K-ras Mutations In Pancreatic Juice Research Articles

A meta-analysis of the diagnostic value of detecting K-ras mutation in pancreatic juice as a molecular marker for pancreatic cancer

BackgroundK-ras codon 12 mutation is one of the earliest genetic changes in the development of pancreatic cancer (PC) and accurate detection of K-ras mutations is gaining increasing attention in the field of molecular diagnosis. MethodsOriginal research articles which evaluated the diagnostic accuracy of K-ras mutation detection in PC were selected. Data were presented as forest plots and summary receiver operating characteristic curve analysis was used to summarize the overall test performance. ResultsWe assessed 16 studies from 15 published articles. The pooled sensitivity and specificity were 59% (95%CI: 54%–64%) and 87% (95%CI: 84%–89%), respectively. The pooled positive likelihood ratio and negative likelihood ratio were 4.13 (95%CI: 2.73–6.25) and 0.42 (95%CI: 0.32–0.56), respectively, and the pooled diagnostic odds ratio was 13.66 (95% CI: 7.25–25.74). ConclusionsOur results indicate that the analysis of K-ras mutations in pancreatic juice has a considerable diagnostic value in PC. Further studies with rigorous design, large sample size, and multi-regional co-operation are needed.

Molecular Analysis to Detect Pancreatic Ductal Adenocarcinoma in High-Risk Groups

Screening of high-risk groups for pancreatic cancer has not been adopted because of concerns regarding specificity and sensitivity. Suitability of a combination of 3 novel molecular screening techniques was investigated. Pancreatic juice was extracted from 146 patients with pancreatic ductal adenocarcinoma, chronic pancreatitis, or biliary tract stones. p53 mutations were analyzed by using a modified yeast functional assay, K-ras status was analyzed using mutation-specific real-time PCR and the proportion of p16(INK4a) promoter methylation was estimated using comparative methylation-specific real-time PCR. p53 mutations were detected in 20 of 48 (42%) cancer cases, none of 49 controls, and 2 of 49 (4%) patients with pancreatitis. K-ras mutations were detected in 31 of 57 (54%) cancer patients, 13 of 61 (21%) controls, and 23 of 67 (34%) patients with pancreatitis. Twenty-six of 42 (62%) cancer patients had promoter methylation levels > 12%, compared with 3 of 24 (13%) controls, and 2 of 26 (8%) with pancreatitis. Mutations in p53 or high-level p16(INK4a) promoter methylation occurred in 29 of 36 (80%) patients with cancer, 3 of 24 (13%) controls, and 3 of 22 (13%) with pancreatitis. Three patients (8%) of 36 with cancer; 14 of 24 (58%) controls, and 13 of 22 (59%) patients with pancreatitis had no marker. The gallstone disease patients had a high rate of positive K-ras mutations, possibly reflecting the fact that they were not disease free. Combination molecular analysis increased the discrimination between patients with malignant and benign disease. This level of discrimination would allow patients in high-risk groups to be stratified from negligible risk to over 50% probability of an early cancer.

Serum tumor markers and molecular biological diagnosis in pancreatic cancer.

Recent studies on genetic abnormalities in pancreatic ductal cancer have led to the investigation of tumor markers and genetic markers in both serum and pancreatic juice (PJ). Serum type 1 chain carbohydrate antigens such as CA19-9 are positive in nearly 80% of patients with pancreatic cancer (PCa), of which most are in advanced stage, whereas false-positive rates are relatively high at 20%-30% in benign hepatobiliary and pancreatic diseases. Although the prevalence of type 2 chain carbohydrate antigens, such as SLX, is relatively low, cancer specificity of these antigens is high. However, serum tumor markers have limited diagnostic value for early detection of PCa. In PJ collected endoscopically from patients with PCa, K-ras mutations (KRM) are detectable in > 80%, whereas KRM are observed in 20%-30% of PJ from patients with chronic pancreatitis (CP), reflecting benign mucous cell hyperplasia harboring KRM. Thus, a qualitative analysis of KRM in PJ is unsuitable for diagnosis of PCa. On the other hand, using an hybridization protection assay that can quantitatively determine KRM, KRM were positive in 66% of PCa but only in 40% of CP cases, indicating that qualitative analysis of KRM in PJ may be useful for differentiating PCa from CP. p53 Mutations are found in 4%-50% in PJ from patients with PCa but are not detectable in PJ from CP, suggesting that the specificity of p53 mutations is very high for PCa. Furthermore, p53 mutations were detected in 7 of 15 (47%) patients with PCa in which the PJ cytologic diagnosis was negative. Telomerase (TE) activity or its catalytic subunit, h-TERT, was reportedly positive >80% in PJ from PCa but was detected in <20% of PJ from CP. TE activity in PJ from CP originates from lymphocytes. The development and application of these new genetic and epigenetic markers with high specificity and sensitivity for PCa in serum and PJ will significantly improve our diagnostic accuracy.

Diagnosis of Pancreatic Cancer by Detecting Telomerase Activity in Pancreatic Juice: Comparison With K- Ras Mutations

Telomerase activity is reported to be specific and very frequent in human malignancy. K-ras mutations are also very frequently detected in pancreatic cancer, but their specificity for pancreatic cancer is controversial. We examined the telomerase activity and K-ras mutations in pancreatic juice from patients with pancreatic disease. Pancreatic juice was obtained endoscopically at endoscopic retrograde pancreatography from 10 patients with pancreatic cancer, three with chronic pancreatitis, and three with a normal pancreas. The telomerase activity in pancreatic juice was assayed by telomeric repeat amplification protocol. K-ras mutations in exon 1 codon 12 were examined by the two-step polymerase chain reaction combined with restriction enzyme digestion, followed by single-strand conformation polymorphism analysis and direct sequencing. Telomerase activity of >5.0 was detected in eight of 10 (80%) subjects with pancreatic cancer, but in none with chronic pancreatitis or normal pancreas. K-ras mutations were detected not only in eight of 10 (80%) subjects with pancreatic cancer but also in two of three with chronic pancreatitis and in one of three with a normal pancreas. It was shown that the detection of telomerase activity in pancreatic juice is a more useful diagnostic tool for pancreatic cancer than that of K-ras mutations.

Quantitative determination of K-ras mutations in pancreatic juice for diagnosis of pancreatic cancer using hybridization protection assay.

K-ras mutations at codon 12 (KRM) have been detected in approximately 80% of samples of pure pancreatic juice (PPJ) from patients with pancreatic cancer (PCa) and are a promising potential tumor marker. However, the frequent presence of KRM was reported in PPJ from noncancerous patients as determined by a highly sensitive method, raising questions as to the cancer specificity of this marker. Therefore we evaluated whether the hybridization protection assay (HPA), which can quantitatively determine KRM in PPJ, is useful for the diagnosis of PCa, differentiating from chronic pancreatitis (CP). PPJ was collected endoscopically from 29 patients with PCa, 26 patients with CP, and the 11 cases as the control group. Polymerase chain reaction (PCR) and HPA using an acridinium ester-labeled DNA probe for KRM were performed with DNA extracted from these samples. The results were compared with those obtained by PCR-restriction fragment length polymorphism (RFLP). The mean + 2 SD of chemiluminescence in the control group was 11,020 RLUs. When 11,020 RLUs was taken as the cut-off value, KRM was detected by PCR-HPA in 19 (66%) of 29 of PCa and one (4%) of 26 of CP cases. Analysis of PPJ by PCR-RFLP demonstrated KRM in 22 (79%) of 28 of PCa and five (19%) of 26 of CP cases. However, four of five patients with CP who were KRM-positive by PCR-RFLP were defined as negative by PCR-HPA, suggesting that PCR-HPA is superior to PCR-RFLP for the discrimination between PCa and CP. These findings indicate that quantitative analysis of KRM in PPJ using the PCR-HPA method is a promising approach for the diagnosis of PCa, differentiating from CP with a suitable cut-off value, as in the case with the use of conventional serum tumor marker.

Pancreatic cancer: medical aspects.

Although pancreatic cancer (PC) continues to be a formidable disease, numerous treatment strategies are evolving that we hope will result in improved patient survival. To prolong the survival of patients with PC, it is essential to detect PC at the earliest stage possible and to develop effective nonsurgical treatments for this disease. The current strategies for the early diagnosis of PC include the development of diagnostic modalities and screening programs for the early detection of PC and the determination of high-risk groups for PC. K-ras mutations in pancreatic juice obtained endoscopically have been studied recently in association with the early diagnosis of PC, although the interpretation of the presence of a mutated K-ras gene requires caution. The role of the current nonsurgical treatments for PC has been limited. Identification of an effective new chemotherapeutic agent is a high priority, and the enrollment of patients with PC with metastatic disease into well-designed clinical trials is essential. New targets for therapy based on the understanding of the molecular biology of PC may provide avenues for future trials. We must continue to search actively for more accurate methods of diagnosis and more effective methods of treatment for PC.

Detection of K-ras gene mutations at codon 12 in the pancreatic juice of patients with intraductal papillary mucinous tumors of the pancreas.

The authors previously found specific mutations of the K-ras gene at codon 12 in the pancreatic juice of 67% of patients (6 of 9) with pancreatic ductal carcinoma, and the detection of these mutations was useful for diagnosis. This study was performed to detect and evaluate K-ras mutations in pancreatic juice from patients with intraductal papillary mucinous tumor of the pancreas, which is considered a low grade malignancy. The results were interpreted from the viewpoint of clinical significance. K-ras mutations were examined using seminested polymerase chain reaction analysis combined with restriction enzyme digestion, followed by nonradioisotopic single strand DNA conformation polymorphism. Twelve of thirteen cases (92%) of intraductal papillary mucinous tumor of the pancreas, confirmed histologically (9 adenomas and 4 carcinomas), and 26 of 43 cases (60%) of ductal carcinoma showed specific K-ras gene mutations in the pancreatic juice. Furthermore, 4 of 22 patients (18%) with chronic pancreatitis, followed for more than 1 year without a sign of pancreatic tumor, showed K-ras mutations. In contrast, no mutations of the K-ras gene were detected in the pancreatic juice from 28 normal controls. K-ras mutations were found in the pancreatic juice of all but one patient with intraductal papillary mucinous tumor of the pancreas, but they were not useful for distinguishing carcinoma from adenoma. The authors concluded that K-ras mutations are not a specific marker for pancreatic neoplasms because similar mutations were detected in the pancreatic juice from patients with chronic pancreatitis. At the present time, the detection of K-ras mutations in pancreatic juice should be used clinically as an adjunct diagnostic modality for pancreatic diseases.

Identification of K-ras Mutations in Pancreatic Juice

Letters1 June 1996Identification of K-ras Mutations in Pancreatic JuicePhillippe Berthelemy, MD, Michele Bouisson, PhD, and Lucien Pradayrol, PhDPhillippe Berthelemy, MDInstitut National de la Sante et de la Recherche Medicale; F31054 Toulouse, FranceSearch for more papers by this author, Michele Bouisson, PhDInstitut National de la Sante et de la Recherche Medicale; F31054 Toulouse, FranceSearch for more papers by this author, and Lucien Pradayrol, PhDInstitut National de la Sante et de la Recherche Medicale; F31054 Toulouse, FranceSearch for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-124-11-199606010-00013 SectionsAboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail IN RESPONSE:We agree with Gutiirrez and colleagues that pancreatic cancer is a multistep process involving several oncogenes and tumor suppressor genes. Pancreatic cancer, however, is the human tumor with the highest incidence of ras mutations identified to date [1]. Furthermore, the finding of mutations exclusively affecting codon 12 in the K-ras gene was unexpected, given the results of previous experimental carcinogenesis studies. Until recently, our knowledge of the molecular mechanisms of pancreatic cancer was poor compared with our knowledge of the mechanisms of colon cancer. At least two different factors make this research difficult. First, most animal models, except ...