Case Report: Exceptional long-term survival in metastatic pancreatic ductal adenocarcinoma after repeated high-dose hypofractionated lesion-directed radiotherapy.

Metastatic pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis, and survival beyond a decade is exceptional. We report a 59-year-old man with stage IV PDAC presenting with oligometastatic disease involving a pancreatic head/uncinate primary tumor, clustered right posterior hepatic metastases, and left supraclavicular nodal metastasis. Endoscopic ultrasound-guided biopsy of the pancreatic primary lesion confirmed poorly differentiated adenocarcinoma; metastatic involvement was diagnosed radiographically. Baseline disease was limited to three locally treatable sites, and CA19-9 remained within the normal range throughout follow-up. The patient received four courses of high-dose hypofractionated, high-BED lesion-directed radiotherapy with limited systemic therapy. RT1 treated the three baseline disease sites with concurrent oral S-1. Post-RT1 MRI showed partial response of the pancreatic primary tumor and right posterior hepatic metastases according to RECIST 1.1, and PET/CT showed resolution of abnormal pancreatic hypermetabolism in the pancreatic lesion, with a post-treatment SUVmax of 1.1. Metachronous oligoprogression subsequently occurred in the liver and lung: RT2 and RT3 each treated one new hepatic lesion with concurrent S-1, and RT4 treated three clinically progressive pulmonary metastatic targets without concurrent systemic therapy. No grade ≥3 treatment-related toxicity was documented. After RT4, no further systemic antitumor therapy was administered. Radiographic non-progression was documented for approximately 5 years and 5 months after the final thoracic radiotherapy, until February 2023. At telephone follow-up on May 27, 2026, the patient remained alive, independent in daily living, and had an ECOG performance status of 0-1. Overall survival exceeded 11 years and 8 months from diagnosis. This case highlights exceptional long-term survival in oligometastatic and oligoprogressive metastatic PDAC after repeated high-BED lesion-directed radiotherapy. This observation is hypothesis-generating and should not be interpreted as evidence that radiotherapy can replace systemic therapy.