E298: Complete Primary Pathological Response Following Neoadjuvant Therapy in Patients Undergoing Major Pancreatic Resection

Nine patients were identified to have a complete primary pathological response (ypT0) on post-operative histological analysis. Before treatment, five were considered borderline resectable due to contact with major vascular structures and four were locally advanced with involvement of major vascular structures. All patients underwent staging CT and ¹⁸FDG-PET/CT imaging, with a mean SUVmax of the primary lesion at 7.28. Eight patients received neoadjuvant FOLFIRINOX chemotherapy, five received further radiotherapy (45Gy/15#) with concomitant capecitabine. Post-neoadjuvant treatment ¹⁸FDG-PET/CT was performed in four patients, with a mean SUVmax of 4.38 (p=0.07). Mean pre- and post-treatment serum Ca19-9 was 84.7 and 16.8 respectively (p=0.05). The mean time from completion of neoadjuvant treatment to surgery was 11.7 weeks. Seven patients were found to have pancreatic ductal adenocarcinoma and two duodenal adenocarcinoma, the mean lymph node yield was 23.5, with two patients found to have one lymph node (ypN1) involved. All resections were reported to be R0. The mean length of stay was 10.8 days. At the time of analysis, all patients remain alive and under active surveillance with only one case of recurrence at the surgical bed reported at 16 months.  The current mean overall survival is 20.9 months.

Conclusions: Complete primary pathological response is uncommon but possible following neoadjuvant treatment in patients with primary pancreatic ductal and duodenal adenocarcinomas. The long-term clinical course and impact on recurrence and survival for this distinct cohort of patients need to be further evaluated.