Preliminary Investigation of the Efficacy and Indications of Proton Beam Therapy for Stage IV Pancreatic Adenocarcinoma

Hisashi Yamaguchi; Takahiro Kato; Yuki Narita; Michitaka Honda; Koichi Hamada; Yojiro Ishikawa; Ichiro Seto; Yoshiaki Takagawa; Yasuhiro Kikuchi; Masao Murakami

doi:10.7759/cureus.57771

Preliminary Investigation of the Efficacy and Indications of Proton Beam Therapy for Stage IV Pancreatic Adenocarcinoma

Cureus. 2024 Apr 7;16(4):e57771. doi: 10.7759/cureus.57771. eCollection 2024 Apr.

Authors

Affiliations

¹ Department of Minimally Invasive Surgical and Medical Oncology, Fukushima Medical University, Fukushima, JPN.
² School of Health Sciences, Fukushima Medical University, Fukushima, JPN.
³ Department of Radiation Oncology, Southern Tohoku Proton Therapy Center, Koriyama, JPN.
⁴ Radiology, Tohoku Medical and Pharmaceutical University, Sendai, JPN.

Abstract

Background: The present study aimed to evaluate proton beam therapy (PBT) for stage IV pancreatic adenocarcinoma and its metastases and define the criteria for eligibility. Materials and methods: We retrospectively evaluated the patients who had a histopathological diagnosis of pancreatic adenocarcinoma, had progressed to stage IV, and underwent PBT for both the primary and some metastatic lesions between 2017 and 2022. PBT was performed using the passive scattering technique.

Results: Sixteen patients (median age, 72 years; range, 55-85 years) were enrolled. All patients had stage IV pancreatic cancer at the initiation of PBT. The median duration from the date of stage IV diagnosis to the initiation of PBT was 5.8 (range, 0.4-13.5) months. Three patients had been diagnosed as having recurrent stage IV cancer at other institutions before their referral to our hospital because they had local recurrence and distant metastases after the resection of the primary tumor. Chemotherapy was as follows: pre-PBT, 0, 1, 2, and 3 lines in 4, 7, 4, and 1 patients, respectively; concurrent with PBT, 0 and 1 line in 11 and 5 patients, respectively; post-PBT, 0 and 1 line in 5 and 5 patients, respectively; and unknown, 6 patients. The median survival times (MSTs) from the date of stage IV diagnosis for the with or without non-irradiated active metastatic tumor were 11.4 and 20.1 months, respectively. Univariate analysis revealed that the performance status (PS) levels (p < 0.01), the carbohydrate antigen (CA) 19-9 tumor marker levels (p < 0.01), active tumors not treated with irradiation (p = 0.02), and with or without post-PBT chemotherapy (p < 0.01) were statistically significant factors. Multivariate analysis revealed that the CA 19-9 tumor marker levels (p= 0.04), the number of metastatic lesions (p = 0.049), and with or without non-irradiated active metastatic tumors (p = 0.02) were significant factors.

Conclusion: PBT is indicated when the number of metastases is limited to ≤ 4 lesions and all tumors can be irradiated within the smallest possible number of irradiation fields that can be performed within the patient's tolerable time, which is a subjective duration that depends on the patient's reaction during each session. It may be a viable treatment option for patients with oligometastatic pancreatic cancer.

Keywords: ductal pancreatic adenocarcinoma; oligometastasis; pancreas cancer metastases; pancreatic adenocarcinoma treatment; preliminary investigation; proton beam therapy; stage iv disease.