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Background: The aim of this study is to examine the outcomes of an accelerated fractionated irradiation for N0 glottic carcinoma. Methods: In this retrospective analysis, 29 patients with N0 glottic carcinoma treated by radiation therapy were enrolled. Thirteen patients had T1a disease, six had T1b disease, and ten had T2 disease. A fractional dose of 2.1 Gy was administered to seven patients. The total doses were 65.1 and 67.2 Gy in four and three patients, respectively. A fractional dose of 2.25 Gy was administered to 22 patients. The total doses were 63 and 67.5 Gy in 21 patients and 1 patient with T2 disease, respectively. Additionally, 13 patients underwent the use of TS-1 (80–100 mg per day). Results: The median follow-up period was 33 months, and the 3-year local control rate was 95.6%. No patient had a lymph node or distant recurrence. As acute adverse events, grades 2 and 3 dermatitis were observed in 18 patients and 1 patient, and grades 2 and 3 mucositis were observed in 15 patients and 1 patient. As a late adverse event, one patient required tracheotomy because of laryngeal edema occurring. Conclusions: Accelerated fractionated irradiation may be an option in the radiation therapy of N0 glottic carcinoma because of its ability to shorten the treatment time.

Abstract Background Carbon‐ion radiotherapy (C‐ion RT) is effective for head and neck mucosal melanoma (HN‐MM), including radioresistant mucosal melanoma. Melanoma also responds effectively to immune checkpoint inhibitors (ICIs). Data on the efficacy and safety of ICIs for HN‐MM are insufficient. Aims To analyze the efficacy and safety of ICI salvage therapy in patients with HN‐MM recurrence after C‐ion RT. Methods and Results This retrospective study analyzed the medical records of 52 patients with HN‐MM treated with C‐ion RT between 2012 and 2020. A dose of 57.6 or 64.0 Gy (relative biological effectiveness) was provided in 16 fractions. The primary endpoint was 3‐year overall survival (OS) rate. The median follow‐up time was 26.8 months for all patients. A total of 29 patients had local recurrence or distant metastasis, and 16 patients who received ICI therapy. The 3‐year OS rate in the ICI group (n = 16) and best supportive care group (n = 13) were 53.8% and 0.0%, respectively (p = 0.837); the difference was not statistically significant. There were no deaths after 1 year among patients who underwent ICI therapy. No adverse events associated with C‐ion RT were related to or exacerbated by ICI. Conclusion ICI salvage therapy is effective and safe for patients with HN‐MM recurrence after C‐ion RT.

Background: Tooth loss reduces quality of life; however, little is known about tooth loss caused by carbon ion radiotherapy (CIRT). Here, we aimed to elucidate the incidence of tooth loss post-CIRT for head and neck tumors and to identify risk-predictive dosimetric parameters. Methods: This study enrolled 14 patients (i.e., 171 teeth in total) with head and neck non-squamous cell carcinoma. All patients received CIRT comprised of 57.6 or 64.0 Gy (relative biological effectiveness, RBE) in 16 fractions. Dose–volume analysis of the teeth was performed using receiver operating characteristic (ROC) curve analysis with VX (i.e., the volume irradiated with X Gy (RBE)). Results: The median follow-up period was 69.1 months. The median time of tooth loss was 38.6 months. The 5 year cumulative incidence of tooth loss was 13.3%. The volume of irradiated teeth was significantly greater for the lost teeth than for the remaining teeth throughout the dose range. Using the cut-offs calculated from ROC curve analysis, V30–V60 showed high accuracy (i.e., >94%) for predicting tooth loss, with V50 being the most accurate (cut-off, 58.1%; accuracy, 0.95). Conclusions: This is the first report to examine the incidence of tooth loss post-CIRT and to identify risk-predictive dosimetric parameters.

Abstract Background Adenoid cystic carcinoma (ACC) is a rare malignant tumor involving mostly the head and neck region, and frequently the salivary glands. The development of lung metastasis after treatment of the primary tumor is a common occurrence in ACC. Although lung metastases show a slow rate of growth, approximately 10% of patients die from distant metastases. The radioresistance of ACC limits the efficacy of conventional radiotherapy for lung metastases, and the optimal dose remains to be determined. Stereotactic body radiotherapy (SBRT) using CyberKnife can deliver a high dose to the lung tumor, while sparing the surrounding normal lung tissues, leading to favorable local control in non-squamous cell lung cancer and metastatic lung tumors. We report a case of lung metastases from ACC treated successfully with SBRT using CyberKnife. Case presentation A 76-year-old Japanese man with ACC who was treated with carbon ion radiotherapy for a primary oropharynx tumor presented with three metastatic lesions in the lung. The tumor masses were located in the right upper, right lower, and left lower lobes of the lungs. Surgical resection was not indicated because of the presence of multiple tumors. The patient underwent SBRT at 60 Gy in 10 sequential fractions for each tumor. The biologically effective dose based on an alpha/beta ratio of 2 Gy was 240 Gy per tumor. The percentage of the total lung volume irradiated with >20 Gy was 4.9%, 3.2%, and 2.6% for each tumor. The patient developed acute radiation pneumonitis during the initial therapy, which resolved at 6 months after the CyberKnife treatment. At 21 months after the first CyberKnife treatment, three tumors showed no signs of recurrence. No late toxicity was observed. Conclusions SBRT using CyberKnife is an effective and feasible approach to the management of multiple lung metastases of ACC.

Abstract This study aimed to evaluate the efficacy of carbon‐ion radiotherapy in combination with chemotherapy using dacarbazine, nimustine, and vincristine (DAV therapy) in mucosal melanoma. Twenty‐one patients with clinically localized mucosal melanoma of the head and neck were enrolled. The primary endpoint was 3‐year overall survival (OS). Secondary endpoints included local control, progression‐free survival (PFS), and adverse event occurrence. Carbon‐ion radiotherapy with a dose of 57.6‐64.0 Gy (relative biological effectiveness) in 16 fractions was delivered concurrently with DAV therapy, and 2 cycles of adjuvant DAV therapy were administered every 6 weeks. The median follow‐up periods were 15.5 months for all patients, and 31.2 months for 12 surviving patients. All patients had locally advanced T4a or T4b disease in the rhino‐sinus area. In 16 patients (76.2%), 3 cycles of planned DAV therapy were completed. The 3‐year OS and PFS rates were 49.2% and 37.0% respectively. The 3‐year local control rate was 92.3%. Eleven patients (52%) developed distant metastasis, which was the most frequent pattern of the first failure. Commonly presenting acute grade 2‐3 toxicities associated with radiotherapy and chemotherapy were mucositis (11 patients [53%]) and leukopenia (9 patients [43%]), which improved with conservative therapy. None of the patients developed grade 3 or greater late toxicities. Carbon‐ion radiotherapy in combination with DAV therapy led to excellent local control for advanced mucosal melanoma within acceptable toxicities. The efficacy of additional DAV therapy in improving survival was weaker than expected as distant metastases still occurred frequently. Trial registration no. UMIN000007939.

Abstract This phase II study's aim was to confirm the efficacy and safety of hypofractionated carbon‐ion radiotherapy in patients with stage I peripheral nonsmall cell lung cancer (NSCLC). The study encompassed 37 patients with histologically proven peripheral stage I NSCLC in the period June 2010‐March 2015. All underwent the planned full dose of carbon‐ion radiotherapy, administered with relative biological effectiveness of 52.8 Gy and 60 Gy (divided into four fractions over 1 week) for T1 and T2a tumors, respectively. The 2‐year local control rate was set as the primary endpoint, while overall survival, progression‐free survival, and the incidence rates of acute and late adverse events were secondary endpoints. The patients were followed up for 56.3 months overall and 62.2 months in the surviving patients, respectively. The actuarial local control rates were 91.2% after 2 years, and 88.1% after 5 years. No differences were found between the T1 and T2a tumors in the 5‐year local control rate (90.9% vs 86.7%, P = .75). The actuarial overall survival rates achieved 91.9% for 2‐year and 74.9% for 5‐year period. T1 tumors showed actuarial 5‐year overall survival rates of 80%, compared to 66.7% in T2a tumors. Two patients with T2a tumors and either severe emphysema or bronchiectasis experienced lung toxicity ≥ grade 2, in contrast to T1 patients who only experienced mild toxicities (lower than grade 2). The findings suggest that carbon‐ion radiotherapy is effective and safe for peripheral stage I NSCLC; however, further clinical evaluations are needed to confirm its therapeutic efficacy. Trial registration: UMIN000003797. Registered 21 June 2010, prospectively registered.

Abstract 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.

Background: Layer-stacking irradiation (LSI) results in the accumulation of multiple small spread-out Bragg peaks along the beam direction. Although the superiority of LSI to conventional passive irradiation (CPI) regarding normal tissue sparing is theoretically evident, the clinical benefit of LSI has not been demonstrated. Here, we compared LSI with CPI using the same treatment planning-computed tomography images used for carbon ion radiotherapy (CIRT).Methods: Twenty-one parotid tumors were analyzed. The clinical target volume (CTV) 1 and CTV2 encompassed the parotid grand and the tumor, respectively. CTV1 and CTV2 received 36 Gy (RBE: relative biological effectiveness) in nine fractions and 64 Gy (RBE) in 16 fractions, respectively, using either LSI or CPI. CTV coverage was assessed by DX%, which is the dose covering at least X% of the target volume. Skin dose was assessed by SX, which is the skin surface area receiving at least X Gy (RBE).Results: For CTV1 and CTV2, there were no significant differences in D2% between LSI and CPI. D50% and D98% were slightly higher for CPI; however, the absolute difference between the two methods was

Abstract Background The skin is considered a critical organ at risk in carbon ion radiotherapy (CIRT) for locally advanced malignant bone and soft tissue tumors (MBSTs). The predictive factors for acute skin reactions after CIRT have not been investigated. The present study aimed to identify these factors and evaluate the correlation between the severity of acute skin reactions and skin dose parameters. Methods CIRT with total doses of 64.0–70.4 Gy (relative biological effectiveness [RBE]) was administered to 22 patients with MBSTs. The skin-tumor distance (STD), maximum skin total dose (Dmax), and area of the skin receiving a total dose of X Gy (RBE) were evaluated. Results All patients developed acute skin reactions after CIRT, including Grades 1 and 2 dermatitis in 15 (71%) and 6 (29%) patients, respectively. There was a significant difference in the STD between the two groups (P = 0.007), and the cut-off value of STD for predicting Grade 2 acute skin reactions was 11 mm. There was a significant difference in Dmax between the groups (P

Mouthpieces are used to fix the positions of the lower jaw and teeth during carbon-ion radiotherapy for head and neck tumors. We used a customized mouthpiece to reduce radiation mucositis by displacing the tongue. Acute radiation mucositis gradually increased for the palate and tongue after approximately six irradiation fractions (maximal mean grade: palate, 2.5 during radiation fractions 15; tongue, 0.8 during radiation fractions 12 and 13). The mean grade of mucositis was significantly lower for the tongue than for the palate from irradiation fraction six until two weeks after irradiation. Keywords: Carbon-ion radiotherapy, Head and neck tumor, Customized mouthpiece

Purpose: Mediastinal and hilar lymph node metastasis is one of the recurrence patterns after definitive treatment of lung cancer. Salvage radiotherapy (RT) can be a treatment option for lymph node metastasis. However, the usefulness of additional RT remains unclear after surgery or RT for the primary lung tumor. We retrospectively evaluated the efficacy and safety of hypofractionated carbon-ion RT for isolated lymph node metastasis.Methods and Materials: Between April 2013 and August 2016, 15 consecutive patients with isolated lymph node metastasis underwent carbon-ion RT. The pretreatment evaluations confirmed the isolated lymph node metastasis and the absence of local recurrence or distant metastasis, which was oligometastatic disease. The median age was 72 (range, 51–83) years, with 11 male patients. The first treatments for primary lung tumors were carbon-ion RT for 8 patients and surgery for 7 patients. There were 9 adenocarcinomas, 4 squamous cell carcinomas, 1 adenosquamous cell carcinoma, and 1 mucoepidermoid carcinoma. Most patients (93%) were irradiated with 52.8 Gy relative biological effectiveness in 12 fractions for 3 weeks. There were no patients treated with concurrent or adjuvant therapy such as chemotherapy, molecular-targeted therapy, or immunotherapy. Adverse events were evaluated according to the Common Terminology Criteria for Adverse Events (version 4.0).Results: The median follow-up for surviving patients was 28 months. One patient experienced local lymph node recurrence, and the 2-year local control rate was 92% for all patients. Distant metastasis was observed in 7 patients, and 2-year progression-free survival rate was 47%. During follow-up, there were 4 deaths from lung cancer, and the 2-year overall survival rate was 75%. There were 2 patients with acute grade 2 esophagitis and 2 with late grade 2 cough, which were improved by conservative therapy. There were no other grade 2 or higher adverse events.Conclusions: Hypofractionated carbon-ion RT showed excellent local control and overall survival without severe toxicities in lung cancer patients with isolated lymph node metastasis after surgery or carbon-ion RT for primary lung tumors. A multi-institutional prospective study is required to establish the efficacy and safety of carbon-ion RT.

Purpose: To perform a prospective study to evaluate the efficacy and safety of isolated recurrent tumor re-irradiation with carbon-ion radiotherapy (RT).Methods and Materials: The inclusion criteria were clinically proven recurrent tumors, measurable by computed tomography or magnetic resonance imaging, patients ≥ 16 years old, performance status scores between 0 and 2, isolated tumor at a previously irradiated site, and a life expectancy > 6 months. The exclusion criteria were tumor invasion into the gastrointestinal tract or a major blood vessel, uncontrolled infection, early recurrence (16 months) between the first RT and re-irradiation had significantly better outcomes than the shorter interval group (≤ 16 months).Conclusions: Re-irradiation, using carbon-ion RT with radical intent, had favorable local control and overall survival rates without severe toxicities for selected patients. Re-irradiation has the potential to improve clinical outcomes for isolated, local, recurrent tumors; further investigations are required to confirm the therapeutic efficacy.

The safety and efficacy of carbon-ion radiotherapy for advanced non-small cell lung cancer have not been established. We evaluated the clinical outcomes and dose-volume histogram parameters of carbon-ion radiotherapy compared with photon therapy in T2b-4N0M0 non-small cell lung cancer. Twenty-three patients were treated with carbon-ion radiotherapy between May 2011 and December 2015. Seven, 14, and 2 patients had T2b, T3, and T4, respectively. The median age was 78 (range, 53-91) years, with 22 male patients. There were 12 adenocarcinomas, 8 squamous cell carcinomas, 1 non-small cell lung carcinoma, and 2 clinically diagnosed lung cancers. Eleven patients were operable, and 12 patients were inoperable. Most patients (91%) were treated with carbon-ion radiotherapy of 60.0 Gy relative biological effectiveness (RBE) in 4 fractions or 64.0 Gy (RBE) in 16 fractions. Local control and overall survival rates were calculated. Dose-volume histogram parameters of normal lung and tumor coverages were compared between carbon-ion radiotherapy and photon therapies, including three-dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRT). The median follow-up of surviving patients was 25 months. Three patients experienced local recurrence, and the 2-year local control rate was 81%. During follow-up, 5 patients died of lung cancer, and 1 died of intercurrent disease. The 2-year overall survival rate was 70%. Operable patients had a better overall survival rate compared with inoperable patients (100% vs. 43%; P = 0.04). There was no grade ≥2 radiation pneumonitis. In dose-volume histogram analysis, carbon-ion radiotherapy had a significantly lower dose to normal lung and greater tumor coverage compared with photon therapies. Carbon-ion radiotherapy was effectively and safely performed for T2b-4N0M0 non-small cell lung cancer, and the dose distribution was superior compared with those for photon therapies. A Japanese multi-institutional study is ongoing to prospectively evaluate these patients and establish the use of carbon-ion radiotherapy.

To evaluate the dose-response relationship for development of acute radiation mucositis (ARM) using an oral mucosal dose surface model (OMDS-model) in carbon ion radiotherapy (C-ion RT) for head and neck tumors.Thirty-nine patients receiving C-ion RT for head and neck cancer were evaluated for ARM (once per week for 6 weeks) according to the Common Terminology Criteria for Adverse Events (CTCAE), version 4.0, and the Radiation Therapy Oncology Group (RTOG) scoring systems. The irradiation schedule typically used was 64 Gy [relative biological effectiveness (RBE)] in 16 fractions for 4 weeks. Maximum point doses in the palate and tongue were compared with ARM in each patient.The location of the ARM coincided with the high-dose area in the OMDS-model. There was a clear dose-response relationship between maximum point dose and ARM grade assessed using the RTOG criteria but not the CTCAE. The threshold doses for grade 2-3 ARM in the palate and tongue were 43.0 Gy(RBE) and 54.3 Gy(RBE), respectively.The OMDS-model was useful for predicting the location and severity of ARM. Maximum point doses in the model correlated well with grade 2-3 ARM.

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. [ABSTRACT FROM AUTHOR]

The present study (University Hospital Medical Information Network study no. UMIN000003797) aimed to evaluate whether the maximum standardized uptake value (SUVmax) of pretreatment 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) is prognostic factor for stage I non-small cell lung cancer (NSCLC) treated with carbon ion radiotherapy (C-ion RT). Patients treated between June 2010 and June 2013 at Gunma University Heavy Ion Medical Center (Maebashi, Japan) on a prospective protocol were included in the present study. Patients with T1a-b and T2a NSCLC were treated with C-ion RT at a dose of 52.8 Gy [relative biological effectiveness (RBE)] and 60.0 Gy (RBE), respectively, in four fractions. Prior to treatment, all patients underwent FDG-PET, in which the SUVmax of primary tumors was evaluated. Local control, progression-free survival (PFS), and overall survival (OS) were calculated. A total of 45 patients were analyzed and the median follow-up period was 28.9 months. The 2-year local control, PFS and OS rates for all patients were 93, 78 and 89%, respectively. The mean SUVmax of primary tumors was 5.5, and patients were divided into higher (≥5.5) and lower (<5.5) SUVmax groups. The 2-year PFS rates were 61 and 89% for the higher and lower SUVmax groups, respectively (P=0.01), and the 2-year OS rates for the higher and lower SUVmax groups were 76 and 96%, respectively (P=0.01). The higher SUVmax group exhibited a significantly worse PFS and OS compared with the lower SUVmax group; however, the SUVmax was not associated with the local control rate. In total, 2 patients (4%) experienced grade 2 or 3 radiation pneumonitis, with their symptoms improved through conservative treatment. No patients experienced any grade 4 or 5 toxicities. The results of the present study indicate that pretreatment SUVmax is a prognostic indicator for outcomes in patients with stage I NSCLC treated with C-ion RT. [ABSTRACT FROM AUTHOR]

Background: To assess the efficacy of concurrent chemoradiotherapy (CCRT) with daily low-dose cisplatin (CDDP) plus weekly docetaxel (DTX) for patients with T2N0 glottic cancer.Methods: Between January 2004 and December 2013, 62 treatment-naive patients with histologically proven T2N0 glottic cancer were treated with concurrent chemoradiotherapy. Radiation therapy (RT; 2 Gy daily fractions up to a total dose of 66 Gy) was administered in combination with daily low-dose CDDP (6 mg/m2, five times a week), plus weekly DTX (10 mg/m2) for up to 4 weeks from the commencement of RT.Results: Median duration of follow-up was 70 months. The actuarial 3-year and 5-year overall survival rates were 95% and 93%. The 3-year and 5-year cause-specific survival rates were both 100%. The actuarial 3-year and 5-year local control rates were 94% and 94%, respectively. Hematologic toxicity (neutoropenia of severity ≥ Grade 3) was observed in 8% of the patients, and non-hematologic toxicity (radiation mucositis of severity ≥ Grade 3) developed in one patient (2%). Radiation dermatitis of severity ≥ Grade 3 and laryngeal necrosis developed in one patient.Conclusion: CCRT with weekly DTX and low-dose CDDP appears to be a practical and safe modality and is expected to improve local control.Trial Registration: UMIN000025046 . Registered 1 October 2015, retrospectively registered. [ABSTRACT FROM AUTHOR]

Background: Oral mucosal melanoma is a rare disease with a relatively poor prognosis. Carbon ion radiotherapy has been shown to be effective against radiotherapy-resistant tumors owing to its excellent dose concentration and high biological effect. Case presentation: Our patient was a 66-year-old Japanese man with oral mucosal melanoma of his right maxillary gingiva (T4aN0M0). He received carbon ion radiotherapy at 57.6 Gy (relative biological effectiveness) in 16 fractions for 4 weeks. Concomitant chemotherapy (dacarbazine + nimustine + vincristine) was administered at the same time as carbon ion radiotherapy initiation. Two courses of adjuvant chemotherapy were given after carbon ion radiotherapy. Although he experienced grade 2 acute oral mucositis, his symptoms improved within a few weeks of undergoing carbon ion radiotherapy. He was alive at the time of reporting, 35 months after treatment, without any recurrence. Late toxicity has not been observed. Conclusions: Carbon ion radiotherapy for oral mucosal melanoma resulted in a good local effect. [ABSTRACT FROM AUTHOR]

Background A single-institutional prospective study of optimal hypofractionated conformal radiotherapy for large brain metastases with high risk factors was performed based on the risk prediction of radiation-related complications. Methods Eighty-eight patients with large brain metastases ⩾10 cm3 in critical areas treated from January 2010 to February 2014 using the CyberKnife were evaluated. The optimal dose and number of fractions were determined based on the surrounding brain volume circumscribed with a single dose equivalent (SDE) of 14 Gy (V14) to be less than 7 cm3 for individual lesions. Univariate and multivariate analyses were conducted. Results As a result of optimal treatment, 92 tumors ranging from 10 to 74.6 cm3 (median, 16.2 cm3) in volume were treated with a median prescribed isodose of 57% and a median fraction number of five. In order to compare the results according to the tumor volume, the tumors were divided into the following three groups: 1) 10-19.9 cm3, 2) 20-29.9 cm3 and 3) ⩾30 cm3. The lesions were treated with a median prescribed isodose of 57%, 56% and 55%, respectively, and the median fraction number was five in all three groups. However, all tumors ⩾20 cm3 were treated with ⩾ five fractions. The median SDE of the maximum dose in the three groups was 47.2 Gy, 48.5 Gy and 46.5 Gy, respectively. Local tumor control was obtained in 90.2% of the patients, and the median survival was nine months, with a median follow-up period of seven months (range, 3-41 months). There were no significant differences in the survival rates among the three groups. Six tumors exhibited marginal recurrence 7-36 months after treatment. Ten patients developed symptomatic brain edema or recurrence of pre-existing edema, seven of whom required osmo-steroid therapy. No patients developed radiation necrosis requiring surgical resection. Conclusion Our findings demonstrate that the administration of optimal hypofractionated conformal radiotherapy based on the dose-volume prediction of complications (risk line for hypofractionation), as well as Kjellberg's necrosis risk line used in single-session radiosurgery, is effective and safe for large brain metastases or other lesions in critical areas. [ABSTRACT FROM AUTHOR]

[Purpose/Objective] Neck lymph node (LN) recurrences in irradiated field occur in 10 to 25%, which are important pattern of failure for cancer patients. Nevertheless, there are only few reports about salvage re-irradiation for LN recurrences. We investigated the efficacy and toxicity of CyberKnife (CK) treatment for neck LN recurrences after conventional radiotherapy (CRT). [Material/methods] Between 2008 and 2014, 16 patients with neck LN recurrences after CRT were treated with CK in our institution. All of the recurrences were unsuitable for other treatment due to medical reasons. The treatment fractions were decided depending on tumor and surrounding critical structures' volume. The dose to the 10 cm3 of skin and mucosa was limited to be < 14 Gy given as stereotactic radiosurgery (SRS) to avoid adverse effects. Local control (LC) and overall survival (OS) were estimated using the Kaplan-Meier method. [Results] The follow up period after CK ranged from 2 to 53 months (median, 19 months). The previous CRT dose ranged from 50 to 70 Gy (median, 70 Gy). Neck dissection had been performed for 6 patients (38%) before CK. The target volume ranged 0.05 to 91 cm3 (median, 1.2 cm3). The prescribed isodoses ranged from 49 to 89% (median, 64%) for the target. The intended prescribed marginal dose was ranged 18 to 40 Gy in 1 to 8 fractions. The marginal dose as EQD2 (a/b = 10) ranged from 40 to 58 (median, 50 Gy). SRS, the 3-fraction, 5-fraction, 6-fraction and 8-fraction radiotherapy was administered to 46, 8, 3, 1 and 1 lesion, respectively. The local recurrence was observed in 10 lesions of 7 patients. The 1-year LC and OS rate was 83% and 63%, respectively. Fatal bleeding was observed in one patient who had huge (91 cm3) and widespread tumor invasion to carotid artery before CK. The 1-year LC with the target volume ? 1.0 cm3 was significantly higher than with the target volume >1.0 cm3 (p = 0.013). There is no significant difference in the 1-year LC due to the marginal dose for SRS (? 20 Gy versus > 20 Gy). [Conclusion] CK for neck LN recurrences were performed safely and feasibly in most cases. Thus, CK is a candidate as a salvage treatment. We have to pay much attention to large and wide spread tumor invasion before CK. [ABSTRACT FROM AUTHOR]