[Surgical therapy of intraductal papillary mucinous neoplasms of the pancreas]

Static and Dynamic 68Ga-FAPI PET/CT for the Detection of Malignant Transformation of Intraductal Papillary Mucinous Neoplasia of the Pancreas

Pancreatic ductal adenocarcinoma (PDAC) may arise from intraductal papillary mucinous neoplasms (IPMN) with malignant transformation, but a significant portion of IPMN remains to show benign behavior. Therefore, it is important to differentiate between benign IPMN and IPMN lesions undergoing malignant transformation. However, nonoperative differentiation by ultrasound, CT, MRI, and carbohydrate antigen 19-9 (CA19-9) is still unsatisfactory. Here, we assessed the clinical feasibility of additional assessment of malignancy by PET using ⁶⁸Ga-labeled fibroblast activation protein inhibitors (⁶⁸Ga-FAPI PET) in 25 patients with MRI- or CT-proven cystic pancreatic lesions. Methods: Twenty-five patients with cystic pancreatic lesions who were followed up in the European Pancreas Center of Heidelberg University hospital and who were led to surgical resection or fine-needle aspiration due to suspicious clinical, laboratory chemistry, or radiologic findings were examined by static (all patients) and dynamic (20 patients) ⁶⁸Ga-FAPI PET. Cystic pancreatic lesions were delineated and SUV_max and SUV_mean were determined. Time-activity curves and dynamic parameters (time to peak, K ₁, k ₂, K3, k ₄) were extracted from dynamic PET data. Receiver-operating curves of static and dynamic PET parameters were calculated. Results: Eleven of the patients had menacing IPMN (high-grade IPMN with [6 cases] or without [5 cases] progression into PDAC) and 11 low-grade IPMN; 3 patients had other benign entities. Menacing IMPN showed significantly elevated ⁶⁸Ga-FAPI uptake compared with low-grade IPMN and other benign cystic lesions. In dynamic imaging, menacing IPMN showed increasing time-activity curves followed by slow decrease afterward; time-activity curves of low-grade IPMN showed an immediate peak followed by rapid decrease for about 10 min and slower decrease for the rest of the time. Receiver-operating curves showed high sensitivity and specificity (area under the curve greater than 80%) of static and dynamic PET parameters for the differentiation of IPMN subtypes. Conclusion: ⁶⁸Ga-FAPI PET is a helpful new tool for the differentiation of menacing and low-grade IPMN and shows the potential to avoid unnecessary surgery for nonmalignant pancreatic IPMN.

[Branch duct intraductal papillary mucinous neoplasm - surgical approach]

Due to increasing precision of modern imaging modalities, intraductal papillary mucinous neoplasms (IPMN) of the pancreas are found with increasing prevalence. Despite their malignant potential IPMN are often kept under surveillance and are not immediately resected. The 2012 International Consensus Guidelines of Fukuoka have been widely accepted for the management of IPMN. They recommend surgical resection for branch duct IPMN with "high risk stigmata", while branch duct IPMN with "worrisome features" should undergo observation without immediate resection. Consequently, patients with asymptomatic branch duct IPMN and a presumed low malignant potential mostly undergo primary surveillance to avoid surgery-related morbidity and mortality following pancreatic resection; however, with respect to the cumulative risk of malignant transformation over time, surgical resection might also be indicated for patients with branch duct IPMN with "worrisome features". This article discusses the indications for surgery and different options of resection of branch duct IPMN.

Main- and Branch-Duct Intraductal Papillary Mucinous Neoplasms: Extent of Surgical Resection

Background

Surgical treatment of intraductal papillary mucinous neoplasms (IPMN) requires a differentiated approach regarding indications and extent of resection.

Methods

The review summarizes the current literature on indication, timing, and surgical procedures in IPMN.

Results

The most important differentiation has to be made between main-duct and branch-duct IPMN as well as mixed-type lesions that biologically mimic main-duct types. In main-duct and mixed-type IPMN, the resection should be indicated by the time of the diagnosis – in accordance with the international consensus guidelines – and should follow oncological principles. Depending on IPMN localization, this implies partial pancreatoduodenectomy, distal pancreatectomy, or total pancreatectomy and includes the corresponding types of lymphadenectomy. Furthermore, branch-duct IPMN > 3 cm or bearing high-risk features (mural nodules in magnetic resonance imaging, computed tomography, or endoscopic ultrasound imaging; symptomatic lesions; elevated tumor markers) are similarly treated. As the risk for malignancy in smaller branch-duct IPMN is lower, the decision for surgical treatment is often individually made – despite the updated 2012 guidelines. In these lesions, limited surgical approaches, including enucleation and central pancreatectomy, are possible.

Conclusion

Timely and radical resection of IPMN offers the unique opportunity to prevent pancreatic cancer, and even in malignant IPMN surgery can offer a curative approach with excellent long-term outcome in early stages. A structured imaging follow-up should be considered to recognize IPMN recurrence and metachronous pancreatic cancer as well as gastrointestinal neoplasias by endoscopic surveillance.