Innovative Combination Treatment to Expand the Indications of Particle Therapy: Spacer Placement Surgery Using Bio-Absorbable Polyglycolic Acid Spacer.

BACKGROUND: Particle therapy has favorable dose distribution and high curability. However, radiotherapy for malignant tumors adjacent to the gastrointestinal tract is contraindicated owing to its low tolerance. To overcome this, combination treatment with surgery to make a space between the tumor and adjacent gastrointestinal tract followed by particle therapy has been developed. Several materials have been used for the spacer and recently, we developed the absorbable polyglycolic acid (PGA) spacer, which has been used since 2019. This study is the first report of consecutive case series of spacer placement surgery using the PGA spacer. STUDY DESIGN: Fifty consecutive patients undergoing spacer placement surgery with the PGA spacer were evaluated. Postoperative laboratory data, morbidity related to the treatment, and spacer volume after treatment were evaluated. RESULTS: There were no treatment-related deaths, and all but 2 patients completed combination treatment. The median ratios of postoperative PGA spacer volume to the pretreatment volume were 96.9%, 87.7%, and 74.6% at weeks 2, 4, and 8, respectively. The spacer volume was maintained at 80% at 7 weeks and was predicted to be 50% at 15 weeks and 20% in 24 weeks. CONCLUSIONS: Spacer placement surgery using the PGA spacer was feasible and tolerable. The PGA spacers maintained sufficient thickness during the duration of subsequent particle therapy. Combination treatment using the PGA spacer is innovative and has the potential to become a new standard curative local treatment.

Comparison of passive-scattered and intensity-modulated proton beam therapy of craniospinal irradiation with proton beams for pediatric and young adult patients with brain tumors.

PURPOSE: To investigate the dose stability of craniospinal irradiation based on irradiation method of proton beam therapy (PBT). METHODS AND MATERIALS: Twenty-four pediatric and young adult brain tumor patients (age: 1-24 years) were examined. Treatment method was passive-scattered PBT (PSPT) in 8 patients and intensity-modulated PBT (IMPT) in 16 patients. The whole vertebral body (WVB) technique was used in 13 patients whose ages were younger than 10, and vertebral body sparing (VBS) technique was used for the remaining 11 patients aged 10 and above. Dose stability of planning target volume (PTV) against set-up error was investigated. RESULTS: The minimum dose (Dmin) of IMPT was higher than that of PSPT (p = 0.01). Inhomogeneity index (INH) of IMPT was lower than that of PSPT (p = 0.004). When the irradiation field of the cervical spinal cord level (C level) was shifted, the maximum dose (Dmax) was lower in IMPT, and mean dose (Dmean) was higher than PSPT as movement became greater to the cranial-caudal direction (p = 0.000-0.043). Dmin was higher and INH was lower in IMPT in all directions (p = 0.000-0.034). When the irradiation field of the lumber spinal cord level (L level) was shifted, Dmax was lower in IMPT as movement became greater to the cranial direction (p = 0.000-0.028). Dmin was higher and INH was lower in IMPT in all directions (p = 0.000-0.022). CONCLUSIONS: The PTV doses of IMPT and PSPT are robust and stable in both anterior-posterior and lateral directions at both C level and L level, but IMPT is more robust and stable than PSPT for cranial-caudal movements. TRIAL REGISTRY: Clinical Trial Registration number: No. 04-03.

Clinical impact of spacer placement surgery with expanded polytetrafluoroethylene sheet for particle therapy.

BACKGROUND: Spacer placement surgery is useful in particle therapy (PT) for patients with abdominopelvic malignant tumors located adjacent to the gastrointestinal tract. This study aimed to assess the safety, efficacy, and long-term outcomes of spacer placement surgery using an expanded polytetrafluoroethylene (ePTFE) spacer. METHODS: This study included 131 patients who underwent ePTFE spacer placement surgery and subsequent PT between September 2006 and June 2019. The overall survival (OS) and local control (LC) rates were calculated using Kaplan-Meier method. Spacer-related complications were classified according to the National Cancer Institute Common Terminology Criteria for Adverse Events (version 5.0). RESULTS: The median follow-up period after spacer placement surgery was 36.8 months. The 3-year estimated OS and LC rates were 60.5% and 76.5%, respectively. A total of 130 patients (99.2%) were able to complete PT. Spacer-related complications of ≥ grade 3 were observed in four patients (3.1%) in the acute phase and 13 patients (9.9%) in the late phase. Ten patients (7.6%) required removal of the ePTFE spacer. CONCLUSIONS: Spacer placement surgery using an ePTFE spacer for abdominopelvic malignant tumors is technically feasible and acceptable for subsequent PT. However, severe spacer-related late complications were observed in some patients. Since long-term placement of a non-absorbable ePTFE spacer is associated with risks for morbidity and infection, careful long-term follow-up and prompt therapeutic intervention are essential when complications associated with the ePTFE spacer occur. TRIAL REGISTRATION: retrospectively registered.

Comparison of Craniospinal Irradiation Using Proton Beams According to Irradiation Method and Initial Experience Treating Pediatric Patients.

Purpose: This study compared craniospinal irradiation using proton beam therapy (PBT) according to irradiation method and investigated the initial effects. Methods and Materials: Twenty-four pediatric patients (1-24 years old) who received proton craniospinal irradiation were examined. Passive scattered PBT (PSPT) and intensity modulated PBT (IMPT) were used in 8 and 16 patients, respectively. The whole vertebral body technique was used for 13 patients <10 years old, and the vertebral body sparing (VBS) technique was used for the remaining 11 patients aged ≥10 years. The follow-up period was 17 to 44 (median, 27) months. Organ-at-risk and planning target volume (PTV) doses and other clinical data were examined. Results: The maximum lens dose using IMPT was lower than that using PSPT (P = .008). The mean thyroid, lung, esophagus, and kidney doses were lower in patients treated using the VBS technique compared with the whole vertebral body technique (all P < .001). The minimum PTV dose of IMPT was higher than that of PSPT (P = .01). The inhomogeneity index of IMPT was lower than that of PSPT (P = .004). Conclusions: IMPT is better than PSPT at reducing the dose to the lens. The VBS technique can decrease the doses to neck-chest-abdomen organs. The PTV coverage of IMPT is superior to that of PSPT.

Local surgery feasibility and safety after carbon ion radiotherapy for primary bone sarcomas.

BACKGROUND: It is known that several complications are caused by local surgery after radiotherapy. Clinical reports that describe the postoperative complications associated with surgery after carbon ion radiotherapy are sparse. This study aimed to elucidate local surgery feasibility after carbon ion radiotherapy specifically for primary bone sarcomas. METHODS: The medical, surgical, and irradiation records of patients who had local surgery at the area irradiated with carbon ion beams between 2004 and 2018 were reviewed retrospectively to evaluate the feasibility and indication of local surgery after CIRT. RESULTS: There were eight patients who had 10 local surgeries at the irradiated sites among the 42 carbon ion radiotherapy patients. There were seven males and one female with a median age of 50 years (range 26-73 years). The reasons for surgery were three for skin toxicity and associated infection, five for bone collapse, and associated implant failure, and two for tumor regrowth. All surgical fields included the area of more than 60 Gy (RBE) irradiated dose. All three surgical cases caused by skin toxicity and associated infection had Grade I wound complication after surgery according to the Clavien-Dindo Classification. CONCLUSION: Local surgery after CIRT appeared feasible in selected patients with primary bone sarcoma, especially for the patients with bone collapse and associated implant failure. However, infection and prescribed irradiation dose at the incision site must be carefully evaluated.

Combination chemotherapy of doxorubicin and ifosfamide with proton beam therapy for myoepithelial carcinoma originating in the paraspinal region: A case report and literature review.

Soft tissue myoepithelial carcinoma (MEC) is an extremely rare mesenchymal tumor that has a poor prognosis unless complete surgical resection is achieved. The present study reported a case of a 38-year-old woman with a tumor in the left paraspinal region at L2 to L3 with vertebral destruction. MEC was diagnosed based on molecular pathological examination of a biopsy specimen. Because curative surgery was expected to be difficult, a combination of chemotherapy with doxorubicin and ifosfamide and proton beam therapy as local therapy was performed, resulting in long-term survival for at least 7.8 years. To the best of our knowledge, this is the first case of soft tissue MEC for which classical cytotoxic chemotherapy and proton beam therapy were effective. Although surgical resection with negative margins is the mainstay of treatment for MEC, adequate doxorubicin-based systemic therapy and high-dose radiation therapy may be a feasible alternative in patients with unresectable or advanced MEC. Future studies on the relationship between molecular pathological features, including biomarkers, and the selection of therapeutic agents are warranted.

Carbon ion radiotherapy for unresectable primary undifferentiated pleomorphic sarcoma of the 11th thoracic spine: a case report.

Objective: Primary undifferentiated pleomorphic sarcoma (UPS) of the bone is rare. However, the common sites are the knee and proximal femur and humerus, while spinal involvement is rare. We report a case of primary UPS of the 11th thoracic vertebra, where corpectomy would have been difficult and extensive, treated with carbon ion radiotherapy. Case report: A 76-year-old man presented with an osteolytic tumor of the 11th thoracic vertebra on plain computed tomography (CT). The spinal cord was compressed and displaced posteriorly by the tumor on magnetic resonance imaging (MRI), and extraosseous extension was observed. An incisional biopsy was performed, and primary UPS of the 11th thoracic vertebra was diagnosed pathologically. Total en bloc spondylectomy was considered to be challenging because of the extraosseous extension and the patient's age; thus, carbon ion radiotherapy (70.4 GyE / 32 fraction) was performed. Denosumab (120 mg) was administered subcutaneously every four weeks. No adjuvant chemotherapy was administered. Four years post-treatment, imaging revealed a compression fracture of the 11th thoracic vertebra, but there was no recurrence. Conclusion: Despite a poor prognosis and an aggressive course of UPS of the spine, the tumor continues to be controlled without local recurrence four years after carbon ion radiotherapy.

Clinical Outcome of Patients with Pelvic and Retroperitoneal Bone and Soft Tissue Sarcoma: A Retrospective Multicenter Study in Japan.

This study aimed to retrospectively analyze the clinical outcomes of patients with pelvic and retroperitoneal bone and soft tissue sarcoma (BSTS). Overall, 187 patients with BSTS in the pelvis and retroperitoneal region treated at 19 specialized sarcoma centers in Japan were included. The prognostic factors related to overall survival (OS), local control (LC), and progression-free survival (PFS) were evaluated. The 3-year OS and LC rates in the 187 patients were 71.7% and 79.1%, respectively. The 3-year PFS in 166 patients without any distant metastases at the time of primary tumor diagnosis was 48.6%. Osteosarcoma showed significantly worse OS and PFS than other sarcomas of the pelvis and retroperitoneum. In the univariate analyses, larger primary tumor size, soft tissue tumor, distant metastasis at the time of primary tumor diagnosis, P2 location, chemotherapy, and osteosarcoma were poor prognostic factors correlated with OS. Larger primary tumor size, higher age, soft tissue tumor, chemotherapy, and osteosarcoma were poor prognostic factors correlated with PFS in patients without any metastasis at the initial presentation. Larger primary tumor size was the only poor prognostic factor correlation with LC. This study has clarified the epidemiology and prognosis of patients with pelvic and retroperitoneal BSTS in Japan.

Space-Making Particle Therapy for Unresectable Hilar Cholangiocarcinoma.

INTRODUCTION: Although the primary treatment option for hilar cholangiocarcinoma (HC) has been surgical resection, most patients present with unresectable advanced tumors at the time of diagnosis. Particle therapy (PT) holds great potential for HC, even though the anatomical proximity to the gastrointestinal tract prevents delivering a radical dose to the tumor. Space-making PT (SMPT), consisting of spacer placement surgery and subsequent PT, has been developed to minimize complications and maximize the therapeutic benefit of dose escalation for HC. This study aimed to conduct a dosimetric evaluation and examine the effectiveness of SMPT for the treatment of HC. METHODS: Between 2007 and 2018, 12 patients with unresectable HC treated with SMPT were enrolled. The treatment outcomes and effectiveness of spacer placement surgery were evaluated through analyses of pre- and post-surgical parameters of dose-volume histograms. RESULTS: All patients completed the planned SMPT protocol. The median survival time was 29.6 months, and the 1- and 3-year overall survival rates were 82.5% and 45.8%, respectively. The mean V95% value (volume irradiated with 95% of the planned treatment dose) of the gross tumor volume and clinical target volume after spacer placement surgery improved to 98.5% and 96.6% from preoperative values of 85.6% and 78.1%, respectively (p = 0.0196 and p = 0.0053, respectively). Grade 3 or higher adverse events after SMPT were seen in 6 patients. DISCUSSION/CONCLUSION: SMPT led to improvements in dosimetric parameters and showed good feasibility and excellent outcomes. SMPT can be a promising novel alternative for unresectable HC.

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.

The comparison of acute toxicities associated with craniospinal irradiation between photon beam therapy and proton beam therapy in children with brain tumors.

INTRODUCTION: This study aimed to evaluate acute toxicities associated with irradiation between the X-CSI (photon beam craniospinal irradiation) and P-CSI (proton beam craniospinal irradiation) groups in children with brain tumors. METHODS: Sixty-two consecutive patients who received initial craniospinal irradiation (CSI) for brain tumors in our center between January 1, 2011 and May 31, 2021, were included in the study. Acute toxicities were retrospectively evaluated during CSI using Common Terminology Criteria for Adverse Events version 5.0. Maximum grades of fatigue, headache, insomnia, nausea, vomiting, dermatitis, constipation, abdominal pain, oropharyngeal mucositis, and hematological toxicities were evaluated. RESULTS: Thirty-six patients received X-CSI, and 26 patients received P-CSI. The median dose of CSI was 18.0 Gy in the X-CSI group and 23.4 Gy (relative biological effectiveness) in the P-CSI group (p < 0.001). The P-CSI group had a lower incidence of more than grade 2 nausea (11.5% vs. 69.4%, p = 0.008) and vomiting (7.7% vs. 38.8%, p < 0.001), compared with the X-CSI group. Multivariate logistic regression analysis with adjustments for potential confounding factors of doses of CSI showed that proton radiation therapy was associated with a marked reduced risk of more than grade 2 nausea and vomiting during CSI (adjusted odds ratio, 0.050; 95% confidential interval, 0.011-0.24; p < 0.001). CONCLUSION: The present study suggests that P-CSI reduces the acute gastrointestinal toxicities associated with irradiation.

Poorly Differentiated Chordoma of the Clivus With Loss of SMARCB1 Expression in a Pediatric Patient: A Case Report.

Poorly differentiated chordoma (PDC) is a rare, aggressive subtype of chordoma. A two-year-old girl presented with cervical pain, limb paralysis and respiratory failure. Magnetic resonance imaging and positron emission tomography-computed tomography revealed a tumor compressing the pons at the clivus and osteoblastic metastatic lesions of the left upper arm and right iliac bone. Her tumors shrank substantially after treatment with chemotherapy and proton beam therapy. Our initial diagnosis was an atypical teratoma/rhabdoid tumor, but final diagnosis of PDC was made on the basis of the immunohistochemical expression of brachyury. In addition, the detection of SMARCB1/INI1 mutation confirmed the diagnosis of PDC.

Particle therapy using protons or carbon ions for cancer patients with cardiac implantable electronic devices (CIED): a retrospective multi-institutional study.

PURPOSE: To evaluate the outcomes of particle therapy in cancer patients with cardiac implantable electronic devices (CIEDs). MATERIALS AND METHODS: From April 2001 to March 2013, 19,585 patients were treated with proton beam therapy (PBT) or carbon ion therapy (CIT) at 8 institutions. Of these, 69 patients (0.4%, PBT 46, CIT 22, and PBT + CIT 1) with CIEDs (64 pacemakers, 4 implantable cardioverter defibrillators, and 1 with a cardiac resynchronization therapy defibrillator) were retrospectively reviewed. All the patients with CIEDs in this study were treated with the passive scattering type of particle beam therapy. RESULTS: Six (13%) of the 47 PBT patients, and none of the 23 CIT patients experienced CIED malfunctions (p = 0.105). Electrical resets (7) and over-sensing (3) occurred transiently in 6 patients. The distance between the edge of the irradiation field and the CIED was not associated with the incidence of malfunctions in 20 patients with lung cancer. A larger field size had a higher event rate but the test to evaluate trends as not statistically significant (p = 0.196). CONCLUSION: Differences in the frequency of occurrence of device malfunctions for patients treated with PBT and patients treated with CIT did not reach statistical significance. The present study can be regarded as a benchmark study about the incidence of malfunctioning of CIED in passive scattering particle beam therapy and can be used as a reference for active scanning particle beam therapy.

Simulation study using the spots deletion technique in spot scanning proton beam therapy for prostate cancers.

The aim of the present study was to investigate the effects on the dose distribution and beam delivery time in spot scanning proton beam therapy (PBT) incorporating the spot deletion technique. A spot scanning plan was created for 30 patients with prostate cancer. The plan was then modified via two processes: Spots with lower weighting depositions were deleted (process A) and spots that were distant from the clinical target volume (CTV) were deleted (process B). The dose distribution to the organs at risk (OAR), the expanded CTV (exCTV), which was defined by a uniform expansion of the CTV by a radius of 5 mm, and the beam delivery time were compared among initial and modified plans. The V50 Gy [relative biological effectiveness (RBE)] to the rectum and bladder, and V60 Gy(RBE) to the urethral bulb, inhomogeneity index (INH) of the exCTV showed a difference (P=1.1x10-14, P=6.4x10-14, P=2.7x10-7, P=3.2x10-17), although only changes by process B were significant. Modified plan by process B showed the V50 Gy(RBE) to the rectum and bladder decreased by -2.4±1.6 and -2.3±1.4%, and the V60 Gy (RBE) to the urethral bulb decreased by -15.9±19.4%. The INH of the exCTV increased by 0.05±0.03%. On the other hand, modification of the initial plan by process A did not affect the dose of the OAR, exCTV or beam delivery time. In spot scanning PBT, modification of the initial radiotherapy plan by systemic deletion of spots distant from the CTV could result in a dose reduction to the OAR.

Separation Effect and Development of Implantation Technique of Hydrogel Spacer for Prostate Cancers.

PURPOSE: The purpose of this study is to improve the placement of a hydrogel spacer in patients with prostate cancer receiving radiation therapy. METHODS AND MATERIALS: A total of 160 patients with prostate cancer were classified into 3 groups: No spacer (group 1; n = 30), spacer placed using conventional technique (group 2; n = 100), and spacer placed using new technique (group 3; n = 30). When placing the spacer, the tip of the needle is placed at the middle of the prostate gland (group 2), or at a level corresponding to a cranial:caudal ratio of 6:4 and as close to the prostate gland as possible (group 3). The separation effect was examined and compared among the groups. RESULTS: The separation in group 2 was larger than that in group 1 from the base to the apex level of the prostate (4 mm), but the separation in group 3 was larger than that in group 2 from the middle to the apex level of the prostate (4 mm). The separation values for the middle to the apex, the spacer thickness from the apex level to the apex (10 mm), the rectal exclusion from the middle to the apex, and the laterality were correlated with the 50 and 60 Gy relative biologic effectiveness (Gy[RBE]) rectal dose (P = 4.1 × 10-9 - .046). The separation vales were strongly correlated with the spacer thickness at the apex (10 mm) and the apex (4 mm; P = 1.1 × 10-18 - 1.8 × 10-17). The rectal volumes at 10 to 60 Gy(RBE) differed among the groups (P = 5.1 × 10-19 - 5.4 × 10-3). The rectal volumes in group 2 were smaller than those in group 1 at all dose levels, but those in group 3 were smaller than those in group 2 at dose levels of 30 to 50 Gy(RBE). CONCLUSIONS: The separation, spacer thickness, and rectal exclusion from the middle to the apex of the prostate and the laterality of the hydrogel spacer affected the reduction in the rectal dose. The rectal dose can be further reduced by implanting a spacer on the caudal and prostate side.

Predicted probabilities of brain injury after carbon ion radiotherapy for head and neck and skull base tumors in long-term survivors.

BACKGROUND AND PURPOSE: We aimed to determine the risk factors for radiation-induced brain injury (RIBI1) after carbon ion radiotherapy (CIRT) to predict their probabilities in long-term survivors. MATERIALS AND METHODS: We evaluated 104 patients with head, neck, and skull base tumors who underwent CIRT in a regimen of 32 fractions and were followed up for at least 24 months. RIBI was assessed using the Common Terminology Criteria for Adverse Events. RESULTS: The median follow-up period was 45.5 months; 19 (18.3 %) patients developed grade ≥2 RIBI. The maximal absolute dose covering 5 mL of the brain (D5ml) was the only significant risk factor for grade ≥2 RIBI in the multivariate logistic regression analysis (p = 0.001). The tolerance doses of D5ml for the 5% and 50% probabilities of developing grade ≥2 RIBI were estimated to be 55.4 Gy (relative biological effectiveness [RBE]) and 68.4 Gy (RBE) by a logistic model, respectively. CONCLUSION: D5ml was most significantly associated with grade ≥2 RIBI and may enable the prediction of its probability.

Salvage hepatectomy for local recurrence after particle therapy using proton and carbon ion beams for liver cancer.

AIM: With the increased use of particle therapy for liver cancer, local recurrence after particle therapy increased. Salvage hepatectomy is an acceptable treatment option for local recurrence following particle therapy; however, its safety and effectiveness remain unclear. Therefore, this multi-center study aimed to verify the feasibility and efficacy of salvage hepatectomy and assess clinical issues associated with its application. METHODS: We retrospectively assessed the perioperative outcomes, prognosis, and pathological characteristics of 15 patients who underwent salvage hepatectomy for local recurrence after particle therapy between 2006 and 2019. RESULTS: Hepatocellular carcinoma and metastatic liver tumors were noted in eight and seven patients, respectively. The mean total dose and number of fractions were 66.5 Gy and 12, respectively, and the mean interval between particle therapy and surgery was 30.1 months. Major hepatectomy was performed in seven cases. Moreover, the mortality rate was 0%, and surgical complications of Clavien-Dindo grade IIIa or higher were observed in four cases (27%)-two bile leakages, one pleural effusion, and one refractory skin fistula. The median overall survival time and 5-year overall survival rate after salvage hepatectomy were 29.9 months and 43.1%, respectively. Histological examination of the irradiated liver tissue surrounding the tumor showed sinusoidal dilatation, loss of hepatocyte, and fibrosis in most cases. CONCLUSION: Salvage hepatectomy after particle therapy is a feasible therapy; however, the risk of refractory complications associated with particle therapy is relatively high. Therefore, the first-line treatment for resectable liver cancer should be carefully determined considering second-line treatment after local recurrence.

Dose distribution effects of spot-scanning proton beam therapy equipped with a multi-leaf collimator for pediatric brain tumors.

The present study simulated the effect of spot-scanning proton beam therapy (PBT) performed using a device equipped with a multi-leaf collimator (MLC) to calculate the dose distribution. Simulation studies using 18 pediatric patients with brain tumors in the posterior fossa were performed. Treatment plans were created for the MLC at different stages: Fully open (initial plan), fully closed to allow an irradiated area extending to 15 mm from the clinical target volume (CTV) (15-mm plan), or closing only the leaves where an organ at risk (OAR) overlapped with a border at 10 or 5 mm from the CTV (10- and 5-mm plans, respectively). The mean dose values for the brainstem, cervical cord, brain and cochlea in all MLC closure plans decreased as the MLC was closed (P=9.9×10-10, P=1.3×10-17, P=2.1×10-16 and P=2.0×10-5, respectively). The maximum dose (Dmax) values of the cervical cord and cochlea in all MLC closure plans were also decreased as the MLC was closed (P=3.0×10-4 and P=1.1×10-5, respectively). The dose to the CTV was almost unchanged. In 10 patients, the Dmax of the brain in all MLC-closure plans was higher than that of the initial plan, but the maximum increase was only 0.8 gray relative biological effectiveness [Gy(RBE)]. In conclusion, the existing MLC installed in the treatment device can be used to decrease the OAR dose significantly using spot-scanning PBT without a large capital investment. The dose from the scattered particles was small.

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.

Proton beam therapy for children and adolescents and young adults (AYAs): JASTRO and JSPHO Guidelines.

Children and adolescents and young adults (AYAs) with cancer are often treated with a multidisciplinary approach. This includes use of radiotherapy, which is important for local control, but may also cause adverse events in the long term, including second cancer. The risks for limited growth and development, endocrine dysfunction, reduced fertility and second cancer in children and AYAs are reduced by proton beam therapy (PBT), which has a dose distribution that decreases irradiation of normal organs while still targeting the tumor. To define the outcomes and characteristics of PBT in cancer treatment in pediatric and AYA patients, this document was developed by the Japanese Society for Radiation Oncology (JASTRO) and the Japanese Society of Pediatric Hematology/Oncology (JSPHO).