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We aimed to predict the minimum distance between a tumor and the gastrointestinal (GI) tract that can satisfy the dose constraint by creating simulation plans with carbon-ion (C-ion) radiotherapy (RT) and photon RT for each case assuming insertion of virtual spacers of various thicknesses. We enrolled 55 patients with a pelvic tumor adjacent to the GI tract. Virtual spacers were defined as the overlap volume between the GI tract and the volume expanded 7–17 mm from the gross tumor volume (GTV). Simulation plans (70 Gy in 35 fractions for at least 95% of the planning target volume [PTV]) were created with the lowest possible dose to the GI tract under conditions that meet the dose constraints of the PTV. We defined the minimum thickness of virtual spacers meeting D2 cc of the GI tract

Highlights • Carbon-ion re-irradiation for pancreatic cancer; feasibility and efficacy. • Adjuvant chemotherapy improve local control of re-irradiation using carbon ions. • Carbon-ion radiotherapy for recurrent pancreatic cancer; reasonable option., Background and purpose Patients who receive carbon-ion radiotherapy (C-ion RT) for primary pancreatic cancer may experience locoregional recurrence; however, the treatment options for such patients are limited. We aimed to investigate the feasibility and efficacy of carbon-ion re-irradiation for patients with pancreatic cancer who experienced recurrence after initial C-ion RT. Materials and methods Twenty-one patients with recurrent pancreatic cancer who underwent repeat C-ion RT between December 2010 and November 2016 at our institute were retrospectively evaluated. The sites of post-initial C-ion RT failure were in-field central in 16 patients (76.2%) and marginal in 5 (23.8%). The median doses of initial and repeat C-ion RT were both 52.8 Gy (relative biological effectiveness [RBE]). Thirteen patients (61.9%) received concurrent chemotherapy with re-irradiation, while 11 (52.4%) received adjuvant chemotherapy. Results The median follow-up period after re-irradiation was 11 months. The 1-year local control, progression-free survival, and overall survival rates were 53.5%, 24.5%, and 48.7%, respectively. Toxicity data was obtained from the patients’ charts. Only 1 patient (4.8%) developed grade 3 acute toxicities and none developed grade ≥3 late toxicities. Univariate analysis indicated that patients who received adjuvant chemotherapy had significantly improved local control rates compared with those who did not; the 1-year local control rates were 80.0% and 0.0%, respectively (P = 0.0469). Conclusion Repeating C-ion RT may be a reasonable option with tolerable toxicity for patients with recurrent pancreatic cancers. Adjuvant chemotherapy appears to improve the local control rate. This is the first study to examine re-irradiation using C-ion for recurrent pancreatic cancer after initial C-ion RT.

Background In definitive chemoradiotherapy (CRTx) for esophageal cancer, a radiotherapy (RT) dose of 50.4 Gy in 28 fractions has been the standard in many countries, while 60 Gy in 30 fractions has been frequently used in Japan. To clarify the optimal RT dose in CRTx for esophageal cancer, we compared clinical outcomes with the two doses using data from the Comprehensive Registry of Esophageal Cancer in Japan by the Japan Esophageal Society (JES). Methods Of the patients enrolled in the registry for 2015–2017 surveys (patients treated between 2009 and 2011), 996 patients who received definitive CRTx with 50.4 Gy or 60 Gy for thoracic esophageal cancer were eligible for analysis. Results The complete response (CR) rates in the 50.4 Gy and 60 Gy groups were 49.1% and 46.4%, respectively (p = 0.5851). The 5-year overall survival (OS) rates in the 50.4 Gy group and 60 Gy group for stages I, II/III and IV were 64.2% and 57.2%, 35.0% and 27.0%, and 18.0% and 15.3%, respectively. Since no significant difference was found between the two groups, the 50.4 Gy group was not inferior to the 60 Gy group with regard to OS. Conclusions The analysis revealed that the 50.4 Gy group had a non-inferior outcome in comparison with the 60 Gy group for stages I, II/III and IV thoracic esophageal cancer. These results were obtained from a large database for the first time in Japan.

Purpose We investigated the efficacy and safety of carbon-ion radiotherapy (C-ion RT) for locally recurrent rectal cancer (LRRC). Patients and methods Data from patients with LRRC treated with C-ion RT from November 2003 to December 2014 at three institutions were retrospectively analyzed. The endpoints of this clinical trial were overall survival (OS), local control (LC), and acute/late toxicity. Results A total of 224 patients' data were collected. The prescribed dose was 70.4 Gy (relative biological effectiveness [RBE]-weighted absorbed dose) or 73.6 Gy (RBE) in 16 fractions. The median follow-up period from the initiation of C-ion RT was 62 months (range 6–169 months). The OS rates were 73% (95% confidence interval [CI], 67%–79%) at 3 years and 51% (95%CI 44%–58%) at 5 years. The LC rates were 93% (95%CI 88%–96%) at 3 years, and 88% (95%CI 82%–93%) at 5 years. Grade 3 acute toxicity was observed in three patients: gastrointestinal toxicity (n = 1) and pelvic infection (n = 2). Grade 3 late toxicity was observed in 12 patients: skin reaction (n = 2), gastrointestinal toxicity (n = 2), neuropathy (n = 1), and pelvic infection (n = 7). There was no grade 4 or 5 acute or late toxicity. Conclusions This first multi-institutional analysis of C-ion RT for LRRC indicated relatively favorable outcomes with limited toxicities.

The efficacy and safety of carbon ion radiotherapy (C-ion RT) for locoregional recurrence after surgery for pancreatic cancer were retrospectively evaluated. The results for 30 patients showed that C-ion RT was performed safely with relatively long overall survival, good local control, and minimal toxicity.

Purpose The aim of this multi-institutional study was to evaluate the efficacy and safety of carbon-ion radiotherapy (C-ion RT) for locally advanced pancreatic cancer (LAPC). Methods and Materials Patients with LAPC treated with C-ion RT from April 2012 to December 2014 at 3 institutions were retrospectively analyzed. Patients with pathologically-confirmed invasive ductal adenocarcinoma of the pancreas were eligible. The prescribed dose was 52.8 Gy (relative biological effectiveness weighted absorbed dose; RBE) or 55.2 Gy (RBE) in 12 fractions. Overall survival (OS), distant metastasis-free survival (DMFS), local recurrence (LR), and toxicity were evaluated. Results In total, 72 patients were included in this study. Tumors in the head of the pancreas were seen in 30 patients (42%), while those in the body or tail of the pancreas were seen in 42 patients (58%). Fifty-six patients (78%) received concurrent chemotherapy. The OS rates were 73% (95% confidence interval [CI], 62%-84%) at 1 year, and 46% (95% CI, 31%-61%) at 2 years with a median OS of 21.5 months (95% CI, 11.8-31.2 months). The 1- and 2-year DMFS rates were 41% (95% CI, 29%-52%) and 28% (95% CI, 16%-40%), respectively. The 1- and 2-year cumulative incidences of LR were 16% (95% CI, 9%-26%) and 24% (95% CI, 14%-36%), respectively. Nineteen patients (26%) experienced acute grade 3 or 4 hematological toxicities. Two patients (3%) had grade 3 anorexia. Late gastrointestinal (GI) grade 3 toxicity was observed in 1 patient (1%). No patients developed late grade 4 or 5 toxicity. Conclusions The first multi-institutional analysis of C-ion RT for LAPC indicated relatively favorable outcomes with limited toxicities, especially for tumors not in close proximity to GI tract.

This study aimed to evaluate the efficacy and safety of reirradiation with intensity-modulated radiation therapy (IMRT) for spinal metastases. We retrospectively analyzed 23 patients with spinal metastases who underwent IMRT reirradiation between December 2006 and July 2013. We evaluated the spinal radiation doses during the first and second radiation therapy courses, the interval between the courses, and the clinical outcomes after reirradiation, including skeletal-related events, local control rates (LCRs), overall survival (OS), and toxicities. The median time from the first irradiation to reirradiation was 13 months (range, 2–75 months). The median reirradiation dose delivered to 90% of the planning target volume was 24.5 Gy in 5 fractions (range, 14.7–50 Gy in 3–25 fractions). Nineteen patients experienced pain at reirradiation, and 15 of these attained pain relief. Two of the three patients with paresis in the upper or lower extremities upon initiation of reirradiation demonstrated improvement. Local progression was identified in four patients. The median time to local progression was 37 months. The 1- and 2-year LCRs after reirradiation were 88% and 75%, respectively. The 1- and 2-year OS rates after reirradiation were 45% and 20%, respectively, with a median OS of 12 months. No late toxicities occurred. In conclusion, spinal metastasis reirradiation using IMRT appears safe; pain relief and paresis improvement and/or prevention can be expected, along with a reduced risk of radiation-induced toxicity, especially in the spinal cord.

Background The safety and effectiveness of carbon-ion radiotherapy (CIRT) for isolated para-aortic lymph node (PALN) metastasis was evaluated retrospectively. Methods CIRT for isolated PALN metastasis from CRC was performed in 34 cases from June 2006 to August 2015 in our institute. A median dose of 52.8 Gy(RBE) (range, 48-52.8 Gy(RBE)) was delivered with a median daily dose of 4.4 Gy(RBE) (range, 4.0-4.4 Gy(RBE)). Results The median follow-up duration for all patients was 24.4 months (range, 7-82.8 months). There were 13 cases (38.2%) who achieved complete response after treatment. The local control rates at 2 and 3 years were 70.1% and 70.1%, respectively. The overall survival rates at 2 and 3 years were 83.3% and 63.0%, respectively. The 3-year survival rates for Stage I-III were 68.7%, while those for Stage IV was 0%. The overall survival of cases with rectal cancer or with high CA19-9 values pre-CIRT tended to be worse. The median survival period was 41.7 months. Twelve of the 34 patients survived for more than 3 years. There were no adverse effects of Grade 3 or higher. Conclusions CIRT for isolated PALN recurrence after curative resection for CRC appears effective and safe, and it is considered a promising therapy.

OBJECTIVE: \nPancreatic cancer is a difficult to treat disease with a persistently high mortality rate. We evaluated dose distribution simulation with respiratory-gated carbon-ion pencil beam scanning (C-PBS) with a simultaneous integrated boost (SIB) to increase tumour dose, sparing organs at risk (OARs). \nMETHODS: \nUsing four-dimensional CT data of 12 patients, we delineated gross tumour volume and two clinical target volumes (CTVs). To consider beam range intrafractional uncertainty, we calculated field-specific target volumes, from which two planning target volumes (PTVs) were generated. PTV1 would receive a planned dose of 55.2 Gy [relative biological effectiveness (RBE)-weighted absorbed dose] in 12 fractions, and PTV2 would receive an SIB dose up to 67.2 Gy (RBE). Dose assessments were conducted with regard to the targets and OARs. \nRESULTS: \nCTV2 dose covering 95% of the volume (D95%) increased from 50.3 ± 5.1 Gy (RBE) to 62.5 ± 3.5 Gy (RBE) for a planned dose from 55.2 Gy (RBE) to 67.2 Gy (RBE). For 4 of 12 patients with a distance of ≥5 mm between the tumour and the gastrointestinal tract, CTV2 D95% was ≥95% of planned dose at all dose levels. \nCONCLUSION: \nWe quantified dose escalation with respiratory-gated C-PBS using SIB for pancreatic cancer and revealed that OAR dose was not affected to the same degree as the tumour dose. Advances in knowledge: A simulation study on respiratory-gated C-PBS with SIB for pancreatic cancer was performed. The results indicated the feasibility of dose escalation for pancreatic cancer, which should be confirmed in clinical trials.