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Background: Factors associated with long-term survival in gemcitabine-concurrent proton radiotherapy (GPT) for non-metastatic, locally advanced pancreatic cancer (LAPC) remain unclear. This study aimed to determine the factors associated with long-term survival in GPT for non-metastatic LAPC.Methods: The medical records of 123 patients with LAPC treated with GPT between February 2009 and December 2019 at Hyogo Ion Beam Medical Center were retrospectively reviewed to assess the factors associated with long-term survival outcomes.Results: The median overall survival of the total cohort treated with GPT was 18.7 months. The 1- and 2-year overall, local progression-free, and progression-free survival rates were 70.4% and 35.7%, 78.2% and 59.0%, and 38.6% and 20.8%, respectively. Multivariate analysis revealed that LAPCs at the pancreatic body-tail and those without anterior peripancreatic invasion were independently associated with longer overall survival (P = 0.040 and P = 0.015, respectively). The median overall survival of patients with LAPC at the pancreatic body-tail and those with LAPC without anterior peripancreatic invasion were 24.1 and 28.1 months, respectively. LAPCs at the pancreatic body-tail had a higher volume ratio irradiated over 60 Gy equivalents at gross tumor volume than those at the pancreatic head (P < 0.001). LAPCs with anterior peripancreatic invasion had more peritoneal recurrence within 6 months after GTP than those without anterior peripancreatic invasion (P = 0.039).Conclusions: GPT is a promising treatment option for patients with LAPC at the pancreatic body-tail and those with LAPC without anterior peripancreatic invasion. [ABSTRACT FROM AUTHOR]

Background: Particle radiotherapy has increasingly gained acceptance for locally advanced pancreatic cancers owing to superior tumor conformity and dosimetry compared to conventional photon radiotherapy. However, the close proximity of the pancreas to the stomach and duodenum leads to radiation-induced gastrointestinal toxicities, which hinder the delivery of curative doses to the tumor. To overcome this problem, a surgical spacer was placed between the tumor and gastrointestinal tract, and subsequent proton radiotherapy was performed in this study.Methods: Data from 9 patients who underwent surgical spacer placement and subsequent proton radiotherapy were analyzed. The safety and feasibility of the spacer placement surgery were evaluated; the impact of the spacer on dosimetry was also assessed using dose volume histogram (DVH) analyses, before and after surgical spacer placement.Results: Surgical spacer placement and subsequent proton radiotherapy were successfully completed in all cases. Surgical spacer placement significantly improved the dose intensity covering 95%, mean, and minimum doses for the gross tumor volume, and the clinical and planning target volume based on the DVH, while respecting the dose constraints of the gastrointestinal tract. Based on the Common Terminology Criteria for Adverse Events, two patients (22.2%) developed gastrointestinal ulcer (Grade 2) at 1 and 35 months, and one patient (11.1%) developed gastric perforation (Grade 4) at 4 months after proton radiotherapy.Conclusions: Surgical spacer placement in the locally advanced pancreatic body and tail cancers is relatively safe and technically feasible. Comparing radiation plans, surgical spacer placement seems to improve the dose distribution in the locally advanced pancreatic body and tail cancers, which are close to the gastrointestinal tract. [ABSTRACT FROM AUTHOR]

Background: Borderline resectable pancreatic cancer (BRPC) is frequently associated with positive surgical margins and a poor prognosis because the tumor is in contact with major vessels. This study evaluated the relationship between the margin-negative (R0) resection rate and findings indicating peripancreatic vascular invasion on multidetector computed tomography (MDCT) imaging after neoadjuvant chemoradiotherapy (NACRT) in patients with BRPC.Methods: Twenty-nine BRPC patients who underwent laparotomy after neoadjuvant S-1 with concurrent radiotherapy were studied retrospectively. Peripancreatic major vessel invasion was evaluated based on the length of tumor-vessel contact on MDCT. The R0 resection rates were compared between the progression of vascular invasion (PVI) group and the non-progression of vascular invasion (NVI) group.Results: There were 3 patients with partial responses (10%), 25 with stable disease (86%), and 1 with progressive disease (3%) according to the RECISTv1.1 criteria. Regarding vascular invasion, 9 patients (31%) were classified as having PVI, and 20 patients (69%) were classified as having NVI. Of the 29 patients, 27 (93%) received an R0 resection, and all the PVI patients received an R0 resection (9/9; R0 resection rate = 100%) while 90% (18/20) of the NVI patients underwent an R0 resection. The exact 95% confidence interval of risk difference between those R0 resection rates was - 10.0% [- 31.7-20.4%].Conclusions: Patients with BRPC after NACRT achieved high R0 resection rates regardless of the vascular invasion status. BRPC patients can undergo R0 resections unless progressive disease is observed after NACRT.Trial Registration: UMIN-CTR, UMIN000009172 . Registered 23 October 2012. [ABSTRACT FROM AUTHOR]