More than 2% of the adult U.S. population harbors a pancreatic cyst. These often pose a difficult management problem because conventional criteria cannot always distinguish cysts with malignant potential from those that are innocuous. One of the most common cystic neoplasms of the pancreas, and a bona fide precursor to invasive adenocarcinoma, is called intraductal papillary mucinous neoplasm (IPMN). To help reveal the pathogenesis of these lesions, we purified the DNA from IPMN cyst fluids from 19 patients and searched for mutations in 169 genes commonly altered in human cancers. In addition to the expected KRAS mutations, we identified recurrent mutations at codon 201 of GNAS. A larger number (113) of additional IPMNs were then analyzed to determine the prevalence of KRAS and GNAS mutations. In total, we found that GNAS mutations were present in 66% of IPMNs and that either KRAS or GNAS mutations could be identified in 96%. In eight cases, we could investigate invasive adenocarcinomas that developed in association with IPMNs containing GNAS mutations. In seven of these eight cases, the GNAS mutations present in the IPMNs were also found in the invasive lesion. GNAS mutations were not found in other types of cystic neoplasms of the pancreas or in invasive adenocarcinomas not associated with IPMNs. In addition to defining a new pathway for pancreatic neoplasia, these data suggest that GNAS mutations can inform the diagnosis and management of patients with cystic pancreatic lesions.

International experts met to discuss recent advances and to revise the 2004 recommendations for assessing and reporting precursor lesions to invasive carcinomas of the pancreas, including pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasm (IPMN), mucinous cystic neoplasm, and other lesions. Consensus recommendations include the following: 1) To improve concordance and to align with practical consequences, a two-tiered system (low vs. high-grade) is proposed for all precursor lesions, with the provision that the current PanIN-2 and neoplasms with intermediate-grade dysplasia now be categorized as low-grade. Thus, “high-grade dysplasia” is to be reserved for only the uppermost end of the spectrum (“carcinoma in situ” type lesions). 2) Current data indicate that PanIN of any grade at a margin of a resected pancreas with invasive carcinoma does not have prognostic implications; the clinical significance of dysplasia at a margin in a resected pancreas with IPMN lacking invasive carcinoma remains to be determined. 3) Intraductal lesions 0.5–1 cm can be either large PanINs or small IPMNs. The term “incipient IPMN” should be reserved for lesions in this size with intestinal- or oncocytic-papillae or GNAS mutations. 4) Measurement of the distance between an IPMN and invasive carcinoma and sampling of intervening tissue are recommended to assess concomitant versus associated status. Conceptually, concomitant invasive carcinoma (in contrast with the “associated” group) ought to be genetically distinct from an IPMN elsewhere in the gland. 5) “Intraductal spread of invasive carcinoma” (aka, “colonization”) is recommended to describe lesions of invasive carcinoma invading back into and extending along the duct system, which may morphologically mimic high-grade PanIN or even IPMN. 6) “Simple mucinous cyst” is recommended to describe cysts > 1 cm having gastric-type flat mucinous lining at most minimal atypia without ovarian-type stroma to distinguish them from IPMN. 7) Human lesions resembling the acinar-to-ductal metaplasia and atypical flat lesions of genetically engineered mouse models exist and may reflect an alternate pathway of carcinogenesis; however, their biological significance requires further study. These revised recommendations are expected to improve our management and understanding of precursor lesions in the pancreas.

More information is needed about genetic factors that initiate development of pancreatic intraepithelial neoplasms (PanINs)—the most common precursors of pancreatic ductal adenocarcinoma. We show that >99% of the earliest stage, lowest-grade, PanIN-1 lesions contain mutations in KRAS, p16/CDKN2A, GNAS, or BRAF. These findings could improve our understanding the development and progression of these pre-malignant lesions.

Background There are no established guidelines for pathologic diagnosis/reporting of IPMNs. Design An international multidisciplinary group brought together by the Verona Pancreas Group in Italy-2013, was tasked to devise recommendations. Results 1) Crucial to rule out invasive carcinoma with extensive (if not complete) sampling. 2) Invasive component is to be documented in a full synoptic report including its size, type, grade, stage. 3) The term “minimally invasive” should be avoided; instead, invasion size with stage and substaging of T1 (1a, b, c; ≤0.5, >0.5–≤1, >1 cm), is to be documented. 4) Largest diameter of the invasion, not the distance from the nearest duct, is to be used. 5) A category of “indeterminate/(suspicious) for invasion” is acceptable for rare cases. 6) The term “malignant” IPMN should be avoided. 7) The highest grade of dysplasia in the non-invasive component is to be documented separately. 8) Lesion size is to be correlated with imaging findings in cysts with rupture. 9) The main duct diameter, and if possible, its involvement is to be documented; however, it is not required to provide main vs branch duct classification in the resected tumor. 10) Subtyping as gastric/intestinal/pancreatobiliary/oncocytic/mixed is of value. 11) Frozen section is to be performed highly selectively, with appreciation of its shortcomings. 12) These principles also apply to other similar tumoral intraepithelial neoplasms (mucinous cystic neoplasms, intra-ampullary, intra-biliary/cholecystic). Conclusion These recommendations will ensure proper communication of salient tumor characteristics to the management teams, accurate comparison of data between analyses, and development of more effective management algorithms.

Cancer biomarkers are currently the subject of intense research because of their potential utility for diagnosis, prognosis, and targeted therapy. In theory, the gene products resulting from somatic mutations are the ultimate protein biomarkers, being not simply associated with tumors but actually responsible for tumorigenesis. We show here that the altered protein products resulting from somatic mutations can be identified directly and quantified by mass spectrometry. The peptides expressed from normal and mutant alleles were detected by selected reaction monitoring (SRM) of their product ions using a triple-quadrupole mass spectrometer. As a prototypical example of this approach, we demonstrated that it is possible to quantify the number and fraction of mutant Ras protein present in cancer cell lines. There were an average of 1.3 million molecules of Ras protein per cell, and the ratio of mutant to normal Ras proteins ranged from 0.49 to 5.6. Similarly, we found that mutant Ras proteins could be detected and quantified in clinical specimens such as colorectal and pancreatic tumor tissues as well as in premalignant pancreatic cyst fluids. In addition to answering basic questions about the relative levels of genetically abnormal proteins in tumors, this approach could prove useful for diagnostic applications.genetics | proteomics | pancreatic cancer | genetic diagnosis | companion diagnostics