Long-term follow-up of complete Barrett's eradication endoscopic mucosal resection (CBE-EMR) for the treatment of high grade dysplasia and intramucosal carcinoma.

BACKGROUND AND STUDY AIMS: In patients with Barrett's esophagus (BE), targeted endoscopic mucosal resection (EMR) of visible lesions of high grade dysplasia (HGD) or intramucosal adenocarcinoma (IMC) is effective, but carries the risk of leaving in place synchronous lesions and Barrett's epithelium with the potential for recurrent disease. We evaluated the safety and long-term efficacy of complete Barrett's eradication EMR (CBE-EMR) for the treatment of patients with HGD or IMC, independently of the presence of macroscopically visible lesions or surgical risk. PATIENTS AND METHODS: 26 consecutive patients with BE and HGD or IMC underwent CBE-EMRs, which were performed with the endoscopic cap suction method and/or a 2.3-mm monofilament mucosectomy snare. Endoscopic follow up after completion of resection was carried out to assess the rate of residual or recurrent BE with or without HGD or IMC. RESULTS: 24 patients completed the study. They underwent a total of 44 EMR sessions with a median of 3 pieces (range 1-8) removed per session. Two patients with immediate bleeding were successfully managed endoscopically. Three patients developed an early esophageal stricture that was completely resolved with a single endoscopic dilation. After a median follow-up of 28 months (range 15-51 months), persistent endoscopic and histologic eradication of BE was demonstrated in 21 patients (87.5 %). In two patients, Barrett's epithelium was detected beneath the neosquamous epithelium 3 months after completion of the resection. In the remaining patient, IMC was found in a nodule seen and removed by EMR at 12-month surveillance endoscopy. CONCLUSIONS: CBE-EMR is a safe and highly effective long-term treatment that should be offered to all patients with Barrett's esophagus with HGD and IMC.

TP53 and gastric carcinoma: a review.

In this article, we survey the major p53 (TP53) alterations identified in gastric carcinomas and their precursors. These include p53 expression, mutations, and loss of heterozygosity (LOH). Not only are the various abnormalities summarized, but in addition there is a survey of the literature with respect to the impact of these changes on patient prognosis and treatment response. The majority of published studies involve the immunohistochemical detection of the protein. These use different antibodies, different detection techniques, and different methods of interpretation. Therefore not surprisingly, the results of many of the studies are contradictory with one another. Overall, however, it appears that p53 alterations occur early in the development of gastric carcinoma, being present even in the nonneoplastic mucosa and they increase in frequency as one progresses along the pathway of gastric carcinoma development. p53 immunoreactivity is seen in 17%-90.7% of invasive gastric carcinomas. p53 alterations occur much more commonly in proximal lesions than in distal ones, suggesting that the molecular events leading to the development of gastric carcinoma may be very different in proximal vs. distal tumors. p53 mutations occur in 0%-77% of gastric carcinomas. The mutations are distributed widely across the gene from exons 4-11 with hot spots of mutation at codons 175, 248, 273, 282, 245, and 213. G:C>A:T transitions at CpG sites are the commonest type of mutation. At least 60% of carcinomas with mutations also exhibit p53 LOH.

A unique basal pattern of p53 expression in ulcerative colitis is associated with mutation in the p53 gene.

AIMS: The p53 protein is implicated in the control of cell proliferation, differentiation, and death. As part of a study characterizing p53 alterations in colonic mucosa of patients with ulcerative colitis, we identified a unique pattern of basal p53 immunoreactivity. METHODS AND RESULTS: Tissue samples (n=180) from 42 ulcerative colitis patients were evaluated for p53 alterations by immunohistochemistry, loss of heterozygosity analysis, polymerase chain reaction-single-strand conformation polymorphism and direct sequencing. In addition, the expression of the p53- associated proteins p21waf1/cip1 and MDM2 was evaluated immunohistochemically. Three basic patterns of p53 immunoreactivity were observed: (i) isolated immunoreactive cells in the crypt bases; (ii) strongly positive cells confined to the basal half of the glands; and (iii) diffusely staining cells. The basal staining pattern was observed in both non-neoplastic tissues and in some areas of dysplasia, and was associated with normal expression of p21waf1/cip1 in all cases, and with p53 mutation in seven of 11 cases. CONCLUSIONS: The basal pattern of p53 expression is associated with mutation in the p53 gene, and appears to be an early change in a subgroup of ulcerative colitis patients. The significance of this pattern of immunoreactivity and the mechanism by which it develops are discussed.

Heterotopic ovarian splenoma: report of a first case.

We present a case of ovarian splenoma, a form of heterotopic splenic hamartoma consisting of red pulp tissue. The hamartoma was located in ovarian stroma in an otherwise normal ovary. The histology showed interanastomosing vascular channels of splenic sinusoidal red pulp lined by cells that were immunoreactive for antibodies to von Willebrand antigen and CD8, findings consistent with splenic lining cells. The sinuses were lined by cuboidal to flattened cells with ovoid and grooved bland-looking nuclei. Ultrastructurally, the tumor cells showed Weibel-Palade bodies and lysosomes. To our knowledge, this is the first case of splenic tissue arising in an ovary, and it underlines the trend noted in the literature that splenic hamartoma,although a rare entity, can arise in many retroperitoneal organs, including the ovary.

Expression of survivin, YB-1, and KI-67 in sporadic adenomas and dysplasia-associated lesions or masses in ulcerative colitis.

Sporadic adenomas are said to exhibit an orderly growth pattern with a reversal of proliferative and apoptotic cell distribution as compared with normal colonic crypts. Dysplastic polyps of patients with ulcerative colitis (UC) may represent dysplasia-associated lesions or masses (DALM) with a high associated cancer risk, or, alternatively, may represent sporadic adenomas. Histologic criteria to differentiate between sporadic adenomas and DALM have not focused on the balance between cell renewal and cell loss. The expression of the novel anti-apoptosis gene product, survivin, and the proliferation markers, Ki-67 and Y-box binding protein (YB-1), were investigated by immunohistochemical localization in sporadic adenomas and DALM lesions of patients with UC. In adenomas, KI-67 was expressed preponderantly at the luminal aspect of the polyp, whereas its expression was diffuse in DALM. Survivin was detected diffusely in both adenomas and DALM. YB-1 showed positive staining in the deep aspect of adenomatous glands but only to a minor degree at the surface, whereas both deep and diffuse expression patterns of YB-1 were seen in DALM. The authors conclude that DALM and sporadic adenomas exhibit different patterns of cellular proliferation and that molecular markers of cell proliferation, Ki-67 and YB-1, may be useful to distinguish sporadic adenomas from DALM. However, the similar expression of survivin suggests that the underlying mechanisms that regulate apoptotic cell death are uniform in these lesions.

Glut-1 expression in dysplastic and regenerative lesions of the colon.

Monosaccaride transporter proteins are responsible for transmembrane transport of monosaccarides into cells. Glucose transporter protein 1 (Glut-1) is most prevalent in the cell membranes of erythrocytes and facilitates transport of glucose in tissues with barrier functions, i.e. blood brain barrier. Expression of Glut-1 in malignant tumors is increased due to increased metabolic need of the proliferating cell populations. In colorectal adenomas and carcinomas, membranous expression of Glut-1 has been associated with higher grade of tumors and decreased survival time. We studied the expression of Glut-1 in dysplastic proliferations of the colon which included sporadic adenomas and dysplasia associated lesions (DALM) in patients with ulcerative colitis and reactive/regenerative proliferations of the colon, including non-dysplastic chronic colitis, acute colitis and ischemia. Two patterns of Glut-1 expression were detected. Most adenomas and DALMs showed at least focal membranous expression of Glut-1. In addition a second staining pattern was recognized which consisted of prominent supranuclear dots. This pattern of staining was not only seen in adenomas and DALM but also in non-dysplastic areas immediately surrounding sporadic adenomas, in regenerative chronic colitis and in areas surrounding acute inflammation. Areas away from dysplasia did not show any positive staining for Glut-1. We conclude that two distinct patterns of Glut-1 expression may be found in colonic epithelial proliferation: membranous staining, associated with dysplasia, and, heretofore not described, supranuclear staining which may be related to Glut-1 expression secondary to expression of specific growth factors and not necessarily related to dysplasia.

HPV subtype analysis in lower genital tract neoplasms of female renal transplant recipients.

OBJECTIVE: Immunocompromised patients, such as female renal transplant recipients, have an increased incidence of neoplasms involving the lower genital tract (i.e., cervix, vagina, vulva). The relationship between lower genital tract neoplasms and human papillomavirus (HPV) infection has been established and high-risk oncogenic subtypes have been identified (HPV 16, 18, 45, and 56). The purpose of this study is to evaluate HPV subtypes present in lower genital tract neoplasms of post renal transplant women and compare HPV subtypes found in these patients with immunocompetent patients having similar neoplasms and normal immunocompetent controls. METHODS: Twenty specimens from lower genital tract neoplasms of 16 renal transplant patients, 13 specimens from 13 immunocompetent patients with similar histology, and 13 patients with normal lower genital tract histology were analyzed for the presence of HPV using polymerase chain reaction. HPV primers including the L1 (late) region consensus primers and primers specific for the HPV E6 (early) region for subtypes 6, 11, 16, and 18 were amplified with DNA from the above patient samples. RESULTS: Overall, HPV was detected in 21/46 specimens tested. Thirteen of the HPV-positive specimens were from transplant patients, and 8 were from immunocompetent patients (5 immunocompetent with disease and 3 normal patients). This difference in the total number of HPV-positive cases was statistically significant between the transplant and immunocompetent group (P = 0.02). Although no difference in HPV 6 and/or 11 was detected between the two groups, HPV subtypes 16 and/or 18 approached statistical significant difference (P = 0.06). CONCLUSIONS: High-risk oncogenic HPV subtypes 16 and/or 18 were found at a higher rate in transplant patients compared with their immunocompetent counterparts. The combination of immunocompromise and increased HPV 16 and/or 18 positivity may place these patients at increased risk for aggressive lower genital tract neoplastic progression.

Genetic alterations in chronic ulcerative colitis-associated adenoma-like DALMs are similar to non-colitic sporadic adenomas.

Recent molecular studies have shown that there are differences in the prevalence and timing of certain molecular events between chronic ulcerative colitis (CUC)-associated dysplastic lesions and non-CUC-related sporadic adenomas. However, little is known regarding the molecular features of a specific subtype of CUC-related dysplasia-associated lesion or mass (DALM) that clinically, endoscopically, and pathologically resemble sporadic adenomas, and whether these lesions can be separated from non-CUC-related sporadic adenomas on the basis of their molecular genotype. Therefore, the purpose of this study was to evaluate loss of heterozygosity (LOH) of 3p, APC, and p16 in a specific group of CUC-associated "adenoma-like" DALMs and to compare the results of this tumor with those in a well-defined group of CUC-associated non-adenoma-like DALMs and non-CUC-associated sporadic adenomas. Polypectomy or resection specimens from 21 CUC patients with an adenoma-like DALM, 8 CUC patients with at least one nonadenoma-like DALM (12 lesions in total), and 23 non-CUC patients with a sporadic adenoma were evaluated for LOH of 3p, APC, and p16 by PCR analysis. The results were compared among the three different study groups and correlated with the clinical features of the patients and the pathology of their tumors. Chronic ulcerative colitis-associated adenoma-like DALMs showed LOH of 3p in five of 18 (28%) cases. This value was not significantly different from the 5% of non-CUC sporadic adenomas (p = 0.14) that were positive. However, 50% of CUC-associated non-adenoma-like DALMs were positive for LOH of 3p, and this value was significantly higher (p = 0.01) than the other groups. The frequency of LOH of APC did not differ significantly between the three patient groups (33%, 33%, and 43% in the three groups, respectively). Similar to the 3p results, CUC-associated adenoma-like DALMs and non-CUC-associated sporadic adenomas showed a similar low frequency of positivity for LOH of p16 (5% and 4%, respectively) in comparison to 56% of CUC-associated non-adenoma-like DALMs (p = 0.003). For all markers, no significant differences were detected in the CUC-associated adenoma-like DALM group between lesions that occurred within colitis compared with those that occurred in areas not involved by colitis. Chronic ulcerative colitis-associated non-adenoma-like DALMs have a different molecular genotype than CUC-related adenoma-like DALMs and non-CUC sporadic adenomas. Our data also suggests that the latter two groups of neoplasms may in fact represent a similar, if not identical, pathogenetic entity.

Alterations in exon 4 of the p53 gene in gastric carcinoma.

BACKGROUND & AIMS: Our long-term goal was to evaluate the role of p53 in the prognosis of gastric cancer. We previously showed a discrepancy between p53 expression and the presence of mutations when only exons 5-9 were examined. We then evaluated exon 4. METHODS: DNA was sequenced from 217 gastric cancers to detect exon 4 alterations. Codon 72 was examined by restriction enzyme digestion. RESULTS: Mutations were present in 3.2% of tumors. In addition, 2 polymorphic sites were found at codons 36 and 72. Polymorphisms at codon 36 were only found in 2 patients. In contrast, the codon 72 polymorphism was very frequent. The genotype frequency was arg/arg (54%), arg/pro (33%), and pro/pro (14%). The genotype of the polymorphic site varied with race (P = 0.001): 64% of whites had the arg/arg genotype, compared with 24% of blacks. The difference in genotype by site, sex, or histological tumor type was not statistically significant (P = 0.067). CONCLUSIONS: There are several exon 4 alterations in gastric cancers. These include the rare mutations and the very rare codon 36 polymorphism. The most common change is the codon 72 polymorphism, the genotype of which differs significantly with race. The more common arg/arg genotype in whites may explain why whites are more prone to develop cardiac cancer, whereas the more common proline allele in blacks may explain why they are more prone to develop antral cancers. Further studies are required to determine whether the codon 72 polymorphism affects patient predisposition to gastric cancer.

Microsatellite instability and K-ras mutations in patients with ulcerative colitis.

Patients with inflammatory bowel disease (IBD), particularly ulcerative colitis (UC), have an increased incidence of colorectal carcinoma. The underlying mechanism is unknown, but we postulated that microsatellite instability (MSI) might predispose the colonic mucosa of UC patients to mutations, thereby increasing their cancer risk. We also sought to determine the frequency of K-ras mutations, to determine whether MSI predisposed to K-ras mutations and to compare the molecular phenotype of biopsy and resection specimens in the same patient. We also sought to determine whether molecular alterations found in biopsy specimens presaged their presence in subsequent resection specimens. Two hundred fifty-eight specimens from 52 patients were examined for K-ras mutations by direct sequencing. Seventy-one of the specimens were neoplastic. MSI was evaluated after polymerase chain reaction (PCR) amplification using primers directed at 8 microsatellite loci. Of the patients, 18.2% had K-ras mutations, and 30.8% had MSI in at least 1 locus. Of K-ras mutations, 81.8% were G to A substitutions involving the second nucleotide of codons 12 or 13. Only 0.7% of the samples showed a high level of MSI. No relationship existed between MSI and K-ras mutations, even in the 2 samples with high-level MSI. The numbers are small, but it appeared that MSI in biopsies failed to predict its presence in resection specimens. In contrast, K-ras mutations present in biopsy specimens tended to predict their presence in resections. K-ras mutations were found predominantly in neoplastic mucosae, whereas MSI was found predominantly in regenerative mucosae. The lack of any relationship between MSI and K-ras mutations suggests that MSI in the UC replicative mucosa does not predispose to colonic neoplasia via a K-ras-mediated pathway. This is probably related to the fact that the MSI is generally low-level MSI.

Distinction between dysplasia-associated lesion or mass (DALM) and adenoma in patients with ulcerative colitis.

Polyps with epithelial dysplasia in ulcerative colitis (UC) represent either dysplasia-associated lesions or masses (DALMs) or sporadic adenomas. DALMs are frequently associated with associated carcinoma and are an indication for colectomy. Removal of the polyp is treatment of choice for sporadic adenomas. Differentiating between these 2 lesions is not always easy. The goal of this study was to distinguish DALMs from adenomas in patients with UC on a genetic basis. We evaluated genetic alterations in DALMs and compared them with a previously published set of dysplastic polyps in patients with UC that were considered adenomas for the following reasons: (1) polyps were located outside of current active disease; (2) polyps had histological features of sporadic adenomas; and (3) patients displayed a uneventful follow-up after polypectomy (UC-adenomas). In addition, adenomas not associated with UC were studied. Genetic alterations on chromosome 3p were assessed for the markers D3S1766, D3S2409, and D3S2387. LOH with or without microsatellite instability was found in 70%, 37%, and 57% of cases of DALM, respectively. In contrast, UC-adenomas lesions exhibited genetic alterations in 8.3%, 11.7%, and 15.3% for the respective markers. Spontaneous adenomas exhibited genetic alterations in 10.5%, 7.1%, and 0% of cases, which were not significantly different from the UC-adenoma results. These results indicate that UC-adenomas are genetically and biologically similar to sporadic adenomas and that UC-adenomas may biologically represent sporadic adenomas, supporting on a genetic basis the criteria chosen to diagnose adenomas in UC. Genetic markers on chromosome 3p may be useful in the differential diagnosis between DALM and UC-adenomas.

Microsatellite instability is uncommon in intestinal mucosa of patients with Crohn's disease.

Patients with long-standing inflammatory bowel disease have an increased risk for colorectal carcinoma. Microsatellite instability occurs in colonic neoplasms and has been reported in colonic tissues from patients with ulcerative colitis. Patients with Crohn's disease also have an increased risk for colorectal cancer, although it is lower than that associated with ulcerative colitis. This study was designed to determine whether microsatellite instability occurs in Crohn's disease, and whether it occurs with similar frequency to that observed in ulcerative colitis. In all, 177 tissue samples from 33 patients with Crohn's disease were evaluated for microsatellite alterations. Microsatellite instability occurred in five different tissue samples from one of 33 Crohn's disease patients. Four of the five tissue samples showed microsatellite instability at more than one locus. We conclude that microsatellite instability is less common in Crohn's disease than ulcerative colitis and may reflect differences in cancer risk between these two forms of inflammatory bowel disease.

PRK, a cell cycle gene localized to 8p21, is downregulated in head and neck cancer.

The human PRK gene encodes a protein serine/threonine kinase of the polo family and plays an essential role in regulating meiosis and mitosis. We have previously shown that PRK expression is downregulated in a significant fraction of lung carcinomas. Our current studies reveal that PRK mRNA expression is downregulated in a majority (26 out of 35 patients) of primary head and neck squamous-cell carcinomas (HNSCC) compared with adjacent uninvolved tissues from the same patients, regardless of stage. In addition, PRK transcripts were undetectable in one of the two HNSCC cell lines analyzed. Ectopic expression of PRK, but not a PRK deletion construct, in transformed A549 fibroblast cells suppresses their proliferation. Furthermore, fluorescence in situ hybridization analyses show that the PRK gene localizes to chromosome band 8p21, a region that exhibits a high frequency of loss of heterozygosity in a variety of human cancers, including head and neck cancers, and that is proposed to contain two putative tumor suppressor genes. Considering that PRK plays an important role in the regulation of the G2/M transition and cell cycle progression, our current studies suggest that deregulated expression of PRK may contribute to tumor development. Genes Chromosomes Cancer 27:332-336, 2000.

Esophageal squamous cell carcinomas arising in patients from a high-risk area of North China lack an association with Epstein-Barr virus.

The aim of this study was to determine whether EBV associates with esophageal squamous cell carcinoma (ESCC), the most common malignancy in some parts of northern China, because these tumors frequently have an intense lymphocyte infiltrate. Fifty-one paraffin-embedded samples of ESCC from a high-risk area of North China were studied. The tumors included 9 well-differentiated, 31 moderately differentiated, and 11 poorly differentiated tumors. The cancer tissues and their nonmalignant adjacent mucosa (16 dysplastic and 42 normal) were evaluated by in situ hybridization using an antisense EBV-encoded RNA-1 probe and PCR amplification for EBV BamHI W fragment. In all cases, EBV was negative by both in situ hybridization and PCR. Our study suggests that EBV does not play a role in the carcinogenesis of ESCC in the geographic region.

The relation of p53 gene mutations to gastric cancer subsite and phenotype.

OBJECTIVES: We investigated p53 gene mutations in advanced gastric cancers by direct DNA sequencing, in order to determine the frequency of mutations in gastric cancers having different epidemiological backgrounds, tumors of the cardia were compared with those arising in the antrum or corpus. Intestinal type cancers were compared with diffuse or other histologic types. We have chosen to assess the frequency of mutations solely based on DNA sequencing. METHODS: Paraffin embedded tissues from 100 gastric cancers were evaluated. The mutational status of the p53 gene in exons 5 through 9 were determined by direct sequencing of PCR products. RESULTS: Mutations in exons 5, 6, 7 and 8 were found in 35 of 100(35%)stomach cancers. One tumor had mutations in both exons 5 and 8. No mutations were detected in exon 9. p53 gene mutations were significantly more frequent in cancers of the cardia (19/35; 54%) than the antrum and corpus (16/65 (25%)) (p < or = 0.005). p53 mutations were more frequent in intestinal type cancers (28/67; 42%) than diffuse cancers or other histologic types of cancer (7/33; 21%), but the difference was not statistically significant. CONCLUSIONS: Cancers of the cardia more frequently contain p53 mutations than do antral and corpus cancers, suggesting that cancers in the proximal and distal stomach evolve through different molecular pathways.

Microsatellite instability is absent in liver and biliary mucosa of patients with primary sclerosing cholangitis.

Microsatellite instability occurs in the colonic mucosa of patients with inflammatory bowel disease and may predispose the mucosa to neoplastic transformation. It is unknown whether microsatellite instability also plays a role in the neoplastic risk associated with primary sclerosing cholangitis. We examined 134 tissue samples from 21 patients with sclerosing cholangitis for microsatellite instability at eight loci. All tissues were also stained immunohistochemically using an antibody to the proliferation marker Ki-67. Microsatellite instability did not occur in any samples from the intrahepatic or extrahepatic biliary system, although one patient demonstrated instability in the colon. Ki-67 indices ranged from 0 to 2.5 in nondysplastic biliary epithelium and from 1.5 to 29.4 in areas of dysplasia. The absence of microsatellite instability in sclerosing cholangitis suggests that the genetic basis of neoplastic progression in chronic inflammatory disease of the bile ducts differs from that of intestinal cancers arising in the setting of chronic inflammatory bowel disease and may relate to differences in the microenvironment in these two sites.

p53 immunoreactivity and single-strand conformational polymorphism analysis often fail to predict p53 mutational status.

The intent of this study was to investigate the ability of p53 expression and single-strand conformational polymorphism analysis (SSCP) to predict p53 mutational status in archival, paraffin-embedded tissues of gastric cancer. We evaluated paraffin-embedded tissues from 78 patients with advanced gastric cancer. The mutational status of the p53 gene (exons 5-9) was examined by SSCP analysis and by direct sequencing. These results were compared with p53 expression as assessed by immunohistochemical analysis (IHC). We graded p53 expression on a scale from 0 to 8 on the basis of both the intensity and the number of cells staining. Overall, we detected p53 immunoreactivity in 75.6% of the gastric cases; 19 (32.2%) of these cases scored from 1 to 4, and 40 (67.8%) cases scored from 5 to 8. p53 gene mutations were detected in 18 cases (23.1%) by SSCP and in 28 cases (36%) by direct sequencing. Thus, SSCP failed to detect 38% of the mutations found by sequencing. The majority of missed mutations involved exons 7 and 8. The concordance between IHC and SSCP was 37%, and the concordance between IHC and direct sequencing was 50%. Forty-five percent of cases positive by IHC failed to show mutations in exons 5 through 9. Five percent of cases negative by IHC (4 cases) contained mutations. One had a 1-base pair insertion; one had a mutation that resulted in a stop codon; the third had a mutation in exon 8; and the fourth had a mutation in both exons 5 and 8. Our findings indicate that p53 immunoreactivity correlates with the presence or absence of gene mutations in 50% of advanced gastric cancers when exons 5 through 9 are examined and that IHC cannot be reproducibly used as a marker of mutation in the most commonly mutated exons of the p53 gene. Furthermore, the sensitivity of SSCP for detecting mutations is only 62%. Thus, SSCP analysis cannot be used reliably to screen for p53 mutations.

A germline hMSH2 alteration is unrelated to colonic microsatellite instability in patients with ulcerative colitis.

Recently, a polymorphism in the hMSH2 DNA mismatch repair gene has been associated with the development of dysplasia in ulcerative colitis (UC) patients. This polymorphism is of interest because DNA mismatch repair defects result in alterations in microsatellite stability. The current study was designed to determine whether this hMSH2 polymorphism associates with the development of microsatellite instability and dysplasia in UC patients. The hMSH2 genotype of 96 UC patients was determined by direct DNA sequencing. In addition, we examined 363 samples of colonic mucosa from 93 of these UC patients for microsatellite mutation by polymerase chain reaction (PCR) at eight loci. Three cases had insufficient DNA for microsatellite instability studies. The hMSH2 polymorphism was identified in 13 of the 96 patients examined (13.5%). The polymorphism was observed in 7 of 46 patients with dysplasia (15.2%), and in 6 of 50 patients without dysplasia (12.0%). Microsatellite instability was identified in 35 tissue samples (25 regenerative, one indefinite for dysplasia, eight dysplasias, and one invasive carcinoma) from 26 patients. Two patients with microsatellite instability had the hMSH2 alteration. The 11 remaining patients had the hMSH2 polymorphism, but no evidence of microsatellite mutations with any of the markers tested. We were unable to confirm the previously reported findings that the specific germline hMSH2 alteration represents a marker for increased risk of dysplasia in patients with UC, nor is it responsible for the development of microsatellite instability in these patients.