Marcia I. Canto

Recurrent GNAS Mutations Define an Unexpected Pathway for Pancreatic Cyst Development

A mutation in the gene GNAS serves as a marker for pancreatic cysts that can progress to become invasive adenocarcinomas, guiding therapy. Staying Out of the Operating Room Like bad traffic, surgery is something to be avoided if at all possible. This was the guiding principle of Wu et al. when conducting their research on pancreatic cysts, found in more than 2% of the population. Physician and patient face a dilemma: Some pancreatic cysts will progress to form dangerous invasive carcinoma and some persist harmlessly forever. So, to err on the side of safety, many harmless cysts are removed, exposing patients to unnecessary risk. By sequencing DNA from pancreatic cysts and invasive pancreatic cancers, the authors have now determined that the presence of mutations in two oncogenes can identify the cysts that are likely to progress to carcinoma and so are good candidates for surgical removal. (Without KRAS or GNAS mutations, the cyst may be better left in place.) The authors assessed DNA from the cyst fluid of 19 intraductal papillary mucinous neoplasms and the corresponding normal tissue by massively parallel sequencing for mutations in 169 cancer genes. Two results stood out—one expected and one unexpected. Fourteen of the 19 tumors showed mutations in the known pancreatic oncogene KRAS, and 6 of the 19 carried a mutation in GNAS, a well-known oncogene in other tumor types. Of a larger set of fluid samples from these cystic neoplasms (132), 96% carried a mutation in at least one of the two oncogenes. In contrast, 44 benign cysts exhibited no GNAS or KRAS mutations. Cystic fluid that contains DNA with both the GNAS and KRAS mutations indicates, with high sensitivity and specificity, that the lesion is likely to be an intraductal papillary mucinous neoplasm (at risk for developing into an invasive carcinoma) and not a benign serous cystadenomas. These genetic markers could distinguish between benign tumors and more problematic neoplasms, enabling some patients to avoid the undesirable experience of surgery. 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.

Screening for pancreatic neoplasia in high-risk individuals: an EUS-based approach ☆

BACKGROUND & AIMS Relatives of patients with pancreatic cancer and persons with certain inherited syndromes are at increased risk for developing pancreatic cancer. We prospectively evaluated the feasibility of screening for pancreatic neoplasia in high-risk individuals. METHODS Individuals from familial pancreatic cancer kindreds and a patient with Peutz-Jeghers syndrome underwent screening endoscopic ultrasound (EUS). If the EUS was abnormal, EUS-guided fine-needle aspiration, endoscopic retrograde cholangiopancreatography (ERCP), and spiral computed tomography (CT) were performed. Patients with abnormalities suggesting neoplasia had surgery. RESULTS Thirty-eight patients were studied; 31 (mean age, 58 yr; 42% men) from kindreds with > or =3 affected with pancreatic cancer; 6 from kindreds with 2 affected relatives, 1 was a patient with Peutz-Jeghers syndrome. None had symptoms referable to the pancreas or suggestive of malignancy. Six pancreatic masses were found by EUS: 1 invasive ductal adenocarcinoma, 1 benign intraductal papillary mucinous neoplasm, 2 serous cystadenomas, and 2 nonneoplastic masses. Hence, the diagnostic yield for detecting clinically significant pancreatic neoplasms was 5.3% (2 of 38). The 1 patient with pancreatic cancer was treated and still is alive and disease-free >5 years after surgery. EUS changes similar to those associated with chronic pancreatitis were found, which were more common in patients with a history of regular alcohol intake (P = 0.02), but also occurred in patients who did not consume alcohol. Screening also led to a new diagnosis and treatment of symptomatic upper-gastrointestinal conditions in 18.4% of patients. CONCLUSIONS EUS-based screening of asymptomatic high-risk individuals can detect prevalent resectable pancreatic neoplasia but false-positive diagnoses also occur.

Whole-exome sequencing of neoplastic cysts of the pancreas reveals recurrent mutations in components of ubiquitin-dependent pathways

More than 2% of adults harbor a pancreatic cyst, a subset of which progresses to invasive lesions with lethal consequences. To assess the genomic landscapes of neoplastic cysts of the pancreas, we determined the exomic sequences of DNA from the neoplastic epithelium of eight surgically resected cysts of each of the major neoplastic cyst types: serous cystadenomas (SCAs), intraductal papillary mucinous neoplasms (IPMNs), mucinous cystic neoplasms (MCNs), and solid pseudopapillary neoplasms (SPNs). SPNs are low-grade malignancies, and IPMNs and MCNs, but not SCAs, have the capacity to progress to cancer. We found that SCAs, IPMNs, MCNs, and SPNs contained 10 ± 4.6, 27 ± 12, 16 ± 7.6, and 2.9 ± 2.1 somatic mutations per tumor, respectively. Among the mutations identified, E3 ubiquitin ligase components were of particular note. Four of the eight SCAs contained mutations of the von Hippel–Lindau gene (VHL), a key component of the VHL ubiquitin ligase complex that has previously been associated with renal cell carcinomas, SCAs, and other neoplasms. Six of the eight IPMNs and three of the eight MCNs harbored mutations of RNF43, a gene coding for a protein with intrinsic E3 ubiquitin ligase activity that has not previously been found to be genetically altered in any human cancer. The preponderance of inactivating mutations in RNF43 unequivocally establish it as a suppressor of both IPMNs and MCNs. SPNs contained remarkably few genetic alterations but always contained mutations of CTNNB1, previously demonstrated to inhibit degradation of the encoded protein (β-catenin) by E3 ubiquitin ligases. These results highlight the essential role of ubiquitin ligases in these neoplasms and have important implications for the diagnosis and treatment of patients with cystic tumors.

International Cancer of the Pancreas Screening (CAPS) Consortium summit on the management of patients with increased risk for familial pancreatic cancer.

Background Screening individuals at increased risk for pancreatic cancer (PC) detects early, potentially curable, pancreatic neoplasia. Objective To develop consortium statements on screening, surveillance and management of high-risk individuals with an inherited predisposition to PC. Methods A 49-expert multidisciplinary international consortium met to discuss pancreatic screening and vote on statements. Consensus was considered reached if ≥75% agreed or disagreed. Results There was excellent agreement that, to be successful, a screening programme should detect and treat T1N0M0 margin-negative PC and high-grade dysplastic precursor lesions (pancreatic intraepithelial neoplasia and intraductal papillary mucinous neoplasm). It was agreed that the following were candidates for screening: first-degree relatives (FDRs) of patients with PC from a familial PC kindred with at least two affected FDRs; patients with Peutz–Jeghers syndrome; and p16, BRCA2 and hereditary non-polyposis colorectal cancer (HNPCC) mutation carriers with ≥1 affected FDR. Consensus was not reached for the age to initiate screening or stop surveillance. It was agreed that initial screening should include endoscopic ultrasonography (EUS) and/or MRI/magnetic resonance cholangiopancreatography not CT or endoscopic retrograde cholangiopancreatography. There was no consensus on the need for EUS fine-needle aspiration to evaluate cysts. There was disagreement on optimal screening modalities and intervals for follow-up imaging. When surgery is recommended it should be performed at a high-volume centre. There was great disagreement as to which screening abnormalities were of sufficient concern to for surgery to be recommended. Conclusions Screening is recommended for high-risk individuals, but more evidence is needed, particularly for how to manage patients with detected lesions. Screening and subsequent management should take place at high-volume centres with multidisciplinary teams, preferably within research protocols.

Frequent Detection of Pancreatic Lesions in Asymptomatic High-Risk Individuals

BACKGROUND & AIMS The risk of pancreatic cancer is increased in patients with a strong family history of pancreatic cancer or a predisposing germline mutation. Screening can detect curable, noninvasive pancreatic neoplasms, but the optimal imaging approach is not known. We determined the baseline prevalence and characteristics of pancreatic abnormalities using 3 imaging tests to screen asymptomatic, high-risk individuals (HRIs). METHODS We screened 225 asymptomatic adult HRIs at 5 academic US medical centers once, using computed tomography (CT), magnetic resonance imaging (MRI), and endoscopic ultrasonography (EUS). We compared results in a blinded, independent fashion. RESULTS Ninety-two of 216 HRIs (42%) were found to have at least 1 pancreatic mass (84 cystic, 3 solid) or a dilated pancreatic duct (n = 5) by any of the imaging modalities. Fifty-one of the 84 HRIs with a cyst (60.7%) had multiple lesions, typically small (mean, 0.55 cm; range, 2-39 mm), in multiple locations. The prevalence of pancreatic lesions increased with age; they were detected in 14% of subjects younger than 50 years old, 34% of subjects 50-59 years old, and 53% of subjects 60-69 years old (P < .0001). CT, MRI, and EUS detected a pancreatic abnormality in 11%, 33.3%, and 42.6% of the HRIs, respectively. Among these abnormalities, proven or suspected neoplasms were identified in 85 HRIs (82 intraductal papillary mucinous neoplasms and 3 pancreatic endocrine tumors). Three of 5 HRIs who underwent pancreatic resection had high-grade dysplasia in less than 3 cm intraductal papillary mucinous neoplasms and in multiple intraepithelial neoplasias. CONCLUSIONS Screening of asymptomatic HRIs frequently detects small pancreatic cysts, including curable, noninvasive high-grade neoplasms. EUS and MRI detect pancreatic lesions better than CT.

Serum diagnosis of pancreatic adenocarcinoma using surface-enhanced laser desorption and ionization mass spectrometry.

Purpose: Each year in the United States, ∼ 30,000 people die from pancreatic cancer. Fewer than 5% of patients survive >5 years after diagnosis, because most patients present with advanced disease. Early diagnosis may improve the prognosis of patients with pancreatic cancer. Experimental Design: In an attempt to improve on current approaches to the serological diagnosis of pancreatic cancer, we analyzed serum samples from patients with and without pancreatic cancer using surface-enhanced laser desorption and ionization (SELDI) protein chip mass spectrometry. Using a case-control study design, serum samples from 60 patients with resectable pancreatic adenocarcinoma were compared with samples from 60 age- and sex-matched patients with nonmalignant pancreatic diseases, as well as 60 age- and sex-matched healthy controls. To increase the number of proteins potentially identifiable, serum was fractionated using anion exchange and profiled on two ProteinChip surfaces (metal affinity capture and weak cation exchange). Results: We determined a minimum set of protein peaks able to discriminate between patient groups and used the unified maximum separability algorithm to compare the performance of the individual marker panels alone or in conjunction with CA19–9. Among the peaks identified by SELDI profiling that had the ability to distinguish between patient groups, the 2 most discriminating protein peaks could differentiate patients with pancreatic cancer from healthy controls with a sensitivity of 78% and specificity of 97%. These 2 markers performed significantly better than the current standard serum marker, CA19–9 (P < 0.05). The diagnostic accuracy of the 2 markers was improved by using them in combination with CA 19-9. Similarly, a combination of 3 SELDI markers and CA19–9 was superior to CA19–9 alone in distinguishing individuals with pancreatic cancer from the combined pancreatic disease controls and healthy subject groups (P = 0.078). SELDI markers were also better than CA19–9 in distinguishing patients with pancreatic cancer from those with pancreatitis. Conclusion: SELDI profiling of serum can be used to accurately differentiate patients with pancreatic cancer from those with other pancreatic diseases and from healthy controls.

Endosonographic differentiation of benign and malignant stromal cell tumors

BACKGROUND Endosonography (EUS) is a valuable technique for diagnosing gastrointestinal stromal cell tumors. However, EUS features that are predictive of malignancy in these tumors have not been defined. METHODS Videotapes and photographs of EUS examinations performed prior to surgical resection of 35 stromal cell tumors (9 malignant) were blindly reviewed by a single examiner. EUS features associated with malignancy were determined. Interobserver agreement in interpreting these features was then measured among a panel of five expert endosonographers who judged EUS videotapes of 35 resected stromal cell tumors (10 malignant). RESULTS Stepwise logistic regression analysis demonstrated that tumor size (diameter > 4 cm), irregular extraluminal border, echogenic foci, and cystic spaces were independently associated with malignancy in stromal cell tumors (p < 0.05). Interobserver agreement for irregular extraluminal border, echogenic foci, and cystic spaces, as measured by mean kappa statistic, was 0.43, 0.39, and 0.28, respectively. For the five experts, the sensitivity for detecting malignancy ranged between 80% to 100% when at least two of the three features were judged to be present. The likelihood of finding malignancy ranged between 0% to 11% for the experts when all three features were judged absent. CONCLUSIONS Tumor size and certain EUS features are useful for predicting malignancy in stromal cell tumors. Absence of these features indicates benign disease. Agreement among experts in interpreting these EUS features is fair to moderate.

Advances in counselling and surveillance of patients at risk for pancreatic cancer

Even with significant advances in imaging and our understanding of pancreatic cancer genetics, the survival rates for pancreatic cancer remain quite dismal. Although still at an early stage, there are efforts in place to develop surveillance and prevention strategies for people at high risk for pancreatic cancer. This comprehensive review article summarises the predispositions that put people at a high risk of developing pancreatic cancer and the current status in the counselling and surveillance of these people using not only available medical literature, but also incorporating international expert opinion.

Confocal laser endomicroscopy in Barrett's esophagus and endoscopically inapparent Barrett's neoplasia: a prospective, randomized, double-blind, controlled, crossover trial

BACKGROUND The detection of high-grade dysplasia and cancer in Barretts esophagus (BE) can be challenging. Confocal laser endomicroscopy (CLE) allows in vivo visualization of mucosal histology during endoscopy. OBJECTIVE To determine whether CLE with optical biopsy and targeted mucosal biopsy improves the diagnostic yield of endoscopically inapparent, BE-associated neoplasia compared to standard endoscopy with a 4-quadrant, random biopsy protocol. DESIGN Prospective, double-blind, randomized, crossover study. SETTING Single, tertiary-care academic center. PATIENTS This study involved patients with BE undergoing routine surveillance or referred for treatment of nonlocalized, endoscopically inapparent, BE-associated neoplasia. INTERVENTION All participants underwent both a confocal endomicroscopy with a targeted biopsy procedure and standard endoscopy with a 4-quadrant biopsy procedure in a randomized order. MAIN OUTCOME MEASUREMENTS Increase in diagnostic yield for neoplasia, reduction in mucosal biopsy number, final pathologic diagnosis. RESULTS CLE with targeted biopsy almost doubled the diagnostic yield for neoplasia and was equivalent to the standard protocol for the final diagnosis of neoplasia. Two thirds of patients in the surveillance group did not need any mucosal biopsies at all. LIMITATION Single-center study. CONCLUSION CLE with targeted biopsy significantly improves the diagnostic yield for endoscopically inapparent BE neoplasia compared to a standard endoscopy with a random-biopsy protocol. CLE with targeted biopsy also greatly reduces the number of biopsies needed per patient and allows some patients without neoplasia to completely forgo mucosal biopsy.

Focus on pancreas cancer

Cancer research focused on deciphering the human genome sequence is dissecting the pathobiology of pancreatic cancer and is leading to new targets for diagnosis, prevention, and therapy. This new era raises new challenges for translating these new discoveries. New animal models are required for understanding the biologic significance of identified genetic pathways, for rapidly evaluating potential new therapies, and for revealing potential synergistic interactions among interventions that target multiple biologic pathways. In addition, innovative clinical trial designs are required that incorporate new endpoints for evaluating these new therapeutic interventions that are cancer specific. To this end, noninvasive methods for repetitive sampling of tissues from treated patients and for imaging biologic responses are also essential.