planning

For hypo-fractionated multi-ion therapy (HFMIT), the stochastic microdosimetric kinetic (SMK) model had been developed to estimate the biological effectiveness of radiation beams with wide linear energy transfer (LET) and dose ranges. The HFMIT will be applied to radioresistant tumors with oxygen-deficient regions. The response of cells to radiation is strongly dependent on the oxygen condition in addition to radiation type, LET and absorbed dose. This study presents an adaptation of the SMK model to account for oxygen-pressure dependent cell responses, and develops the oxygen-effect-incorporated stochastic microdosimetric kinetic (OSMK) model. In the model, following assumptions were made: the numbers of radiation-induced sublethal lesions (double-strand breaks) are reduced due to lack of oxygen, and the numbers of oxygen-mediated lesions are reduced for radiation with high LET. The model parameters were determined by fitting survival data under aerobic and anoxic conditions for human salivary gland tumor cells and V79 cells exposed to helium-, carbon-, and neon-ion beams over the LET range of 18.5-654.0 keVμm^-1. The OSMK model provided good agreement with the experimental survival data of the cells with determination coefficients >0.9. In terms of oxygen enhancement ratio, the OSMK model reproduced the experimental data behavior, including slight dependence on particle type at the same LET. The OSMK model was then implemented into the in-house treatment planning software for the HFMIT to validate its applicability in clinical practice. A treatment plan with helium- and neon-ion beams was made for a pancreatic cancer case assuming an oxygen-deficient region within the tumor. The biological optimization based on the OSMK model preferentially placed the neon-ion beam to the hypoxic region, while it placed both helium- and neon-ion beams to the surrounding normoxic region. The OSMK model offered the accuracy and usability required for hypoxia-based biological optimization in HFMIT treatment planning.

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.

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.

Long-term outcomes of skull base chordoma treated with high-dose carbon-ion radiotherapy

Background

We evaluated the long‐term efficacy and safety of carbon‐ion radiotherapy (C‐ion RT) for skull base chordoma, a rare neoplasm.

Methods

Thirty‐four patients with skull base chordoma who were treated with C‐ion RT were prospectively enrolled and analyzed retrospectively. C‐ion RT was delivered with 60.8 Gy (relative biological effectiveness [RBE]) in 16 fractions at four fractions per week.

Results

The median follow‐up period was 108 months. The 5‐ and 9‐year local control rates were 76.9% and 69.2%, respectively. The 5‐ and 9‐year overall survival rates were 93.5% and 77.4%, respectively. Regarding grade 3 or more severe late reactions, one patient developed a grade 3 mucosal ulcer, two developed grade 4 ipsilateral optic nerve injuries, and one developed a grade 5 mucosal ulcer at 9 years and 3 months after C‐ion RT.

Conclusion

C‐ion RT with 60.8 Gy (RBE)/16 fractions is a promising treatment option for inoperable skull base chordoma.

Long-term outcomes and toxicities of carbon-ion radiotherapy in malignant tumors of the sphenoid sinus

BACKGROUND

Most of the primary sphenoid sinus tumors present with locally advanced stages with involvement of adjacent critical structures and are not amenable to radical resection. We sought to evaluate the safety and efficacy of carbon-ion radiotherapy (C-ion RT) for sphenoid sinus malignancies.

METHODS

This is a retrospective analysis of 22 patients of primary sphenoid carcinomas treated with definitive C-ion RT.

RESULTS

Adenoid cystic carcinoma was the most common histology (15 patients, 68.2%). The median follow-up of this cohort was 48.5 months. The actuarial local control and overall survival at 5 years were 51.0% and 62.7%, respectively. Grade 4 visual impairment and grade 4 brain necrosis were seen in six and one patient, respectively.

CONCLUSION

C-ion RT can provide a reasonably good clinical outcome in locally advanced sphenoid sinus malignancies with a marginally higher late toxicity profile because of extremely close proximity of the target volume to critical structures.

Multicenter study of carbon-ion radiation therapy for nonsquamous cell carcinomas of the oral cavity

Background

The aim of this study was to evaluate the efficacy and safety of carbon‐ion radiation therapy for nonsquamous cell carcinomas of the oral cavity in a multicenter study.

Methods

Retrospective analysis of the clinicopathological features and outcomes of 76 patients with oral nonsquamous cell carcinomas with N0‐1 M0 status and were treated with carbon‐ion radiation therapy at four institutions in Japan between November 2003 and December 2014 was performed.

Results

Salivary gland carcinoma, mucosal melanoma, and three other carcinomas were found in 46, 27, and 3 patients, respectively. T1‐3, T4a, and T4b disease was diagnosed in 27, 18, and 31 patients, respectively. Median follow‐up period was 31.1 months (range, 3‐118 months). Three‐year local control, progression‐free survival, and overall survival of all patients were 86.8%, 63.1%, and 78.4%, respectively. Multivariate analysis showed T classification (T4) to be a significant independent poor prognostic factor for local control. Acute grade 3 mucositis was observed in 38 patients. Grades 3 and 4 late morbidities were observed in 9 and 4 patients, respectively. No grade 5 late toxicity was observed.

Conclusions

Oral nonsquamous cell carcinomas could be treated effectively, with acceptable toxicity, by carbon‐ion radiation therapy.

First prospective feasibility study of carbon-ion radiotherapy using compact superconducting rotating gantry

Objective:

We had developed compact rotating gantry for carbon ion using superconducting magnets in 2015 which became clinically operational in 2017. The objective of this study was to assess the clinical feasibility and safety of using compact rotating gantry with three-dimensional active scanning in delivery of carbon-ion radiotherapy (C-ion RT) for relatively stationary tumours.

Methods:

A prospective feasibility study was conducted with 10 patients who had been treated with C-ion RT using compact rotating gantry between April 2017 and April 2018 at Hospital of the National Institute of Radiological Sciences (NIRS) for head and neck and prostate cancers. The primary end point was evaluation of acute toxicities within 3 months of starting C-ion RT.

Results:

Out of 10 cases 8 were of head and neck cancers and 2 were of prostate cancers. All of those eight head and neck cases were of locally advanced stages. Both of the prostate cancer patients belong to intermediate risk categories. None of the patients developed even Grade 2 or more severe skin reactions. Six out of eight cases with head and neck cancers experienced Grade 2 mucosal reactions; however, nobody developed Grade 3 or more severe mucosal reactions. There was no gastrointestinal reaction observed in prostate cancer patients. One patient developed Grade 2 genitourinary reaction.

Conclusion:

C-ion RT using compact rotating gantry and three-dimensional active scanning is a safe and feasible treatment for relatively less mobile tumours.

Advances in knowledge:

This study will be the first step to establish the use of superconducting rotating gantry in C-ionRT in clinical setting paving the way for treating large number of patients and make it a standard of practice in the future.

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.

A step towards international prospective trials in carbon ion radiotherapy: investigation of factors influencing dose distribution in the facilities in operation based on a case of skull base chordoma

Background

Carbon ion radiotherapy (CIRT) has been delivered to more than 20,000 patients worldwide. International trials have been recommended in order to emphasize the actual benefits. The ULICE program (Union of Light Ion Centers in Europe) addressed the need for harmonization of CIRT practices. A comparative knowledge of the sources and magnitudes of uncertainties altering dose distribution and clinical effects during the whole CIRT procedure is required in that aim.

Methods

As part of ULICE WP2 task group, we sent a centrally reviewed questionnaire exploring candidate sources of uncertainties in dose deposition to the ten CIRT facilities in operation by February 2017. We aimed to explore native beam characterization, immobilization, anatomic data acquisition, target volumes and organs at risks delineation, treatment planning, dose delivery, quality assurance prior and during treatment. The responders had to consider the clinical case of a clival chordoma eligible for postoperative CIRT according to their clinical practice. With the results, our task group discussed ways to harmonize CIRT practices.

Results

We received 5 surveys from facilities that have treated 77% of the patients worldwide per November 2017. We pointed out the singularity of the facilities and beam delivery systems, a divergent definition of target volumes, the multiplicity of TPS and equieffective dose calculation approximations.

Conclusion

Multiple uncertainties affect equieffective dose definition, deposition and calculation in CIRT. Although it is not possible to harmonize all the steps of the CIRT planning between the centers, our working group proposed counter-measures addressing the improvable limitations.

Feasibility of carbon-ion radiotherapy for oral non-squamous cell carcinomas

Background

This study evaluated carbon‐ion radiotherapy (C‐ion RT) for oral non‐squamous cell carcinomas (non‐SCC).

Methods

We retrospectively obtained data from 74 patients who underwent C‐ion RT for oral malignancies between April 1997 and March 2016. The C‐ion RT was administered in 16 fractions at a total dose of 57.6 or 64.0 Gy (relative biological effectiveness).

Results

Forty‐three patients had salivary gland carcinomas, 29 patients had mucosal melanoma, and 2 patients had other types of pathologies. The tumors were classified as T1‐T3 (24 cases), T4a (21 cases), or T4b (29 cases). The median follow‐up was 49 months. The 5‐year rates were 78.8% for local control, 36.2% for progression‐free survival, and 58.3% for overall survival. Although 10 patients developed grade 3 osteoradionecrosis after C‐ion RT, all patients maintained their mastication and deglutition functions after sequestrectomy and prosthesis placement.

Conclusion

C‐ion RT was effective for oral non‐SCC and had acceptable toxicities.

A retrospective multicenter study of carbon-ion radiotherapy for external auditory canal and middle ear carcinomas

Background

We conducted a retrospective multicenter study to assess the clinical outcomes of carbon‐ion radiotherapy (CIRT) for head and neck malignancies (Japan Carbon‐Ion Radiation Oncology Study Group [J‐CROS] study: 1402 HN). We aimed to evaluate the safety and efficacy of CIRT in patients with external auditory canal (EAC) and middle ear (ME) carcinomas.

Methods

Thirty‐one patients treated with CIRT at four Japanese institutions were analyzed. Fourteen patients (45.2%) had squamous cell carcinomas, 13 (41.9%) had adenoid cystic carcinomas, and four (12.9%) had other types. Nineteen (61.3%), six (19.4%), three (9.7%), and three (9.7%) patients had T4, T3, T2, and T1 disease, respectively. All patients had N0M0 status. The median radiation dose was 64 Gy (relative biological effectiveness) in 16 fractions. The median gross tumor volume was 33.3 mL.

Results

The median follow‐up period was 18.4 months (range, 5.1‐85.6). The 1‐ and 3‐year local control and overall survival rates were 75.0% and 55.0% and 79.3% and 58.7%, respectively. Regarding grade 3 or higher toxicities, three patients (9.7%) had grade 3 dermatitis, one (3.2%) had grade 3 mucositis, and two (6.5%) had grade 3 central nervous necrosis (ie, radiation‐induced brain necrosis). No grade 4 or worse reactions were observed.

Conclusion

CIRT was effective for EAC and ME carcinomas.

A multi-institutional retrospective study of carbon-ion radiotherapy for non-squamous cell malignant tumors of the nasopharynx: Subanalysis of Japan Carbon-Ion Radiation Oncology Study Group study 1402 HN

Background

This multi‐institutional retrospective study focused on the clinical outcome of carbon‐ion radiotherapy (C‐ion RT) for non‐squamous cell malignant tumors of the nasopharynx.

Methods

The Japan Carbon‐ion Radiation Oncology Study Group collected and analyzed data for 43 patients with non‐squamous cell malignant tumors of the nasopharynx treated with C‐ion RT at four institutions in Japan.

Results

Twenty‐nine patients had adenoid cystic carcinomas, seven had malignant melanomas, three had adenocarcinomas, two had mucoepidermoid carcinomas, and two had other pathologies. Twenty‐six of the 43 patients (61%) had T4 tumors. The most common dose‐fractionation schedule was 64 Gy (relative biological effectiveness) in 16 fractions. The median follow‐up period was 30 months. The 2‐year local control (LC) and overall survival (OS) rates were 88% and 84%, respectively. For late toxicity, one patient developed grade 4 optic nerve disorder and two developed grade 5 pharyngeal hemorrhage. Actual incidence of grade 3 or higher late adverse events was 19%, and included cranial nerve dysfunction, jaw bone necrosis, central nervous system necrosis, and ear inflammation.

Conclusions

C‐ion RT provided good LC and OS rates with acceptable toxicity for treatment of non‐squamous cell malignant tumors of the nasopharynx.

A retrospective multicenter study of carbon-ion radiotherapy for major salivary gland carcinomas: Subanalysis of J-CROS 1402 HN

A retrospective multicenter study was carried out to assess the clinical outcomes of carbon-ion radiotherapy for head and neck malignancies (Japan Carbon-Ion Radiation Oncology Study Group [J-CROS] study: 1402 HN). We evaluated the safety and efficacy of carbon-ion radiotherapy in patients with major salivary gland carcinoma. Sixty-nine patients treated with carbon-ion radiotherapy at four Japanese institutions were analyzed. Thirty-three patients (48%) had adenoid cystic carcinomas, 10 (14%) had mucoepidermoid carcinomas, and 26 (38%) had other disease types. Three patients (4%) had T1 disease, 8 (12%) had T2, 25 (36%) had T3, and 33 (48%) had T4. The median radiation dose was 64 Gy (relative biological effectiveness) in 16 fractions. The median gross tumor volume was 27 mL. The median follow-up period was 32.7 months. The 3-year local control rate and overall survival rate were 81% and 94%, respectively. Regarding acute toxicities, seven patients had grade 3 mucositis and seven had grade 3 dermatitis. Regarding late toxicities, one patient had grade 3 dysphagia and one had a grade 3 brain abscess. No grade 4 or worse late reactions were observed. In conclusion, definitive carbon-ion radiotherapy was effective with acceptable toxicity for major salivary gland carcinomas.

A Retrospective Multicenter Study of Carbon Ion Radiotherapy for Locally Advanced Olfactory Neuroblastomas

The purpose was to evaluate efficacy and safety of carbon ion radiotherapy (C-ion RT) in patients with locally advanced olfactory neuroblastomas (ONBs). This study was a sub-analysis of the Japan Carbon-Ion Radiation Oncology Study Group Study (1402 HN, UMIN000024473). Clinical data of T4 ONBs treated with C-ion RT at four Institutions between November 2003 and December 2014 were retrospectively reviewed. Twenty-one patients underwent C-ion RT. Seven patients had T4a and 14 had T4b tumours without cervical node metastases. The median follow-up period was 39 (range=5-111) months. The 3-year overall survival and local control rates were 88.4% and 83.0%, respectively. Grade 4 late toxicity was observed in three patients, including ipsilateral optic nerve disorder (n=2) and ipsilateral retinopathy (n=1). C-Ion RT is effective and can be a curative modality for T4 ONBs. Prospective multicenter studies are warranted to confirm these findings.

A custom-made mouthpiece incorporating tongue depressors and elevators to reduce radiation-induced tongue mucositis during carbon-ion radiation therapy for head and neck cancer

We introduce a custom-made mouthpiece for carbon-ion radiation therapy for head and neck malignancy. The mouthpiece incorporates either a tongue depressor or elevator depending on tumor location. The risk of tongue mucositis may be reduced without compromising therapeutic efficacy through mouthpiece shaping.

Long-term outcomes after carbon-ion radiotherapy for oral mucosal malignant melanoma

Oral mucosal malignant melanoma (OMM) is extremely rare and has a poor prognosis. Owing to its rarity, it has not yet been possible to establish an optimal treatment modality. The objective of this study was to evaluate the long-term efficacy of carbon-ion radiotherapy (C-ion RT) for OMM. Between 1997 and 2013, 19 patients with OMM were treated with C-ion RT alone. Patient ages ranged from 44 to 84 years (median, 69 years). Nine men and 10 women were included. OMMs were restaged in accordance with the seventh edition of the tumour/node/metastasis (TNM) Staging System of the International Union Against Cancer. Before treatment, 14 patients had T3 disease and 5 had T4a disease. Three patients were classified as having N1 disease. All patients were classified as having M0. The hard palate was the most frequently involved oral subsite. All patients were treated with 57.6 Gy (relative biological effectiveness) in 16 fractions. The median follow-up period was 61 months (range, 8-190 months). The 5-year local control, overall survival and progression-free survival rates were 89.5%, 57.4% and 51.6%, respectively. For local control and overall survival, T classification was found to be a significant prognostic factor. Grade 2 and 3 osteoradionecrosis was observed in three and four patients, respectively. The presence of teeth within the planning target volume was a significant risk factor for developing osteoradionecrosis. C-ion RT was an effective treatment option with acceptable toxicity for OMM.

Multi-institutional retrospective study of mucoepidermoid carcinoma treated with carbon-ion radiotherapy

This study aimed to evaluate the clinical outcomes of patients with mucoepidermoid carcinomas in the head and neck treated with carbon‐ion radiotherapy. Data from 26 patients who underwent carbon‐ion radiotherapy in four facilities were analyzed in this multi‐institutional retrospective study: the Japan Carbon‐ion Radiation Oncology Study Group. The median follow‐up time was 34 months. One patient experienced local recurrence, and the 3‐year local control rate was 95%. One patient developed lymph node recurrence and five developed distant metastases. The 3‐year progression‐free survival rate was 73%. Five patients died, two of mucoepidermoid carcinoma and three of intercurrent disease. The 3‐year overall survival rate was 89%. Acute mucositis and dermatitis of grade 3 or higher were experienced by 19% and 8% of patients, respectively; these improved with conservative therapy. Late mucositis and osteonecrosis of jaw were observed in 12% and 23% of patients, respectively. The 3‐year cumulative rate of any late adverse event of grade 3 or higher was 14%. None of the patients died of the acute or late adverse events. Carbon‐ion radiotherapy was efficacious and safe for treating mucoepidermoid carcinoma in this multi‐institutional retrospective study (registration no. UMIN000024473). We are currently undertaking a prospective multicenter study.

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.

Radiation-induced Parotid Gland Atrophy in Patients with Head and Neck Cancer After Carbon-ion Radiotherapy

BACKGROUND/AIM

This study aimed to clarify the relationship between dosimetric factors and parotid gland (PG) atrophy after carbon ion radiotherapy (C-ion RT).

PATIENTS AND METHODS

Fifty-four patients with head and neck tumours were enrolled and 93 irradiated PGs were analyzed. Thirty and 24 patients were treated with total doses [relative biological effectiveness (RBE)] of 57.6 Gy and 64.0 Gy, respectively, in 16 fractions. PG volumes were measured using computed tomographic images obtained before C-ion RT and every 3-6 months thereafter.

RESULTS

The median follow-up period was 46.4 months (range=24.0-123.0 months). Univariate analysis showed that PG volumes receiving more than 5, 10, 15, and 20 Gy RBE (V5, V10, V15 and V20, respectively), mean dose, and maximum dose were significantly associated with PG atrophy. Multivariate analysis indicated that only V5 was significantly associated with atrophy.

CONCLUSION

Increasing V5 was a significant risk factor for PG atrophy after C-ion RT.

Definitive carbon-ion radiotherapy for locally advanced parotid gland carcinomas

BACKGROUND

The purpose of this study was to present our evaluation of the safety and efficacy of carbon-ion radiotherapy (C-ion RT) for locally advanced parotid gland carcinomas.

METHODS

Clinicopathological features and outcomes were evaluated in 46 patients receiving C-ion RT for parotid gland carcinomas.

RESULTS

Sixteen patients had adenoid cystic carcinoma; 8 had adenocarcinoma, 8 had mucoepidermoid carcinoma, and 14 had other carcinomas. T2, T3, T4a, and T4b diseases were diagnosed in 3, 18, 8, and 17 patients, respectively. C-ion RT was provided to 25 patients as the primary treatment, to 20 patients for local recurrences after surgery, and to 1 patient for residual tumor after surgery. During follow-up (median duration, 62 months), 5-year local control and overall survival (OS) rates were 74.5% and 70.1%, respectively. Of the 30 patients without facial nerve palsy before C-ion RT, 25 showed no radiation-induced facial nerve palsy.

CONCLUSION

C-ion RT is effective and has acceptable toxicity levels for locally advanced parotid gland carcinomas. © 2016 Wiley Periodicals, Inc. Head Neck 39: 724-729, 2017.

Comparing laparoscopic appendectomy to open appendectomy in managing generalised purulent peritonitis from complicated appendicitis: the uncharted path

BACKGROUND

The objective of the study was to compare the outcomes of patients with generalised purulent peritonitis from complicated appendicitis diagnosed intraoperatively who were managed laparoscopically to those managed via the open approach in a single institution.

METHOD

Data were collected from all cases admitted at Sebokeng Hospital, Johannesburg, over the past two years (2008 and 2009) with an intraoperative diagnosis of generalised purulent peritonitis from complicated appendicitis. Cases managed laparoscopically or by the open approach were analysed. The demographic findings, theatre duration, complications, days to the commencement of a full ward diet and the length of the hospital stay were the analysed parameters.

RESULTS

One hundred and twenty appendectomies with generalised purulent peritonitis were performed during the study period. Of these, 58 patients underwent open appendectomy, and 62 patients had laparoscopic appendectomy. Both groups were comparable with regard to the demographics and preoperative findings. Theatre duration was significantly higher in the laparoscopic appendectomy group -116 minutes for a laparoscopic appendectomy compared to 87 minutes for an open appendectomy. The rate of intra-abdominal sepsis was also higher in the laparoscopic appendectomy group - 13% for a laparoscopic appendectomy, and 9% for an open appendectomy. A statistically significant decrease in the wound sepsis rate was shown in the laparoscopic appendectomy group. No statistical significant difference was demonstrated with regard to other postoperative complications, days to the commencement of a full ward diet and the length of hospital stay in both groups. More time (an average of 3.7 days) was spent in the intensive care unit and high care unit by those in the open appendectomy group, than those in the laparoscopic appendectomy group (an average of 2.0 days). However, age, duration of symptoms, clinical presentation and white blood cell count were influencing factors on the outcome measures in the open appendectomy group.

CONCLUSION

Generalised purulent peritonitis from complicated appendicitis can be managed successfully laparoscopically. Both approaches are feasible, safe and have comparable outcomes. The laparoscopic approach resulted in fewer postoperative wound sepsis complications.

Single-energy metal artefact reduction with CT for carbon-ion radiation therapy treatment planning

OBJECTIVE

One approach to improving image quality of CT is to use metal artefact reduction image processing, such as single-energy metal artefact reduction (SEMAR). To quantify the impact of image correction on the quality of carbon-ion dose distribution, treatment planning using SEMAR was evaluated.

METHODS

Using a head phantom into which metal screws could be inserted, we acquired standard planning CT images. We calculated dose distributions using phantom images with and without metal added, and with and without SEMAR. Hounsfield unit (HU) and dose distribution variation of these images with and without SEMAR were measured using metal-free image subtraction. We similarly analysed the image data sets of two patients with head and neck cancer who had dental implants.

RESULTS

HU difference between metal-containing images and metal-free images without and with SEMAR were -79.5 ± 97.2 HU and -1.4 ± 19.5 HU on severe artefact area, respectively. The range of dose distribution difference from the prescribed dose between uncorrected and SEMAR-corrected images varied from -19.5% to -3.4% within planning target volume (PTV). PTV-D95 (%) for uncorrected and SEMAR-corrected image data were 82.4% and 95.4%, respectively. For data in patients with metal dental work, PTV-D95 (%) for uncorrected and SEMAR-corrected data were 92.2% and 92.5% (Patient 1), and 90.9% and 95.7% (Patient 2), respectively.

CONCLUSION

SEMAR algorithm shows promise in improving CT image quality and in ensuring an accurate representation of dose distribution.

ADVANCES IN KNOWLEDGE

SEMAR may improve treatment accuracy without the need for dental implant extraction in patients with head and neck cancer.

Evaluation of the safety and efficacy of carbon ion radiotherapy for locally advanced adenoid cystic carcinoma of the tongue base

BACKGROUND

Most cases of adenoid cystic carcinoma (ACC) of the tongue base are radioresistant, and are diagnosed in the advanced stage. Therefore, we evaluated the safety and efficacy of carbon ion radiotherapy (C-ion RT) for locally advanced ACC of the tongue base.

METHODS

Eighteen patients with ACC of the tongue base were treated with C-ion RT between May 2002 and April 2014. Seventeen patients had T4a disease and 1 patient had T2 disease before C-ion RT.

RESULTS

The median follow-up period was 57 months (range, 10-132 months). The 5-year local control rate was 92%. The 5-year overall survival (OS) and disease-free survival (DFS) rates were 72% and 44%, respectively. Regarding late reactions, 2 patients developed grade 3 mandible osteoradionecrosis, and 1 had grade 3 hemorrhage of the tongue base.

CONCLUSION

C-ion RT was effective with acceptable toxicities for locally advanced ACC of the tongue base. © 2016 Wiley Periodicals, Inc. Head Neck 38: E2122-E2126, 2016.