Ki-ras codon 12 point and P53 mutations: a molecular examination of the main tumor, liver, portal vein, peripheral arterial blood and para-aortic lymph node in pancreatic cancer

Preoperative detection of KRAS G12D mutation in ctDNA is a powerful predictor for early recurrence of resectable PDAC patients

Background

About 25–37% of resectable pancreatic ductal adenocarcinoma (PDAC) had a great chance of early recurrence after radical resection, which is mainly due to preoperative micrometastasis. We herein demonstrated the profiles of ctDNA in resectable PDAC and use of ctDNA to identify patients with potential micrometastasis.

Methods

A total of 113 and 44 resectable PDACs were enrolled in discovery and validation cohorts, separately. A panel containing 50 genes was used to screen ctDNA by an NGS-based assessment with high specificity.

Results

In the discovery cohort, the overall detection rate was 38.05% (43/113). Among positive ctDNA, KRAS mutation had the highest detection rate (23.01%, 26/113), while the others were <5%. Survival analysis showed that plasma KRAS mutations, especially KRAS G12D mutation, had significant association with OS and RFS of resectable PDAC. Plasma KRAS G12D mutation showed a strong correlation with early distant metastasis. In the validation cohort, survival analysis showed similar association between plasma KRAS G12D mutation and poor outcomes.

Conclusions

This study demonstrated that plasma KRAS mutations, especially KRAS G12D mutation, served as a useful predictive biomarker for prognosis of resectable PDAC. More importantly, due to high correlation with micrometastasis, preoperative detection of plasma KRAS G12D mutation helps in optimising surgical selection of resectable PDAC.

Progression of Chronic Pancreatitis to Pancreatic Cancer: Is There a Role of Gene Mutations as a Screening Tool?

OBJECTIVES

Early detection of pancreatic ductal adenocarcinoma still remains a challenge. Patients with chronic pancreatitis (CP) have a markedly increased risk of pancreatic cancer. Mutations in oncogenes and/or tumor suppressor genes play a role in development of pancreatic ductal adenocarcinoma. This study assessed mutations in KRAS and p53 gene in blood as a screening tool for malignant transformation in CP patients.

METHODS

This was a cohort, single-center study including 294 CP patients. DNA was isolated from plasma of CP patients, and KRAS mutations were identified using polymerase chain reaction-restriction fragment length polymorphism. Patients with positive KRAS mutation were screened for malignancy using positron emission tomography or endoscopic ultrasound. Mutations in p53 gene were analyzed by sequencing. Tissue samples from CP and pancreatic cancer patients were also tested for mutations in KRAS and p53 genes.

RESULTS

The plasma samples of 64 CP patients were positive for KRAS mutation, and 4 had mutation in p53 gene also. No patient positive for KRAS mutation and/or p53 mutation was found to have malignant transformation.

CONCLUSION

Detection of KRAS or p53 mutation in plasma is not an effective screening tool for pancreatic cancer because accumulation of multiple mutations is required for malignant transformation in the pancreas.

Systematic review of the clinical significance of lymph node micrometastases of pancreatic adenocarcinoma following surgical resection

OBJECTIVES

The aim of this study is to perform a systematic review of the clinical impact of lymph node micrometastasis in pancreatic adenocarcinoma following surgical resection.

METHODS

A systematic review was conducted and published literature were searched using "pancreas or pancreatic" and "cancer or carcinoma or neoplasm", and "micrometastasis or micrometastses" in the PubMed, EMBAE, and Web of Science.

RESULTS

Thirteen publications with 726 patients and 3701 lymph nodes were included in this systematic review. The detection method was immunohistochemical stains or polymerase chain reaction. The pooled proportion of patients with positive lymph node micrometastasis was 43.1% (95% Confidence interval (CI) 0.254-0.628). The pooled proportion of positive lymph node micrometastasis (number of positive lymph node micrometastasis/total number of lymph nodes examined) was 10.8% (95% CI 4.8-22.6). Among the conventional H &E negative patients, the reported 5-year survival rates of the patients without lymph node micrometastases vs. those with lymph node micrometastases in the ranged from 50% to 61% and from 0% to 36%, respectively Patients with lymph node micrometastasis showed poorer survival (Hazard ratio 4.29, 95% CI 1.27-14.41).

CONCLUSIONS

The presence of lymph node micrometastasis is associated with poorer survival. Lymph node micrometastasis is applicable to stratify the risk of recurrence and the need for adjuvant therapy of post-resection patients with pancreatic adenocarcinoma in the conventional H & E lymph node negative patients.

A comparative analysis of K-ras mutation and carcinoembryonic antigen in pancreatic cyst fluid

BACKGROUND/AIMS

Analysis of cystic fluid may be useful in distinguishing between benign and malignant cysts which has significant impact on their management. The aim of our study was to assess the diagnostic utility of carcinoembryonic antigen (CEA) and K-ras gene mutation in pancreatic cysts fluid.

METHODS

The study included 56 patients with pancreatic cystic fluid collected for analysis. The cysts were classified as benign (simple cysts, pseudocysts, serous cystadenoma) - 39 patients or premalignant/malignant (mucinous cystadenoma, IPMN, cystadenocarcinoma) - 17 patients. The patients history, CEA fluid concentrations and presence of K-ras mutation were analyzed.

RESULTS

CEA were higher in patients with malignant cysts (mean levels 238 ± 12.5 ng/ml; range 32.8-4985 ng/ml) compared to benign lesions (mean levels 34.5 ± 3.7 ng/ml; range 3.9-693 ng/ml; p < 0.001). K-ras mutation correctly classified 11 of 17 patients with premalignant/malignant lesions. It was also detected in 1 patient with final diagnosis of benign cyst (the sensitivity 64.7% and the specificity 97.4%; p < 0.01). If CEA and molecular analysis were combined in that cysts with either CEA level>45 ng/ml or presence of K-ras mutation, than 16 of 17 premalignant/malignant cysts were correctly identified (94.1%).

CONCLUSION

Molecular analysis of pancreatic cyst fluid adds diagnostic value to the preoperative diagnosis and should be considered when cyst cytologic examination is negative for malignancy.

Meta-analysis of immunohistochemical prognostic markers in resected pancreatic cancer

BACKGROUND

The potential prognostic value of several commonly investigated immunohistochemical markers in resected pancreatic cancer is variably reported. The objective of this study was to conduct a systematic review of literature evaluating p53, p16, smad4, bcl-2, bax, vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR) expression as prognostic factors in resected pancreatic adenocarcinoma and to conduct a subsequent meta-analysis to quantify the overall prognostic effect.

METHODS

Relevant literature was identified using Medline, EMBASE and ISI Web of Science. The primary end point was overall survival assessed on univariate analysis. Only studies analysing resected pancreatic adenocarcinoma were eligible for inclusion and the summary log(e) hazard ratio (logHR) and variance were pooled using an inverse variance approach. Evidence of heterogeneity was evaluated using the χ(2) test for heterogeneity and its impact on the meta-analysis was assessed by the I(2) statisic. Hazard ratios greater than one reflect adverse survival associated with positive immunostaining.

RESULTS

Vascular endothelial growth factor emerged as the most potentially informative prognostic marker (11 eligible studies, n=767, HR=1.51 (95% confidence interval, CI=1.18-1.92)) with no evidence of any significant publication bias (Egger's test, P=0.269). Bcl-2 (5 eligible studies, n=314, HR=0.51 (95% CI=0.38-0.68)), bax (5 studies, n=274, HR=0.63 (95% CI=0.48-0.83)) and p16 (3 studies, n=229, HR=0.63 (95% CI=0.43-0.92)) also returned significant overall survival differences, but in smaller patient series due to a lack of evaluable literature. Neither p53 (17 studies, n=925, HR=1.22 (95% CI=0.96-1.56)), smad4 (5 studies, n=540, HR=0.88 (95% CI=0.61-1.27)) nor EGFR (4 studies, n=250, HR=1.35 (95% CI=0.80-2.27)) was found to represent significant prognostic factors when analysing the pooled patient data. There was evidence of significant heterogeneity in four of the seven study groups.

CONCLUSION

These results support the case for immunohistochemical expression of VEGF representing a significant and reproducible marker of adverse prognosis in resected pancreatic cancer.

Correlations between p53 gene mutations and histologic characteristics of pancreatic ductal carcinoma

OBJECTIVE

With the aim of improving early detection of pancreatic carcinoma, we attempted to make correlations among positive immunohistochemical detection of p53 expression, mutations in the p53 gene, and detailed histologic features of pancreatic carcinoma.

METHODS

Seven cases of invasive pancreatic ductal carcinoma demonstrating p53 overexpression were analyzed. Serial 4- and 20-microm sections from paraffin blocks were used for immunodetection of p53 protein and microdissection, respectively. We used direct sequencing of polymerase chain reaction at 101 p53-positive and 10 p53-negative sites to sequence exons 5 to 8 of p53 and then analyzed these results in concert with detailed histologic features.

RESULTS

Regardless of the degree of p53 overexpression, we detected p53 point mutations in all p53-positive lesions, including 22 noninvasive sites, 17 invasive areas, and 1 lymph node metastasis. No significant correlations were measured between specific p53 mutations and histologic features. Within individual tumors, the same p53 mutation was generally, but not always, detected in different areas in invasive and noninvasive lesions.

CONCLUSIONS

Our results demonstrate that p53 mutation is an early genetic event affecting a diversity of molecular pathways in pancreatic carcinogenesis and indicates a possibility of early diagnosis of pancreatic carcinoma by detecting a few p53-positive cells obtained from the pancreatic fluid.

Pancreatic cancer: a generalized disease--prognostic impact of cancer cell dissemination

BACKGROUND

Pancreatic ductal adenocarcinoma is the fifth leading cause of death among all malignancies, leading to approximately 40,000 deaths each year in Europe. The annual incidence rate for all types of pancreatic cancer is approximately nine new cases per 100,000 people, ranking it as the 11th among all cancers. Stage, grade and resection margin status are currently accepted as the most accurate pathologic variables predicting survival. All classification systems fail prognostically to distinguish between different stages. Even in patients with seemingly early tumours (T1, N0), the likelihood of relapse is high. This reflects the shortcomings of the pathologic staging to sufficiently discriminate patients with a high risk to develop tumour recurrence from those that carry a lower risk.

RESULTS

On the other hand, none of the currently used systems includes or takes into consideration the role of disseminated tumour cells neither in the lymph nodes nor in the bone marrow. Occult residual tumour disease is suggested when either bone marrow or lymph nodes, from which tumour relapse may originate, are affected by micrometastatic lesions undetectable by conventional histopathology. For detection, antibodies against tumour-associated targets can be used to detect individual epithelial tumour cells both in lymph nodes and in bone marrow. The clinical significance of these immunohistochemical analyses is still controversial. Various monoclonal antibodies are still in use for micrometastatic detection, thus contributing to the incongruity of data and validity of results. These assays have been rarely used in patients with pancreatic carcinoma.

CONCLUSION

The presence or absence of lymph-node metastases can predict the likelihood of survival for most, if not all, patients with pancreatic ductal adenocancer and the likelihood that metastases will develop at distant sites.

Impact of disseminated tumor cells in gastrointestinal cancer

The detection of epithelial cells by sensitive immunological and molecular methods in blood, lymph nodes or bone marrow of gastrointestinal cancer patients may open a new approach to clinical metastasis research. The phenotypic and genomic characterization of these cells is of great value in the prediction of the further course of the disease and the monitoring of response to treatment. In addition, the role of ultrastaging in blood, lymph nodes and bone marrow of cancer patients for the indication of multimodal therapy is discussed in this review. The impact of prognostic or predictive factors for new treatment protocols in patients with gastrointestinal cancer was evaluated as well as the correlation with clinical factors.

[Significance of occult lymphatic tumor spread in pancreatic cancer]

PURPOSE

The aim of this study was to determine the frequency and effect on prognosis of occult tumor cells in regional lymph nodes judged to be tumor-free in conventional histopathology of pancreatic cancer patients.

PATIENTS AND METHODS

Among 115 patients who underwent pancreatic resection for pancreatic (n=84) or distal common bile duct malignancy (n=12) or carcinoma of the papilla (n=19), 48 (42%) were staged pN0. Archival paraffin blocks of 271 resected regional lymph nodes of 41 pN0 patients were reevaluated for occult tumor cells using monoclonal antibody Ber-EP4. Cases with or without isolated tumor cells were compared regarding the distribution of various clinicopathological factors.

RESULTS

Of 41 pN0 patients, 16 (39%) exhibited single Ber-Ep4 immunoreactive cells or small cell clusters in at least one lymph node. The occurrence of occult tumor cells was not dependent on other clinicopathological factors such as pT stage, grading, or curative resection. However, those cells were encountered more frequently in common bile duct carcinomas (100%) than in pancreatic (36%) or papilla (20%) carcinomas (P=0.009). Occult tumor cells impaired prognosis significantly in uni- and multivariate analyses (estimated 5-year survival 53% for pN0((i-)) vs 10% for pN0((i+)) and 9% for pN1/N2; P=0.0047).

CONCLUSION

Occult tumor cells are frequent in apparently tumor-free lymph nodes of pancreatic cancer patients and often overlooked in conventional histopathology. They are encountered even in limited stages of disease and they impair prognosis, which is comparable to that of patients with true lymphatic metastases. Occult tumor cells in lymph nodes of pancreatic cancer patients could be used to stratify adjuvant therapy.

Differing molecular pathology of pancreatic adenocarcinoma in Egyptian and United States patients

Variations in genetic mutations in pancreatic carcinoma between different populations have not been studied extensively, especially in developing countries where pancreatic cancer is rare. We studied the molecular pathology of 44 pancreatic carcinomas from patients residing in a heavily polluted region in the Nile River delta and compared the findings with tumors from 44 United States (US) patients. We evaluated K-ras mutations in codon 12, p53 mutations in exons 5-8, and Gadd45a mutations in exons 1 and 4. Overall, rates of K-ras, p53 and Gadd45 mutations were not statistically different in tumors of patients from Egypt and the US (67.4 vs. 63.4%; 27.3 vs. 36.4% and 9.1 vs. 4.5%, respectively). However, there were distinct differences in the specific types of K-ras and p53 mutations between the 2 groups. In K-ras, G --> T transversion mutation was more frequent in the tumors from Egypt than from the US (58.6 vs. 26.9%), whereas G --> C transversion was detected in 26.9% of US tumors but none from Egypt (p = 0.003). We also found a trend toward differences in the p53 exons in which mutations occurred, with higher frequency of exon 5 mutation and lower frequency of exon 6 mutation in Egyptian tumors. Logistic regression showed that K-ras G --> T transversion mutations and p53 exon 6 mutations were predicted by the country of residence of the patients. Our study identifies that there are differences in the types of mutations found in tumors from pancreatic carcinoma patients in Egypt and the US, and suggests that environmental factors may explain these differences.

Detection of disseminated tumour cells in the liver of cancer patients

AIMS

The liver is a common site of metastasis from a variety of solid malignancies. This is due to disseminated tumour cells (DTC) that have spread prior to or during surgery from the primary carcinoma. This article gives a short overview of the data published on the detection of DTC in the liver and describes the commonly used detection methods and respective markers.

METHODS

A literature survey was performed in public medical databases comprising the last 15 years with focus on DTC detection in liver tissue of cancer patients.

KEY FINDINGS

Although the liver is a preferred site of metastasis, only a few studies have analysed the DTC incidence in inconspicuous liver tissue. The available reports include only patients with pancreatic and colorectal carcinomas. In patients with pancreatic cancer the DTC incidence varied from 5 to 76%. No follow-up data has been reported so far. In patients with colorectal carcinoma hepatic DTC were found in 5-69% of cases. A negative prognostic influence of hepatic DTC was reported in all but one studies with follow-up information.

CONCLUSIONS

The detection of DTC in the liver can contribute to identify patients with increased risk who could benefit from an intensified follow-up or new treatment strategies.

Clinical significance of K-ras and c-erbB-2 mutations in pancreatic adenocarcinoma and chronic pancreatitis

BACKGROUND

The differentiation of chronic pancreatitis (CP) from pancreatic adenocarcinoma (PA) remains the great challenge for clinicians. The purpose of this study was to compare the prevalence of K-ras and c-erbB-2 mutations in PA and CP in order to evaluate their usefulness in differential diagnosis of those diseases.

METHODS

The study included 49 patients who underwent Whipple resection or distal pancreatectomy for pancreatic adenocarcinoma (26 subjects) or chronic pancreatitis (23 subjects). DNA from pancreatic tissue was analyzed for K-ras codon 12 and c-erbB-2 mutations with PCR amplifications.

RESULTS

The K-ras gene mutation has been shown in 20 (76.9%) PA cases and in 8 (34.8%) CP cases (p<0.01). Prevalence of c-erbB-2 amplification in patients with PA was 17 (65.3%), which was not different from CP, 16 (56.5%) (p=0.58). There was a significant correlation between K-ras mutation and lymph node metastases (p=0.025) as well as between K-ras mutation and G3 tumor differentiation (p=0.037). Overall median survival in patients with PA was 9.5 mo. There was no relationship between presence of K-ras (p=0.58) or c-erbB-2 (p=0.17) mutation and survival time in PA patients.

CONCLUSION

Those results may indicate that both K-ras and c-erbB-2 play a role in pancreatic carcinogenesis, however only K-ras may provide an additional tool in differential diagnosis of CP and PC.

Clinical significance of K-ras and c-erbB-2 mutations in pancreatic adenocarcinoma and chronic pancreatitis

BACKGROUND

The differentiation of chronic pancreatitis (CP) from pancreatic adenocarcinoma (PA) remains the great challenge for clinicians. The purpose of this study was to compare the prevalence of K-ras and c-erbB-2 mutations in PA and CP in order to evaluate their usefulness in differential diagnosis of those diseases.

METHODS

The study included 49 patients who underwent Whipple resection or distal pancreatectomy for pancreatic adenocarcinoma (26 subjects) or chronic pancreatitis (23 subjects). DNA from pancreatic tissue was analyzed for K-ras codon 12 and c-erbB-2 mutations with PCR amplifications.

RESULTS

The K-ras gene mutation has been shown in 20 (76.9%) PA cases and in 8 (34.8%) CP cases (p<0.01). Prevalence of c-erbB-2 amplification in patients with PA was 17 (65.3%), which was not different from CP, 16 (56.5%) (p=0.58). There was a significant correlation between K-ras mutation and lymph node metastases (p=0.025) as well as between K-ras mutation and G3 tumor differentiation (p=0.037). Overall median survival in patients with PA was 9.5 mo. There was no relationship between presence of K-ras (p=0.58) or c-erbB-2 (p=0.17) mutation and survival time in PA patients.

CONCLUSION

Those results may indicate that both K-ras and c-erbB-2 play a role in pancreatic carcinogenesis, however only K-ras may provide an additional tool in differential diagnosis of CP and PC.

Detection of CK20mRNA in peripheral blood of pancreatic cancer and its clinical significance

AIM: To detect the expression of CK20mRNA in peripheral blood of pancreatic cancer and evaluate its clinical significance.

METHODS: Expression of CK20mRNA in peripheral blood was detected by fluorogenic qualitative reverse transcription-polymerase chain reaction (RT-PCR) in 40 cases of pancreatic cancer at the night before operation, in 5 cases of benign pancreatic diseases, in 5 cases of healthy individuals. The relationships were investigated between CK20mRNA expression and the clinicopathological variables, and clinical follow-up outcome in those patients with pancreatic cancer having undergone radical resection.

RESULTS: Of the 40 patients with pancreatic cancer, 23 (57.5%) cases were positive for CK20mRNA expression. CK20mRNA expression was significantly correlated with lymphatic metastasis (P = 0.008), histopathological grading (P = 0.009), and pathological stage (P = 0.021); there was no significant correlation between CK20mRNA expression and age, gender, tumor diameter, and depth of invasion. The cumulative metastasis rates of patients with CK20mRNA expression were higher than those of patients with no CK20mRNA expression within 6 mo (34.7% vs 5.9%, P = 0.043) or 12 mo (73.9% vs 35.3%, P = 0.02) after operation. CK20mRNA expression in peripheral blood of pancreatic cancer indicated poorer prognosis. The survival rate of patients with CK20mRNA expression was lower than that of patients with negative CK20mRNA expression (Log-Rank = 13.31, P = 0.0003).

CONCLUSION: CK20mRNA is a sensitive and specific molecular marker for the detection of micrometastasis in peripheral blood of patients with pancreatic cancer. The CK20mRNA expression in peripheral blood is correlated with biological characteristic of pancreatic cancer. It can help to predict the prognosis of pancreatic cancer after operation, and to determine which patient will benefit from aggressive adjuvant therapies.