Introduction: Pancreatic cancer is the fourth leading cause of cancer-related death in the USA. Early detection of pancreatic cancer may help improve patient survival. It has been hypothesized that acute idiopathic or chronic pancreatitis is associated with an increased risk of pancreatic cancer; however, these conditions may also represent an early manifestation of pancreatic cancer, rather than just being risk factors. Endoscopic ultrasound (EUS) is a sensitive diagnostic modality for the detection of small, early-stage pancreatic tumors. The aim of this study was to evaluate the diagnostic yield of EUS for pancreatic cancer in patients with acute idiopathic or chronic pancreatitis when cross-sectional imaging (CT and/or MRI) was negative for a mass lesion in the pancreas.

Methods: This study was an IRB-approved retrospective chart review conducted for the period of August 2005 to September 2018. Any patient presenting with acute idiopathic or chronic pancreatitis with a CT and/or MRI imaging negative for a pancreatic mass lesion that underwent an EUS during the study period was selected for inclusion. A retrospective review was performed to evaluate the outcomes of patients who had pancreatic cancer diagnosed from an EUS-FNA (fine needle aspiration) sample. Data were collected on patient demographics and clinical characteristics, inclusive of specific post-diagnosis treatment course. An "event rate" was calculated and is defined as the number of positive pancreatic cancer diagnoses on EUS-FNA from all patients presenting with acute idiopathic or chronic pancreatitis who underwent an EUS examination following a CT and/or MRI study negative for pancreatic mass lesion.

Results: A total of 565 patients met inclusion criteria, with 30 cases of confirmed pancreatic cancer diagnosed with EUS-FNA from this group. The event rate for EUS diagnosis of pancreatic cancer was 5.3%. The majority of patients (52.0%) diagnosed with cancer were stages I-II.

Conclusions: Endoscopic ultrasound should be a routine part of the diagnostic algorithm when evaluating a patient with acute idiopathic or chronic pancreatitis of unclear etiology, particularly when cross-sectional imaging is negative for a mass lesion and clinical suspicion is high for neoplasia. Further prospective studies are needed to evaluate the role of EUS in this setting.