Deterioration of pancreatic exocrine function in carbon ion radiotherapy for pancreatic cancer

Shintaro Shiba; Yuhei Miyasaka; Masahiko Okamoto; Shuichiro Komatsu; Shohei Okazaki; Kei Shibuya; Tatsuya Ohno

doi:10.1016/j.ctro.2021.09.007

Deterioration of pancreatic exocrine function in carbon ion radiotherapy for pancreatic cancer

Clin Transl Radiat Oncol. 2021 Oct 3:31:80-85. doi: 10.1016/j.ctro.2021.09.007. eCollection 2021 Nov.

Authors

Shintaro Shiba^{1

2}, Yuhei Miyasaka², Masahiko Okamoto¹, Shuichiro Komatsu¹, Shohei Okazaki², Kei Shibuya¹, Tatsuya Ohno¹

Affiliations

¹ Department of Radiation Oncology, Gunma University Graduate School of Medicine, 3-39-22, Showa-machi, Maebashi, Gunma 371-8511, Japan.
² Gunma University Heavy Ion Medical Center, 3-39-22, Showa-machi, Maebashi, Gunma 371-8511, Japan.

Abstract

Background and purpose: In radiotherapy (RT) for pancreatic cancer, the pancreas is considered an important organ at risk. However, there are insufficient reports on pancreatic function deterioration after X-ray RT as organ at risk, and there are no reports on those after carbon ion (C-ion) RT. Here, we evaluated pancreatic exocrine insufficiency (PEI) after C-ion RT using dose-volume histogram (DVH) analysis.

Materials and methods: Data were retrospectively collected from patients who had undergone C-ion RT for pancreatic cancer between July 2013 and June 2019. The prescribed C-ion doses were 55.2 Gy (relative biological effectiveness) in 12 fractions. Serum pancreatic amylase and lipase values were measured before and after C-ion RT. In DVH analysis, we assessed V_5Gy-50Gy and V_<5 _Gy-50Gy of pancreatic volume and analyzed whether these DVH parameters involved PEI.

Results: Thirty-three patients were included in the analysis. The median follow-up duration after the initiation of C-ion RT in these patients was 15.8 months (range, 4.3-64.8). During and after treatment, 57.6% of patients developed PEI within 13.6 months, defined as pancreatic amylase and lipase deficiencies. In DVH analysis, V_<5Gy was the most effective factor for the PEI, and the cutoff value for developing PEI in V_<5Gy was 4.57 cm³.

Conclusion: We showed that pancreatic exocrine function declined after C-ion RT for pancreatic cancer and that PEI was initiated early in the course of C-ion RT. Additionally, a low dose of DVH parameters, such as V_<5Gy, was a prognostic factor of PEI.

Keywords: Carbon ion radiotherapy; Dose-volume histogram; Pancreatic cancer; Pancreatic exocrine insufficiency; Pancreatic function.