An autopsy study to clarify characteristics of local recurrence after extended pancreatectomy with intraoperative radiation therapy in patients with pancreatic cancer

Purpose Local relapses frequently occur even after curative resection of pancreatic cancer. To control local recurrence, we adopted extended radical resection combined with intraoperative radiation therapy. Methods A retrospective review was conducted on 41 patients who underwent extended radical pancreatectomy combined with intraoperative radiation therapy for pancreatic cancer. Fourteen patients underwent autopsies. We took en bloc specimens of the abdominal aorta with surrounding connective tissue to evaluate histological characteristics of local status at autopsies. Results Autopsies disclosed microscopic local recurrence in five (36%) of the 14 patients, although no evidence of local relapse was observed in either follow-up images or macroscopic findings at autopsy. Of the three patients with R1 resection, two had no local recurrence microscopically at autopsy. Histological features of local recurrence in autopsy samples showed small numbers of cancer cells surrounded by thick connective tissue without mass formation. Conclusions The autopsy study revealed that a characteristic of local recurrence after this treatment was tiny cancer cells scattered in dense connective tissue; these cells were undetected by follow-up imaging.