AB084. P056. Intra-operative ultrasound to determine resectability during surgical exploration of primary non-resectable pancreatic cancer following induction chemotherapy

Background: Determining the resectability of primary non-resectable pancreatic cancer after induction chemotherapy is complicated by under-estimation of tumor regression upon pre-operative imaging. Diagnostic modalities to accurately predict resectability are therefore highly needed. This study describes the initial results of intra-operative ultrasound (IOUS) as diagnostic tool during explorative laparotomy of primary non-resectable pancreatic cancer following induction chemotherapy.

Methods: Prospective multicenter study of patients who underwent surgical exploration following two months of induction chemotherapy because of primary non-resectable pancreatic cancer. Patients with RECIST non-progressive disease proceeded to explorative laparotomy with IOUS in the case of <180 arterial or reconstructable venous involvement [i.e., NCCN (borderline) resectable disease] or if they persisted unresectable and had been randomized for local ablative treatment within a clinical trial. IOUS outcomes were compared with pre-operative, post-chemotherapy CT-imaging and pathological examination only in case of a resection specimen.

Results: Twenty LAPC patients underwent explorative laparotomy of which 5 had RECIST partial response and 15 RECIST stable diseases. The majority had received FOLFIRINOX (n=18). CT-imaging classified 1 (5%) patient as NCCN resectable, 9 (45%) as borderline resectable and 10 (50%) as unresectable. Upon IOUS, 5 (25%) patients were deemed resectable, 6 (30%) borderline resectable and 9 (45%) unresectable. Consequently, IOUS deemed 4 NCCN borderline resectable patients to be primary NCCN resectable and 1 unresectable patient to be borderline resectable. Therefore the resectability status was changed in 5/20 (25%) patients. Ultimately, 12 patients underwent resection of which 50% had radical vascular resection margins.

Conclusions: IOUS is a promising tool for the surgeon to determine resectability during surgical exploration of primary non-resectable pancreatic cancer following induction chemotherapy. Future series to assess the diagnostic value, including pathology confirmation of IOUS findings are needed.