High frequency of K-ras mutations in sporadic colorectal adenomas.

The frequency of activating mutations at codons 12 and 13 of the K-ras gene was investigated in 57 sporadic adenomas from 47 patients using the polymerase chain reaction and oligonucleotide hybridisation assay. Sixty eight per cent of the adenomas tested were positive for K-ras mutations. This high frequency, combined with the lack of a correlation between mutations and adenoma size, suggest that K-ras mutations occur earlier in the adenoma-carcinoma sequence than has previously been suggested. The high frequency observed in sporadic adenomas contrasts with the reported low frequency (18%) in adenomas from patients with familial adenomatous polyposis (FAP), suggesting a possible difference in the molecular genesis of FAP and non-FAP adenomas. Finally, it was found that adenomas from patients with a personal history of colorectal cancer were more likely to contain a K-ras mutation than those from patients with no such history. This is a new finding and worthy of further study.     

Somatic mutations in the RET proto-oncogene in sporadic medullary thyroid carcinomas

The frequency and prognostic relevance of RET proto-oncogene somatic mutations in sporadic medullary thyroid carcinoma (MTC) remain controversial. In order to study somatic mutations in the RET proto-oncogene in sporadic MTCs found in the Czech population and to correlate these mutations with clinical and pathological characteristics, we investigated 48 truly sporadic MTCs by sequencing classical risk exons 10, 11, 13, 14, 15 and 16. From the 48 tumors studied, 23 (48%) had somatic mutation in the RET proto-oncogene in exons 10, 11, 15 or 16. The classical somatic mutation Met918Thr in exon 16 was only found in 13 tumors (27%). In five cases, multiple somatic mutations and deletions were detected. A statistically significant correlation between the presence of somatic mutation with more advanced pathological TNM stages was observed. Other clinical and pathological characteristics did not show any statistical significant association with the presence or absence of somatic mutation.     

Somatic mutations in the RET proto-oncogene in sporadic medullary thyroid carcinoma

OBJECTIVE We have determined the frequency of specific mutations in the RET proto-oncogene in sporadic medullary thyroid carcinomas (MTCs) and correlated the presence or absence of a codon 918 mutation with the clinical characteristics of these tumours. DESIGN Thirty paraffin-embedded sporadic MTCs and two frozen MTCs were collected for analysis of specific mutations in the RET proto-oncogene in codons 609, 611, 618 and 620 (exon 10); 630 and 634 (exon 11); 768 (exon 13); 883 (exon 15) and 918 (exon 16). A novel primer was designed which introduced a restriction site for RsaI in the presence of the specific codon 918 mutation (ATG → ACG) in these tumour samples. A ‘clinical-genetic’ correlation was performed comparing the presence or absence of the codon 918 mutation with the following clinical characteristics: age at diagnosis, tumour size, presence or absence of metastases, MTC related morbidity, and base line calcitonin levels at diagnosis or most recent follow-up. PATIENTS Patients were classified as having sporadic MTC if there was no family history of C-cell hyperplasia, MTC, phaeochromocytoma or parathyroid disease. Retrospective review of patient records enabled complete clinical data to be obtained in 28 of 32 patients. MEASUREMENTS Base line calcitonin levels were measured by radioimmunoassay or calcitonin enzyme linked immunoassay. Cysteine codons in exons 10 and 11, specifically codons 609, 611, 618, 620, 630 and 634, were screened for the presence of mutations by sequence analysis. Specific mutations occurring at codons 768, 883 and 918 were screened for by restriction endonuclease digestion of PCR products. RESULTS The mutation at codon 918ATG → ACG was found in 21 of 32 (66%) MTCs and the mutation at codon 883GCT → TTT was found in one of 32 MTCs. Where possible, the presence of ‘germline-type’ mutations in codons 609, 611, 618, 620, 630 and 634 were excluded. Ten MTCs did not have a mutation in codons 768, 883 or 918 of the RET proto-oncogene. The presence or absence of the somatic mutation at codon 918 did not correlate with any of the above clinical characteristics. CONCLUSION Somatic mutations in the RET proto-oncogene occur frequently in sporadic MTCs.     

RET proto-oncogene mutations in thyroid carcinomas: clinical relevance

Different forms of RET mutations are found in papillary and medullary thyroid carcinomas. Rearrangements with other genes (RET/PTC oncogene) play a causative role in a significant proportion of papillary thyroid carcinomas. In this case, several factors influence the frequency and the type of RET/PTC, such as exposure to radiation, age and histological variant of the papillary tumor. On the other hand, the presence of the mutation does not seem to influence the biological behavior of the tumor or its response to conventional treatment modalities. In the setting of medullary thyroid cancer, germline RET point-mutations are implicated in the pathogenesis of virtually all hereditary forms and somatic point-mutations in nearly half of the sporadic forms. The clinical impact of this finding is that family members at-risk of hereditary MTC may be screened by genetic analysis, to distinguish those carrying or not-carrying the mutation. The last can be reassured on their status and relieved from further follow-up. Those with the mutation may be treated at a pre-clinical stage of the disease or even before the disease is started. The present review is focused on the clinical implication of RET gene mutations in thyroid cancer patients.     

Frequent mutations of beta-catenin gene in sporadic secreting adrenocortical adenomas

Objective Molecular alterations remain largely unknown in most sporadic adrenocortical tumours and hyperplasias. In our previous work, we demonstrated the differential expression of several Wnt/β‐catenin signalling‐related genes implicated in ACTH‐independent macronodular adrenal hyperplasias (AIMAH). To better understand the role of Wnt/β‐catenin signalling in adrenocortical tumours, we performed mutational analysis of the β‐catenin gene. Methods We studied 53 human adrenocortical samples (33 adenomas, 4 carcinomas, 13 AIMAH, 3 ACTH‐dependent adrenal hyperplasias) and the human adrenocortical cancer cell line NCI‐H295R. All samples were screened for somatic mutations in exons 3 and 5 of the β‐catenin gene. Eleven and six samples were analysed for β‐catenin protein expression by Western blotting and immunohistochemistry, respectively. Results No mutations were detected in adrenocortical carcinomas, AIMAH and ACTH‐dependent hyperplasias. Genetic alterations were found in 5 (15%) out of 33 adenomas: three cortisol‐secreting adenomas, one aldosterone‐secreting adenoma and one nonfunctional adenoma. Two‐point mutations occurred at serine residues of codons 37 and 45 (S37C and S45F). The remaining three tumours contained deletions of 6, 55 and 271 bp. H295R cells carry an activating S45P mutation. Western blot analysis of samples with 55‐ and 271‐bp deletions showed an additional shorter and more intense band representing an accumulation of the mutated form of β‐catenin protein. In addition, cytoplasmic and/or nuclear accumulation of β‐catenin was observed in mutated adenomas by immunohistochemistry. Conclusions Activating mutations of exon 3 of the β‐catenin gene are frequent in adrenocortical adenomas, and further characterization of the Wnt/β‐catenin signalling pathway should lead to a better understanding of adrenal tumourigenesis.     

Ret proto-oncogene mutations in apparently sporadic Turkish medullary thyroid carcinoma patients: Turkmen study

OBJECTIVE: Medullary thyroid carcinoma (MTC) frequently occurs in a sporadic form, but a substantial number of cases are hereditary and appear as part of the multiple endocrine neoplasia type 2 (MEN2) syndromes. Germline mutations in ret proto-oncogene have been shown to be the underlying cause of MEN2 syndromes. DESIGN: We carried out a multi-center study that aimed to perform mutational analysis of so called sporadic MTC patients. METHODS: Fifty-six MTC patients verified by histopathologic examination were subjected to genetic analysis. Exon 10, 11, 13, 14, 15 and 16 of the ret gene were analyzed by DNA sequencing and restriction enzyme digestion method. RESULTS: Among 56 apparently sporadic MTC patients, we identified 6 (10.7%) ret germline mutation carriers. Three individuals carried mutations at codon 634 in exon 11, one at codon 618 in exon 10, and two at codon 804 in exon 14. Identification of the predisposition gene mutation has allowed DNA-based strategy for direct mutation detection in patients with apparently sporadic MTCs. A substantial number of patients with apparently sporadic MTC carried germline mutations and 50% of their first degree relatives are expected to have or to develop MTC and/or other endocrine tumors. CONCLUSIONS: These results indicate the importance of careful genetic surveillance of any patient with apparently sporadic MTCs.     

Deficiency of Adenomatous Polyposis Coli protein in sporadic colorectal adenomas and its associations with clinical phenotype and histology

AIM: To evaluate the frequency of the loss of the Ad-enomatous Polyposis Coli (APC) protein and to compare the APC status with the characteristics of colorectal adenomas. METHODS: Immunohistochemical analysis of the APC protein was performed on 118 adenomas and the results were compared with parameters of malignant potential, location of adenomas, macroscopic appearance and age of the patients. RESULTS: A complete loss of the APC protein was found in 28 (24%) adenomas, while 90 (76%) were APC positive. The mean size of adenomas was 13.5±14.2 mm (95% CI 10.5-16.5) in APC-positive, and 13.8±15.5 mm (95% CI 7.8-19.8) in APC-negative adenomas (P = 0.364). Statistical analysis revealed no difference between APC-positive and negative adenomas as to the histological type (P = 0.327) and grade of dysplasia (P =0.494). We found that even advanced adenomas did not differ in their APC status from the non-advanced tumors (P = 0.414). Finally, no difference was found when the location (P = 0.157), macroscopic appearance (P = 0.571) and age of patients (P = 0.438) were analysed and compared between both APC positive and negative adenomas. CONCLUSION: Most adenomas expressed full-length APC protein, suggesting that protein expression is not a reliable marker for assessment of APC gene mutation. Complete loss of APC protein did not influence morphology, location, or appearance of adenomas, nor was it affected by the patient's age.     

Genetic and protein markers related to in situ growth and multiplicity in small sporadic colorectal adenomas

BACKGROUND: Some early genetic events in the development of colorectal adenomas are known, but their relationship to in vivo growth characteristics is uncertain. This study compared in situ size changes and other clinicopathological variables with selected genetic and protein markers. METHODS: 56 adenomas (< or = 10 mm) from 39 patients were analysed for APC, CTNNB1 and K-ras mutations, allelic imbalance on 1p and 18q, microsatellite instability and immunohistochemical expression of HLA-DR, BAX, BCL-2 and Ki-67. For 42 of the adenomas, in situ growth was measured over 3 years. The total number of polyps in each patient was recorded. RESULTS: K-ras was mutated in 8/56 adenomas. None of the regressing adenomas revealed such mutations, compared to 20% in those that maintained or increased their size. Multivariate linear regression analysis showed that tumour growth was higher in females compared to males, and was even higher in the presence of a K-ras mutation. APC mutations were found in 37/56 adenomas. CTNNB1 mutations were found in 2/19 adenomas without APC mutation. Deletions of 1p were found in 12/56 adenomas and, seemingly, most frequent in patients with few tumours. The most frequently expressed protein was BAX (33/41), but neither this nor the other proteins showed associations with an in situ growth pattern. CONCLUSION: The multivariate linear regression model showed that patient gender and the presence of K-ras mutation had significant effects on tumour growth. The lack of the proliferative stimulus resulting from a K-ras mutation may contribute to the process of adenoma regression.     

Three randomized long-term surveillance trials in patients with sporadic colorectal adenomas

Objective. Guidelines for surveillance of patients with previous sporadic colorectal adenomas are based on retrospective long-term follow-up and prospective short-term studies. The aim of the present studies was to compare relative risk (RR) of new neoplasia as well as complications, using different intervals between examinations in long-term surveillance. Material and methods. Between l98l and l991, patients with pedunculated and small, flat and sessile adenomas were allocated at random to a 24 months (group A) or 48 months (group B) interval between surveillance colonoscopies (n=671). Patients with flat and sessile adenomas greater than 5 mm in diameter were randomized to intervals of 6 months (group C) or 12 months (group D) between l981 and 1987 (n=73). Finally, 200 patients with similar adenomas as in groups C and D were randomized to 12 months (group E) or 24 months (group F) from 1988 to 2000. The study ended in 2002. Results. Advanced adenomas were equally as frequent in group A and group B, but colorectal cancer (CRC) was found significantly more often in group B (RR?=?6.2 (1.0–117.4)). Severe complications occurred in 4 patients in group A and 2 patients in group B. Advanced new adenomas tended to be more frequent in group D than in C (p=0.08), but only one CRC was detected and this was in group C. There was no significant difference in the risk of CRC between the E and F groups, but the two cancers in group E were both early stage, in contrast to those in group F. Severe complications were seen in one patient in group E and also in group F. Conclusions. The results suggest that 2-year intervals should be used between colonoscopies in patients with previous pedunculated adenomas and small, flat and sessile adenomas, whereas larger, flat and sessile adenomas may need intervals of 1 year.     

舒林酸治疗散发性结直肠腺瘤的临床研究

目的观察舒林酸对散发性结直肠腺瘤的疗效.方法 36例经结肠镜和组织学诊断的散发性结直肠腺瘤病人,随机分为二组,治疗组口服舒林酸400 mg/d,对照组口服安慰剂2片/d,疗程均为4个月.观察治疗前和治疗4个月时腺瘤数目、最大直径、形态及腺瘤异型增生分级变化.结果治疗组和对照组各16例完成试验.治疗前、后比较,治疗组59个腺瘤直径分别为(3.6±2.2)和(2.4±1.5)mm,治疗后腺瘤直径较治疗前明显缩小,差异有非常显著性(P＜0.001);腺瘤形态较治疗前变化明显,出现扁平隆起和红斑.异型增生级别明显降低,差异有非常显著性(P＜0.001);对照组30个腺瘤直径分别为(4.6±2.5)和(3.     

Three randomized long-term surveillance trials in patients with sporadic colorectal adenomas

OBJECTIVE: Guidelines for surveillance of patients with previous sporadic colorectal adenomas are based on retrospective long-term follow-up and prospective short-term studies. The aim of the present studies was to compare relative risk (RR) of new neoplasia as well as complications, using different intervals between examinations in long-term surveillance. MATERIAL AND METHODS: Between l98l and l991, patients with pedunculated and small, flat and sessile adenomas were allocated at random to a 24 months (group A) or 48 months (group B) interval between surveillance colonoscopies (n=671). Patients with flat and sessile adenomas greater than 5 mm in diameter were randomized to intervals of 6 months (group C) or 12 months (group D) between l981 and 1987 (n=73). Finally, 200 patients with similar adenomas as in groups C and D were randomized to 12 months (group E) or 24 months (group F) from 1988 to 2000. The study ended in 2002. RESULTS: Advanced adenomas were equally as frequent in group A and group B, but colorectal cancer (CRC) was found significantly more often in group B (RR = 6.2 (1.0-117.4)). Severe complications occurred in 4 patients in group A and 2 patients in group B. Advanced new adenomas tended to be more frequent in group D than in C (p=0.08), but only one CRC was detected and this was in group C. There was no significant difference in the risk of CRC between the E and F groups, but the two cancers in group E were both early stage, in contrast to those in group F. Severe complications were seen in one patient in group E and also in group F. CONCLUSIONS: The results suggest that 2-year intervals should be used between colonoscopies in patients with previous pedunculated adenomas and small, flat and sessile adenomas, whereas larger, flat and sessile adenomas may need intervals of 1 year.     

Clinical study of sulindac in the treatment of sporadic colorectal adenomas

OBJECTIVE: To investigate the efficacy of sulindac in the treatment of sporadic colorectal adenomas. METHODS: Thirty‐six patients who were diagnosed colonoscopically and pathologically with sporadic colorectal adenomas were randomly divided into two groups. The sulindac group took 400 mg sulindac daily for 4 months and the patients in the control group were given a placebo treatment for the same period of time. All patients underwent pancolono­scopy at the end of the study. The number, size, morphology, and degree of atypia of the adenomas were compared before and after treatment. RESULTS: Four patients were dropped from the study (three in the sulindac group, one in the control group). Sixteen patients in each group completed the trial. In the sulindac group, the average diameter of 59 adenomas before treatment was 3.6 ± 2.2 mm, which was significantly larger than that after treatment (2.4 ± 1.5 mm; P < 0.001). The morphology of adenomas also changed significantly. The degree of atypia of adenomas also decreased after treatment (P < 0.001). No severe side‐effects of sulindac were found during the study. In the control group, the average diameters of adenomas before and after treatment were 4.6 ± 2.5 mm and 3.7 ± 2.2 mm, respectively. There was no significant difference between the average diameters of the adenomas before or after treatment (P > 0.05), nor was there any change in the morphology or the degree of atypia of the adenomas. CONCLUSIONS: Sulindac is effective in reducing the size and degree of atypia of adenomas. This trial demonstrated that sulindac has a regressive effect on sporadic colorectal adenomas. However, its long‐term effect remains to be tested.     

Microsatellite instability in colorectal adenomas: relevance and clinical importance

A number of investigations have recently been published on the role of microsatellite instability (MSI) in the process of colorectal carcinogenesis. The data concerning colorectal adenomas are difficult to compare (due to differences in the tumor collection, selection and number of analyzed loci, definition of high and low instability and histological types), and this review therefore examines the significance of the results of these publications. We then discuss the extent to which MSI and its effects on the integrity of the genome are early or late events in the malignant transformation, and which clinicopathological features are presented by MSI-positive adenomas. Finally, we consider the clinical importance of microsatellite status for the diagnosis of hereditary nonpolyposis colorectal cancer and the possibility of preventing adenomas and carcinomas by nonsteroidal anti-inflammatory drugs.     

Prosthetic synovitis: clinical and histologic characteristics

Our study of 20 patients correlates the clinical picture of each patient with the pathology of synovial tissue obtained at the time of revision arthroplasty. While 12 patients had rheumatoid arthritis and 8 had osteoarthritis, the histopathology was identical. Additionally, while 15 of the 20 had an etiology for the revision, 5 patients were revised for pain alone with no explanation other than the synovitis. The characteristic histologic findings included lining cell hyperplasia, vascular congestion, giant cells, brightly birefringent high density polyethylene chards and cysts that represented ghosts of methyl methacrylate debris.     

The relationship between cyclooxygenase-2 expression and characteristics of malignant transformation in human colorectal adenomas

BACKGROUND AND AIMS: Cyclooxygenase 2 (COX-2) is a target of aspirin and other non-steroidal anti-inflammatory drugs and is implicated in the pathogenesis of colorectal cancer. The objective of this study was to evaluate the extent of COX-2 in pre-malignant colorectal polyps and to assess the relationship between COX-2 and the level of dysplasia in these lesions. METHODS: Whole polypectomy specimens were retrieved from 123 patients by endoscopic or surgical resection. Following formalin fixation and paraffin embedding, the polyps were evaluated histologically for size, type and grade of dysplasia. The extent of COX-2 expression was measured by the avidin-biotin immunohistochemical technique using a monoclonal COX-2 antibody. The extent of COX-2 expression was graded according to percentage epithelial COX-2 expression. RESULTS: The polyps were of the following histological types: 10 hyperplastic, 35 tubular adenomas, 61 tubulovillous adenomas and 17 villous adenomas. Twenty showed mild dysplasia, 65 moderate dysplasia, and 28 focal or severe dysplasia (including eight with focal invasion). The average polyp size was 1.7 cm. Nine hyperplastic polyps were COX-2-negative and one was COX-2-positive. COX-2 expression was more extensive in larger polyps and in polyps with a higher villous component. There was a significant increase in the extent of COX-2 protein with increasing severity of dysplasia. Within a polyp, there was a focal corresponding increase in COX-2 expression within epithelium showing a higher grade of dysplasia. CONCLUSIONS: COX-2 expression is related directly to colorectal adenomatous polyp size, type and grade of dysplasia. This suggests that the role of COX-2 in colorectal cancer may be at an early stage in the adenoma-to-carcinoma sequence and supports the suggestion that inhibition of COX-2 may be useful chemoprevention for this disease.     

Overexpression of p53 protein and histologic grades of dysplasia in colorectal adenomas

PURPOSE: To clarify the relation between tumor-suppressor gene p53 expression and histologic grades of dysplasia in colorectal adenomas, we performed immunohistochemical analysis in a series of 59 colorectal polyps and 40 advanced carcinomas. METHODS: Adenomatous polyps were stained by hematoxylin and eosin and classified into mild, moderate, and severe dysplasia (intramucosal carcinoma), according to the World Health Organization's classification. RESULTS: p53 was positive in 7.1 percent (2/28) of mild, 29.4 percent (5/17) of moderate, and 62.5 percent (5/8) of severe dysplasia. In submucosal and advanced carcinomas, positivity rates were 75 percent (3/4) and 47.5 percent (19/40), respectively. Different staining patterns were found, according to grades of dysplasia. In the adenomas with mild or moderate dysplasia, a few focal crypts showed localized p53-positive staining. Adenomas with severe dysplasia had two different staining types. One was a focal staining type as shown in mild or moderate dysplasia; the other was a diffuse staining type, in which glands with mild or moderate dysplasia, surrounding severe dysplasia area, were also stained. Submucosal and advanced carcinomas showed a strong positive staining in cancer cells only. CONCLUSIONS: Overexpression of p53 protein in adenomas with mild or moderate dysplasia and existence of two types of expression in adenomas with severe dysplasia were observed. These facts suggested the possible existence of different pathways in the adenoma to carcinoma progression.     

AMACR is associated with advanced pathologic risk factors in sporadic colorectal adenomas

AIM: To analyze α-methylacyl CoA racemase (AMACR) expression in relation to various dysplasia phenotypes and clinicopathological parameters of sporadic colorectal adenomas.METHODS: Fifty-f ive cases of sporadic colorectal adenomas were categorized according to the Vienna classif ication for Gastrointestinal Neoplasia.These corresponded to a total of 98 different intra-lesion microscopic f ields that were further independently assigned a histological grade based on the old nomenclature (mild,moderate,severe ...     

CpG island methylation in sporadic colorectal cancers and its relationship to microsatellite instability

BACKGROUND & AIMS: Methylation of CpG islands is increasingly recognized as an important event in colorectal carcinogenesis. We evaluated the extent of CpG island methylation in 426 sporadic colorectal cancers to define its relationship to microsatellite instability and to describe its clinicopathologic and genetic features. METHODS: Fresh cancer tissue was obtained from 417 consecutive individuals undergoing curative surgery for sporadic colorectal cancer. Methylation of p16 and hMLH1 promoters was determined by methylation-specific polymerase chain reaction (PCR), whereas methylation at MINT 1, 2, 12, and 31 loci was assessed by bisulfite PCR. Microsatellite instability and K-ras and p53 status were determined using microsatellite PCR, restriction enzyme-mediated PCR, and immunohistochemistry, respectively. RESULTS: Individual loci were commonly methylated, but locus-specific phenotypic changes were not seen. CpG island methylation was associated with right-sided location, female sex, and older age, as well as high tumor grade, mucinous type, wild-type P53, microsatellite instability, and K-ras mutations. More than half of tumors showing CpG island methylation were microsatellite stable. Compared with microsatellite unstable cancers, they were more commonly left-sided, had fewer intraepithelial lymphocytes, presented later, and had a worse outcome. CONCLUSIONS: Colorectal cancers with CpG island methylation have distinct clinicopathologic features and in some cases lead to sporadic microsatellite unstable cancers.     

Increased prevalence of colorectal neoplasia in korean patients with sporadic duodenal adenomas: a case-control study

Background/Aims

Recent data from Western populations have suggested that patients with sporadic duodenal adenomas are at a higher risk for the development of colorectal neoplasia. In this study, we compared the frequency of colorectal neoplasia in patients with sporadic duodenal adenomas to healthy control subjects.

Methods

This retrospective case-control study used the databases of 3 teaching hospitals in Gyeonggi-do Province, South Korea. The colonoscopy findings of patients with sporadic duodenal adenomas were compared with those of age- and gender-matched healthy individuals who had undergone gastroduodenoscopies and colonoscopies during general screening examinations.

Results

Between 2001 and 2008, 45 patients were diagnosed endoscopically with sporadic duodenal adenomas; 26 (58%) of these patients received colonoscopies. Colorectal neoplasia (42% vs 21%; odds ratio [OR], 2.8; 95% confidence interval [CI], 1.1 to 7.4) and advanced colorectal adenoma (19% vs 3%; OR, 9.0; 95% CI, 1.6 to 50.0) were significantly more common in patients with sporadic duodenal adenomas than in healthy control subjects.

Conclusions

Compared with healthy individuals, patients with sporadic duodenal adenomas were at a significantly higher risk for developing colorectal neoplasia. Such at-risk patients should undergo routine screening colonoscopies.