Molecular evidence of field cancerization in a patient with 7 tumors of the aerodigestive tract.

Exposure of the mucosa of the upper aerodigestive tract to carcinogens can induce genetic changes resulting in various independent clones of neoplastic growth, a concept defined as "field cancerization." The risk of developing multiple tumors in this compartment of the body is well established. We studied 6 distinct tumors of the upper aerodigestive tract of a single patient for loss of heterozygosity (LOH), microsatellite instability (MSI), p53 mutations, and K-ras codon 12 point mutations. We detected a unique pattern of LOH and p53 mutations in all 6 tumors. No tumor showed a K-ras mutation or MSI. The results support the mechanism of "field cancerization" and illustrate the potential power of molecular techniques to elucidate pathogenesis.

DNA quantitation of distal bile duct carcinoma measured by image and flow cytometry.

OBJECTIVE: To evaluate discrepancies between flow cytometry (FCM) and image cytometry (ICM), ploidy incidence and relation between DNA ploidies and survival in distal bile duct carcinomas (DBDCs). STUDY DESIGN: Forty-four archival tumor samples from patients with DBDC who underwent subtotal pancreatoduodenectomy from 1985 to 1996 were examined for DNA ploidy using FCM and ICM. RESULTS: Overall, 59% (26/44) of the tumors were aneuploid by at least one of the two techniques. We detected more cases of aneuploidy with ICM than FCM in formalin-fixed, paraffin-embedded DBDCs, 62% (21/34) versus 33% (13/40), respectively. When results could be compared, moderate strength of agreement (kappa = .45) was demonstrated. No correlation was found between DNA ploidy by FCM, ICM or combined FCM-ICM and survival time (P = .80, P = .35, and P = .54, respectively). CONCLUSION: Approximately 59% of DNA histograms contained aneuploid cell populations. Although ICM, as compared to FCM, is more sensitive in assessing the ploidy status of DBDC, both methods were complementary. Most discrepancies between FCM and ICM were due to the dilution of aneuploid populations by non-neoplastic diploid cells. DNA ploidy assessment in DBDC did not offer the possibility of improving the ability to predict survival.

Diagnostic p53 immunostaining of endobiliary brush cytology: preoperative cytology compared with the surgical specimen.

BACKGROUND: Endobiliary brush cytology is important in the distinction of malignant and benign causes of extrahepatic bile duct obstruction. The additional diagnostic value of p53 immunostaining on these cytology specimens was assessed. METHODS: All patients with extrahepatic bile duct obstruction who underwent endoscopic retrograde cholangiopancreatography (ERCP) with endobiliary brush cytology and subsequent surgery at the Academic Medical Center in Amsterdam during a 3-year period were studied. p53 Immunocytology was compared with the corresponding conventional light microscopic cytology and p53 immunostaining of the subsequent surgical specimen. RESULTS: Fifty-three patients with the following diagnoses were included: pancreatic carcinoma (23), bile duct carcinoma (15), ampullary carcinoma (5), lymph node metastases (2), carcinoma of unknown origin (4), chronic pancreatitis (3), and primary sclerosing cholangitis (1). Fifty-one percent of the carcinomas showed positive p53 immunostaining; all four surgical specimens without carcinoma were negative. The sensitivities of conventional light microscopic cytology, p53 immunocytology, and both tests combined were 29%, 24%, and 43%, respectively. These sensitivities were higher in cases of bile duct carcinoma (46%, 40%, and 66%) compared with cases of pancreatic carcinoma (13%, 9%, and 22%). Specificities of both tests were 100%. CONCLUSIONS: p53 Immunostaining on endobiliary brush cytology may be helpful in the diagnosis of malignant extrahepatic bile duct stenosis, especially in patients with bile duct carcinoma. Cancer (Cancer Cytopathol)

p53 expression as a prognostic determinant in resected distal bile duct carcinoma.

AIMS: To determine the incidence and prognostic value of p53 immunopositivity in resectable distal bile duct carcinoma (DBDC). METHODS: Forty-seven paraffin-embedded archival tumour samples of patients with DBDC, who underwent subtotal pancreatoduodenectomy from 1985 to 1996, were immunohistochemically examined for p53 positivity, using the anti-p53 antibody D07. RESULTS: Nineteen (40%) of the 47 tumours demonstrated positive (>30%) p53 protein immunostaining. Focally positive or negative staining was seen in the remaining 28 (60%) cases. Patients in this low p53 category survived significantly longer than those in the high p53 category, with median survival durations of 29 and 13 months respectively (P=0. 039). p53 positivity was independent of age, sex, tumour size, radicality of resection, histopathological grading, lymph-node status, perineural invasion and vasoinvasive growth. CONCLUSIONS: This study indicates that low (0-30%) p53 expression is a favourable prognostic factor in patients with resected DBDC.

Prognostic value of cell proliferation (Ki-67 antigen) and nuclear DNA content in clinically resectable, distal bile duct carcinoma.

BACKGROUND: The aim of this study was to investigate the prognostic value of cell proliferation (Ki-67 antigen) and DNA content in patients resected for distal bile duct carcinoma (DBDC). METHODS: Formalin-fixed tumor specimens of 35 patients with resected DBDC and a long-term clinical follow-up were analyzed. MIB-1 antibody was used for Ki-67 antigen detection to determine the proportion of proliferating cells. DNA content was measured using flow cytometry. RESULTS: A significant correlation was found between a low MIB-1 index (<20%) and survival (P <.05). Of the 35 tumor specimens, 34 specimens were evaluable by flow cytometry: 22 carcinomas were diploid (65%), and 12 were aneuploid (35%). The median DNA index of aneuploid tumors was 1.36 (range, 1.09 to 1.76). No correlation of DNA-ploidy with survival time was found. CONCLUSION: In contrast to DNA-ploidy pattern, Ki-67 antigen expression showed prognostic significance in resectable DBDC. A Ki-67 positive ratio of > or =20% was associated with decreased survival time.

Diagnostic and prognostic value of incidence of K-ras codon 12 mutations in resected distal bile duct carcinoma.

BACKGROUND AND OBJECTIVES: The K-ras gene is one of the most extensively investigated oncogenes in a wide variety of human tumors, but has rarely been studied in distal bile duct carcinoma (DBDC). We sought to investigate the diagnostic and prognostic value of K-ras codon 12 mutations in this type of tumor. METHODS: Forty-seven patients who had undergone resection for DBDC were analyzed to reveal the incidence of K-ras codon 12 mutations, the locus most frequently involved. A rapid and simple two-step, semi-nested polymerase chain reaction (PCR) technique was used to detect mutations in paraffin-embedded tumor samples. RESULTS: The PCR mismatch amplification technique demonstrated that 35 (75%) of the 47 tumors harbored a point mutation in codon 12 of the K-ras oncogene. Patients with mutated tumors had no statistically different survival time compared to those patients without a mutation in the tumor. In contrast, negative microscopic margins proved to be a significant prognosticator. CONCLUSIONS: K-ras codon 12 mutations are common in DBDC and may be useful in the diagnosis and early detection of these tumors. However, no prognostic value of these mutations could be identified in this analysis. The results of this study also suggest that negative surgical margins remain the mainstay of prognostication in resectable DBDC. However, due to the small number of patients included in this study, the results obtained should be interpreted with care.

Mutational analysis of the P16-binding domain of cyclin-dependent kinase 4 in tumors in the head region of the pancreas.

Alterations in genes involved in cell cycle regulation are common in many tumor types. In pancreatic adenocarcinomas, inactivating mutations in the CDKN2 gene, encoding the cyclin-dependent kinase inhibitor p16, are frequently observed. CDKN2 mutations have also been identified in the germline of 50% of patients with hereditary melanoma. Interestingly, such patients also have an increased risk for pancreatic cancers. In melanoma-prone kindreds with CDKN2 wild-type status, a mutation in one of the targets of p16, cyclin-dependent kinase 4 (CDK4) was reported, which abolishes p16 inhibition. To test the possible involvement of CDK4 mutations in pancreatic carcinoma, we analyzed sequence alterations in the p16-binding domain of CDK4 in DNA isolated from 32 tumors in the head region of the pancreas. Alterations in the CDK4 region between codon 1 and codon 56 were not observed in any of the tumors. Our results do not support disruption of the p16 pathway through CDK4 mutation as an oncogenic mechanism in pancreatic head tumorigenesis.

Multiple hyperplastic polyps in the stomach: evidence for clonality and neoplastic potential.

The origin and neoplastic potential of gastric epithelial polyps remains an area of great interest, and treatment choices are a topic of controversy. This report describes a patient diagnosed with three concurrent hyperplastic gastric polyps that were studied for genetic alterations. The polyps were investigated for alterations in the K-ras oncogene and the p53 tumor suppressor gene and for p21WAF1/Cip1 and MDM2 protein overexpression. In addition, loss of heterozygosity at several loci that are frequently involved in human cancer was analyzed, microsatellite instability, a hallmark of the "mutator" phenotype, was determined, and Epstein-Barr virus infection was investigated. All separate areas from the three independent polyps harbored the same activating point mutation in codon 12 of the K-ras oncogene, indicating a clonal origin. DNA sequence alterations in p53 were not found, although high p53 protein levels could be shown by immunohistochemistry in areas of carcinoma within the largest polyp. No alterations in any of the other molecular markers were observed. The results strongly favor a clonal origin of the three independent gastric polyps and support the notion that these hyperplastic polyps may carry a risk for malignancy.

Peutz-Jeghers polyps, dysplasia, and K-ras codon 12 mutations.

BACKGROUND: Peutz-Jeghers syndrome (PJS) is a rare, autosomal dominant, polyposis syndrome, associated with an increased risk of gastrointestinal and extragastrointestinal malignancy. Occasionally dysplasia occurs in PJS polyps. AIMS: In colorectal carcinomas, mutations in codon 12 of the K-ras oncogene are common and are found at similar frequency in precursor adenomas. Therefore, K-ras codon 12 point mutations in PJS polyps, were evaluated. MATERIALS AND METHODS: Fifty two PJS polyps, including four with dysplasia, collected from 19 patients with PJS, were analysed for mutations in the K-ras codon 12 by a mutant enriched polymerase chain reaction procedure, followed by allele specific oligodeoxynucleotide hybridisation. RESULTS: A K-ras codon 12 mutation was identified, in one colonic polyp with dysplasia. The mutation was found in the non-neoplasmic epithelial cells and not in the dysplastic component of the polyp. CONCLUSIONS: K-ras codon 12 point mutations are very rare in PJS polyps, by contrast with colorectal adenomas. The findings support previous evidence that there seems to be no intrinsic relation between K-ras codon 12 mutation and dysplasia.

Clinical significance of K-ras oncogene activation in ampullary neoplasms.

AIMS: To investigate the prevalence of K-ras codon 12 point mutations in ampullary neoplasms, to explore their clinical usefulness, and to test whether the detection of these mutations could be used to identify ampullary malignancies at an early stage. METHODS: Forty one tumour specimens from 28 patients with ampullary neoplasms were analysed for activating point mutations in K-ras codon 12 using a sensitive polymerase chain reaction (PCR) based assay. RESULTS: Eleven (39%) of the 28 primary tumours harboured point mutations in K-ras. Mutations were identified in seven (41%) of the 17 carcinomas and four (36%) of the 11 adenomas. Four of the possible six permutations in codon 12 were found in these 11 samples. This spectrum of mutations is different from pancreatic carcinoma but resembles that of colorectal neoplasms. Cytological brush specimens were available in 11 cases, and in all of these specimens, the K-ras status in the primary tumour and brush specimens was identical. CONCLUSIONS: K-ras codon 12 point mutations occur in about 40% of ampullary neoplasms at a relatively early stage in tumorigenesis. The pattern of mutations in these tumours resembles that of the adenoma-carcinoma sequence in the colorectum. These results indicate that ampullary neoplasms can be detected at an early stage by searching for genetic alterations in the K-ras oncogene in cytological brush specimens.

Evaluation of p53 protein expression as a marker for long-term prognosis in colorectal carcinoma.

Mutation of the p53 gene is reported to be of prognostic importance in colorectal carcinomas. Immunohistochemical staining of the accumulated p53 gene product may be a simple alternative for p53 mutation analysis. Previous studies addressing the prognostic importance of p53 expression, however, yielded contradictory results. Therefore, we evaluated the importance of p53 expression as a marker for long-term prognosis in a well-characterised study population of 109 colorectal carcinomas. After antigen retrieval with target unmasking fluid (TUF), immunostaining of p53 was performed with both monoclonal antibody DO7 and polyclonal antibody CM1. Objective quantification of the p53 signal was assessed by a computerised image analyser. p53 expression was higher in non-mucinous tumours than in mucinous tumours (p53 labelling index = 30% and 17% respectively, P = 0.05), and in metastatic tumours compared with non-metastatic tumours (p53 labelling index = 37% and 22% respectively, P = 0.05). Other histopathological features were not related to p53 expression. In multivariate analysis, Dukes' stage (P = 0.02) and histological grade (P = 0.05) stood out as independent markers for prognosis. p53 expression was not an independent marker for prognosis. At present, p53 expression is not a useful marker for long-term prognosis. Further insight into the relationship between p53 mutations and p53 expression is needed to elucidate more precisely the clinical relevance of p53 alterations.

Molecular markers for diagnostic cytology of neoplasms in the head region of the pancreas: mutation of K-ras and overexpression of the p53 protein product.

AIMS: To determine the potential efficiency of molecular markers specific for neoplastic change--mutations of the K-ras oncogene and the p53 tumour suppressor gene--in diagnosing pancreatic carcinoma. METHODS: Archival cytology samples obtained from 17 patients with established pancreatic carcinoma were assayed for alterations in K-ras and p53. To detect changes in p53 expression, immunocytochemistry with polyclonal antibody CM1 was performed on the archival cytology slides after destaining. Mutations in K-ras codon 12 were then analysed on the scrapings of the same slides using mutant enriched polymerase chain reaction (PCR) amplification and restriction fragment length polymorphism analysis with allele specific oligonucleotide hybridisation for confirmation and characterisation. RESULTS: False negative results were recorded for five of the cytology slides when compared with p53 immunostaining of the surgical resection specimen. These five cases had been stained previously with Giemsa which interacts adversely with the immunostaining in contrast to the Papanicolaou procedure. The K-ras codon 12 mutations followed the well established distribution frequency and spectrum for pancreatic cancer and corresponded with the findings in the resection specimens in all cases. Two scrapings yielded insufficient DNA for PCR. Importantly, for two cases with an inconclusive cytology diagnosis on routine light microscopy, the diagnosis was confirmed by one of the molecular markers. The application of the molecular markers increased the diagnostic accuracy of cytology in this small study from 76 to 89%. CONCLUSIONS: The study indicates that assessment of alterations in the K-ras and p53 genes may be a valuable adjunct to diagnostic cytopathology of the head region of the pancreas, although there are some difficulties which will have to be overcome.

Expression of mutant p53 protein and CD44 variant proteins in colorectal tumorigenesis.

Colorectal tumorigenesis evolves through a series of molecular genetic changes, providing putative markers for tumour progression. This study investigated the relation between expression of the tumour suppressor gene p53 and splice variants v5 and v6 of the cell adhesion molecule CD44 by immunohistochemistry on tissue samples of early adenomas (n = 12), late adneomas (n = 12), Dukes's A and B carcinomas (n = 21), and Dukes's C and D carcinomas (n = 22) and compared these results with expression of these proteins in normal colonic mucosa (n = 17). A statistically significant trend of increasing expression was seen for both p53 (p < 0.005) and CD44 variant exon v6 (p < 0.0005) in subsequent stages of this tumour progression model. High expression of CD44 v5 was seen in most colorectal neoplasms (83%-96%), independent of stage. A statistically significant correlation was present between p53 expression and expression of variant v6 of CD44 (p < 0.01). Both p53 expression and CD44 v6 expression in adenomas increased with the degree of dysplasia (p < 0.05). The results of this study show that mutant p53 protein and variant v6 of the CD44 glycoprotein are markers of tumour progression in colorectal cancer.

Detection of p53 overexpression in routinely paraffin-embedded tissue of human carcinomas using a novel target unmasking fluid.

With the aid of a newly developed target unmasking fluid (TUF), p53 overexpression was visualized by immunohistochemistry on recent and archival paraffin-embedded tissue samples of colon, stomach, and pancreas neoplasms. Using monoclonal anti-p53 antibody pAb1801 as well as polyclonal antiserum to p53 CM1, TUF-mediated immunohistochemistry was fully concordant for p53 overexpression in paraffin-embedded carcinoma samples compared with freshly frozen tissue from the same tumors. Thus, prognostic and diagnostic assessment of p53 overexpression in malignant tissue, routinely fixed in formalin and embedded in paraffin wax, by TUF-mediated immunohistochemistry with monoclonal and polyclonal antibodies may be adopted as a new tool in diagnostic and research histopathology.

Possible dual role for vasoactive intestinal peptide as gastrointestinal hormone and neurotransmitter substance.

Vasoactive intestinal peptide (V.I.P.) has been found in high concentrations both in the gastrointestinal tract and, unexpectedly, in the central nervous system. Immunocytochemical studies have demonstrated V.I.P. in nerve-fibers. These findings challenge the concept of V.I.P. as a simple gastrointestinal hormone and suggest a possible neurotransmitter function.