Purpose The aim of this study was to clarify the incidence, clinical risk factors, and dose–volume relationship of upper gastrointestinal (GI) ulcer after carbon-ion radiotherapy (C-ion RT) for pancreatic cancer. Materials and methods Fifty-eight pancreatic cancer patients were treated with C-ion RT from April 2014 to December 2015. The total dose was 55.2 Gy (RBE) in 12 fractions. D2cm3 of GI tracts were restricted under 46 Gy (RBE); RBE-weighted absorbed dose. The association between dosimetric parameters (V10–50, Dmax, D1cm3, D2cm3) and GI ulcer was examined using Spearman's correlation. The incidence of GI ulcer was compared between the two groups divided by the cutoff value. Results Twelve patients (21%) experienced gastric ulcer including only one (2%) grade 3 ulcer. There was no grade 4/5 toxicity or duodenal ulcer. V10–30 was significantly associated with gastric ulcer. The 1-year estimated risk of gastric ulcer for the determined cutoff values were 51% vs. 10% (V10, ⩾102 cm3 or less), 42% vs. 9% (V20, ⩾24 cm3 or less), 34% vs. 4% (V30, ⩾6 cm3 or less). Conclusions The incidence of GI ulcer after C-ion RT was very low with the dose constraint of D2cm3 <46 Gy (RBE). To further minimize the risk of GI ulcer, V10–30 should also be reduced.
All Science Journal Classification (ASJC) codes
- Radiology Nuclear Medicine and imaging