Outcomes of nonresected main-duct intraductal papillary mucinous neoplasms of the pancreas

Innovation in the Surgical Management of Pancreatic Cystic Neoplasms: Same Operations, Narrower Indications, and an Individualized Approach to Decision-Making

Historically, the management of pancreatic cystic neoplasms (PCN) has been operative. Early intervention for premalignant lesions, including intraductal papillary mucinous neoplasms (IPMN) and mucinous cystic neoplasms (MCN), offers an opportunity to prevent pancreatic cancer-with potential decrement to patients' short-term and long-term health. The operations performed have remained fundamentally the same, with most patients undergoing pancreatoduodenectomy or distal pancreatectomy using oncologic principles. The role of parenchymal-sparing resection and total pancreatectomy remains controversial. We review innovations in the surgical management of PCN, focusing on the evolution of evidence-based guidelines, short-term and long-term outcomes, and individualized risk-benefit assessment.

Limitations and prospects in the management of IPMN: a retrospective, single-center observational study

BACKGROUND

With increasing use and enhanced accuracy of cross-sectional imaging, the diagnosis of intraductal papillary mucinous neoplasms (IPMNs) of the pancreas has increased over the last few decades. The extent to which malignant transformation occurs remains unclear, making the management of IPMNs controversial. The aim of this study was to evaluate the progression rate and outcome of follow-up in patients with IPMNs.

METHODS

A database of all patients diagnosed with IPMN at the Cantonal Hospital HFR Fribourg, Switzerland, between January 2006 and December 2019 with a follow-up of at least 6 months was analyzed retrospectively. Descriptive statistics were performed on patient demographics, IPMN characteristics, and follow-up data.

RESULTS

A total of 56 patients were included in this study. Ten patients underwent primary surgery, 46 were enrolled in a surveillance program.21.7% (n = 5) of patients under surveillance presented with worrisome features of IPMN; progression rates were significantly higher in these patients (p = 0.043). Most progression occurred in the early follow-up period. Five patients underwent surgery due to progression, of which 2 presented high-grade dysplasia and 2 malignancy on postoperative histology.

CONCLUSIONS

The limited predictive value of current guidelines may lead to surgical overtreatment, and the decision to proceed with surgical resection should be made with caution. Further prospective analyses and the development of novel biomarkers are needed to better understand the natural history of IPMN and improve diagnostic precision.

Modern aspects of the management of pancreatic intraductal papillary mucinous neoplasms: a narrative review

Intraductal papillary mucinous neoplasms (IPMNs) account for approximately 35% of all cystic tumors in the pancreas and represent the largest subgroup. They are characterized by mucin production and intraductal papillary epithelium growth. IPMNs range from benign to malignant lesions. Biomarkers combined with 18F-Fluorodeoxyglucose-positron emission tomography (18FDG-PET) is the best diagnostic tool. The risk of malignant transformation for main-duct IPMNs is between 34-68% and for low-risk branch-duct (BD)-IPMNs it is 1.1%. Monitoring is crucial for determining the optimal time of surgical excision. Novel artificial intelligence combining clinical, tumor biomarkers, imaging and molecular genomics plays a determinant role in the evaluation of such lesions. The first diagnostic tool is multidetector helical computed tomography (MDHCT) or up-to-date magnetic resonance imaging (MRI). MRI detects malignancy by enhancing mural nodules ≥3 mm. Novel endosonographic interventional techniques have been added to the diagnostic armamentarium. Pancreatoscopy is feasible and effective but challenging for evaluating the diagnosis, invasiveness, and extent of IPMNs. Its findings may change the surgical approach. Pancreatic juice and duodenal fluid have been used recently for molecular biological analysis. The genes most frequently altered include Kirsten rat sarcoma viral proto-oncogene (KRAS), tumor protein p53 (TP53), cyclin-dependent kinase inhibitor 2A (CDKN2A), SMAD family member 4 (SMAD4), and guanine nucleotide-binding protein, alpha stimulating (GNAS). Despite the advances in diagnostic modalities, assessment of this premalignant lesion of pancreatic cancer, with its poor prognosis, is a challenging task. Pancreatectomy is the indicated approach for malignant or high-risk IPMNs with potent malignancy. Conservative management or enucleation for preserving the pancreas of low-risk BD-IPMNs is recommended, but long-term follow-up for recurrence is necessary. The management of IPMNs must be individualized based on preoperative high-risk stigmata and worrisome features.

Indication for resection and possibility of observation for intraductal papillary mucinous neoplasm with high-risk stigmata

BACKGROUND/OBJECTIVES

According to the revised international intraductal papillary mucinous neoplasm (IPMN) guidelines (2017), the indication for surgery is based on risk classification. However, some IPMNs with high-risk stigmata (HRS) can be observed for long periods without resection. Hence, we need to reconsider the risk stratification, and this study aimed to propose a novel risk stratification for HRS-IPMNs.

METHODS

We enrolled 328 patients diagnosed with IPMN using endoscopic ultrasound between 2012 and 2019. We compared clinicopathological features between HRS and worrisome features (WF) and evaluated outcomes of HRS-IPMN.

RESULTS

Fifty-three patients (HRS 38, WF 15) underwent resection at initial diagnosis and 275 patients were observed. Following observation for 30 months, 22 patients (17 HRS, 5 WF) underwent resection. Analysis of resected IPMNs (n = 75) revealed that HRS had dominantly pancreatobiliary mucin subtype. Pancreatobiliary-type IPMN had larger nodule sizes and lymphatic invasion and high recurrence with poor prognosis. Seventy-four patients were diagnosed with HRS, 55 underwent resection, and 19 continue to be observed. The resected group had larger nodule sizes (median 8 mm vs. 5 mm; P = 0.060), whereas the observed group had more main pancreatic duct (MPD) dilation (median 10 mm vs. 5 mm; P = 0.005). In the resected HRS group, only patients with MPD dilation ≥10 mm (n = 10) had no recurrence but had a favorable prognosis compared with those nodule size ≥5 mm (n = 45).

CONCLUSIONS

Large nodule size may be associated with pancreatobiliary subtype and poor prognosis; however, patients with MPD dilation ≥10 mm with nodule size <5 mm did not require resection.

Computer-aided differentiates benign from malignant IPMN and MCN with a novel feature selection algorithm

In clinical practice, differentiating benign from malignant intraductal papillary mucinous neoplasm (IPMN) and mucinous cystic neoplasm (MCN) preoperatively is crucial for deciding future treating algorithm. However, it remains challenging as benign and malignant lesions usually show similarities in both imaging appearances and clinical indices. Therefore, a robust and accurate computer-aided diagnosis (CAD) system based on radiomics and clinical indices was proposed in this paper to solve this dilemma. In the proposed CAD system, 107 patients were enrolled, where 90 cases were randomly selected for the training set with 5-fold cross validation to build the diagnostic model, while 17 cases were remained for an independent testing set to validate the performance. 436 high-throughput radiomics features while 9 clinical indices were designed and extracted. A novel feature selection algorithm named BLR (Bootstrapping repeated LASSO with Random selections) was proposed to select the most effective features. Then the selected features were sent to Support Vector Machine (SVM) to differentiate the benign or malignant. In the cross-validation cohort and independent testing cohort, the area under receiver operating characteristic curve (AUC) of CAD scheme were 0.83 and 0.92, respectively. The results fully prove the proposed CAD system achieves significant effect in tumors diagnosis.

External validation of nomogram for predicting malignant intraductal papillary mucinous neoplasm (IPMN): from the theory to the clinical practice using the decision curve analysis model

The management of IPMNs is a challenging and controversial issue because the risk of malignancy is difficult to predict. The present study aimed to assess the clinical usefulness of two preoperative nomograms for predicting malignancy of IPMNs allowing their proper management. Retrospective study of patients affected by IPMNs. Two nomograms, regarding main (MD) and branch duct (BD) IPMN, respectively, were evaluated. Only patients who underwent pancreatic resection were collected to test the nomograms because a pathological diagnosis was available. The analysis included: 1-logistic regression analysis to calibrate the nomograms; 2-decision curve analysis (DCA) to test the nomograms concerning their clinical usefulness. 98 patients underwent pancreatic resection. The logistic regression showed that, increasing the score of both the MD-IPMN and BD-IPMN nomograms, significantly increases the probability of IPMN high grade or invasive carcinoma (P = 0.029 and P = 0.033, respectively). DCA of MD-IPMN nomogram showed that there were no net benefits with respect to surgical resection in all cases. DCA of BD-IPMN nomogram, showed a net benefit only for threshold probability between 40 and 60%. For these values, useless pancreatic resection should be avoided in 14.8%. The two nomograms allowed a reliable assessment of the malignancy rate. Their clinical usefulness is limited to BD-IPMN with threshold probability of malignancy of 40–60%, in which the patients can be selected better than the “treat all” strategy.

Cost-effectiveness of consensus guideline based management of pancreatic cysts: The sensitivity and specificity required for guidelines to be cost-effective

BACKGROUND

Detection of cystic lesions of the pancreas has outpaced our ability to stratify low-grade cystic lesions from those at greater risk for pancreatic cancer, raising a concern for overtreatment.

METHODS

We developed a Markov decision model to determine the cost-effectiveness of guideline-based management for asymptomatic pancreatic cysts. Incremental costs per quality-adjusted life year gained and survival were calculated for current management guidelines. A sensitivity analysis estimated the effect on cost-effectiveness and mortality if overtreatment of low-grade cysts is avoided, and the sensitivity and specificity thresholds required of methods of cyst stratification to improve costs expended.

RESULTS

"Surveillance" using current management guidelines had an incremental cost-effectiveness ratio of $171,143/quality adjusted life year compared with no surveillance or operative treatment ("do nothing"). An incremental cost-effectiveness ratio for surveillance decreases to $80,707/quality adjusted life year if the operative overtreatment of low-grade cysts was avoided. Assuming a societal willingness-to-pay of $100,000/quality adjusted life year, the diagnostic specificity for high-risk cysts must be >67% for surveillance to be preferred over surgery and "do nothing." Changes in sensitivity alone cannot make surveillance cost-effective. Most importantly, survival in surveillance is worse than "do nothing" for 3 years after cyst diagnosis, although long-term survival is improved. The disadvantage is eliminated when overtreatment of low-grade cysts is avoided.

CONCLUSION

Current management of pancreatic cystic lesions is not cost-effective and may increase mortality owing to overtreatment of low-grade cysts. The specificity for risk stratification for high-risk cysts must be greater than 67% to make surveillance cost-effective.

Diabetes mellitus in intraductal papillary mucinous neoplasms: A systematic review and meta-analysis

BACKGROUND

Our current knowledge of diabetes mellitus in intraductal papillary mucinous neoplasm is very limited and its prevalence and predictive value for malignant transformation are not clear. This study sought to systematically review the literature to define the prevalence of diabetes mellitus in intraductal papillary mucinous neoplasm and to evaluate the association of diabetes mellitus with the progression to high-grade dysplasia or invasive cancer.

METHODS

A PubMed/Medline systematic search was performed to identify studies reporting data on preoperative diabetes mellitus in intraductal papillary mucinous neoplasm. Articles meeting the predefined inclusion criteria were analyzed and a meta-analysis was performed. The study was preregistered (PROSPERO ID: CRD42020153581).

RESULTS

From the initially detected 827 studies, 27 studies including resected patients with histologically confirmed intraductal papillary mucinous neoplasm were included. The global prevalence of preoperative diabetes mellitus was 25% (1,112 of 4,412); whereas new-onset/worsening diabetes mellitus was reported in 6% of patients (68 of 1,202). The meta-analysis revealed that patients with pre-existing diabetes mellitus had an increased risk of harboring a main pancreatic duct involvement (risk ratio 1.43, 95% confidence interval: 1.21-1.69, P < .001), high-grade dysplasia (risk ratio 1.27, 95% confidence interval: 1.01-1.59, P = .04), and invasive cancer (risk ratio 1.61, 95% confidence interval: 1.33-1.95, P < .001).

CONCLUSION

The prevalence of diabetes mellitus in intraductal papillary mucinous neoplasm is high, and diabetic patients demonstrate an increased risk of a more aggressive disease. Therefore, diabetes mellitus should be increasingly considered in the stratification of patients with intraductal papillary mucinous neoplasm. Further investigations to determine the mechanisms behind the association with progression should be carried out.

Carcinoembryonic antigen level in the pancreatic juice is effective in malignancy diagnosis and prediction of future malignant transformation of intraductal papillary mucinous neoplasm of the pancreas

BACKGROUND

The present study aimed to determine the ability of diagnosing malignancy and predicting malignant transformation in patients with IPMN using carcinoembryonic antigen (CEA) level in the pancreatic juice.

METHODS

We enrolled patients with IPMN who underwent endoscopic retrograde pancreatography (ERP) between 2002 and 2018. We examined the ability of diagnosing malignancy in 63 patients who underwent surgery (surgical group). Furthermore, we examined the value of predicting malignant transformation in 52 patients who underwent follow-up for over 1 year after ERP (follow-up group).

RESULTS

In the surgical group, the overall sensitivity and specificity of CEA level (≥ 97 ng/ml) in the pancreatic juice for diagnosing malignancy were 45% and 100%, respectively. The specificity was excellent for all IPMN types; however, the sensitivity was highest in main duct type, followed by mixed type and branch duct type. In the follow-up group, malignant transformation was observed in four patients (7.7%) during the follow-up, and the median time until malignant transformation was 58 months. High CEA level in the pancreatic juice demonstrated a statistically significant difference in multivariate analysis and was found to be an independent predictor of malignant transformation (hazard ratio 17; P = 0.02). The cumulative malignant transformation rate was significantly higher in the high CEA group than that in the low CEA group (5-year cumulative malignant transformation rates, 69% vs. 0%, P < 0.001).

CONCLUSIONS

Carcinoembryonic antigen level in the pancreatic juice is useful not only in diagnosing malignancy but also in predicting future malignant transformations in IPMN patients receiving follow-up.

Intraductal papillary mucinous neoplasms of the pancreas and European guidelines: importance of the surgery type in the decision-making process

BACKGROUND

The European Consensus 2018 established a new algorithm with absolute and relative criteria for intraductal papillary mucinous neoplasms of the pancreas (IPMN) management. The aim of this study was to validate these criteria and analyse the outcomes in function of the surgical procedure and IPMN subtype.

METHODS

Clinical, radiological and surgical data (procedure, morbidity/mortality rates) of patients who underwent surgery for IPMN between 2007 and 2017. The predictive value of the different criteria was analysed.

RESULTS

124 patients (men 67%; mean age 65 years) underwent surgery for IPMN (n = 62 malignant tumours; 50%). Jaundice, cyst ≥4 cm and Wirsung duct size 5-9.9 mm or ≥ 10 mm were significantly associated with malignancy (4.77 < OR < 11.85 p < 0.0001). The positive predictive value of any isolated criterion ranged from 71 to 87%, whereas that of three relative criteria together reached 100%. The mortality and morbidity (grade III-IV complications according to the Dindo-Clavien classification) rates were 3 and 8%, respectively. Morbidity/mortality after duodenopancreatectomy and total pancreatectomy were significantly higher for benign IPMN (p = 0.01).

CONCLUSION

Considering the morbidity associated with extended surgery, particularly for benign IPMN, the results of the present study suggest that high-risk surgery should be considered only in the presence of three relative criteria and including the surgery type in the decision-making algorithm.

Surgical management of intraductal papillary mucinous neoplasm with main duct involvement: an international expert survey and case-vignette study

BACKGROUND

The risk of invasive cancer in resected intraductal papillary mucinous neoplasm with main pancreatic duct involvement is 33%-60%. Most guidelines, therefore, advise resection of main duct intraductal papillary mucinous neoplasm and mixed type intraductal papillary mucinous neoplasm in surgically fit patients, although advice on the surgical strategy (partial or total pancreatectomy) differs. We performed a survey amongst international experts to guide the design of future studies and help to prepare for a single international set of guidelines.

METHODS

An online survey including case vignettes was sent to 221 international experts who had published on main duct/mixed type intraductal papillary mucinous neoplasm in the previous decade and to all surgeon and gastroenterologist members of the pancreatic cyst guideline committees of the European Study Group and the International Association of Pancreatology.

RESULTS

Overall, 97 experts (67 surgeons, 30 gastroenterologists) from 19 countries replied (44% response rate). Most (93%) worked in an academic hospital, with a median of 15 years' experience with intraductal papillary mucinous neoplasm treatment. In main duct/mixed type intraductal papillary mucinous neoplasm patients with pancreatic duct dilation (>5 mm) in the entire pancreas, 41% (n = 37) advised nonoperative surveillance every 3-6 months, whereas 59% (n = 54) advised operative intervention. Of those who advised operative intervention, 46% (n = 25) would perform a total pancreatectomy and 31% (n = 17) pancreatoduodenectomy with follow-up. No structural differences in advice were seen between surgeons and gastroenterologists, between continents where the respondents lived, and based on years of experience.

CONCLUSION

This international survey identified a clinically relevant lack of consensus in the treatment strategy in main duct/mixed type intraductal papillary mucinous neoplasm among experts. Studies with long-term follow-up including quality of life after partial and total pancreatectomy for main duct/mixed type intraductal papillary mucinous neoplasm are required.

Meta-analysis of mortality in patients with high-risk intraductal papillary mucinous neoplasms under observation

BACKGROUND

Although consensus guidelines suggest that patients with high-risk intraductal papillary mucinous neoplasms (IPMNs) should have surgery, a non-operative strategy is often selected in patients who are poor surgical candidates. The aim was to determine the risk of disease-related death from IPMN in patients with worrisome features or high-risk stigmata who were kept under observation.

METHODS

A PubMed literature search was undertaken of articles published from August 1992 to June 2016 (updated October 2017). The methodology was developed from PRISMA and MOOSE checklists. Incidence proportions and rates of overall and IPMN-related deaths were calculated, with subgroup analyses for main-duct/mixed-type and branch-duct IPMNs. Quality of the studies, publication bias and heterogeneity were explored.

RESULTS

Six studies reported data on overall mortality and eight described disease-specific mortality for 556 patients during follow-up ranging from 24·9 to 60·0 months. Pooled rates of overall and IPMN-related mortality were 30·9 (95 per cent c.i. 19·6 to 45·1) and 11·6 (6·0 to 21·2) per cent respectively. The pooled incidence rate for overall mortality was substantially higher than that for IPMN-related mortality: 78 (95 per cent c.i. 44 to 111) and 23 (9 to 37) per 1000 patient-years respectively. The pooled incidence rate for disease-specific mortality was considerably lower for branch-duct than for main-duct or mixed-type IPMNs: 5 (0 to 10) and 32 (12 to 52) per 1000 patient-years respectively.

CONCLUSION

In patients unfit for surgery, IPMN-related mortality among patients with worrisome features and high-risk stigmata is low, and the risk of death from other causes much higher.

Should Patients With Cystic Lesions of the Pancreas Undergo Long-term Radiographic Surveillance?: Results of 3024 Patients Evaluated at a Single Institution

OBJECTIVE

In 2015, the American Gastroenterological Association recommended the discontinuation of radiographic surveillance after 5 years for patients with stable pancreatic cysts. The current study evaluated the yield of continued surveillance of pancreatic cysts up to and after 5 years of follow up.

METHODS

A prospectively maintained registry of patients evaluated for pancreatic cysts was queried (1995-2016). Patients who initially underwent radiographic surveillance were divided into those with <5 years and ≥5 years of follow up. Analyses for the presence of cyst growth (>5 mm increase in diameter), cross-over to resection, and development of carcinoma were performed.

RESULTS

A total of 3024 patients were identified, with 2472 (82%) undergoing initial surveillance. The ≥5 year group (n = 596) experienced a greater frequency of cyst growth (44% vs. 20%; P < 0.0001), a lower rate of cross-over to resection (8% vs 11%; P = 0.02), and a similar frequency of progression to carcinoma (2% vs 3%; P = 0.07) compared with the <5 year group (n = 1876). Within the ≥5 year group, 412 patients (69%) had demonstrated radiographic stability at the 5-year time point. This subgroup, when compared with the <5 year group, experienced similar rates of cyst growth (19% vs. 20%; P= 0.95) and lower rates of cross-over to resection (5% vs 11%; P< 0.0001) and development of carcinoma (1% vs 3%; P= 0.008). The observed rate of developing cancer in the group that was stable at the 5-year time point was 31.3 per 100,000 per year, whereas the expected national age-adjusted incidence rate for this same group was 7.04 per 100,000 per year.

CONCLUSION

Cyst size stability at the 5-year time point did not preclude future growth, cross-over to resection, or carcinoma development. Patients who were stable at 5 years had a nearly 3-fold higher risk of developing cancer compared with the general population and should continue long-term surveillance.

[Resection of main duct and mixed type IPMN ≥5 mm]

The incidence of cystic pancreatic lesions is steadily increasing due to the technical advances in imaging. Within the group of cystic pancreatic lesions intraductal papillary mucinous neoplasms (IPMNs) depict an important entity. Due to a possible progression to malignancy the clinical strategy has to be well chosen. For primary diagnostic work-up imaging by magnetic resonance imaging (MRI) with MR cholangiopancreatography (MRCP) and computed tomography (CT) scanning is recommended. Additional information can be gained by endosonography and a biopsy of the cystic lesion, allowing analysis of biomarkers, such as GNAS and KRAS mutation as wells as NLR. These can help to differentiate between IPMN and other cystic lesions although the clinical importance for the diagnosis of main duct (MD) and mixed IPMN is limited. The current guidelines (Fukuoka and EU guidelines) recommend resection of MD and mixed IPMN following oncological standards. For the definition of MD-IPMN, a duct dilatation between 5-10 mm is needed when following the current guidelines; however, current publications claim an even lower cut-off of ≥5 mm due to the risk of malignant progression. Intraoperative frozen sections are recommended to evaluate the margins status and extended resection is recommended for residual high-grade dysplasia. Surveillance of potentially at risk patients is recommended at regular intervals of 6-12 months while patients with malignant IPMN should be followed according to pancreatic cancer protocols. A screening for extrapancreatic malignancy is not indicated.

Natural History of Pancreatic Cysts

Pancreatic cystic neoplasms are discovered with increasing frequency. Accurate knowledge of the natural history of cystic neoplasms is crucial to develop useful and cost-effective strategies for surveillance and surgical resection. To date, the natural history of cystic neoplasms is still incomplete due to lack of adequate diagnostic accuracy in the absence of surgical pathology. Nevertheless, current evidence points to risk factors for malignant transformation to help clinical management. New biomarkers that accurately distinguish cyst neoplasms and those most likely to progress to cancer would help clarify the natural history of cystic neoplasms.

Comparing 3 guidelines on the management of surgically removed pancreatic cysts with regard to pathological outcome

BACKGROUND AND AIMS

Currently, 3 guidelines are available for the management of pancreatic cysts. These guidelines vary in their indication for resection of high-risk cysts. We retrospectively compared the final pathologic outcome of surgically removed pancreatic cysts with the indications for resection according to 3 different guidelines.

METHODS

Patients who underwent pancreatic resection were extracted from our prospective pancreatic cyst database (2006-present). The final histopathologic diagnosis was compared with the initial indication for surgery stated by the guidelines of the International Association of Pancreatology (IAP), European Study Group on Cystic tumors of the Pancreas and American Gastroenterological Association (AGA). We considered surgery in retrospect justified for malignancy, high-grade dysplasia, solid pseudopapillary neoplasms, neuroendocrine tumors or symptom improvement. Furthermore, we evaluated the patients with suspected intraductal papillary mucinous neoplasm (IPMN) separately.

RESULTS

Overall, 115 patients underwent pancreatic resection. The preoperative diagnosis was correct in 83 of 115 patients (72%) and differentiation between benign and premalignant in 99 of 115 patients (86%). In retrospect, surgery was justified according to the aforementioned criteria in 52 of 115 patients (45%). For patients with suspected IPMN (n = 75) resection was justified in 36 of 67 (54%), 36 of 68 (53%), and 32 of 54 (59%) of patients who would have had surgery based on the IAP, European, or AGA guidelines, respectively. The AGA guideline would have avoided resection in 21 of 75 (28%) patients, versus 8 of 75 (11%) and 7 of 75 (9%) when the IAP or European guideline would have been applied strictly. Nevertheless, 4 of 33 patients (12%) with high-grade dysplasia or malignancy would have been missed with the AGA guidelines, compared with none with the IAP or European guidelines.

CONCLUSION

Although fewer patients undergo unnecessary surgery based on the AGA guidelines, the risk of missing malignancy or high-grade dysplasia with this guideline seems considerably high.

Endoscopic ultrasound-guided fine-needle aspiration plus KRAS and GNAS mutation in malignant intraductal papillary mucinous neoplasm of the pancreas

Background:KRAS and GNAS mutations are common in intraductal papillary mucinous neoplasia of the pancreas (IPMN). The aims of this study were to assess the role of pre-therapeutic cytopathology combined with KRAS and GNAS mutation assays within cystic fluid sampled by endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) to predict malignancy of IPMN. Patients and methods: We prospectively included 37 IPMN patients with clinical and/or imaging predictors of malignancy (men: 24; mean age: 69.5 years). Cytopathology (performed on cystic fluid and/or IPMN nodules), KRAS (Exon 2, codon 12) and GNAS (Exon 8, codon 201) mutations assays (using TaqMan^® allelic discrimination) were performed on EUS-FNA material. The final diagnosis was obtained from IPMN resections (n = 18); surgical biopsies, EUS-FNA analyses, and follow-up (n = 19): 10 and 27 IPMN were benign and malignant, respectively. Results: Sensitivity, specificity, positive and negative predictive values, and accuracy of cytopathology alone to diagnose IPMN malignancy were 55 %, 100 %, 100 %, 45 %, and 66 %, respectively. When KRAS-mutation analysis was combined with cytopathology these values were 92 %, 50 %, 83 %, 71 %, and 81 %, respectively. GNAS assays did not improve the performances of cytopathology alone or those of cytopathology plus a KRAS assay. Conclusions: In patients with a likelihood of malignant IPMN at pre-therapeutic investigation, testing for KRAS mutations in cystic fluid sampling by EUS-FNA improved the results of cytopathology for the diagnosis of malignancy whereas GNAS mutation assay did not.