Identification of patients with branch-duct intraductal papillary mucinous neoplasm and very low risk of cancer: multicentre study.

Background: Different surveillance strategies for patients with low-risk branch-duct (BD) intraductal papillary neoplasm (IPMN) have been described. The aim of this study was to describe the natural history of low-risk BD-IPMN, and to identify risk factors for the development of worrisome features (WF)/high-risk stigmata (HRS) and of pancreatic malignancies.

Methods: This was a multicentre retrospective study of patients with BD-IPMN who were under active surveillance between January 2006 and December 2015. Patients were eligible if they had a low-risk lesion and had a minimum follow-up of 24 months. Outcomes were development of WF/HRS or cytologically/histologically confirmed malignant IPMN.

Results: Of 837 patients included, 168 (20 per cent) developed WF/HRS. At the end of the observation time, 132 patients (79 per cent) with WF/HRS were still under surveillance without progression to pancreatic cancer. Factors associated with the development of WF or HRS in multivariable analysis included localized nodules (versus diffuse: hazard ratio (HR) 0.43, 95 per cent c.i. 0.26 to 0.68), cyst size 15-19 mm (versus less than 15 mm: HR 1.88, 1.23 to 2.87) or at least 20 mm (versus less than 15 mm: HR 3.25, 2.30 to 4.60), main pancreatic duct size over 3 mm (versus 3 mm or less: HR 2.17, 1.41 to 3.34), and symptoms at diagnosis (versus no symptoms: HR 2.29, 1.52 to 3.45). Surveillance in an endoscopy-oriented centre was also associated with increased detection of WF or HRS (versus radiology-oriented: HR 2.46, 1.74 to 3.47).

Conclusion: Conservative management of patients with low-risk BD-IPMN is safe and feasible.