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.

Accelerated age-related CpG island methylation in ulcerative colitis.

CpG island hypermethylation is a mechanism of gene silencing that can be usurped by neoplastic cells to inactivate undesirable genes. In the colon, hypermethylation often starts in normal mucosa as a function of age and is markedly increased in cancer. To test the hypothesis that subjects at increased risk of colon cancer have higher levels of methylation in their nonneoplastic mucosa, we studied methylation patterns of five genes in the normal and dysplastic mucosa of patients with ulcerative colitis (UC), a condition associated with a marked increased risk of colon cancer. One gene (Mlh1) was unmethylated in all tissues examined. All four remaining genes had low but detectable levels of methylation in the epithelium of UC patients without evidence of dysplasia, and this methylation was not different from non-UC controls. By contrast, all four genes were highly methylated in dysplastic epithelium from high-grade dysplasia (HGD)/cancer patients with UC; methylation in HGD versus controls averaged 40.0% versus 7.4% (P = 0.00003) for ER, 44.0% versus 3.0% (P < 0.00003) for MYOD, 9.4% versus 2.4% (P = 0.03) for p16 exon 1, and 57.5% versus 30.6% (P = 0.01) for CSPG2. Importantly, three of the four genes were also highly methylated in the normal appearing (nondysplastic) epithelium from these same HGD/cancer patients, indicating that methylation precedes dysplasia and is widespread in these patients. Compared with controls, methylation averaged 20.1% versus 7.2% (P = 0.07) for ER, 18.4% versus 3.0% (P < 0.008) for MYOD, and 7.9% versus 2.4% (P = 0.007) for p16 exon 1. These results are consistent with the hypothesis that age-related methylation marks (and may lead to) the field defect that reflects acquired predisposition to colorectal neoplasia. Furthermore, the data suggest that chronic inflammation is associated with high levels of methylation, perhaps as a result of increased cell turnover, and that UC can be viewed as resulting in premature aging of colorectal epithelial cells.

Ursodiol use is associated with lower prevalence of colonic neoplasia in patients with ulcerative colitis and primary sclerosing cholangitis.

BACKGROUND: Patients with ulcerative colitis and primary sclerosing cholangitis are at high risk for colonic dysplasia and cancer. This risk approaches 50% after 25 years of colitis. Ursodiol has been shown to protect against development of colorectal neoplasia in animal models. OBJECTIVE: To assess the relationship between ursodiol use and colonic dysplasia, the precursor to colon cancer, in patients with ulcerative colitis and primary sclerosing cholangitis. DESIGN: Cross-sectional study. SETTING: University medical center. PATIENTS: 59 patients with ulcerative colitis and primary sclerosing cholangitis who were undergoing colonoscopic surveillance for colonic dysplasia. MEASUREMENTS: Use of ursodiol was assessed in all patients. The presence or absence of colonic dysplasia was evaluated by colonoscopic surveillance. Other variables assessed were age at onset and duration of ulcerative colitis; duration of primary sclerosing cholangitis; Child-Pugh classification; and use of sulfasalazine, other 5-aminosalicylic acid preparations, prednisone, cyclosporine, azathioprine, and methotrexate. RESULTS: Ursodiol use was strongly associated with decreased prevalence of colonic dysplasia (odds ratio, 0.18 [95% CI, 0.05 to 0.61]; P = 0.005). The association between dysplasia and ursodiol use remained after adjustment for sex, age at onset of colitis, duration of colitis, duration of sclerosing cholangitis, severity of liver disease, and sulfasalazine use (adjusted odds ratio, 0.14 [CI, 0.03 to 0.64]; P = 0.01). Younger age at onset of colitis was associated with an increased risk for dysplasia. CONCLUSIONS: Ursodiol use appears to be associated with a lower frequency of colonic dysplasia in patients with ulcerative colitis and primary sclerosing cholangitis. A randomized trial investigating the chemoprotective effect of ursodiol in patients with ulcerative colitis may be warranted.

Inherited pancreatic cancer: surveillance and treatment strategies for affected families.

BACKGROUND: Nearly 10% of pancreatic cancers are hereditary in origin, and in some individuals, the risk of pancreatic cancer approaches 50%. A number of defined syndromes can predispose families to pancreatic cancer, although many of the mechanisms that result in familial pancreatic cancers are unknown. This article reviews current knowledge regarding familial pancreatic cancers and highlights the rationale for screening and surveillance. Methods for screening and surveillance of these high-risk individuals are described that allow the detection of pancreatic dysplasia, the precursor to pancreatic cancer. We also describe a single-center experience with the management and surveillance of familial pancreatic cancer kindreds. METHODS: Thirty-five patients from 13 familial pancreatic cancer kindreds underwent screening and/or surveillance. Endoscopic ultrasound (EUS) is the initial test of choice. Endoscopic retrograde cholangiopancreatography (ERCP) is reserved for symptomatic individuals or to investigate abnormal findings on EUS. In the proper clinical setting, patients with abnormal findings on both EUS and ERCP are candidates for total pancreatectomy. RESULTS: Twelve of 35 patients were noted to have abnormal findings on EUS and ERCP. All of these individuals underwent pancreatectomy, 10 total and 2 partial. The patients who underwent partial pancreatectomy are currently awaiting resection of the pancreatic remnant. Histopathologic examination of all 12 specimens demonstrated pancreatic dysplasia (the precursor lesion to pancreatic cancer). These specimens had no evidence of pancreatic cancer; nor were any of the resected pancreata normal. Follow-up of the 35 high-risk patients at present varies from 1 to 48 months, and none of the patients under surveillance have developed pancreatic cancer. CONCLUSION: The screening and surveillance of high-risk members of familial pancreatic cancer kindreds using EUS and ERCP is an effective method for identifying individuals with pancreatic dysplasia prior to the onset of invasive pancreatic cancer. The surveillance needs to be performed by a team of specialists who have experience in dealing with pancreatic cancer and its precursors.

The role of cyclooxygenase 2 in ulcerative colitis-associated neoplasia.

Cyclooxygenase 2 (COX-2) overexpression has been described in sporadic colonic neoplasia, but its role in ulcerative colitis (UC) neoplastic progression remains unexplored. Although the specific role of cyclooxygenase in colonic neoplasia is uncertain, its inhibition by nonsteroidal anti-inflammatory drugs decreases the risk of sporadic colonic adenocarcinoma and causes regression of adenomas in familial adenomatous polyposis. To investigate the role of COX-2 in UC-associated neoplasia, we assessed COX-2 protein and mRNA expression throughout the spectrum of UC-associated neoplastic lesions in four total colectomy specimens, using immunocytochemistry and a novel TaqMan reverse transcriptase-polymerase chain reaction assay. The findings were correlated with DNA ploidy and inflammatory activity. We found COX-2 overexpression throughout the neoplastic spectrum in UC (P: < 0.0001, R:(2)=0.53), even in diploid samples that were negative for dysplasia. Overall, neoplastic change explained 53% of the variation in COX-2 expression, whereas inflammatory activity explained only 11%. COX-2 was overexpressed in all aneuploid samples and in 38% of diploid samples (P: = 0.0074). cDNA representational difference analysis was also performed and revealed that COX-2 mRNA was an up-regulated cDNA representational difference analysis difference product. COX-2 overexpression occurs early in UC-associated neoplasia, and the increase cannot be explained by inflammatory activity alone. The data suggest that COX-2-specific inhibitors may have a chemopreventative role in UC but the possibility that they could exacerbate UC inflammatory activity needs to be tested.

Cancer surveillance of patients from familial pancreatic cancer kindreds.

The family history can be used to determine which family members warrant surveillance and when to start it. Surveillance should be started at least 1 decade before the earliest age of pancreatic cancer in the family. EUS is the basic, least-invasive surveillance tool; however, findings are similar to those seen in chronic pancreatitis. All patients who have a positive EUS or who have symptoms warrant ERCP. Changes on ERCP of ductal stricturing and clubbed or saccular side branches are suggestive of patients who may need pancreatectomy in the setting of hereditary pancreatic cancer. The goal for surveillance of familial pancreatic cancer patients is to diagnose them before the development of cancer, when they have dysplasia or carcinoma in situ, and to perform a complete pancreatectomy. Timing is crucial for determining when a patient warrants surgery; if performed too early, the patient is put at risk for the morbidity and mortality of a total pancreatectomy, which is not inconsequential. If the patient survives the operation, he or she is often left a brittle diabetic. The alternative of diagnosing too late is more worrisome because the patient dies of pancreatic cancer. An essential ingredient to a good patient outcome is a team approach to these patients, using gastroenterologists, surgeons, and pathologists who have expertise and interest in pancreatic disease.

Pancolonic chromosomal instability precedes dysplasia and cancer in ulcerative colitis.

Patients with long-standing ulcerative colitis (UC) are at increased risk for colon cancer. These cancers are thought to arise from preexisting dysplasia in a field of abnormal cells that often exhibits aneuploidy and p53 abnormalities. Using dual color fluorescence in situ hybridization with centromere probes and locus-specific arm probes for chromosomes 8, 11, 17, and 18, we demonstrate that chromosomal instability (CIN) is present throughout the colon of UC patients with high-grade dysplasia or cancer. In rectal biopsies that were negative for dysplasia, abnormalities in chromosomal arms, especially losses, were most common, whereas centromere gains were most common in dysplasia and cancer. The frequency and type of abnormalities varied between the chromosomes examined; chromosome 8 was the least affected, and 17p loss was found to be an early and frequent event. Chromosomal arm instability showed 100% sensitivity and specificity for distinguishing control biopsies from histologically negative rectal biopsies from these UC patients, raising the possibility that a screen for CIN might detect the subset of UC patients who are at greatest risk for development of dysplasia and cancer. These results suggest that dysplasia and cancer in UC arise from a process of CIN that affects the entire colon; this may provide the mutator phenotype that predisposes to loss of tumor suppressor genes and evolution of cancer.

Early diagnosis and treatment of pancreatic dysplasia in patients with a family history of pancreatic cancer.

BACKGROUND: Pancreatic cancer, the fourth most common cause of cancer death in the United States, is hereditary in an estimated 10% of cases. Surveillance of patients with a familial predisposition for pancreatic cancer has not been systematically evaluated. OBJECTIVE: To develop a surveillance program that can identify and treat patients who have precancerous conditions of the pancreas and a family history of pancreatic cancer. DESIGN: Prospective cohort study. SETTING: University medical center. PATIENTS: 14 patients from three kindreds with a history of pancreatic cancer. INTERVENTIONS: Endoscopic ultrasonography, endoscopic retrograde cholangiopancreatography (ERCP), spiral computed tomography, and serum carcinoembryonic antigen and CA19-9 analysis were performed in all patients. Four affected patients were tested for the K-ras mutation. MAIN OUTCOME MEASUREMENT: Pancreatic dysplasia was determined by histologic evaluation. RESULTS: Seven of the 14 patients were believed to have dysplasia on the basis of clinical history and abnormalities on endoscopic ultrasonography and ERCP and were referred for pancreatectomy. All 7 patients had histologic evidence of dysplasia in pancreatectomy specimens. Findings on endoscopic ultrasonography were subtle, nonspecific, and similar to those seen in patients with chronic pancreatitis. Findings on ERCP ranged from mild and focal side-branch duct irregularities and small sacculations to main-duct strictures and grapelike clusters of saccules. Some of these changes are typical of chronic pancreatitis, but others are more distinctive. Spiral computed tomography and serum tumor markers had low sensitivity in the detection of pancreatic dysplasia. Analysis for the K-ras mutation yielded positive results in 3 of 4 patients with dysplasia. CONCLUSIONS: Thorough screening of patients with a family history of pancreatic cancer is feasible. Clinical data combined with imaging studies (endoscopic ultrasonography and ERCP) can be used to identify high-risk patients who have dysplasia. The role of molecular genetic testing is uncertain at this time.

Persistent nausea and anorexia after marrow transplantation: a prospective study of 78 patients.

BACKGROUND: Persistent nausea, vomiting, anorexia, and poor oral intake are common after hematopoietic cell transplantation. In the past, herpesvirus infections and acute intestinal graft-versus-host disease (GVHD) were the most common causes. METHODS: We studied 76 patients with 78 episodes of these symptoms to discern the causes. Diagnoses were based on histology of skin and intestinal biopsy specimens, viral cultures, and responses to therapy. RESULTS: The mean day of study entry was day 57+/-31.3 posttransplant. Acute GVHD was the most common cause of symptoms, affecting 63 patients (81%) as the sole cause of symptoms and an additional 4 patients (5%) who had other concurrent causes. Patients with GVHD had marrow donors who were unrelated or HLA-mismatched in 27/63 cases. Gastric edema, erythema, and apoptotic epithelial cells were the most useful findings for the diagnosis of GVHD. Prednisone therapy (1-2 mg/kg/day) was effective in 58 of 63 patients (92%). Infection by herpes simplex virus, cytomegalovirus, or Candida was found in six patients, three of whom had concurrent GVHD. Other causes of symptoms were medications (one patients), parenteral nutrition (one patient), and sagittal sinus thrombosis (one patient). CONCLUSIONS: Acute GVHD is now the dominant cause of persistent nausea and anorexia in marrow transplant patients who are beyond day 20 posttransplant. The diagnosis can be made clinically in most cases and confirmed by endoscopic biopsy of gastric mucosa. Infections, medications, and rare cases of central nervous system disease are much less common.

Microsatellite instability in nonneoplastic mucosa from patients with chronic ulcerative colitis.

Microsatellite instability (MIN) has been detected in many cancer types; however, recently we also observed it in the nonneoplastic but inflammatory setting of pancreatitis. Consequently, we sought to examine whether MIN was present in another inflammatory condition, ulcerative colitis (UC). MIN was found in 50% of UC patients whose colonic mucosa was negative for dysplasia, 46% of those with high-grade dysplasia, and 40% of those with cancer but in none of the ischemic or infectious colitis controls (P<0.03). Thus, UC patients may have MIN within mucosa that has no histological evidence of neoplastic change. MIN in this setting may reflect the inability of DNA repair mechanisms to compensate for the stress of chronic inflammation, and may be one mechanism for the heightened neoplastic risk in UC.

Risk and natural history of colonic neoplasia in patients with primary sclerosing cholangitis and ulcerative colitis.

BACKGROUND & AIMS: Primary sclerosing cholangitis (PSC) has been suggested as a risk factor for the development of colorectal cancer in ulcerative colitis (UC); however, previous studies of this association have been limited by small numbers of patients with PSC or have been performed retrospectively. This study prospectively evaluates the risk and natural history of colonic tumorigenesis in patients with PSC and UC and compares it with patients with UC without PSC. METHODS: Twenty patients with PSC and UC and 25 control patients with UC were followed prospectively by colonoscopic surveillance using extensive mucosal biopsy sampling. All control patients with UC had disease extending beyond the sigmoid colon of > or = 8 years' duration; patients with PSC and UC were studied regardless of disease duration. RESULTS: Forty-five percent (9 of 20) of the patients with PSC and UC had dysplasia compared with 16% (4 of 25) of the control patients with UC (P < or = 0.002). Prior liver transplantation did not affect the risk of colonic dysplasia. The time course for progression to dysplasia was similar between the patients with PSC and UC and the patients with UC; however, the patients with PSC and UC were five times more likely to develop dysplasia. CONCLUSIONS: Patients with PSC and UC represent a subset of patients with UC who are at markedly increased risk for colonic neoplasia and who need close colonoscopic surveillance with extensive biopsy sampling.

Cyclosporin use in the precolectomy chronic ulcerative colitis patient: a community experience and its relationship to prospective and controlled clinical trials. Pacific Northwest Gastroenterology Society.

OBJECTIVE: To define what effect seminal and controlled clinical trials have on practice patterns within a gastroenterological community. To define whether these practice patterns reproduce reported treatment methods and whether results comparable with those reported in such trials are noted within a community practice setting. METHODS: Mailed surveies, with telephone follow-up, were sent to all members of the Pacific Northwest Gastroenterology Society. Respondents were queried regarding cyclosporin use in the precolectomy chronic ulcerative colitis (CUC) patient. Data collected included patient demographics, disease duration and extent, pre-treatment use of steroids, method, dosage, and duration of cyclosporin therapy, side effects, and short-term and subsequent clinical results. RESULTS: Twenty-one percent of 81 respondents had used cyclosporin for precolectomy CUC, approximately one-half using constant infusion and one-half using parenteral bolus therapy. Side effects attributed to the cyclosporin were noted in eight of 30 patients (27%), and acute colectomy was avoided in 17 patients (57%). Subsequent colectomy was required in an additional nine patients (73% total) within a 6-month follow-up period, a significantly higher colectomy rate than that reported in prospective trials. CONCLUSIONS: Potential reasons precluding cyclosporin use within the gastroenterological community may include lack of knowledge about cyclosporin therapy for CUC, lack of opportunity, skepticism, fear of medication side effects, survey sampling error, or treatment philosophy. Potential reasons for failure to duplicate the results reported in controlled trials are more complex but may include inadequate treatment duration the learning curve associated with the use of a new medication, or acceptance of colectomy as the treatment of choice in patients with acutely or chronically debilitating disease.

Microsatellite instability and K-ras mutations associated with pancreatic adenocarcinoma and pancreatitis.

ras oncogene mutations and microsatellite instability (MIN) have been described in pancreatic cancer studies from paraffin blocks and fresh frozen tissue. We sought to determine whether they could be detected in endoscopic retrograde cholangiopancreatography-derived pancreatic juice. ras mutations were detected in the pancreatic juice of 40% (2 of 5) of patients with pancreatic cancer and 2 of 5 patients with pancreatitis. MIN was detected at a single locus in the pancreatic juice of 40% of pancreatic cancer patients and at > or = 2 loci of 100% of pancreatitis patients. The finding of MIN in pancreatitis specimens was verified in studies performed on paraffin blocks. MIN was not detected in normal pancreas controls. All of the cancer patients who had ras mutations in their pancreatic juice also had evidence of MIN at one or more loci (P < or = 0.05), suggesting that MIN is associated with the development of a ras mutation. More importantly, the finding of MIN in pancreatitis specimens suggests that MIN can occur in nonneoplastic conditions of the pancreas and may represent the saturation of an intact mismatch repair system.

A germline substitution in the human MSH2 gene is associated with high-grade dysplasia and cancer in ulcerative colitis.

BACKGROUND & AIMS: The DNA mismatch repair gene human MSH2 shows a germline mutation in certain family members with hereditary nonpolyposis colorectal cancer. There is an increased risk of colorectal cancer in patients with ulcerative colitis (UC) with extensive disease of > 8 years' duration; however, specific constitutional predisposing genetic abnormalities have not yet been identified. METHODS: A germline human MSH2 abnormality was sought in patients with UC with high-grade dysplasia or carcinoma. RESULTS: After direct sequencing of exon 13 and flanking regions of human MSH2, a germline T to C substitution was shown at the -6 intronic splice acceptor site of exon 13. This substitution was found in 14 of 53 patients with UC with high-grade dysplasia or carcinoma (26%) compared with 4 of 36 high-risk patients with UC without dysplasia or cancer (11%) (P < or = 0.04) and in 7 of 80 healthy adult blood donors (9%) (P < or = 0.003). The patients with UC who had the substitution were three times more likely to develop neoplasia than patients with UC who did not carry it. CONCLUSIONS: An intronic splice-site substitution in the human MSH2 gene is present in the general population but may predispose to cancer in the setting of UC.

Familial pancreatic adenocarcinoma: association with diabetes and early molecular diagnosis.

We report a large pedigree in which pancreatic cancer is inherited in an autosomal dominant fashion. Diabetes and exocrine insufficiency was observed in all family members who eventually developed pancreatic cancer. The presence of diabetes, often years before the diagnosis of cancer, allowed identification of those people who had inherited the predisposing allele and who were thus at high risk for the development of malignancy. This family shows that genetic factors can have a striking effect on the development of pancreatic malignancy and diabetes mellitus. Moreover, preclinical diagnosis of pancreatic cancer in family members provided a unique opportunity to study early molecular changes that accompany the development of human pancreatic cancer. Finally, the molecular approach applied here to the early diagnosis of pancreatic cancer may prove valuable in this family for identification of subjects at risk.

Mutations in the p53 gene: an early marker of neoplastic progression in ulcerative colitis.

BACKGROUND/AIMS: In long-term extensive ulcerative colitis, aneuploidy occurs earlier and loss of heterozygosity for p53 (p53 LOH) later during histological progression towards carcinoma. This study determined the time of onset of p53 mutation in this progression. METHODS: We developed a rapid, sensitive screening assay for p53 mutations at codon 248. The geographic distribution of this p53 mutation was mapped in two fresh colectomy specimens with mutations of codon 248 (1 cancer, 1 dysplasia) and correlated with patterns of clonal expansion, histological progression, and allelic loss. Numerous samples from throughout both colons were analyzed (216 for histology, 142 for DNA content, 104 for mutation, and 41 for p53 LOH). RESULTS: p53 mutation correlated highly with histological grade and was distributed more extensively than p53 LOH. Mutation, but not LOH, was also found in diploid, nondysplastic colonic mucosa adjacent to dysplastic areas. CONCLUSIONS: These findings suggest that p53 mutation appears to be an early genetic event that precedes p53 LOH. The very close correlation of p53 mutation with aneuploidy (P > 0.0001) emphasizes the role of normal p53 at the G1 checkpoint to help prevent entry of genetically damaged cells into the cell cycle.

DNA aneuploidy in colonic biopsies predicts future development of dysplasia in ulcerative colitis.

The objective of the present study was to determine whether abnormal epithelial DNA content (aneuploidy) in colonic biopsy specimens from ulcerative colitis (UC) patients correlated with and predicted histological progression to dysplasia. Aneuploidy was absent in 20 low-cancer risk patients. In 81 high-cancer risk patients aneuploidy correlated significantly with the severity of histological abnormality (negative, indefinite, dysplasia, or cancer). Statistically our data suggest that many more biopsy specimens than are usually taken are needed to detect focal dysplastic lesions. Prospective study of 25 high risk patients without dysplasia revealed 5 with aneuploidy, all of whom progressed to dysplasia in 1-2.5 years, whereas 19 patients without aneuploidy did not progress to either aneuploidy or dysplasia within 2-9 years. Our data indicate that aneuploidy in mucosal biopsy specimens correlates with histological grade and identifies a subset of patients without dysplasia who are more likely to develop it. It was concluded that more frequent and extensive colonoscopic surveillance of this minority subset of high risk patients and less frequent surveillance in the remaining majority may reduce cost and detect more curable lesions.

Neoplastic progression in ulcerative colitis: histology, DNA content, and loss of a p53 allele.

Neoplastic progression in patients with chronic ulcerative colitis (UC) is characterized by the development of epithelial dysplasia, which is accompanied by genetic abnormalities that can be detected by flow cytometric and molecular biologic methods. Distribution of and correlation between histologic abnormalities, DNA content, and loss of heterozygosity for a p53 allele (p53 LOH) in the colons of nine UC patients were analyzed. Loss of a p53 allele was found in 85% (22/26) of biopsy specimens classified histologically as carcinoma, 63% (25/40) of biopsy specimens with high grade dysplasia, and 33% (7/21) of biopsy specimens with low grade dysplasia. Loss of heterozygosity for p53 was also found in 9% (5/57) of biopsy specimens indefinite for dysplasia and in 1/18 biopsy specimens negative for dysplasia, showing that this genetic change may occur early in the histological progression towards carcinoma. Aneuploid DNA contents were more common than p53 LOH in regions with negative, indefinite or low grade dysplastic histology; moreover, p53 LOH was detected only in aneuploid cells and not in diploid epithelium. Aneuploidy alone was not as specific a marker for the concomitant presence of dysplasia or carcinoma in a biopsy sample as aneuploidy combined with p53 LOH. These findings show that aneuploidy may precede both p53 LOH and epithelial dysplasia. Two UC patients' colons contained geographically separated clones of cells with different aneuploidies that also showed loss of different p53 alleles, suggesting that neoplasia may arise within different populations of cells in separate areas of the same colon.