Rapid Growth Rates of Suspected Pancreatic Cyst Branch Duct Intraductal Papillary Mucinous Neoplasms Predict Malignancy.

BACKGROUND: The majority of branch duct intraductal papillary mucinous neoplasms (BD-IPMNs) are recommended for surveillance imaging based on consensus guidelines. However, growth rates that should prompt concern for malignant transformation of BD-IPMN are unknown. AIMS: To determine whether BD-IPMN growth can predict an increased risk of malignancy and define growth rates concerning for malignant BD-IPMN.
METHODS: The study is a retrospective, multicenter study of suspected BD-IPMN patients undergoing imaging surveillance. All patients underwent EUS evaluation followed by surveillance imaging.
RESULTS: Two hundred and eighty-four patients with suspected BD-IPMN without worrisome features or high-risk stigmata were followed for a median 56 months and underwent a median of four imaging studies. Nine patients (3.2 %) developed malignant BD-IPMN. Malignant BD-IPMN grew at a faster rate (18.6 vs. 0.8 mm/year; P = 0.05) compared to benign BD-IPMN. BD-IPMN growth rate between 2 and 5 mm/year was associated with an increased risk of malignancy with hazard ratio (HR) of 11.4 (95 % CI 2.2-58.6) when compared to subjects with BD-IPMN growth rate <2 mm/year (P = 0.004). BD-IPMN growth rate ≥5 mm/year had a hazard ratio of 19.5 (95 % CI 2.4-157.8) (P = 0.005). BD-IPMN growth rate of 2 mm/year had a sensitivity of 78 %, specificity of 90 %, and accuracy of 88 % to identify malignancy. Total BD-IPMN growth was also associated with increased risk of malignancy (P = 0.003) with all malignant IPMNs growing at least 10 mm prior to cancer diagnosis.
CONCLUSIONS: BD-IPMN growth rates ≥2 mm/year and total growth of ≥10 mm should be considered worrisome features for BD-IPMN at increased risk of malignancy.