Determination of Pancreatic Steatosis Prevalence and Correlation With High-risk Cyst Features in Patients With Pre-malignant Pancreatic Cystic Neoplasms Using Magnetic Resonance Imaging and Endoscopic Ultrasound

Pancreatic cancer is the fifth leading cause of cancer mortality in Hong Kong and the seventh leading cause of cancer mortality worldwide. In 2020, approximately 496000 new cases of pancreatic cancers were diagnosed globally . Pancreatic cancer is a highly fatal cancer with a case-fatality rate of 94.0% globally. In Hong Kong, both the incidence and mortality of pancreatic cancer have increased over the past decade.

Due to the deep-seated location of pancreas, it is difficult to diagnose pancreatic cancer at an early stage, which in turn leads to delays in cancer treatment and poorer survival. Despite advances in oncologic treatment, the 5-year survival rate of metastatic pancreatic cancer remains poor (~2.9%). As such, there has been growing interest to improve pancreatic cancer prevention and survival by:

1. reduction of modifiable risk factors (eg, cigarette smoking, obesity, diabetes),
2. screening for early detection of high-risk pre-malignant lesions in selected high-risks patients with strong family history of pancreatic cancer and/or certain germline mutations of pancreatic cancer susceptibility genes (eg, BRCA1, BRAC2, DNA mismatch repair genes in Lynch Syndrome, etc) by magnetic resonance imaging (MRI) or endoscopic ultrasound (EUS), and
3. surveillance of pre-malignant precursor lesions such as mucinous pancreatic cystic neoplasms (PCN) by imaging and/or EUS to identify high-risk neoplastic progression indicated for surgical resection

The prevalence of incidentally found pancreatic cystic lesions ranges from 2.1% to 13.5% in patients undergoing CT or MRI for non-pancreatic indications. In patients with pre-malignant mucinous PCN (intraductal papillary mucinous neoplasms (IPMN) and mucinous cystic neoplasms (MCN)), pancreatic cancer can originate from the pre-malignant PCN, or develop in other parts of the pancreas uninvolved by the original PCN due to "field-defect". While the malignant potentials of different PCNs vary, the frequency of invasive carcinoma and high-grade dysplasia in IPMN remains substantial, ranging from 36-100% in the main duct type (MD-IPMN) and from 14-48% in the branch duct type (BD-IPMN).

Multiple consensus guidelines and society guidelines have been developed based on cyst structural characteristics and cyst related symptoms to guide management between surgical resection or surveillance of pre-malignant PCN. The 2017 revised international consensus guidelines (Fukuoka guidelines) recommend surgical resection for all MD-IPMN and BD-IPMN with high-risk stigmata of malignancy or worrisome features confirmed by EUS (definite mural nodule > 5mm, main pancreatic duct involvement (dilation / abrupt change in calibre), cytology suspicious or positive for malignancy on EUS guided fine needle aspiration). On the other hand, surveillance of asymptomatic BD-IPMN without high-risk stigmata or worrisome features would be performed with cross-sectional imaging and/or EUS periodically, with intervals tailored to the size of the BD-IPMN.