Genetics of Pancreatic Cancer

Genotype/phenotype of familial pancreatic cancer

It is estimated that 5% to 10% of pancreatic cancer cases are attributable to hereditary factors. We believe that the number of cases that are genetic in etiology are even greater, however, based not on a classic autosomal dominant pattern of inheritance but rather when one takes into account low-penetrant inherited susceptibility factors. There is also a growing recognition that the development of pancreatic cancer in pancreatic cancer-prone families is dependent not only on genetic variables but on nongenetic factors. The aim of this article is to review the challenges in identifying pancreatic cancer-prone families and how environmental factors interact with genetic factors in these families.

Familial pancreatic cancer syndromes

Hereditary pancreatic cancer (PC) is rare and extremely heterogeneous, and it accounts for approximately 2% of all PC cases. The major component of hereditary PC is the familial pancreatic cancer syndrome. Although up to 20% of hereditary PC cases are associated with germline mutations in the BRCA2, CDKN2A, PRSS1,STKI1, or MMR genes, the major underlying gene defect(s) is still unknown. Although hereditary PC is rare, the data on PC families that have been collected by various study groups worldwide provide a unique opportunity to evaluate the natural history, causative gene alterations, new diagnosis and chemoprevention strategies as well as treatment modalities.

Regulation of vascular endothelial growth factor receptor-2 expression in pancreatic cancer cells by Sp proteins

Vascular endothelial growth factor receptor-2 (VEGFR2/KDR) is an important mediator of angiogenesis, and VEGFR2 mRNA is expressed in several pancreatic cancer cell lines. Deletion analysis of the VEGFR2 promoter in Panc-1, AsPC-1, and MiaPaCa-2 pancreatic cancer cells shows that the proximal region of the promoter is primarily responsible for VEGFR2 expression, and two GC-rich sites at -58 and -44 are critical elements in all three cell lines. Panc-1, AsPC-1, and MiaPaCa-2 cells also express Sp1, Sp3, and Sp4 proteins which bind to the GC-rich region of the VEGFR2 promoter in electrophoretic mobility shift and chromatin immunoprecipitation assays. RNA interference with small inhibitory RNAs for Sp1, Sp3, and Sp4 decreases VEGFR2 mRNA and reporter gene activity in transfection assays, confirming that VEGFR2 expression in pancreatic cancer cells is regulated by Sp proteins. These results suggest that VEGFR2 cannot only be targeted by receptor tyrosine kinase inhibitors but also by drugs that downregulate Sp proteins or block Sp-dependent transactivation.

Intraductal papillary mucinous neoplasm of the pancreas: can benign lesions be differentiated from malignant lesions with multidetector CT?

Intraductal papillary mucinous neoplasm (IPMN) of the pancreas is a distinct clinicopathologic entity that is being recognized with increasing frequency. In 25%-44% of IPMNs treated with surgical resection, associated invasive carcinoma has been reported. Surgical resection is the treatment of choice for most IPMNs. Preoperative determination of the presence or absence of associated invasive carcinoma is crucial. The prognosis is worse if there is associated invasive carcinoma; when invasive carcinoma is present, the surgical procedure may be modified to include resection of regional lymph nodes. The spectrum of appearances of IPMN, which includes adenoma, borderline lesion, and lesions with associated carcinoma in situ or invasive carcinoma, was studied with 16-section multidetector computed tomography (CT) and histologic correlation. CT was performed with dual-phase acquisition; the reconstructed images were reviewed on a workstation with axial scrolling and interactive multiplanar reformation and three-dimensional reformation techniques. Features predictive of invasive carcinoma in IPMN at CT and other imaging studies include involvement of the main pancreatic duct, marked dilatation of the main pancreatic duct, diffuse or multifocal involvement, the presence of a large mural nodule or solid mass, large size of the mass, and obstruction of the common bile duct.

Intraductal papillary mucinous neoplasms of the pancreas: effect of invasion and pancreatic margin status on recurrence and survival

BACKGROUND

The natural history and prognosis for patients with intraductal papillary mucinous neoplasms (IPMN) with and without invasion remain poorly defined. This study evaluated the outcome after pancreatectomy for IPMN according to the pancreatic transection margin status and the presence or absence of invasive carcinoma.

METHODS

Data from a prospective pancreatic tumor database and medical records were reviewed for all patients who underwent pancreatic resection for IPMN at our institution between July 1990 and July 2003. Surgical specimens were re-reviewed by a single pathologist.

RESULTS

IPMN was diagnosed in 35 (26%) of 137 patients who underwent pancreatic resection for cystic neoplasms. Invasive IPMN was confirmed in 13 (37%) of 35 patients. Noninvasive IPMN was found in 22 (63%) of 35 patients; pathology re-review changed the original diagnosis from invasive to noninvasive IPMN in 6 patients. Noninvasive IPMN was found at the final pancreatic margin in eight patients; none developed recurrent disease at a median follow-up of 34 months. Recurrent disease was identified in 7 (58%) of 13 patients with invasive IPMN and in none with noninvasive IPMN. The median overall survival was 22.9 and 84.9 months in patients with invasive and noninvasive IPMN, respectively (P=.0009).

CONCLUSIONS

Distinction between invasive and noninvasive IPMN is essential in estimating prognosis and determining the need for adjuvant therapy and the frequency of follow-up surveillance. Noninvasive IPMN, even if present at the pancreatic margin, was not associated with recurrent disease. In contrast, invasive IPMN was associated with early recurrence and short survival.

5,10-Methylenetetrahydrofolate reductase polymorphisms and the risk of pancreatic cancer

To test the hypothesis that 5,10-methylenetetrahydrofolate reductase (MTHFR) polymorphisms modify the risk of pancreatic cancer, we conducted a hospital-based, case-control study involving 347 patients with newly diagnosed pancreatic adenocarcinoma and 348 healthy controls, frequency matched by age, sex, and race. MTHFR polymorphisms were determined using the PCR-RFLP method. Association of these polymorphisms with the risk of pancreatic cancer was estimated by unconditional logistic regression analysis. We found that the C667T (but not the A1298C) polymorphism had a significant main effect on the risk of pancreatic cancer. The frequencies of the MTHFR 667CC, 667CT, and 667TT genotypes were 49.5%, 38.6%, and 11.9%, respectively, among cases compared with 48.5%, 45.0%, and 6.5%, respectively, among controls. Individuals with the 667TT genotype displayed a 2-fold increased risk for pancreatic cancer compared with those with the CC/CT genotypes [adjusted odds ratio (OR), 2.14; 95% confidence interval (95% CI), 1.14-4.01]. Multivariate analyses found that the effect of the 677TT genotype on the risk of pancreatic cancer was present among ever smokers (OR, 5.53; 95% CI, 2.0-15.3) and ever alcohol drinkers (OR, 3.16; 95% CI, 1.30-7.69) but not in never smokers (OR, 0.82; 95% CI, 0.33-2.06) and never drinkers (OR, 1.42; 95% CI, 0.56-3.62). Furthermore, a positive interaction between the MTHFR TT genotype and heavy smoking or heavy alcohol consumption was detected. The OR (95% CI) of pancreatic cancer was 6.83 (1.91-24.38) for heavy smokers among the TT carriers compared with never smokers with the CC/CT genotypes and 4.23 (0.88-20.3) for heavy drinkers with the TT genotype compared with nondrinkers with the CC/CT genotypes. These observations support a role for folate metabolism in pancreatic cancer, especially among smokers and heavy drinkers.

Molecular Markers of Early Pancreatic Cancer

Pancreatic cancer is a deadly disease and the fourth most common cause of cancer death in the United States. Since chemotherapy and radiotherapy have thus far largely failed to significantly improve the survival of patients with pancreatic ductal adenocarcinoma, there is considerable interest in identifying better diagnostic markers of pancreatic neoplasia. Not only could better markers improve the early diagnosis of pancreatic cancer and allow more patients to undergo curative surgical resection, but also could potentially be used for patients at high risk of developing pancreatic cancer to identify precancerous lesions while they are amenable to cure. A wealth of information has recently become available about gene expression, DNA methylation, and proteomics alterations that occur in pancreatic cancers creating hope that better diagnostic markers of pancreatic cancer will be soon forthcoming.

Genetics of hereditary pancreatic carcinoma

Several tumor syndromes are known to have an increased incidence of pancreatic carcinoma. Unfortunately, the incidence of pancreatic carcinoma almost equals its mortality. Because of intense research activities in the past decade, several genetic alterations have been identified that are responsible for the so-called sporadic pancreatic carcinoma development. National and international research activities only recently have begun focusing on the molecular pathogenesis of hereditary risk factors for pancreatic carcinoma. It is hoped that these genetic studies will aid the development of clinical management strategies for pancreatic carcinoma prevention.

Identification of high-risk pancreatic cancer-prone families

Pancreatic cancer-prone families provide a unique resource for studying the etiology, natural history, genetics, and treatment of pancreatic cancer. The only effective way of identifying these families is by obtaining a complete family history, since it is not possible to differentiate sporadic pancreatic cancer cases from hereditary cases based on either clinical presentation or features. These families also would benefit greatly from early detection or prevention strategies. Ultimately, this knowledge could be applied to the more common sporadic form of pancreatic cancer, where diagnosis is almost always late, and prognosis remains quite grim.

Genetics of hereditary pancreatic carcinoma

Several tumor syndromes are known to have an increased incidence of pancreatic carcinoma. Unfortunately, the incidence of pancreatic carcinoma almost equals its mortality. Because of intense research activities in the past decade, several genetic alterations have been identified that are responsible for the so-called sporadic pancreatic carcinoma development. National and international research activities only recently have begun focusing on the molecular pathogenesis of hereditary risk factors for pancreatic carcinoma. It is hoped that these genetic studies will aid the development of clinical management strategies for pancreatic carcinoma prevention.

The HaP-T1 Syrian golden hamster pancreatic cancer model: cell implantation is better than tissue implantation

OBJECTIVES

Pancreatic cancer is characterized by a poor prognosis and an unsatisfactory response to conventional therapy. Appropriate experimental animal models that mimic the disease are essential to establish new therapies. The aim of this study was to compare homologous orthotopic cell implantation (OCI) and orthotopic tissue implantation (OTI) methods in the nitrosamine-derived HaP-T1 Syrian golden hamster pancreatic cancer model.

METHODS

Pancreatic tumors were induced in 32 Syrian hamsters by the OCI (n = 16) and OTI (n = 16) techniques. OTI and OCI subgroups (n = 4) were killed at 1, 2, 5, and 8 weeks post-implantation. Tumor uptake and growth and the rates of local invasion and metastases were compared at autopsy.

RESULTS

Tumor uptake was 100% by OCI and 88% by OTI. Induced pancreatic tumors were significantly larger in the OCI group (mean weight, 1.7 g vs. 0.26 g, P < 0.01.) The incidence of local invasion and rates of lymph node, liver, and peritoneal metastases were all significantly higher in the OCI group.

CONCLUSION

The OCI method is more effective than OTI in terms of tumor uptake. Tumor growth and the rates of local invasion and spontaneous metastases are higher with OCI than OTI. The OCI method is better than OTI and can contribute to the development of therapeutic strategies in pancreatic cancer research.

Prevalence of familial pancreatic cancer in Germany

Based on several case-control studies, it has been estimated that familial aggregation and genetic susceptibility play a role in up to 10% of patients with pancreatic cancer, although conclusive epidemiologic data are still lacking. Therefore, we evaluated the prevalence of familial pancreatic cancer and differences to its sporadic form in a prospective multicenter trial. A total of 479 consecutive patients with newly diagnosed, histologically confirmed adenocarcinoma of the pancreas were prospectively evaluated regarding medical and family history, treatment and pathology of the tumour. A family history for pancreatic cancer was confirmed whenever possible by reviewing the tumour specimens and medical reports. Statistical analysis was performed by calculating odds ratios, regression analysis with a logit-model and the Kaplan-Meier method. Twenty-three of 479 (prevalence 4.8%, 95% CI 3.1-7.1) patients reported at least 1 first-degree relative with pancreatic cancer. The familial aggregation could be confirmed by histology in 5 of 23 patients (1.1%, 95% CI 0.3-2.4), by medical records in 9 of 23 patients (1.9%, 95% CI 0.9-3.5) and by standardized interviews of first-degree relatives in 17 of 23 patients (3.5%, 95% CI 2.1-5.6), respectively. There were no statistical significant differences between familial and sporadic pancreatic cancer cases regarding sex ratio, age of onset, presence of diabetes mellitus and pancreatitis, tumour histology and stage, prognosis after palliative or curative treatment as well as associated tumours in index patients and families, respectively. The prevalence of familial pancreatic cancer in Germany is at most 3.5% (range 1.1-3.5%) depending on the mode of confirmation of the pancreatic carcinoma in relatives. This prevalence is lower than so far postulated in the literature. There were no significant clinical differences between the familial and sporadic form of pancreatic cancer.

STR typing of ductal adenocarcinomas of the pancreas and healthy control tissue in 18 individuals

Recently, different work groups have demonstrated that short tandem repeat (STR) typing of various tumor tissues may lead to erroneous results due to tumor microsatellite instability (MSI). This may have considerable implications for genetic profiling of tumor tissue, e.g. in paternity testing or sample individualization. To elucidate whether this is true for ductal adenocarcinomas (DAC) of the pancreas, we genetically investigated tumor and corresponding healthy tissue from 18 patients using a commercially available multiplex PCR kit commonly used in forensic laboratories. STR typing of the samples revealed no differences between tumor and healthy tissue in 17 out of 18 samples. One sample, however, showed an allele expansion at locus D21S11. In heterozygous cases, peak heights varied strongly at different loci, mocking a loss of heterozygozity. This investigation shows that even though tetranucleotide MSI in pancreatic DAC is a rare event, the interpretation of genetic profiles obtained from cancerous samples can be difficult and lead to misinterpretations.

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.

INK4/ARF germline alterations in pancreatic cancer patients

BACKGROUND

Roughly 40% of germinal mutations in melanoma families (MF) affect p16(INK4a) and p14(ARF). We investigated the association between INK4/ARF alterations and the occurrence of pancreatic cancer in MF and in sporadic pancreatic cancer (SPC) patients.

PATIENTS AND METHODS

Forty-nine MF, 66 SPC cases and 54 controls were enrolled. The INK4/ARF locus was screened.

RESULTS

As compared with the general population, the risk of pancreatic cancer (PC) was increased 9.4-fold [95% confidence interval (CI) 2.7-33.4] and 2.2-fold (95% CI 0.8-5.7) in G101W-positive and -negative MF, respectively, while mean ages at onset were 61 and 77 years, respectively. A 1.7 (95% CI 1.06-2.79) increased risk of cancer at any site was observed among first-degree relatives of SPC cases as compared with controls. The G101W founder mutation was detected in 4% of SPC cases but the rate increased to 13% when tumor clustering in either branch of families was taken into account. One G101W-positive PC patient with a melanoma in a first-degree relative harbored a germline deletion of the second allele, including exon 1B.

CONCLUSIONS

The presence of a deletion including exon 1B in two PC patients points to the involvement of p14(ARF) in the development of PC and may suggest that the increased risk of PC in MF is caused by impairment of both loci.

Pancreatic cancer

Pancreatic cancer remains a major unsolved health problem, with conventional cancer treatments having little impact on disease course. Almost all patients who have pancreatic cancer develop metastases and die. The main risk factors are smoking, age, and some genetic disorders, although the primary causes are poorly understood. Advances in molecular biology have, however, greatly improved understanding of the pathogenesis of pancreatic cancer. Many patients have mutations of the K-ras oncogene, and various tumour-suppressor genes are also inactivated. Growth factors also play an important part. However, disease prognosis is extremely poor. Around 15-20% of patients have resectable disease, but only around 20% of these survive to 5 years. For locally advanced, unresectable, and metastatic disease, treatment is palliative, although fluorouracil chemoradiation for locally advanced and gemcitabine chemotherapy for metastatic disease can provide palliative benefits. Despite pancreatic cancer's resistance to currently available treatments, new methods are being investigated. Preoperative chemoradiation is being advocated, with seemingly sound reasoning, and a wider role for gemcitabine is being explored. However, new therapeutic strategies based on the molecular biology of pancreatic cancer seem to hold the greatest promise.

Familial pancreatic carcinoma in Jews

Pancreatic cancer (PC) is the most fatal of all gastrointestinal cancers, wherein its mortality compares strikingly with its incidence. Unfortunately, 80-90% of PCs are diagnosed in the nonresectable stage. While the lifetime risk of PC in developed countries is approximately 1-3%, it is the fifth most common cause of cancer deaths among both males and females in Western countries. It occurs in excess in Jews. Approximately 5-10% of PC shows familial clustering. Examination of such familial clusters must take into consideration cancers of diverse anatomic sites, such as malignant melanoma in the familial atypical multiple melanoma (FAMMM) syndrome due to the CDKN2A (p16) germline mutation, and combinations of colorectal and endometrial carcinoma, ovarian carcinoma, and several other cancers in hereditary nonpolyposis colorectal cancer (HNPCC), which are due to mismatch repair germline mutations, the most common of which are MSH2 and MLH1 . Other hereditary disorders predisposing to PC include Peutz-Jeghers syndrome, due to the STK11 mutation, familial pancreatitis due to the cationic trypsinogen gene, site-specific familial pancreatic cancer which may be due to the 4q32-34 mutation, hereditary breast-ovarian cancer (HBOC) syndrome that is due to BRCA2 and possibly some families with HBOC that is due to BRCA1 , familial adenomatous polyposis due to the ATP gene, and ataxia telangiectasia due to the ATM germline mutation. This extant heterogeneity mandates that the physician be knowledgeable about these PC-prone syndromes which play such an important role when considering the differential diagnosis of hereditary PC. Unfortunately, there are no PC screening programs with acceptable sensitivity and specificity. However, the gold standard for screening at this time is endoscopic ultrasound. Clearly, there is a great need for the development of novel screening approaches with acceptable sensitivity and specificity. Further research is needed to elucidate those etiologic factors that contribute to the apparent excess of PC in Ashkenazi Jews. Attention should also be given to the search for mutations predisposing to PC in Jews so that opportunities to learn more about the disease's pathogenesis, as well as screening and control, may take place.

Challenging pancreatic cancer-prone pedigrees: a nosologic dilemma

OBJECTIVES

Our objective is to describe 11 pancreatic cancer (PC)-prone families, none of which are consonant with known hereditary cancer syndromes, in an attempt to portray familial aggregations of this disease that might be encountered in a clinical practice setting.

METHODS

We selected 11 families containing two or more first- and/or second-degree relatives affected with PC from a registry of 200 PC-prone kindreds. Each proband and/or key relative(s) was interviewed and completed a detailed family history questionnaire (after providing informed consent) that allowed us to extend the pedigree as far as possible with retrieval of primary medical and pathology documents, whenever available.

RESULTS

All of the 11 families show PC features that merit clinical attention and raise questions as to whether this familial clustering could be due to "chance" alone, exposure to certain common environmental factors, such as cigarette smoking, and/or polygenic, multifactorial, or Mendelian inherited factors.

CONCLUSIONS

It is estimated that about 5% of PC may have a primary hereditary etiology. Because of early death, reduced penetrance, and often profuse phenotypic and genotypic heterogeneity, particularly with respect to variable age of onset and association with diverse patterns of cancer at different anatomic sites, the pedigrees require extension for ultimate diagnosis. Physician knowledge about PC's natural history and syndrome delineation should ultimately foster earlier diagnoses and possibly prevention of this disease. These high-risk patients may provide a source of DNA for formal linkage analysis in the search for culprit cancer-prone susceptibility loci.

CDKN2A germline mutations in familial pancreatic cancer

OBJECTIVE

To evaluate the prevalence of mutations in the CDKN2A gene encoding p16 and p14 in familial pancreatic cancer (FPC).

SUMMARY BACKGROUND DATA

The genetic basis of FPC is still widely unknown. Recently, it has been shown that germline mutations in the p16 tumor suppressor gene can predispose to pancreatic cancer. The presence of p14 germline mutations has yet not been determined in this setting.

METHODS

Eighteen families with at least two first-degree relatives with histologically confirmed pancreatic cancer and five families with at least one patient with pancreatic cancer and another first-degree relative with malignant melanoma of the German National Case Collection for Familial Pancreatic Cancer were analyzed for CDKN2A germline mutations including p16 and p14 by direct DNA sequencing. All participating family members were genetically counseled and evaluated by a three-generation pedigree.

RESULTS

None of 18 FPC families without malignant melanoma revealed p16 mutations, compared to 2 of 5 families with pancreatic cancer and melanoma. Truncating p16 germline mutations Q50X and E119X were identified in the affected patients of pancreatic cancer plus melanoma families. None of the 23 families revealed p14 germline mutations.

CONCLUSIONS

CDKN2A germline mutations are rare in FPC families. However, these data provide further evidence for a pancreatic cancer-melanoma syndrome associated with CDKN2A germline mutations affecting p16. Thus, all members of families with combined occurrence of pancreatic cancer and melanoma should be counseled and offered screening for p16 mutations to identify high-risk family members who should be enrolled in a clinical screening program.

Histology of cystic tumors of the pancreas

The cystic tumors of the pancreas constitute a considerable diagnostic challenge because of their overlapping clinical, radiologic, and pathologic features. They may be difficult to differentiate from one another and from benign lesions such as pseudocysts. Because many of the tumors in this group are potentially curable, correct diagnosis is essential for proper patient management. Even when correctly diagnosed, thorough microscopic evaluation is required for the mucin-producing tumors to correctly determine their degree of malignant progression in any given case. Most recently, molecular analysis of these tumors has demonstrated definitively that the serous and mucinous types of cystic neoplasms of the pancreas are unrelated pathogenetically. Conversely, molecular data indicate similarities between the mucinous types of cystic tumors and ductal adenocarcinoma of the pancreas, but the essential molecular differences that underlie the differences in biological behavior are as yet undetermined.

Update of familial pancreatic cancer in Germany

BACKGROUND/AIMS

The prevalence of familial pancreatic cancer (FPC) and the characteristics of FPC have not yet been well investigated in the German population. Therefore, a German case collection for FPC was established in July 1999 to collect and evaluate data on FPC families.

METHODS

The prevalence of pancreatic cancer (PC) as well as other tumours and diseases was studied in families with at least 2 first-degree relatives with histologically confirmed PC, and in families of patients with PC and a first-degree relative with malignant melanoma. All participating family members were genetically counselled and evaluated by a standardised questionnaire.

RESULTS

In an 18-month period, 73 independent kindreds with potential FPC contacted the national case collection. So far, 20 kindreds have fulfilled the criteria for FPC and have undergone complete workups. Most families revealed an autosomal dominant pattern of inheritance. Twelve families revealed an isolated accumulation of PC. Importantly, in 8 of 20 (35%) families, additional tumour types such as melanoma, breast and prostate cancer occurred.

CONCLUSION

The observed phenotypic heterogeneity indicates an association with predisposing tumour suppressor genes p16 and BRCA2 in up to 30% of FPC families. Mutation analysis of these candidate genes might lead to the identification of the predisposing gene defect in a proportion of FPC families.

Molecular diagnosis of early pancreatic ductal adenocarcinoma in high-risk patients

The prevalence of pancreatic cancer in the general population is too low--even in high-prevalence areas such as Northern Europe and North America (8-12 per 10(5) population)--relative to the diagnostic accuracy of present detection methods to permit primary screening in the asymptomatic adult population. The recognition that the lifetime risk of developing pancreatic cancer for patients with hereditary pancreatitis (HP) is extremely high (20% by the age of 60 years and 40% by the age of 70 years) poses considerable challenges and opportunities for secondary screening in those patients without any clinical features of pancreatic cancer. Even for secondary screening, the detection of cancer at a biological stage that would be amenable to cure by surgery (total pancreatectomy) still requires diagnostic modalities with a very high sensitivity and specificity. Conventional radiological imaging methods such as endoluminal ultrasound and endoscopic retrograde pancreatography, which have proved to be valuable in the early detection of early neoplastic lesions in patients with familial pancreatic cancer, may well be applicable to patients with HP but only in those without gross morphological features of chronic pancreatitis (other than parenchymal atrophy). Unfortunately, most cases of HP also have associated gross features of chronic pancreatitis that are likely to seriously undermine the diagnostic value of these conventional imaging modalities. Pre-malignant molecular changes can be detected in the pancreatic juice of patients. Thus, the application of molecular screening in patients with HP is potentially the most powerful method of detection of early pancreatic cancer. Although mutant (mt) K-ras can be detected in the pancreatic juice of most patients with pancreatic cancer, it is also present in patients with non-inherited chronic pancreatitis who do not progress to pancreatic cancer (at least in the short to medium term), as well as increasingly in the older population without pancreatic disease. Nevertheless, the presence of mt-K-ras may identify a genuinely higher-risk group, enabling additional diagnostic imaging and molecular resources to be focussed on such a group. What is clear is that prospective multi-centre studies, such as that being pursued by the European Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer (EUROPAC), are essential for the development of an effective secondary screening programme for these patients.

Hereditary pancreatic cancer

Hereditary pancreatic cancer (PC) appears to be exceedingly heterogeneous, as evidenced by its association with a variety of integrally associated diverse cancers and/or differing mendelian inherited cancer syndromes, which include the Lynch syndrome II variant of hereditary nonpolyposis colorectal cancer, hereditary breast-ovarian cancer syndrome in families with the BRCA2 mutation, hereditary pancreatitis, Peutz-Jeghers polyposis and the familial atypical multiple-mole melanoma syndrome in families with the CDKN2A (p16) germline mutation. Because of this heterogeneity, we provide a conservative estimate that about 5% (1,460) of PC cases in the US annually are hereditary. Although this number is relatively small, members of hereditary PC families serve as excellent models for studying the etiology, natural history, biomarkers, pathogenesis, potential carcinogenic exposures and their perturbation of underlying genetic events, and treatment of PC. These individuals would benefit greatly from method(s) capable of detecting cancer at an early stage, and such knowledge would also be useful for improving the diagnosis of the much more common 'sporadic' form of PC.

Evidence for a major gene influencing risk of pancreatic cancer

Family history of pancreatic cancer, the fifth leading cause of cancer death in the United States, confers a 1.5-13-fold higher risk of developing pancreatic cancer. Pancreatic cancer is associated with several genetic syndromes, including hereditary breast cancer (BRCA2), familial atypical multiple mole melanoma (FAMMM) syndrome, Peutz-Jeghers syndrome, hereditary pancreatitis, and hereditary nonpolyposis colorectal cancer (HNPCC). However, these syndromes explain little of the observed familial aggregation of pancreatic cancer. We performed complex segregation analysis on 287 families ascertained through an index case diagnosed with pancreatic cancer at the Johns Hopkins Medical Institutions between January 1, 1994 and December 31, 1999. We tested for the presence of a major gene controlling either the "age-at-onset of pancreatic cancer" of "susceptibility to pancreatic cancer," and incorporated smoking data on kindred members as a covariate. We found evidence for involvement of a major gene in the etiology of pancreatic cancer. Whether inheritance was modeled as "age-at-onset" or "susceptibility," nongenetic transmission models were strongly rejected. However, modeling "age-at-onset" provided a better fit to the observed data than did modeling "susceptibility." The most parsimonious models included autosomal-dominant inheritance of a rare allele. Under the age-at-onset model, approximately 0.7% of the population appears to be at high risk of developing pancreatic cancer due to this putative gene, whereas 0.4% of the population is at high risk under the susceptibility model. Inclusion of smoking as a covariate did not significantly improve the fit of these models. This hospital-based segregation analysis of pancreatic cancer found evidence supporting the role of a rare major gene influencing risk of pancreatic cancer.

K-ras, p53, and DPC4 (MAD4) alterations in fine-needle aspirates of the pancreas: a molecular panel correlates with and supplements cytologic diagnosis

Between January 1997 and February 2000, 101 fine-needle pancreatic aspirates were obtained. After a cytologic diagnosis was made, possible molecular alterations were determined on the 94 aspirates with adequate tissue using a molecular panel (K-ras, p53, and DPC4 [MAD4] genes). The 94 aspirates were categorized as follows: diagnostic of adenocarcinoma, 48 (51%); atypical (suggestive of but not diagnostic of adenocarcinoma), 19 (20%); negative for adenocarcinoma, 25 (2 7%); diagnostic of a neoplasm other than adenocarcinoma, 2 (2%). Clinical follow-up revealed that 3 patients (12%) with negative cytologic diagnoses and 12 patients (63%) with atypical cytologic diagnoses had adenocarcinoma. Of 63 with a final diagnosis of adenocarcinoma, 42 (67%) had an alteration in at least 1 of the genes analyzed. In contrast, only 2 (6%) of 31 patients without adenocarcinoma had an alteration in 1 gene on the panel. Overall, the molecular analyses supported the diagnosis of adenocarcinoma in 6 (32%) of 19 aspirates originally diagnosed as atypical by cytology alone. A molecular panel that includes the K-ras, p53, and DPC4 (MAD4) genes correlates with and can supplement traditional cytologic diagnosis of pancreatic fine-needle aspirates.

Mixed acinar-endocrine carcinoma arising in the ampulla of Vater

We present a case of mixed acinar-endocrine carcinoma arising in the periampullary region of the duodenum. The patient was a 78-year-old male with a periampullary mass diagnosed during upper endoscopy. On gross dissection, the mass was 2.3 cm in diameter, noncystic, and confined to the duodenal submucosa. Microscopically, the tumor formed nests that were positive for amylase, trypsin (weakly), and synaptophysin (diffusely). Ultrastructurally, the tumor had 2 populations of granules with mean diameters of 175 nm and 540 nm, consistent with endocrine and zymogen granules, respectively. These studies were consistent with a mixed acinar-endocrine carcinoma that arose in the duodenum. A review of the literature revealed 1 report of an acinar cell carcinoma arising in jejunal pancreatic heterotopia. The present article is the first reported case of an acinar cell carcinoma arising in the periampullary region of the duodenum, possibly in a focus of pancreatic heterotopia.

Serous oligocystic adenoma of the pancreas: a clinicopathological and immunohistochemical study of three cases with ultrastructural findings

AIMS

Serous oligocystic adenoma of the pancreas is an uncommon benign neoplasm and is a recently described entity. To date, there are 19 adult cases of this tumour. We report three additional cases, two with macrocystic and one with unilocular types. We describe their clinicopathological, immunohistochemical and ultrastructural findings and review the world's literature.

METHODS

For a 10-year period, we reviewed all benign cystic lesions of the pancreas with emphasis on serous oligocystic adenoma. We characterised serous oligocystic adenoma as an ill-demarcated or encapsulated mass, composed largely or exclusively of macrocysts (cysts measuring 20mm or more) but few in number (oligolocular). Grossly, it may contain only a single cyst (unilocular) of any size with a few satellite cysts observed on histological examination. Special stains and immunohistochemistry as well as electron microscopy were performed on three and two cases of serous oligocystic adenoma, respectively.

RESULTS

Between 1990 and 2000, we collected 26 benign cystic lesions of the pancreas, three of which were serous oligocystic adenomas (two with macrocystic and one with unilocular types). Many of the cells lining the cysts showed PAS positivity. There was negative staining for PAS with diastase digestion, Alcian blue and mucicarmine. All cases showed positive staining for CAM5.2, AE1/AE3, EMA and CK7. The proliferation index marker was low. There was negative staining for CK20, insulin, glucagon, somatostatin, synaptophysin, chromogranin A, CEA and p53. Ultrastructural studies on two cases revealed similar findings. The single row of uniform epithelial cells lining the cysts was composed of simple cuboidal to flat cells which rested on a thin basal lamina. Their nuclei were round to ovoid. Glycogen granules were identified in the cytoplasm. Short microvilli emerged from the epithelial apical surface. Adjacent tumour cells were connected by microfilaments.

CONCLUSIONS

Serous oligocystic adenomas of the pancreas are uncommon benign tumours. Prior to this study, 19 adults with these lesions were reported in the world's literature. No correct pre-operative diagnosis was carried out on all 22 cases. The 20 patients with follow-up ranging from 2 months to 5 years did not show tumour recurrence or malignant transformation.

Early detection of pancreatic carcinoma

The poor prognosis and late presentation of pancreatic cancer patients emphasize the importance of an effective early detection strategy for patients at risk of developing pancreatic cancer. In current practice, the use of CA 19-9 levels and imaging techniques is not optimal for detecting small pancreatic lesions. It is hoped that the understanding of genetic alterations in combination with the development of high-throughput sensitive techniques will lead to the rapid discovery of a panel of biomarkers that will save lives by enabling aggressive therapy at the time when tumors are curable.

Familial fibrocystic pancreatic atrophy with endocrine cell hyperplasia and pancreatic carcinoma

Understanding the pathology of familial pancreatic carcinoma may provide important insights into pancreatic tumorigenesis. We now describe in detail the pancreatic pathology of an autosomal dominant pancreatic carcinoma kindred with distinct clinical, genetic, and pathologic manifestations differing from all other reported forms of sporadic or familial pancreatic neoplasia. Affected individuals develop a prodrome of diabetes mellitus, pancreatic exocrine insufficiency, and characteristic pancreatic imaging abnormalities. Eleven family members have undergone total pancreatectomy, revealing a unique and characteristic fibrocystic, lobulocentric pancreatic atrophy. This was patchy to diffuse in distribution and was invariably associated with a nesidioblastosis-like endocrine cell hyperplasia. All but one resected pancreas demonstrated glandular epithelial dysplasia: 10 had low-grade dysplasia (pancreatic intraductal neoplasia grade II of III or PanIN II) and seven also had high-grade dysplasia (pancreatic intraductal neoplasia grade III of III or PanIN III). Dysplasia was multifocal in small-to medium-sized duct-like structures within areas of acinar atrophy, microcystic change, and mucinous hyperplasia. Two pancreata had carcinomas of multiple and unusual histologic subtypes, including small cell undifferentiated carcinoma and giant cell anaplastic carcinoma. The findings in this kindred yield important information on a distinctive and previously unrecognized pancreatic cancer precursor. Recognition of this entity may help identify additional kindreds and perhaps the underlying genetic defect. As is the case for other familial cancers, the as yet unknown specific genetic defect may have wider implications for pancreatic cancer in general.

The molecular genetics of pancreatic ductal carcinoma: a review

In the last several years, numerous advances in the field of molecular genetics have been applied to pancreatic ductal carcinoma- the 5th leading cause of cancer death in the United States. This review summaries the current knowledge about adenocarcinoma of the pancreas.

Selected features of nonendocrine pancreatic cancer

We survey some interesting features of gene expression in nonendocrine pancreatic cancer, the response to some less widely known agents as they impact on pancreatic cell proliferation and programmed death, and several developing approaches to therapy. The proliferative and cellular suicide responses of Panc-1 cells to the free radical spin trap, NTBN, and to the 5-lipoxygenease inhibitor, MK 886, the latter assessed with CLONTECH Atlas Human cDNA Array 1, are reviewed. Difficulties in identifying those factors whose suppression or augmentation could result in inhibition of malignantly transformed cell properties are considered.

Differential expression of metastasis-associated genes in papilla of vater and pancreatic cancer correlates with disease stage

PURPOSE

Papilla of Vater cancer has a much better prognosis than pancreatic cancer. It is not known whether this is the result of differences in the tumor biology of the two malignancies. Because metastasis formation is a critical step in tumor progression and a negative prognostic factor, we compared the expression of nm23-H1 and KAI1, two metastasis-suppressing genes, in papilla of Vater cancer and pancreatic cancer.

PATIENTS AND METHODS

Analysis was performed in nine normal human papilla of Vater samples, 27 papilla of Vater cancers, 16 normal pancreatic samples, and 29 pancreatic cancers. Expression of nm23-H1 and KAI1 was analyzed by Northern blot analysis and in situ hybridization. In addition, immunohistochemistry was performed to localize the respective proteins.

RESULTS

There was no difference in nm23-H1 and KAI1 mRNA expression levels in normal versus cancerous papilla of Vater samples. In contrast, nm23-H1 and KAI1 RNA expression was upregulated in early tumor stages of pancreatic cancer and reduced in advanced tumor stages. When expression of nm23-H1 and KAI1 RNA was analyzed by use of in situ hybridization, normal epithelial cells of the papilla of Vater exhibited mRNA staining intensity similar to that of papilla of Vater cancer cells. Similar levels of nm23-H1 and KAI1 immunoreactivity also were observed in these samples. In contrast, early stage pancreatic cancer samples exhibited stronger nm23-H1 and KAI1 immunoreactivity than normal controls. Furthermore, early pancreatic cancer stages exhibited higher KAI1 and nm23-H1 immunostaining than advanced tumor stages.

CONCLUSION

Differences in the expression patterns of the two tumor suppressor genes nm23-H1 and KAI1 may contribute to the different prognoses of papilla of Vater cancer and pancreatic cancer. Our findings support the hypothesis that biologic differences rather than earlier diagnosis influence the different outcomes of these two tumor entities.

The role of genetic factors in the etiology of pancreatic adenocarcinoma: an update

Pancreatic cancer is a disease with a very poor prognosis and its etiology is still largely elusive. The only consistent environmental risk factor is cigarette smoking. A previous history of pancreatitis or diabetes mellitus is also considered to be a risk factor. Epidemiological studies have confirmed that relatives of those with pancreatic cancer have an increased risk of this malignancy, and it has been evaluated that 3-5% of all pancreatic cancer cases are caused by genetic predisposition to the disease. Usually this occurs in the setting of a known inherited cancer syndrome caused by mutations in genes such as BRCA1/2 and CDKN2A. Whether or not a true site-specific pancreatic adenocarcinoma syndrome exists is not known. The real challenge for the management of high risk patients is to develop new screening methods than can identify pre-neoplastic or early neoplastic lesions in a timely manner.

Familial risk of pancreatic cancer

BACKGROUND

Pancreatic cancer is the fifth leading cause of cancer-related mortality in the United STATES: Although smoking and age are known risk factors for pancreatic cancer, several case reports and case-control studies have suggested that there is also a familial risk. We evaluated whether a family history of pancreatic cancer increases the risk of pancreatic cancer in first-degree relatives and whether smoking and younger age at cancer diagnosis further increase this risk.

METHODS

We conducted in-person interviews with 247 patients ("case probands") with pancreatic cancer and 420 population-based control probands to collect risk factor data and pancreatic cancer family history for 1816 first-degree relatives of the case probands and 3157 first-degree relatives of the control probands. We analyzed the data by unconditional logistic regression models, with adjustment for correlated data by use of generalized estimating equations. All statistical tests were two-sided.

RESULTS

A positive family history of pancreatic cancer (i.e., being related to a case proband) or ever-smoking cigarettes approximately doubled the risk of pancreatic cancer (relative risk [RR] = 2.49; 95% confidence interval [CI] = 1.32 to 4.69; RR = 2.04; 95% CI = 1.09 to 3.83, respectively). The RR increased to 8.23 (95% CI = 2.18 to 31.07) for relatives who ever smoked and were related to a case proband who was diagnosed before age 60 years.

CONCLUSION

Routine questioning of patients about a family history of pancreatic cancer, the age of onset of this cancer in their relatives, and the patient's smoking status may identify individuals at high risk of pancreatic cancer. Future research exploring the genetic and environmental interactions associated with the risk of pancreatic cancer is critically important.

Multiple primaries in pancreatic cancer patients: indicator of a genetic predisposition?

BACKGROUND

The genetic basis of several familial cancers including breast and colon cancers has been identified recently. The occurrence of multiple cancers in one individual is also suggestive of a genetic predisposition. To evaluate inherited predisposition in pancreatic cancer we compared the clinical data of pancreatic cancer patients with and without multiple primaries as well as the frequency of malignancies among their relatives.

METHODS

Detailed data on 69 pancreatic cancer patients included survival time and TNM-classification. Index case data were separated into two groups. The first group (group 1) developed only pancreatic cancer during their lifetime, whereas the second group (group 2) developed additional primary tumours. A systematic family history was taken from 59 of these pancreatic cancer patients using a standardized questionnaire. The pancreatic cancers and the multiple primaries of the 59 patients were histologically proven.

RESULTS

Of the 69 pancreatic cancer patients, 13 (18.8%) had multiple primaries. Neither the clinical data nor the survival data of the index cases revealed differences between the two groups (all nominal P-values >0.05). In the family history study blood relatives developed a malignancy in 51% (24 of 47) of the families in group 1 compared to 75% (9 of 12) in group 2. The risk of relatives in group 2 of developing a malignant tumour was significantly higher (P = 0.034) than in group 1 after adjustments for family size and age of disease onset of the index case. The cancer spectrum of the 59 families mainly included tumours of the digestive tract and the reproductive organs.

CONCLUSIONS

A multiple primary cancer history is a common condition among pancreatic cancer patients. Relatives of these patients seem to have an increased risk for the development of distinct malignant solid tumours, which might be caused by an inherited predisposition. Clinical and genetic investigation of pancreatic cancer patients with multiple primaries and their families might lead to the identification of predisposing gene defects providing a new goal for the understanding of a shared genetic basis of different solid tumours.

Genetic counseling and testing for germline p16 mutations in two pancreatic cancer-prone families

The mortality from pancreatic cancer coincides closely with its incidence, indicating a dismal outlook. Hereditary factors probably account for approximately 5%-10% of the pancreatic cancer burden. The molecular genetic etiology of pancreatic cancer is only beginning to be identified. We describe our genetic counseling experience with 2 large families prone to pancreatic cancer-malignant melanoma in which p16 (CDKN2) germline mutations had been identified. Members of each family underwent intensive counseling before and at the time of disclosure of p16 germline mutation findings. Two non-cancer-affected siblings from each of the 2 families had p16 mutations identified in DNA from their peripheral blood lymphocytes. In each case, a parent affected with pancreatic cancer also harbored the p16 mutation identified in DNA from their respective tumor blocks. The sibling pairs stated that they would seriously consider prophylactic pancreatectomy if biomarkers or imaging findings suggested a precancerous state. Our experience highlights limited options for managing these families and emphasizes the need for better tools to diagnose pancreatic cancer at a curable stage.

Multiple primary tumors as an indicator for p16INK4a germline mutations in pancreatic cancer patients?

Multiple primary tumors in pancreatic cancer patients might indicate a genetic predisposition to the development of malignancies. In this study we evaluated whether the mutation rate of the TP53 and p16INK4a genes of pancreatic cancers differs in pancreatic cancer patients with and without multiple primaries. Furthermore, we investigated whether pancreatic cancer patients with multiple primaries carry germline mutations in either p16INK4a, TP53, or BRCA2 tumor suppressor genes to detect a genetic alteration that predisposes to the development of different primaries. Fourteen (23%) of 60 pancreatic cancer patients developed histologically verified additional primaries during their lifetimes. Normal constitutional and tumor DNA of the 14 patients with a positive cancer history, but negative family history, were analyzed for p16INK4a, TP53, and BRCA2 mutations by single-strand conformational variant (SSCV) analysis and direct sequencing. Hypermethylation of the p16INK4a promoter region in pancreatic cancers was identified by methylation-specific polymerase chain reaction (PCR; MSP). Four of 14 pancreatic carcinomas carried somatic intragenic p16INK4a mutations, and another four tumors revealed hypermethylation of the p16INK4a promoter region. Somatic intragenic TP53 mutations were identified in six of 14 tumors. None of the pancreatic cancer patients carried TP53 or BRCA2 germline mutations. In contrast, one of 14 pancreatic cancer patients with multiple primaries carried the p16INK4a mutation A68V in his germline. This mutation was localized in the conserved second ankyrin repeat of p16INK4a and did not occur in 100 control patients. The frequency of somatic TP53 and p16INK4a mutations in pancreatic cancer is similar in patients with and without multiple primaries. TP53 and BRCA2 germline mutations seem not to be significantly associated with the occurrence of multiple primaries in pancreatic cancer patients. However, p16INK4a germline mutations might be causative for tumor development in some pancreatic cancer patients with multiple primaries. The genetic investigation of patients with accumulation of different cancers even without a positive family history may be a new approach for the understanding of the relation of different cancers.

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

OBJECTIVE

Frequent P53 mutations and Ki-ras codon 12 point mutations have been reported in pancreatic cancer. Pancreatic cancer often recurs in the liver and/or lymph nodes shortly after a surgical resection. The purpose of this study is to elucidate the occurrence of microcirculating cancer cells and micrometastasis in pancreatic cancer.

METHODS

P53 mutations and Ki-ras codon 12 point mutations were examined in the main tumor, liver, portal vein, and peripheral arterial blood, and para-aortic lymph nodes of patients with pancreatic cancer using molecular examinations.

RESULTS

P53 mutations in the main tumor were present in nine (29%) of 31 patients with pancreatic cancer, whereas a Ki-ras codon 12 point mutation was evident in 18 (62%) of 29 examined patients. The peripheral arterial and portal vein blood and liver were positive for gene abnormalities in one (5%) of 21, in none (0%) of 19, and in one (1%) of 20, respectively. A P53 mutation in the main tumor was evident in none (0%) of seven stage I or II carcinomas and in nine (38%) of 24 stage III or IV cases, whereas a Ki-ras codon 12 point mutation was present in four (67%) of six stage I or II cases and in 14 (61%) of 23 stage III or IV cases. In addition, 15 (71%) of 21 patients with gene abnormalities (Ki-ras codon 12 point and/or p53 mutation) in the main tumor showed lymph node metastasis at surgery, whereas five (42%) of 12 without gene abnormalities did not demonstrate lymph node metastasis. Two (29%) of six patients with gene abnormalities in the main tumor and without metastatic disease at surgery developed liver metastasis within 6 months after surgery, whereas all five (100%) without the gene abnormalities and metastatic disease at surgery did not develop the metastasis, with the sensitivity being 100%, specificity 44%, the predictive value of the positive test 36%, and the predictive value of the negative test 100%. Two patients who had gene abnormalities in the para-aortic lymph node were free from histopathological metastasis and these two patients developed para-aortic lymph node metastasis within 6 months after surgery.

CONCLUSIONS

A molecular examination of Ki-ras codon 12 and p53 mutations therefore enables us to predict, to some degree, the occurrence of liver and lymph node metastasis in pancreatic carcinoma.

BRCA2 is inactivated late in the development of pancreatic intraepithelial neoplasia: evidence and implications

Patients harboring germline BRCA2 mutations are at an increased risk of developing pancreatic cancer. We investigated the prevalence of biallelic inactivation of BRCA2 in the presumed precursors to invasive pancreatic ductal carcinomas, pancreatic intraepithelial neoplasia (PanIN). Surgical resection specimens from three patients with germline BRCA2 mutations who developed pancreatic ductal adenocarcinoma were studied. Fourteen PanINs were needle-microdissected from paraffin-embedded tissue. DNA was isolated from these microdissected tissues and amplified by primer-mediated pre-amplification. Loss of heterozygosity at the BRCA2 locus was determined by polymerase chain reaction amplification and cycle sequencing. The presence of the wild-type alleles was evaluated at the nucleotide positions of the germline BRCA2 mutations. The K-ras gene was sequenced at codon 12 and 13 to confirm the efficacy of microdissection. By histological evaluation the prevalence of PanINs in these patients was not notably elevated. Loss of the wild-type allele of BRCA2 was present in one high-grade PanIN (PanIN 3), but in none of 13 low-grade PanINs (PanIN 1). In contrast, K-ras mutations were detectable in 7 of the 14 PanINs. These results suggest that biallelic inactivation of the BRCA2 gene is a relatively late event in pancreatic tumorigenesis. In contrast to classical molecular progression models of tumorigenesis, the inactivation of the wild-type allele in a carrier of a recessive tumor susceptibility gene may not always be the first somatic event during the molecular evolution of a cancer. The necessity for earlier genetic alterations before biallelic inactivation of a recessive tumor susceptibility gene such as BRCA2 may explain why affected carriers have normal numbers of neoplastic precursor lesions, a relatively low phenotypic penetrance, and late age of onset of pancreatic and other cancers.

Surgical management of hereditary pancreatic cancer

Pancreatic cancer continues to be a leading cause of cancer death in the United States. Seven genetic syndromes are now known to be associated with an increased incidence of pancreatic cancer. Other familial forms of pancreatic cancer exist although the genetic basis for this predisposition remains elusive. The similarities in the genetic and clinical manifestations of the sporadic and familial forms of pancreatic cancer suggest that pretreatment staging and management of patients with established pancreatic cancer should be similar. For carcinomas of the pancreatic head, pancreaticoduodenectomy should be performed according to current surgical practice, whereas the use of total pancreatectomy should be limited to cases in which margins are found to be positive or if the anatomy precludes a safe pancreaticojejunostomy. Total pancreatectomy may be considered in high-risk kindreds who strongly desire prophylactic surgery and in those with premalignant lesions. Identification of the precise genetic basis for inherited pancreatic cancer will someday make it possible to examine scientifically the effectiveness of specific management strategies.

Genetic, immunohistochemical, and clinical features of medullary carcinoma of the pancreas: A newly described and characterized entity

Medullary carcinomas of the pancreas are a recently described, histologically distinct subset of poorly differentiated adenocarcinomas that may have a unique pathogenesis and clinical course. To further evaluate these neoplasms, we studied genetic, pathological, and clinical features of 13 newly identified medullary carcinomas of the pancreas. Nine (69%) of these had wild-type K-ras genes, and one had microsatellite instability (MSI). This MSI medullary carcinoma, along with three previously reported MSI medullary carcinomas, were examined immunohistochemically for Mlh1 and Msh2 expression, and all four expressed Msh2 but did not express Mlh1. In contrast, all of the medullary carcinomas without MSI expressed both Msh2 and Mlh1. Remarkably, the MSI medullary carcinoma of the pancreas in the present series arose in a patient with a synchronous but histologically distinct cecal carcinoma that also had MSI and did not express Mlh1. The synchronous occurrence of two MSI carcinomas suggests an inherited basis for the development of these carcinomas. Indeed, the medullary phenotype, irrespective of MSI, was highly associated with a family history of cancer in first-degree relatives (P < 0.001). Finally, one medullary carcinoma with lymphoepithelioma-like features contained Epstein-Barr virus-encoded RNA-1 by in situ hybridization. Therefore, because of medullary carcinoma's special genetic, immunohistochemical, and clinical features, recognition of the medullary variant of pancreatic adenocarcinoma is important. Only by classifying medullary carcinoma as special subset of adenocarcinoma can we hope to further elucidate its unique pathogenesis.

Hereditary pancreatic adenocarcinoma. A clinical perspective

Although the total number of patients in these various high-risk groups is relatively small, they nevertheless provide excellent models for studying the cause, natural history, pathogenesis, and treatment of pancreatic cancer. These patients would also benefit greatly from procedures capable of detecting cancer at an early stage. This knowledge would be useful for the much commoner sporadic form of pancreatic cancer, in which diagnosis is almost always late and prognosis fatal. With early diagnosis, surgical resection before the cancer's extension beyond the organ's anatomic confines could be curative. The establishment of a National Familial Pancreatic Cancer Registry is essential and would increase the availability of these invaluable families for medical research.

Expression of p16(INK4A) induces dominant suppression of glioblastoma growth in situ through necrosis and cell cycle arrest

Tumor suppressor genes may represent an important new therapeutic modality in the treatment of human glioblastoma (GBM). p16(INK4A) is a tumor suppressor gene with mutation and/or deletion found in many human tumors, including glioblastomas, melanoma, and leukemias. RT-2 rat GBM cell line was used to investigate if the p16 gene induces dominant suppression of glioblastoma growth. Close to 100% of tumor cells were infected by high titer pCL retrovirus encoding the full-length human p16 cDNA at 5 m.o.i. Infected cells showed a 98% reduction in colony forming assay and a 60% reduction in growth curves in vitro compared to vector control. Exogenous overexpression of p16 induced hypophosphorylation of Rb protein by Western blot analysis. Intracranial injection of p16-infected tumor cells into syngeneic rats resulted in a 95% reduction in tumor volume compared to the controls. Intratumoral injection of p16 retrovirus resulted in tumor necrosis and prominent human p16 transgene expressions. Proliferation marker PCNA was not detected in these human p16-expressed RT-2 tumor cells, suggesting the cells were unable to enter into S phase after p16 expression. In addition, direct repeat intracranial injections of p16 retrovirus prolonged animal survival 3.2-fold compared to the controls (48.4 +/- 13.4 vs 15.0 +/- 2.1 days, p < 0.001). Two out of ten rats were found with dormant tumors at day 60 after p16 retrovirus injection. These results showed that p16 is effective in inhibiting GBM growth in situ. The mechanisms of tumor growth reduction and necrosis in vivo might be due to G1 arrest triggered by p16 expression.

Homologous orthotopic implantation models of pancreatic ductal cancer in Syrian golden hamsters: which is better for metastasis research--cell implantation or tissue implantation?

With a nitrosamine induced hamster pancreatic cancer cell line (HaP-T1), survival time and metastatic rates were compared between orthotopic cell implantation (OCI; n = 5) and orthotopic tissue implantation (OTI; n = 5) models. All the tumors were palpable (100% tumor take) after 1 week in both groups. Hamsters in the OCI group survived 71 +/- 2.17 days (range, 69-75 days), and in the OTI group, 73.8 +/- 4.03 days (range, 58-80 days). After necropsy, spontaneous metastases were noted in 100% of the animals. Direct invasion to adjacent organs was observed in four animals, and liver metastases, in three in the OTI group, which were significantly higher compared with the OCI group. On the other hand, peritoneal dissemination was observed only in the OCI group. Other metastatic sites showed no significant difference between the groups. All the histologically noted metastases had K-ras point mutation confirmed by polymerase chain reaction-restriction fragment length polymorphism (PCR/RFLP) analysis. We conclude that the homologous OTI model may be more useful than the OCI model. The OTI model may contribute to the development of therapeutic strategies in the field of pancreatic cancer research because of the capacity for invasion to adjacent organs, higher liver metastatic rate, and similarity to the clinical picture of the disease.

Atypical hyperplasia of choledocho-pancreatic duct epithelium in an Otsuka Long Evans Tokushima Fatty strain of rats

Epithelial papillary hyperplasia of choledocho-pancreatic duct, associated with cellular atypism, was observed in Otsuka Long Evans Tokushima Fatty (OLETF) rats, a strain originally established as an animal model for non-insulin-dependent diabetes mellitus (NIDDM). To investigate the potential feasibility of OLETF rats as an animal model for pancreatic ductal carcinoma, we examined the pathological characteristics of ductal lesions in OLETF rats aged from 5 to 50 weeks. Hyperplastic lesions in OLETF rats became apparent after 10 weeks of age and increased in severity and frequency of atypical changes in hyperplastic epithelium appearing after 20 weeks. We compared ductal lesions from OLETF rats with those from age-matched Long Evans Tokushima Otsuka (LETO) rats, which share a similar genetic background with OLETF rats but do not develop NIDDM. While LETO rats also display a tendency toward ductal hyperplasia, lesions from OLETF rats were more numerous and larger in size than those from age-matched LETO rats. In addition, lesions from OLETF rats contained a significantly higher number of proliferating cell nuclear antigen-positive cells than those from LETO rats. Finally, lesions in OLETF rats were accompanied by inflammation, and the observed morphological alteration of lesions correlated well with the grade of inflammation.

Pancreatic mucinous cystic neoplasms with sarcomatous stroma: molecular evidence for monoclonal origin with subsequent divergence of the epithelial and sarcomatous components

Neoplasms with mixed carcinomatous and sarcomatous growth patterns occur in many organs and tissues. The pathogenesis of these cancers is thought to be either the result of two independent neoplastic processes merging to form a single tumor, or a neoplasm of monoclonal origin that develops phenotypic diversity. To address this issue, we characterized molecular alterations in separately microdissected epithelial and sarcomatous areas in three cases of pancreatic mucinous cystic neoplasms with sarcomatous stroma. Using microsatellite markers for six chromosomal loci commonly deleted in infiltrating ductal adenocarcinomas of the pancreas, we found genetic alterations to be virtually identical between the sarcomatous and epithelial components of two of the three neoplasms. In the third neoplasm, we found allelic losses and retentions to be identical at five of the six chromosomal loci, but at a single locus, we noted allelic loss in the neoplastic epithelial component but not the sarcomatous component. The same neoplasms were also analyzed for activating point mutations in codon 12 of the K-ras gene by using mutant-enriched polymerase chain reaction and allele-specific oligonucleotide hybridization. A K-ras mutation was identified in the epithelial component of one of the three neoplasms (the same tumor with an additional allelic loss in the neoplastic epithelial cells), but the sarcomatous component of this tumor was wild-type at codon 12 of K-ras, as were both components of the other two neoplasms. Overall, these results suggest a monoclonal origin with subsequent divergence of the neoplastic epithelial and sarcomatous portions of these neoplasms.