Reply to "Letter to Editor: Main-duct Intraductal Papillary Mucinous Neoplasm: High Cancer Risk in Duct Diameter of 5 to 9 mm" by Marco Del Chiaro and Richard D. Schulick.

To the Editor: We read with great interest the study by Hackert et al. The authors showed in a large series of 260 consecutive patients who underwent resection for intraductal papillary mucinous neoplasms (IPMNs) involving the main pancreatic duct (MPD), a total malignancy (which included both invasive cancer and carcinoma in situ) rate of 68%. The malignancy rate was 59% even in patients with an MPD of 5 to 9 mm in diameter. These data show the potentially aggressive phenotype of IPMNs involving the MPD even when the diameter is less than 10 mm. These data cause conflict with the recent IAP Guidelines on Cystic Tumors of the pancreas that suggest surgical resection of IPMNs with an MPD dilatation of 5 to 9 mm only when associated with additional criteria such as jaundice or solid nodules. In 2013, the European Study Group on Cystic Tumors of the Pancreas published the European Expert Consensus Statement on Cystic Tumors of the Pancreas. This paper, not mentioned by the authors, is extensively used by several other European and nonEuropean Centers, for the management of pancreatic cystic neoplasms, including IPMNs. There are several differences between the IAP and European Guidelines. In summary, the European Guidelines suggest a more conservative approach for the management of the branch-duct IPMNs (BD-IPMNs) and a more aggressive approach for the IPMNs types involving the MPD (MD-IPMNs and mixed-type IPMNs) than the IAP guidelines. In the European Guidelines, surgical resection is suggested for patients with an involvement of the MPD with diameter 6 mm. The European Guidelines describe ‘‘absolute’’ and ‘‘relative’’ indications for surgery in patients with IPMNs. ‘‘Absolute indications’’ for surgery include symptoms related to IPMNs (ie, jaundice or acute pancreatitis), (2) solid nodules, and (3) MPD 6 mm. These recent data published by the Heidelberg group seem to support the European Guideline’s more aggressive recommendations for the treatment of patients with IPMNs involving the MPD. Hackert et al included both patients with high-grade dysplasia and those with invasive cancer in the ‘‘malignancy’’ group. Even with this definition of malignancy, the data are very interesting and important, and indicate a more aggressive approach. The main goal of treatment of patients with IPMN should be to resect lesions before evolution to invasive cancer, optimally at the stage of high-grade dysplasia. An equally important goal is to not resect IPMNs that will not evolve to a dangerous lesion. Resection of patients with appropriately selected premalignant lesions can reduce pancreas cancer mortality. The differences between the IAP and European Guidelines emphasize that we are in an evolutionary process in learning how to best treat patient with IPMN. Patients with IPMN have a very heterogeneous disease and there are very diverse biological behaviors and phenotypes even within lesions that have similar imaging characteristics. There is no right or wrong, but we must realize that clinical judgment and experience are equally important and that guidelines are just that— guidelines.