Detection of point mutation in K-ras oncogene at codon 12 in pancreatic diseases

AIM:To investigate frequency and clinical significance of K-ras mutations in pancreatic diseases and to identify its diagnostic values in pancreatic carcinoma.METHODS:117 ductal lesions were identified in the available sections from pancreatic resection specimens of pancreatic ductal adenocarcinoma, comprising 24 pancreatic ductal adenocarcinoma, 19 peritumoral ductal atypical hyperplasia, 58 peritumoral ductal hyperplasia and 19 normal duct at the tumor free resection margin. 24 ductal lesions were got from 24 chronic pancreatitis. DNA was extracted.Codon 12 K-ras mutations were examined using the two-step polymerase chain reaction (PCR) combined with restriction enzyme digestion,followed by nonradioisotopic single-strand conformation polymorphism (SSCP) analysis and by means of automated DNA sequencing.RESULTS: K-ras mutation rate of the pancreatic carcinoma was 79%(19/24) which was significantly higher than that in the chronic pancreatitis 33%(8/24) (P<0.01). It was also found that K-ras mutation rate was progressively increased from normal duct at the tumor flee resectbn margin, peritumoral ductal hyperplasia, peritumoral ductal atypical hyperplasia to pancreatic ductal adenocardnoma. The mutation pattern of K-ras 12 codon of chronic pancreatitis was GGT→GAT, GGT and CGT,which is identical to that in pancreatic carcinoma.CONCLUSION:K-ras mutation may play a role in the malignant transformation of pancreatic ductal cell. K-ras mutation was not specific enough to diagnose pancreatic carcinoma.     

胰头部肿块型胰腺炎的临床特征及K—ras基因突变

目的：分析胰头部肿块型胰腺炎临床特征及K-ras基因突变以明确其为胰腺癌关系。方法：回顾性分析临床及随访资料并应用聚合酶链反应－单链构象多态性分析（PCR－SSCP）方法分别检测胰头部肿块型胰腺炎、胰腺癌、癌旁导管增生、手术切缘正常组织、石蜡包埋组织的K-ras突变。结果：胰头部肿块型胰腺炎和胰头癌血清总胆红素、CA19－9、ERCP检查结果的差异有助于两的鉴别诊断：肿块型胰腺炎增生导管K-ras突变率为40％（6／15），与癌周增生导管31．2％（10／32）的突变率相近，但显低于胰头癌83．3％（15／18）的突变率，且胰腺炎手术后患随访至2000年12月均健在且未发现胰头癌的临床表现。结论：良性胰腺疾病导管增生存在K-ras突变并不一定向恶性发展。     

Early detection of pancreatic cancer in patients with chronic pancreatitis: diagnostic utility of a K-ras point mutation in the pancreatic juice

OBJECTIVE: Point mutations of the K-ras oncogene at codon 12 have been described several months before the onset of pancreatic cancer in isolated cases of chronic pancreatitis (CP). The aim of this study was to evaluate the interest of a prospective follow-up of patients with CP and K-ras mutations at codon 12 in the detection of early pancreatic cancer. METHODS: From February 1996 to March 1998, 36 patients (mean age 52.6 yr, 31 men, five women) with CP (alcoholic: 61.1%, pancreas divisum: 5.6%, autoimmune: 5.6%, unknown origin: 27.7%) were included and then prospectively monitored (median duration of 22 months) for detection of pancreatic carcinoma. K-ras point mutations were examined by two-step polymerase chain reaction combined with restriction enzyme digestion in pancreatic juice collected during endoscopic retrograde pancreatography. RESULTS: Ten patients (27.8%) were positive for K-ras mutation. Patients with and without the mutation were not different with respect to age and sex ratio. K-ras mutations were homogeneously distributed according to the etiology (alcoholic vs nonalcoholic) and morphological characteristics (ductal stricture or mass vs none) of CP. A pancreatic carcinoma was discovered at an invasive stage in two patients, respectively at 7 and 17 months after disclosure of a K-ras mutation, versus none in patients without the mutation (p < 0.02). CONCLUSIONS: Presence of a K-ras gene mutation is not rare in patients with CP and represents an increased risk of developing pancreatic cancer. However, its utility for the detection of early pancreatic cancer remains doubtful in clinical practice.     

Ki-ras oncogene activation in preinvasive pancreatic cancer.

Activation of the Ki-ras oncogene by specific point mutations at codon 12 occurs at a remarkably high frequency in pancreatic ductal adenocarcinoma and is likely to be an important event in the pathogenesis of this cancer. To determine whether ras activation also occurs in noninvasive proliferative lesions of the pancreas, a series of cases of ductal papillary hyperplasia, intraductal papillary neoplasia, and intraduct extensions of ductal adenocarcinoma were examined for activating mutations of Ki-ras at codons 12, 13, and 61 using polymerase chain reaction amplification. Specific mutations at Ki-ras codon 12 were found in 5 of 6 cases (83%) of intraduct extensions of carcinomas and in 12 of 16 (75%) invasive carcinomas. In cases with both intraductal and invasive components, the same mutation was identified in each. No mutations were found in 5 intraductal papillary neoplasms and 9 cases of ductal papillary hyperplasia. The authors conclude that Ki-ras activation at codon 12 is important in the tumorigenesis of ductal adenocarcinoma of the pancreas but is not required in the pathogenesis of ductal papillary hyperplasia or intraductal papillary neoplasm.     

顺序特异性引物法快速检测胰腺癌K—ras基因点突变

目的：研究简捷、特异、敏感的检测胰腺癌K－ras基因点突变的方法及其在胰腺疾病中定性诊断的价值。方法：采用针对K－ras基因点突变方式（CGT、GAT、GTT）设计的顺序特异性引物（SSP），先后对胰腺癌石蜡包埋组织、冰冻新鲜组织、细针穿刺组织及胰液进行多聚酶链反应（PCR），扩增产物借助常规电泳和染色检测有无K－ras基因突变及突变方式。结果：胰腺癌石蜡包埋组织、冰冻新鲜组织、细针穿刺组织及胰液中K－ras基因点突变率分别为74．2％、95．1％、91．4％及94．1％，而所有被检测的慢性胰腺炎、胰岛素瘤、壶腹癌、胆管癌、十二指肠乳头癌及外伤胰腺的组织标本和胰液标本均无K－ras基因突变发生。结论：该检测法简便、快速、特异、敏感，具有临床实用性，可以作为鉴别胰腺肿块良恶性和诊断胰腺癌的一种方法。     

Gene mutations of K-ras in gallbladder mucosae and gallbladder carcinoma with an anomalous junction of the pancreaticobiliary duct

OBJECTIVE: In this study, we examined the mutational spectrum of K-ras in cases of gallbladder and gallbladder carcinoma with an anomalous junction of the pancreaticobiliary duct (AJPBD). METHODS: We examined 35 gallbladders with AJPBD (20 with hyperplasia, 15 with carcinoma) and 38 gallbladders without AJPBD (four normal gallbladders, four with hyperplasia, six with adenoma, 24 with carcinoma). Polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) and direct sequencing were performed to detect mutations in codon 12 or 13 of K-ras. RESULTS: In the cases with AJPBD, the prevalences of K-ras mutation were 15% (3/20) in hyperplasia, 60% (6/10) in stage I carcinoma, and 100% (5/5) in stage II-IV carcinoma. In the cases without AJPBD, the prevalences of K-ras mutation were 0% (0/4) in normal gallbladder, 0% (0/4) in hyperplasia, 17% (1/6) in adenoma, 7% (1/16) in stage I carcinoma, and 38% (3/8) in stage II-IV carcinoma. Prevalences of K-ras mutation in hyperplasia and carcinoma with AJPBD were greater than those without AJPBD (p < 0.05). The point mutation of GGT to GAT in codon 12 was frequently observed in the cases with AJPBD. CONCLUSION: These results suggest that the specific K-ras mutation in codon 12 (GGT to GAT) may contribute to the early stage of carcinogenesis in the gallbladder with AJPBD.     

胰腺超声内镜细针穿刺活检物中K—ras基因定量检测对胰腺癌诊断价值的研究

目的比较不同胰腺超声内镜细针穿刺物中K—ras突变定量值,评价其对胰腺癌辅助诊断的价值。方法收集53例胰腺占位病变的超声内镜细针穿刺物,采用肽核酸（PNA）钳制实时定量PER的方法检测K—ras基因野生及突变拷贝数,根据临床综合诊断,与细胞学比较,评价其诊断价值。结果53例患者最后确诊为胰腺癌37例,非恶性胰腺占位16例,胰腺癌组K—ras基因的突变率为83．8％,非恶性胰腺占位组突变率为18．8％,两组之间比较差异有统计学意义（P〈0．05）。细胞学和K—ran定量检测诊断的灵敏度分别为59．5％和83．8％,将两者联合后诊断胰腺癌的灵敏度可提高至89．2％。结论胰腺组织超声内镜细针穿刺物中K—ras定量检查对胰腺癌有临床辅助诊断价值。     

Clinical usefulness of K-ras gene mutation detection and cytology in pancreatic juice in the diagnosis and screening of pancreatic cancer.

BACKGROUND: The significance of K-ras codon 12 mutation in pancreatic juice is still unclear. Although considerable controversy surrounds this question, the diagnostic utility of K-ras in patients with clinical suspicion of pancreatic cancer (PC) and in PC-risk patients remains unknown. OBJECTIVE: To study prospectively the utility of the K-ras gene mutation and cytology in the diagnosis and screening of PC, and to assess its contribution to clinical decision making. METHODS: Pancreatic juice samples obtained from 90 patients were evaluated prospectively. Group I (n = 40) comprised patients with clinical suspicion of PC; group II (n = 50) comprised 49 patients with chronic pancreatitis and one patient proceeding from a PC family screening. The K-ras mutation was detected by means of artificial restriction fragment length polymorphisms (RFLP) in DNA after polymerase chain reaction (PCR) amplification. RESULTS: In group I, of those patients with a definitive diagnosis of PC, malignant cells were found in 27% and K-ras mutation in 44%. In five cases, molecular analysis contributed to diagnosis (4/11 with negative cytology and 1/2 with insufficient cytological material). K-ras mutation revealed an early tumour in one patient, and was the only sample available for diagnosis in another. In group II, the K-ras gene mutation was detected in 8/49 patients (16%) with chronic pancreatitis, one of whom developed PC (2%). CONCLUSIONS: K-ras mutation analysis of pancreatic juice may complement cytological evaluation in the diagnosis of PC, in spite of its limited contribution to clinical decision making. The presence of K-ras mutation in chronic pancreatitis classifies a subgroup of PC-risk patients who should be evaluated carefully by long-term follow-up.     

Telomerase activity in pure pancreatic juice for the diagnosis of pancreatic cancer may be complementary to K-ras mutation

BACKGROUND: The usefulness of K-ras mutation in pancreatic juice for the diagnosis of pancreatic cancer is questionable. Telomerase is positive in pancreatic cancer but rarely in benign pancreatic diseases. We conducted this study to determine the usefulness of K-ras mutation and telomerase activity in pancreatic juice for the diagnosis of pancreatic cancer. METHODS: Pancreatic juice collected during endoscopic retrograde cholangiopancreatography was examined in 31 patients: 12 with pancreatic cancer, 11 with chronic pancreatitis, and 8 control patients. The K-ras gene was detected by using the restriction fragment length polymorphism method. Telomerase activity was detected by using the telomeric repeat amplification protocol. RESULTS: K-ras mutation was positive in 75% (9 of 12) of pancreatic cancers and in 27% (3 of 11) of cases of chronic pancreatitis but in none of the control patients. Telomerase activity was detected in 92% (11 of 12) of pancreatic cancers and in 18% (2 of 11) of cases of chronic pancreatitis. The diagnostic value in pancreatic cancer was comparable between K-ras mutation and telomerase when evaluated separately. However, by combining these 2 methods, the specificity rose to 100%. CONCLUSIONS: For the diagnosis of pancreatic cancer, telomerase activity in pancreatic juice may possibly be complementary to K-ras mutation because it may decrease the rate of false-positive diagnosis.     

PCR—MASA检测胰腺癌外周血K—ras基因点突变的研究

目的 了解胰腺癌外周血中K—ras基因点突变检测的临床价值。方法 采用PCR—MASA法检测胰腺癌患外周血中K—ras基因点突变。结果胰腺癌外周血标本中K—ras基因点突变率为38．1％(8／21)，而所有被检测的急、慢性胰腺炎、胰岛素瘤、壶腹癌、十二指肠乳头癌、胆管癌及胆石症患外周血标本均无K—ras基因突变。结论 (1)PCR—MASA方法简捷、特异、敏感，扩增产物只需常规电泳、染色即可观察结果，无需酶切、杂交、放射性和非放射性显影；(2)对外周血标本检测K—ras基因第12位密码子有无突变，具有临床实用性，有助于判断胰腺病变良恶性及胰腺癌的早期诊断。     

Telomerase activity in pure pancreatic juice for the diagnosis of pancreatic cancer may be complementary to K-ras mutation

Background: The usefulness of K-ras mutation in pancreatic juice for the diagnosis of pancreatic cancer is questionable. Telomerase is positive in pancreatic cancer but rarely in benign pancreatic diseases. We conducted this study to determine the usefulness of K-ras mutation and telomerase activity in pancreatic juice for the diagnosis of pancreatic cancer. Methods: Pancreatic juice collected during endoscopic retrograde cholangiopancreatography was examined in 31 patients: 12 with pancreatic cancer, 11 with chronic pancreatitis, and 8 control patients. The K-ras gene was detected by using the restriction fragment length polymorphism method. Telomerase activity was detected by using the telomeric repeat amplification protocol. Results: K-ras mutation was positive in 75% (9 of 12) of pancreatic cancers and in 27% (3 of 11) of cases of chronic pancreatitis but in none of the control patients. Telomerase activity was detected in 92% (11 of 12) of pancreatic cancers and in 18% (2 of 11) of cases of chronic pancreatitis. The diagnostic value in pancreatic cancer was comparable between K-ras mutation and telomerase when evaluated separately. However, by combining these 2 methods, the specificity rose to 100%. Conclusions: For the diagnosis of pancreatic cancer, telomerase activity in pancreatic juice may possibly be complementary to K-ras mutation because it may decrease the rate of false-positive diagnosis. (Gastrointest Endosc 2000;51:708-13.)     

Expression of Ki-67, p53, and K-ras in chronic pancreatitis and pancreatic ductal adenocarcinoma

AIM: To examine surgical specimens of pancreas with either chronic pancreatitis or pancreatic cancer in order to study whether ductal hyperplasia and dysplasia in pancreas represent precursor lesions for pancreatic cancer. METHODS: We examined expression of Ki-67, CEA, p53, and K-ras, in the surgical specimens of pancreas with adenocarcinomas (n= 11) and chronic pancreatitis (n = 12). Cellular proliferation was assessed by Ki-67 proliferation index using the proliferation marker Ki-67. In specimens with pancreas cancer, we divided pancreas epithelium into normal (n = 7), ductal hyperplasia (n = 3), dysplasia (n = 4), and cancerous lesion (n = 11) after hematoxylin and eosin staining, Ki-67, and CEA immunohistochemical staining. In cases with chronic pancreatitis, the specimen was pathologically examined as in cases with pancreas cancer, and they were also determined as normal (n = 10), ductal hyperplasia (n = 4), or dysplasia (n = 5). p53 and K-ras expression were also studied by immunohistochemical staining. RESULTS: In pancreatic cancer, the Ki-67 index was 3.73±3.58 in normal site, 6.62±4.39 in ductal hyperplasia, 13.47±4.02 in dysplasia and 37.03±10.05 in cancer tissue, respectively. Overall, p53 was positive in normal ducts, ductal hyperplasia, dysplasia, and carcinoma cells in 0 of 14 (0%), 0 of 7(0%), 7 of 9 (78%), and 10 of 11 (91%), respectively, and K-ras was positive in 0 of 8 (0%), 1 of 3 (33%), 4 of 6 (67%), 4 of 5 (80%), respectively. CONCLUSION: Our results favorably support the hypothesis that ductal hyperplasia and dysplasia of the pancreas might be precursor lesions for pancreas cancer. Further evaluation of oncogenes by the molecular study is needed.     

Significance of K-ras codon 12 point mutation in pancreatic juice in the diagnosis of carcinoma of the pancreas

The significance of K-ras codon 12 point mutation in pancreatic juice in the diagnosis of carcinoma of the pancreas is still unclear. The aim of this study was to evaluate the significance of K-ras codon 12 point mutation in pancreatic juice in the diagnosis of carcinoma of the pancreas. All of the 78 reports written from 1988 to 1996 on K-ras point mutation of carcinoma, mucin-producing tumors, and hyperplastic epithelia of the pancreas in both surgical or autopsy specimens and pancreatic juice are reviewed. As results, in surgical or autopsy specimens, K-ras mutation was found in 81% of ordinary duct cell carcinoma and in 53% of mucin-producing tumor of the pancreas; this mutation was also found in hyperplastic epithelia in chronic pancreatitis (7%) and in autopsy cases without pancreatic diseases. In pancreatic juice, K-ras mutation was found in 72% of ordinary pancreatic carcinoma and in 53% of mucin-producing tumor, respectively. In conclusion, most previous reports have indicated that K-ras mutation in pancreatic juice is useful for a diagnosis of pancreatic carcinoma. However, since K-ras gene mutation was also detected in non-tumorous lesions, the diagnosis of pancreatic carcinomas is not necessarily correct if it is based solely on the detection of K-ras mutation in pancreatic juice. Future studies should focus on analyzing the amino acid sequence of K-ras mutation or the combination of this mutation with other parameters such as tumor markers in pancreatic juice, to enhance its specificity and accuracy.     

Pancreatic cancer in patients with pancreatic cystic lesions: a prospective study in 197 patients.

BACKGROUND & AIMS: K-ras mutation is frequently detected in pancreatic juice of patients with pancreatic small cystic lesions, as well as those with pancreatic cancer. Those cystic lesions are often found by chance with modern radiologic imaging modalities. In this study, we prospectively examined the prognosis of patients with pancreatic cystic lesions, focusing on pancreatic cancer development. METHODS: A total of 197 patients with pancreatic cystic lesions, 80 with intraductal papillary mucinous neoplasm (IPMN) and 117 with non-IPMN cysts, were followed up for 3.8 years on average. Blood tests and imaging diagnosis were performed twice a year. The observed incidence of pancreatic cancer was compared with the expected incidence calculated on the basis of age- and gender-matched mortality of pancreatic cancer in the general Japanese population. RESULTS: Pancreatic cancer developed in 7 patients during the observation period (0.95% per year), infiltrating ductal carcinoma in 5 and intraductal papillary mucinous carcinoma in 2. Three of the ductal cancer cases had pancreatic non-IPMN cyst as preexisting lesion. At least 2 of the carcinomas arose in regions remote from preexisting lesions. The observed incidence of pancreatic cancer was 22.5 times higher (95% confidence interval, 11.0-45.3) than expected mortality from this cancer among general population. CONCLUSIONS: Patients with pancreatic cystic lesions are at a considerably high risk for pancreatic cancer, with a standardized incidence rate of 22.5. Cancer might develop in regions remote from the preexisting cystic lesion, suggesting diffuse pathologic changes predisposing to malignant transformation in the entire pancreas harboring cystic lesions.     

Prevalence and clinical significance of combined K-ras mutation and p53 aberration in pancreatic adenocarcinoma

Summary Conclusion This study could not attribute survival differences to the coincident acquisition of two common genetic alterations, K-ras mutation and p53 overexpression in pancreatic adenocarcinoma patients. Additionally, our data indicate the converse to be true: Those patients lacking both K-ras mutation and aberrant p53 expression showed the shortest survival when compared with cases showing either alteration or both. This study also showed the negative effect of K-ras mutation and p53 expression on pancreas cancer patient's survival after treatment with either radiation therapy or chemotherapy. Background Mutations of the oncogene K-ras at codon 12 are reported to be the most common genetic alteration in pancreatic carcinoma, whereas either overexpression or mutation of the tumor suppressor p53 gene is considered the most common genetic alteration in neoplasia of all types. p53 overexpression has been attributed to survival differences in pancreatic carcinoma, but such association is still controversial. No studies have fully documented the combined incidence of K-ras and p53 alterations in pancreatic adenocarcinoma, or their combined effect on patient survival in a large case series. The influence of radiation or chemotherapy in groups showing both, either, or neither mutation is also undocumented. Methods Paraffin-embedded tissue sections from 76 cases of pancreatic adenocarcinoma were cut for DNA extraction for K-ras analysis and immunohistochemical staining for aberrant p53 expression. K-ras mutation was determined by single-strand conformation polymorphism (SSCP) and slot-blot allele-specific oligonucleotide (ASO) hybridization of PCR-amplified DNA product. p53 expression was scored on the basis of percent nuclear staining with the MAb DO7. Results Sixty-four of 76 cases (84%) showed K-ras mutation, p53 expression, or both. K-ras was mutated in 55 of 76 cases (72%). p53 was expressed in 33 of 76 cases (43%). Twenty-four of 76 cases (31%) showed both K-ras mutation and p53 expression. The presence of both alterations was not related to significant differences in tumor grade, stage, or survival compared to either alteration alone. A sizable subset (16% of cases) lacked either alteration, and surprisingly, this group showed the shortest median survival compared to those with K-ras mutation, p53 expression, or both (p=0.024). Patients whose tumors were K-ras-negative showed the greatest difference in median survival with radiation therapy (median survival 30.8 mo vs 7.8 mo with no radiation,p=0.005).     

Immunohistochemical study of genetic alterations in intraductal and invasive ductal tumors of the pancreas.

BACKGROUND/AIMS: Multiple genetic alterations are involved in the development of pancreatic neoplasm. Here we investigated the incidence of p53, ras, bcl-2 and c-erbB-2 gene alterations in intraductal papillary-mucinous tumors and invasive ductal adenocarcinoma of the pancreas by immunohistochemical method to identify and analyze their relationship in terms of these genetic alterations. METHODOLOGY: Fifty-four pancreatic lesions, including 18 benign (hyperplasia (3) and intraductal papillary adenoma (15)), and 16 malignant (carcinoma in situ (2) and intraductal papillary adenocarcinoma (14)) cases of intraductal papillary-mucinous tumor; and 20 cases of invasive ductal adenocarcinoma, were immunostained by avidin-biotin peroxidase conjugate method. RESULTS: p53 and rasp21 expressions were significantly greater in malignant intraductal (P < 0.01, P < 0.05) and invasive ductal (P < 0.01, P < 0.01) tumors than in benign intraductal papillary-mucinous tumors; while bcl-2 and c-erbB-2 expressions were significantly greater in invasive ductal adenocarcinoma than both benign (P < 0.01, P < 0.05) and malignant (P < 0.05, P < 0.05) intraductal papillary-mucinous tumors. CONCLUSIONS: Different groups of genetic alterations are involved in different phases of pancreatic tumorigenesis. p53 and ras gene alterations occur at an early stage during the development of intraductal papillary-mucinous tumor, while additional alterations of bcl-2 and c-erbB-2 occur during the development of invasive ductal adenocarcinoma of the pancreas.     

DNA Mutational Differences in Cytological Specimens from Pancreatic Cancer and Cholangiocarcinoma

Background/Aims: Preoperative distinction between pancreatic cancer (PC) and extrahepatic cholangiocarcinoma (CC) is desirable due to diverging management options, and to optimize enrollment into neoadjuvant trials. Methods: A single-center retrospective study of patients with PC or CC was undertaken. Four blinded pathologists reviewed all cases and reached a consensus diagnosis (PC or CC). Microdissection-based multiple microsatellite loss analysis and direct sequencing of K-ras oncogene was performed and compared for PC and CC. Results: Of 33 cases studied (17 males; 16 PC, 17 CC; 10 with primary sclerosing cholangitis), a K-ras mutation was present in 14/16 (87.5%) PC and 1/17 (5.9%) CC cases (p<0.001), sensitivity and specificity were 87.5 and 94%, respectively. The mean fractional mutational rate was higher in PC (0.51; 95% CI 0.45–0.58) compared to CC (0.34; 95% CI 0.28–0.39, p<0.001). Conclusions: The presence of a K-ras mutation in cytology specimens distinguishes PC from CC in this study.     

胰液K-ras密码子点突变联合血清CA 199水平与胰腺癌复发关系的研究

目的探讨胰液中K-ras 12密码子点突变联合血清CA199检测与胰腺癌病程的关系。方法测定32例临床及手术证实的胰腺癌患者血清CA199水平,并采用内镜ERCP从胰管收集的胰液标本,聚合酶链反应-限制性片段长度多态性分析(PCR-RFLP)检测胰液K-ras 12基因12密码子点突变,分析胰液中K-ras 12密码子点突变及血清CA199联合检测与胰腺癌术后复发的关系。结果(1)胰液中K-ras 12密码子点突变率为56.3%,与肿瘤大小密切相关(P<0.05)。K-ras 12密码子点突变阳性、阴性表达病例3年复发率分别为66.7%和33.3%。(2)高血清CA199水平且K-ras 12密码子点突变阳性病例组3年复发率为69.2%,而低血清CA199且ras阳性病例组3年复发率为20.0%,差异显著(P<0.05)。结论联合胰液中K-ras 12密码子点突变及血清CA199检测可作为判断胰腺癌术后复发的有效指标,多因素分析对胰腺癌术后复发的判断更有价值。     

Detection of K-ras point mutation and telomerase activity during endoscopic retrograde cholangiopancreatography in diagnosis of pancreatic cancer

AIM: To study the value of monitoring K-ras point mutation at codon 12 and telomerase activity in exfoliated cells obtained from pancreatic duct brushings during endoscopic retrograde cholangiopancreatography (ERCP) in the diagnosis of pancreatic cancer. METHODS: Exfoliated cells obtained from pancreatic duct brushings during ERCP were examined in 27 patients: 23 with pancreatic cancers, 4 with chronic pancreatitis. K-ras point mutation was detected with the polymerase chain reaction and restriction fragment-length polymorphism (PCR-RFLP). Telomerase activity was detected by PCR and telomeric repeat amplification protocol assay (PCR-TRAP-ELISA). RESULTS: The telomerase activities in 27 patients were measured in 21 exfoliated cell samples obtained from pancreatic duct brushings. D450 value of telomerase activities in pancreatic cancer and chronic pancreatitis were 0.446+/-0.27 and 0.041+/-0.0111, respectively. Seventy-seven point eight percent (14/18) of patients with pancreatic cancer and none of the patients with chronic pancreatitis showed telomerase activity in cells collected from pancreatic duct brushings when cutoff value of telomerase activity was set at 2.0. The K-ras gene mutation rate (72.2%) in pancreatic cancer was higher than that in chronic pancreatitis (33.3%) (P<0.05). In considering of both telomerase activities and K-ras point mutation, the total positive rate was 83.3%(15/18), and the specificity was 100%. CONCLUSION: Changes of telomerase activities and K-ras point mutation at codon 12 may be an early event of malignant progression in pancreatic cancer. Detection of telomerase activity and K-ras point mutation at codon 12 may be complementary to each other, and is useful in diagnosis of pancreatic cancer.     

Focal Ductal Branch Dilatation on Magnetic Resonance Cholangiopancreatography: A Hint for Early Diagnosis of Pancreatic Carcinoma

A 63-year-old man with a combination of early pancreatic carcinoma and an intraductal papillary adenoma was reported. A pancreatic cyst was detected by chance at the head of the pancreas by computed tomography for a follow-up study of early rectal carcinoma previously operated. Detailed studies by endoscopic retrograde pancreatography (ERP) showed irregular narrowing of the main pancreatic duct at the pancreatic body and magnetic resonance cholangiopancreatography (MRCP) revealed dilatation of ductal branches draining there. Brushing cytology of the pancreatic duct demonstrated cancer cells and total pancreatectomy was performed. Stepwise histo-pathological examinations of the specimen showed two foci of invasive carcinoma in the neck and body and multiple foci of severe dysplasia, some of which contained carcinoma in situ, in the body of the pancreas. The cystic tumor in the head of the pancreas was an intraductal papillary adenoma. In this case, the scrutiny of a pancreatic cyst including MRCP and ERP led to an early diagnosis of pancreatic cancer. Dilatation of ductal branches depicted by MRCP might be a new hint for early diagnosis of pancreatic carcinoma.