Genetic testing by cancer site: pancreas

Therapeutic Strategies Targeting Tumor Suppressor Genes in Pancreatic Cancer

The high mortality of pancreatic cancer is attributed to the insidious progression of this disease, which results in a delayed diagnosis and advanced disease stage at diagnosis. More than 35% of patients with pancreatic cancer are in stage III, whereas 50% are in stage IV at diagnosis. Thus, understanding the aggressive features of pancreatic cancer will contribute to the resolution of problems, such as its early recurrence, metastasis, and resistance to chemotherapy and radiotherapy. Therefore, new therapeutic strategies targeting tumor suppressor gene products may help prevent the progression of pancreatic cancer. In this review, we discuss several recent clinical trials of pancreatic cancer and recent studies reporting safe and effective treatment modalities for patients with advanced pancreatic cancer.

Threshold Analysis of the Cost-effectiveness of Endoscopic Ultrasound in Patients at High Risk for Pancreatic Ductal Adenocarcinoma

OBJECTIVES

Data from the International Cancer of the Pancreas Screening Consortium studies have demonstrated that screening for pancreatic ductal adenocarcinoma can be effective and that surveillance improves survival in high-risk individuals. Endoscopic ultrasound (EUS) and cross-sectional imaging are both used, although there is some suggestion that EUS is superior. Demonstration of the cost-effectiveness of screening is important to implement screening in high-risk groups.

METHODS

Results from centers with EUS-predominant screening were pooled to evaluate efficacy of index EUS in screening. A decision analysis model simulated the outcome of high-risk patients who undergo screening and evaluated the parameters that would make screening cost-effective at a US $100,000 per quality-adjusted life-year willingness to pay.

RESULTS

One-time index EUS has a sensitivity of 71.25% and specificity of 99.82% to detection to detect high-risk lesions. Screening with index EUS was cost-effective, particularly at lifetime pancreatic cancer probabilities of greater than 10.8%, or at lower probabilities if life expectancy after resection of a lesion that was at least 16 years, and if missed, lesion rates on index EUS are 5% or less.

CONCLUSIONS

Pancreatic cancer screening can be cost-effective through index EUS, particularly for those individuals at high-lifetime risk of cancer.

Familial pancreatic cancer: who should be considered for genetic testing?

BACKGROUND

Determining how many female patients who underwent breast imaging meet the eligibility criteria for genetic testing for familial pancreatic cancer (FPC).

METHODS

A total of 42,904 patients seen at the Newton-Wellesley Hospital between 2007 and 2009 were retrospectively reviewed. The first four categories were based on pancreatic cancer-associated syndromes: (1) hereditary breast and ovarian cancer (HBOC), (2) Lynch syndrome (LS), (3) familial atypical multiple mole melanoma (FAMMM), and (4) family history of FPC (FH-FPC). PancPRO (5) and MelaPRO (6) categories were based on risk scores from Mendelian risk prediction tool.

RESULTS

Exactly 4445 of 42,904 patients were found to be in at least one of the six risk categories. About 5.7% of patients were classified as being at high risk for HBOC, 2.3% as being at high risk for LS, 0.1% as being at high risk for FAMMM, 0.1% as being at high risk for FH-FPC, 2.7% as being at high risk based on PancPRO, and 0.2% as being at high risk based on MelaPRO.

CONCLUSION

About 10.4% of the female patients were classified as being at high risk for FPC. This finding emphasizes the importance of applying criteria to the general population, in order to ensure that individuals with high risk are identified early.

Self-Reported Questionnaire Detects Family History of Cancer in a Pancreatic Cancer Screening Program

Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer death; approximately 5-10% of PDAC is hereditary. Self-administered health history questionnaires (HHQs) may provide a low-cost method to detail family history (FH) of malignancy. Pancreas Center patients were asked to enroll in a registry; 149 with PDAC completed a HHQ which included FH data. Patients with FH of PDAC, or concern for inherited PDAC syndrome, were separately evaluated in a Prevention Program and additionally met with a genetic counselor (GC) to assess PDAC risk (n = 61). FH obtained through GC and HHQ were compared using Wilcoxon signed-rank sum and generalized linear mixed models with Poisson distribution. Agreement between GC and HHQ risk-assessment was assessed using kappa (κ) statistic. In the Prevention Program, HHQ was as precise in detecting FH of cancer as the GC (all p > 0.05). GC and HHQ demonstrated substantial agreement in risk-stratification of the Prevention Program cohort (κ = 0.73, 95% CI 0.59-0.87.) The sensitivity of the HHQ to detect a patient at elevated risk (i.e., moderate- or high-risk) of PDAC, compared to GC, was 82.9% (95% CI 67.3-92.3%) with a specificity of 95% (95% CI 73.1-99.7%). However, seven patients who were classified as average-risk by the HHQ were found to be at an elevated-risk of PDAC by the GC. In the PDAC cohort, 30/149 (20.1%) reported at least one first-degree relative (FDR) with PDAC. The limited sensitivity of the HHQ to detect patients at elevated risk of PDAC in the Prevention Program cohort suggests that a GC adds value in risk-assessment in this population. The HHQ may offer an opportunity to identify high-risk patients in a PDAC population.

Advances in Hereditary Colorectal and Pancreatic Cancers

PURPOSE

Innovations in genetic medicine have led to improvements in the early detection, prevention, and treatment of cancer for patients with inherited risks of gastrointestinal cancer, particularly hereditary colorectal cancer and hereditary pancreatic cancer.

METHODS

This review provides an update on recent data and key advances that have improved the identification, understanding, and management of patients with hereditary colorectal cancer and hereditary pancreatic cancer.

FINDINGS

This review details recent and emerging data that highlight the developing landscape of genetics in hereditary colorectal and pancreatic cancer risk. A summary is provided of the current state-of-the-art practices for identifying, evaluating, and managing patients with suspected hereditary colorectal cancer and pancreatic cancer risk. The impact of next-generation sequencing technologies in the clinical diagnosis of hereditary gastrointestinal cancer and also in discovery efforts of new genes linked to familial cancer risk are discussed. Emerging targeted therapies that may play a particularly important role in the treatment of patients with hereditary forms of colorectal cancer and pancreatic cancer are also reviewed. Current approaches for pancreatic cancer screening and the psychosocial impact of such procedures are also detailed.

IMPLICATIONS

Given the availability of new diagnostic, risk-reducing, and therapeutic strategies that exist for patients with hereditary risk of colorectal or pancreatic cancer, it is imperative that clinicians be vigilant about evaluating patients for hereditary cancer syndromes. Continuing to advance genetics research in hereditary gastrointestinal cancers will allow for more progress to be made in personalized medicine and prevention.

Genetic evaluation and testing for hereditary forms of cancer in the era of next-generation sequencing

The introduction of next-generation sequencing (NGS) technology in testing for hereditary cancer susceptibility allows testing of multiple cancer susceptibility genes simultaneously. While there are many potential benefits to utilizing this technology in the hereditary cancer clinic, including efficiency of time and cost, there are also important limitations that must be considered. The best panel for the given clinical situation should be selected to minimize the number of variants of unknown significance. The inclusion in panels of low penetrance or newly identified genes without specific actionability can be problematic for interpretation. Genetic counselors are an essential part of the hereditary cancer risk assessment team, helping the medical team select the most appropriate test and interpret the often complex results. Genetic counselors obtain an extended family history, counsel patients on the available tests and the potential implications of results for themselves and their family members (pre-test counseling), explain to patients the implications of the test results (post-test counseling), and assist in testing family members at risk.

Germline Mutation of the CCK Receptor: A Novel Biomarker for Pancreas Cancer

OBJECTIVES

Today, genetic biomarkers have been demonstrated to play an important role in identifying at-risk subjects for familial or inherited cancers. We have identified a single-nucleotide polymorphism (SNP) that results in missplicing of the cholecystokinin (CCK) receptor gene and expressing a larger mutated receptor in pancreatic cancer. The purpose of this study was to evaluate the significance and specificity of this SNP as a potential biomarker in patients with pancreatic cancer compared with other gastrointestinal (GI) cancers that also have CCK receptors.

METHODS

DNA was isolated and genotyped for the CCK receptor SNP from frozen tumor tissue from banked specimens of patients with pancreas, gastric, or colon cancer and from human cancer cell lines. Genotype and allelic frequencies were compared between the cancer cohort and two normal control databases using Fisher's exact test and odds ratio (OR). The Kaplan-Meier method was used to estimate the survival for patients with the CCK-B receptor SNP compared with those with the wild-type genotype. Immunohistochemical staining of cancer cells was done to detect the mutated receptor.

RESULTS

Colon and gastric cancer patients had similar genotype frequencies for the CCK receptor SNP as that reported in the normal population. In contrast, the prevalence of the SNP in subjects with pancreatic cancer was twice that of controls and other GI cancers. Survival was adversely affected by the presence of the SNP only in those with pancreatic cancer. Immunoreactivity for the mutated receptor was positive in pancreatic cancer tissues with the SNP but absent in other GI cancers.

CONCLUSIONS

A SNP of the CCK receptor is significantly increased in patients with pancreatic cancer but not in those with other GI malignancies. Therefore, this SNP may be a potential biomarker for pancreatic cancer.

High-risk population in sporadic pancreatic adenocarcinoma: guidelines for screening

BACKGROUND

Pancreatic cancer (PC) is one of the most deadly forms of cancer in the United States, with an annual incidence to death ratio of 0.92 because of the late stage at diagnosis. Identification of high-risk individuals (HRIs) that would be ideal for screening is needed to identify precursor lesions and small early stage disease. Those with a genetic predisposition have largely been identified, but little is known about those at high-risk for sporadic PC. This study asserts that a high-risk population does exist in sporadic pancreatic adenocarcinoma and proposes simple guidelines for screening.

METHODS

A systematic review was conducted of the literature regarding identification of and screening in high-risk groups.

RESULTS

Those with the highest genetic risk of developing PC include those with hereditary pancreatitis (87 times more likely at age 55), Peutz-Jehgers syndrome (132 times more likely at age 50), p16-Leiden mutations (48 times more likely), and familial pancreatic cancer (FPC) kindreds (32 times more likely). Those with the highest risk of developing sporadic PC include those with new-onset diabetes older than 50 y and smoking history.

CONCLUSIONS

Given that sporadic PC is the single largest patient population effected with this devastating disease, some form of screening should be initiated. Currently, the medical community does nothing to attempt early detection of PC. However, sufficient evidence now exists to begin a screening protocol in a high-risk cohort, which would be patients with new-onset diabetes older than 50 y and a smoking history.

A paradoxical chemoresistance and tumor suppressive role of antioxidant in solid cancer cells: a strange case of Dr. Jekyll and Mr. Hyde

Modulation of intracellular antioxidant concentration is a double-edged sword, with both sides exploited for potential therapeutic benefits. While antioxidants may hamper the efficacy of chemotherapy by scavenging reactive oxygen species and free radicals, it is also possible that antioxidants alleviate unwanted chemotherapy-induced toxicity, thus allowing for increased chemotherapy doses. Under normoxic environment, antioxidants neutralize toxic oxidants, such as reactive oxygen species (ROS), maintaining them within narrow boundaries level. This redox balance is achieved by various scavenging systems such as enzymatic system (e.g., superoxide dismutases, catalase, and peroxiredoxins), nonenzymatic systems (e.g., glutathione, cysteine, and thioredoxin), and metal-binding proteins (e.g., ferritin, metallothionein, and ceruloplasmin) that sequester prooxidant metals inhibiting their participation in redox reactions. On the other hand, therapeutic strategies that promote oxidative stress and eventually tumor cells apoptosis have been explored based on availability of chemotherapy agents that inhibit ROS-scavenging systems. These contradictory assertions suggest that antioxidant supplementation during chemotherapy treatment can have varied outcomes depending on the tumor cellular context. Therefore, understanding the antioxidant-driven molecular pathways might be crucial to design new therapeutic strategies to fight cancer progression.