Hyperplastic polyps of the colorectum-innocent or guilty?

From Mixed Hyperplastic/Adenomatous Polyp to Sessile Serrated Lesion: A Long and Winding Road for Long and Winding Crypts

CONTEXT.—

During the past 3 decades, numerous articles in the literature have offered terminology, diagnostic criteria, and consensus recommendations regarding the entity currently referred to by the World Health Organization as sessile serrated lesion. Given the many names and various, variably reproducible diagnostic criteria ascribed to sessile serrated lesion, confusion persists for many pathologists and gastroenterologists regarding the diagnosis. This distinction is important, as sessile serrated lesion can progress to malignancy, unlike its main differential diagnosis, hyperplastic polyp. Research studies have shed light on the characteristic architecture and morphology, immunohistochemical patterns, and molecular alterations of sessile serrated lesion, and multiple consensus meetings around the globe have developed their criteria and nomenclature, often clashing or mixing terms.

OBJECTIVE.—

To provide a narrative review from the entity's early description to our current understanding.

DATA SOURCES.—

The existing scientific and clinical literature, published texts, medical society recommendations, and specialty consensus guidelines.

CONCLUSIONS.—

The current World Health Organization criteria are a distillation of this scientific process, but terminology is still a point of contention worldwide.

High risk of colorectal polyps in men with non-alcoholic fatty liver disease: A systematic review and meta-analysis

BACKGROUND AND AIM

This meta-analysis aims to explore the risk of colorectal polyps among non-alcoholic fatty liver disease (NAFLD) patients.

METHODS

We searched PubMed, EMBASE, and Cochrane library databases using predefined search term to identify eligible studies (published up to 7 November 2019). Data from selected studies were extracted by using a standardized information collection form, and meta-analyses were performed using random-effects model. The statistical heterogeneity among studies (I² ), subgroup analyses, meta-regression analyses, and the possibility of publication bias were assessed.

RESULTS

Twenty observational (12 cross-sectional, two case-control, and six cohort) studies met the eligibility criteria, involving 142 387 asymptomatic adults. In cross-sectional/case-control studies, NAFLD was found to be associated with an increased risk of colorectal polyps (odds ratio [OR] = 1.34; 95% confidence interval [CI] = 1.23-1.47) (including unclassified colorectal polyps, hyperplastic polyps, adenomas, and cancers) with statistically significant heterogeneity (I²  = 67.8%; P < 0.001). NAFLD was also associated with a higher risk of incident colorectal polyps (hazard ratio = 1.60; 95% CI = 1.36-1.87) with low heterogeneity (I²  = 21.8%; P = 0.263) in longitudinal studies. The severity of NAFLD was associated with a higher risk of colorectal adenomas (OR = 1.57; 95% CI = 1.30-1.88), but not colorectal cancer (OR = 1.37; 95% CI = 0.92-2.03). The subgroup analysis according to gender showed that NAFLD was significantly associated with a higher risk of colorectal polyps in the male population without significant heterogeneity (OR = 1.47; 95% CI = 1.29-1.67, I²  = 0%), but not in the female population (OR = 0.88; 95% CI = 0.60-1.29, I²  = 34.2%).

CONCLUSIONS

NAFLD was associated with an increased risk of colorectal polyps. There was a significant difference of the relationship between genders, which suggested more precise screening colonoscopy recommendation in NAFLD patients according to gender.

Serrated polyps and their alternative pathway to the colorectal cancer: a systematic review

Colorectal cancer (CRC) is the third most frequently diagnosed cancer in the world. For a long time, only one pathway of colorectal carcinogenesis was known. In recent years, a new “alternative” pathway through serrated adenoma was described. Recent meta-analysis estimated these cancers as about 10% to 30% of all CRCs. Serrated polyps are the second most popular groups of polyps (after conventional adenomas) found during colonoscopy. Serrated polyps of the colon are clinically and molecularly diverse changes that have common feature as crypt luminal morphology characterized by glandular serration. Evidence suggests that subtypes of serrated polyps, particularly TSA and SSA/P, can lead to adenocarcinoma through the serrated pathway. Moreover, the data indicate that the SSA/P are the precursors of colorectal carcinoma by MSI and may be subject to rapid progression to malignancy. An important step to reduce the incidence of CRC initiated by the serrated pathway is to improve the detection of serrated polyps and to ensure their complete removal during endoscopy. Understanding of the so-called serrated carcinogenesis pathway is an important step forward in expanding possibilities in the prevention of CRC.

How does the serrated polyp pathway alter CRC screening and surveillance?

Screening and surveillance for colorectal cancer (CRC) reduces mortality through the detection of early-stage adenocarcinoma, and more importantly the detection and removal of premalignant polyps. While adenomas have historically been considered the most common and screening-relevant precursor lesions, there is accumulating evidence showing that the serrated pathway is an important contributor to CRC, and a disproportionate contributor to interval or postcolonoscopy CRC, particularly in the proximal colon. The serrated pathway is characterized by mutations in the BRAF gene, high levels of methylation of promoter CpG islands (CIMP-high), and the sessile serrated adenoma/polyp (SSA/P) is the most important precursor lesion. The study of serrated polyps has been complicated by evolving nomenclature, substantial variation among pathologists in the identification of SSA/Ps, high variability in endoscopic detection rates, and uncertainty regarding the relation to synchronous and metachronous colonic neoplasia. This paper presents an overview of the serrated polyp pathway and discusses its clinical implications including its impact on CRC screening.

Ulcerative colitis with inflammatory polyposis in a teenage boy: A case report

Ulcerative colitis in addition to inflammatory polyposis is common. The benign sequel of ulcerative colitis can sometimes mimic colorectal carcinoma. This report describes a rare case of inflammatory polyposis with hundreds of inflammatory polyps in ulcerative colitis which was not easy to distinguish from other polyposis syndromes. A 16-year-old Chinese male suffering from ulcerative colitis for 6 mo underwent colonoscopy, and hundreds of polyps were observed in the sigmoid, causing colonic stenosis. The polyps were restricted to the sigmoid. Although rectal inflammation was detected, no polyps were found in the rectum. A diagnosis of inflammatory polyposis and ulcerative colitis was made. The patient underwent total colectomy and ileal pouch anal anastomosis. The patient recovered well and was discharged on postoperative day 8. Endoscopic surveillance after surgery is crucial as ulcerative colitis with polyposis is a risk factor for colorectal cancer. Recognition of polyposis requires clinical, endoscopic and histopathologic correlation, and helps with chemoprophylaxis of colorectal cancer, as the drugs used postoperatively for colorectal cancer, ulcerative colitis and polyposis are different.

Phenotypic characterization and familial risk in hyperplastic polyposis syndrome

BACKGROUND. Hyperplastic polyposis syndrome (HPS) is a rare condition characterized by numerous hyperplastic polyps (HP) with a pancolonic distribution. Genetic and environmental factors, including smoking, may be responsible for phenotypic differences. OBJECTIVE. To characterize HPS patients' phenotype and to determine HPS risk and colorectal cancer (CRC) risk in the first-degree relatives (FDRs). PATIENTS AND METHODS. Eight HPS patients were followed at our Gastroenterology Department (2008-2012). The data included (1) macroscopic and histological analysis of polyps, (2) demographic information about patients and their families and (3) colonoscopy results of FDR that accepted a screening exam. RESULTS. Six of the eight index cases (ICs) had family history of CRC. Of the 24 FDRs screened, 5 were diagnosed with HPS. In our study, HPS and CRC prevalence in FDR was 625 and 9 times higher than the risk of the general population. Polyps over 10 mm were preferentially located in proximal colon (p < 0.001). Advanced polyps were larger (p < 0.001) than HP and more frequent in older patients (p = 0.0054). Nonsmokers had smaller polyps (p = 0.037) preferentially in the proximal colon (p = 0.04) and a lower age at HPS diagnosis. Patients with CRC family history manifest HPS at an earlier age and patients whose relatives had CRC before 50 years had larger polyps (p = 0.0475). Smokers with CRC family history had larger polyps than nonsmokers (p = 0.048). CONCLUSION. Despite the small sample, the results reflect the phenotypic heterogeneity of HPS as well as the increased family risk of HPS and CRC. This study points out that CRC family history and smoking influence HPS expression.

Serrated colon polyps as precursors to colorectal cancer

Identification of the serrated neoplasia pathway has improved our understanding of the pathogenesis of colorectal cancer (CRC). Insights include an increased recognition of the malignant potential of different types of serrated polyps such as sessile and traditional serrated adenomas. Sessile serrated adenomas share molecular features with colon tumors that have microsatellite instability and a methylator phenotype, indicating that these lesions are precursors that progress via the serrated neoplasia pathway. These data have important implications for clinical practice and CRC prevention, because hyperplastic polyps were previously regarded as having no malignant potential. There is also evidence that the serrated pathway contributes to interval or missed cancers. Endoscopic detection of serrated polyps is a challenge because they are often inconspicuous with indistinct margins and are frequently covered by adherent mucus. It is important for gastroenterologists to recognize the subtle endoscopic features of serrated polyps to facilitate their detection and removal, and thereby ensure a high-quality colonoscopic examination. Recognition of the role of serrated polyps in colon carcinogenesis has led to the inclusion of these lesions in postpolypectomy surveillance guidelines. However, an enhanced effort is needed to identify and completely remove serrated adenomas, with the goal of increasing the effectiveness of colonoscopy to reduce CRC incidence.

Differences in epidemiologic risk factors for colorectal adenomas and serrated polyps by lesion severity and anatomical site

Using a case-control design, we evaluated differences in risk factors for colorectal polyps according to histological type, anatomical site, and severity. Participants were enrollees in the Group Health Cooperative aged 20-79 years who underwent colonoscopy in Seattle, Washington, between 1998 and 2007 and comprised 628 adenoma cases, 594 serrated polyp cases, 247 cases with both types of polyps, and 1,037 polyp-free controls. Participants completed a structured interview, and polyps were evaluated via standardized pathology review. We used multivariable polytomous logistic regression to compare case groups with controls and with the other case groups. Factors for which the strength of the association varied significantly between adenomas and serrated polyps were sex (P < 0.001), use of estrogen-only postmenopausal hormone therapy (P = 0.01), and smoking status (P < 0.001). For lesion severity, prior endoscopy (P < 0.001) and age (P = 0.05) had significantly stronger associations with advanced adenomas than with nonadvanced adenomas; and higher education was positively correlated with sessile serrated polyps but not with other serrated polyps (P = 0.02). Statistically significant, site-specific associations were observed for current cigarette smoking (P = 0.05 among adenomas and P < 0.001 among serrated polyps), postmenopausal estrogen-only therapy (P = 0.01 among adenomas), and obesity (P = 0.01 among serrated polyps). These findings further illustrate the epidemiologic heterogeneity of colorectal neoplasia and may help elucidate carcinogenic mechanisms for distinct pathways.

Estimated mean sojourn time associated with hemoccult SENSA for detection of proximal and distal colorectal cancer

BACKGROUND

Sojourn time is the length of the preclinical screen-detectable phase, a period when a test can detect asymptomatic disease. Mean sojourn time (MST) is an important factor in determining appropriate screening intervals. Available estimates of MST for colorectal cancer (CRC) are imprecise and are associated with the older Hemoccult II test. This article presents MST estimates associated with the newer Hemoccult SENSA test and describes differences in MST by the location of cancer in the colorectum and age at the time of screening.

METHODS

MST was estimated from a cohort of 42,079 patients who underwent Hemoccult SENSA between January 1, 1997 and December 31, 2010. The precision of MST estimates was improved by incorporating information from a meta-analysis of the sensitivity of Hemoccult SENSA into the analytic model.

RESULTS

Estimated MST for cancers in the proximal and distal colorectum, with 95% credible intervals (CrI) in years, were: 3.86 (1.55-6.91) and 3.35 (2.11-4.93) among 45- to 54-year olds; 3.78 (2.18-5.77) and 2.24 (1.48-3.17) among 55- to 64-year olds; and 2.70 (1.41-4.31) and 2.10 (1.34-3.04) among 65- to 74-year olds.

CONCLUSIONS

MST associated with Hemoccult SENSA was longer for CRC in the proximal versus distal colon. We found no evidence that MST increases with age and some evidence that it may decrease.

IMPACT

These results add new information about the natural history of CRC and information about the performance of Hemoccult SENSA.

Colorectal polyp type and the association with charred meat consumption, smoking, and microsomal epoxide hydrolase polymorphisms

We determined the association between charred meat consumption, cigarette smoking, microsomal epoxide hydrolase (mEH) polymorphisms (rs1051740 and rs2234922), and colorectal adenomas and hyperplastic polyps (HPs) and explored gene-environment interactions. Men and women with colorectal adenomas (n = 519), HPs (n = 691), or concurrently with both types of polyps (n = 227) and polyp-free controls (n = 772) receiving a colonoscopy from December 2004 to September 2007 were recruited. Participants completed telephone interviews and provided buccal cell samples; genotyping of mEH was completed using Taqman assays. We conducted polytomous regression and calculated odd ratios (OR) and 95% confidence intervals. Interactions were evaluated using Wald chi-square tests. Consumption of >3 servings of charred meat per week was associated with distal HPs (OR = 2.0, 1.2-3.4) but not adenomas nor either type of proximal polyp. Heavy cigarette smoking (≥ 22 pack-years) was associated with an increased risk for colorectal adenomas (OR = 1.7, 95% CI: 1.2-2.4), HPs (OR = 2.4, 95% CI: 1.7-3.3), and both types (OR = 2.8, 95% CI: 1.8-4.3) with the strongest association for distal polyps. There was no association between mEH genotype and colorectal polyps, nor were any statistically significant gene-environment interactions identified. Future investigation of BaP exposure and colorectal neoplasia should analyze whether associations are dependent upon anatomic location.

Knowledge of the anatomical polyp location might bias the pathological classification of histologically equivocal colorectal serrated polyps - a consensus study performed by pathology trainees

Colorectal serrated polyps (CSPs) comprise hyperplastic polyps (HPs), traditional (TSAs) and sessile (SSAs) serrated adenomas, as well as inflammatory cloacogenic polyps (ICPs). These lesions have typical anatomical locations and share a histomorphological overlap. In this study, we assessed the so far neglected issue as to what extent the histological classification of these lesions performed by pathology trainees is biased by the pathologists' knowledge of the polyp location in dependency on the duration of their training. To reach this aim, 49 CSPs were classified by three pathology trainees blinded to clinical data. In a second round of examination, the same raters were provided with the polyp location. A third round was conducted after a consensus conference. Intra- and inter-rater analyses were performed using Kappa (K) statistics and Spearman correlations. Our data suggest that the histological classification of CSPs performed by pathology trainees might be influenced in a clinically significant fashion by knowledge of the anatomical polyp location depending on the duration of their pathology training.

Association of smoking and flat adenomas: results from an asymptomatic population screened with a high-definition colonoscope

BACKGROUND

Flat adenomas represent a morphologically distinct class of polyps that may be difficult to detect, and little is known regarding risk factors for these lesions. Identification of risk factors for these lesions may aid in colorectal cancer (CRC) screening, because patients at risk for these lesions may require special imaging techniques. Smoking, an important risk factor for CRC, may be associated with molecular changes that increase the risk for flat adenomas.

OBJECTIVE

The aim of this study was to examine the association between smoking and flat adenomas.

DESIGN

Prospective cross-sectional study.

SETTING

University hospital endoscopy center.

PATIENTS

We enrolled asymptomatic patients presenting for CRC screening.

INTERVENTIONS

We screened patients with a high-definition (1080i signal) wide-angle (170 degrees field of view) Olympus 180-series colonoscope. We collected demographics, medication use, family history of CRC, diet history, and smoking history.

MAIN OUTCOME MEASUREMENTS

Polyp morphology, assessed by using the Japanese Research Society Classification (JRSC).

RESULTS

A total of 600 patients were enrolled. We observed that smoking was associated with having a flat adenoma of any size (adjusted odds ratio [OR], 2.53; 95% CI, 1.60-4.00), having only flat adenomas that were > or = 6 mm in diameter (adjusted OR, 3.84; 95% CI, 2.02-7.32), as well as flat advanced adenomas (adjusted OR, 2.81; 95% CI, 1.08-7.30).

LIMITATIONS

The study design may not account for some confounding variables and provides no information regarding smoking status at the time of initiation of flat adenomas.

CONCLUSION

Smoking was associated with flat adenomas in our population. Our findings may explain the earlier onset of CRC in smokers as well as the advanced stage with which they present, with compared with nonsmokers. Smokers may require screening with high-definition colonoscopes to detect flat adenomas.

Sonic hedgehog relates to colorectal carcinogenesis

AIM

The activation of Hedgehog signaling, which is critical to normal mammalian gastrointestinal development, is implicated in the development of various tumors, including colorectal cancer. In the pancreas, a precursor lesion overexpresses the Sonic hedgehog (Shh) when compared with normal tissue and cancer. The present study was designed to investigate Shh related protein expression in hyperplastic polyps and the adenoma-carcinoma sequence in the colon and rectum.

METHODS

Seventeen hyperplastic polyps, 24 adenomas of the colon, 69 adenocarcinomas (31 well-differentiated, 38 moderately-differentiated), and 30 normal colon samples were used in the study. We checked the expression of Shh, both patched (Ptch) and smoothened (Smo), by immunohistochemistry and compared the expression rate of each group.

RESULTS

Almost all adenomas, 22 of 23 (96%), expressed Shh. In other groups, 4 of 17 hyperplastic polyps (24%), 7 of 31 well-differentiated adenocarcinomas (23%), 13 of 38 moderately-differentiated adenocarcinomas (34%) and none of the 30 normal samples expressed Shh. The rate of expression in Ptch and Smo gradually increased in accordance with tumor progression.

CONCLUSION

This result indicates that Shh-related carcinogenesis and Shh expression may be a trigger for the adenoma-carcinoma sequence. This study suggests a potential therapeutic target of hedgehog blockade in carcinogenesis.

Serrated polyps of the large intestine: a molecular study comparing sessile serrated adenomas and hyperplastic polyps

AIMS

To compare the molecular profile of a series of sessile serrated adenomas (SSAs) and hyperplastic polyps (HPs), in order to distinguish these lesions, SSAs having a potential role in the genesis of serrated adenocarcinomas through a serrated pathway in which methylation plays a key role.

METHODS AND RESULTS

Twelve HPs and sixteen SSAs of the right and left colon were investigated for microsatellite instability, DNA mismatch repair genes, p53, p16, and beta-catenin expression, MLH1 and p16 (CDKN2A) gene methylation, and KRAS and BRAF mutations. Both SSAs and HPs were microsatellite stable. MLH1 and MSH2 protein silencing, aberrant cytoplasmic expression and methylation of p16 were found to be exclusive to right-sided SSAs. The MLH1 promoter gene was frequently methylated in right-sided SSAs in contrast with HPs. Abnormal p53 and beta-catenin expression was present in both SSAs and HPs. BRAF and KRAS mutation were mutually exclusive, but KRAS mutation was present only in left-sided SSAs and HPs.

CONCLUSIONS

HPs and SSAs may be related lesions. However, at least right-sided SSAs differ from left-sided SSAs and HPs in the occurrence of MLH1 and p16 methylation, supporting the hypothesis that SSAs could be precursors of serrated adenocarcinomas.

Comparison of a peanut agglutinin test and an immunochemical faecal occult blood test in detecting colorectal neoplasia in symptomatic patients

BACKGROUND

Currently available methods for detection of early-stage colorectal cancer are reliant on faecal occult blood (FOB) tests. Bleeding, however, is not specific for colorectal neoplasia. Enzymatically detected or peanut agglutinin (PNA)-detectable galactose-beta1-3-N-acetyl-galactosamine residues found in rectal mucus have been used to detect colorectal cancer.

METHODS

The sensitivity and specificity of the PNA rectal mucus test were compared with those of an immunological test for faecal occult blood (Hemolex) in 199 symptomatic patients referred for colorectal investigations. All patients also underwent a colonoscopy. SDS-PAGE and PNA-overlay were used to characterize PNA-binding proteins in normal and malignant colorectal tissue.

RESULTS

The PNA test had a similar sensitivity to that of Hemolex for colorectal carcinoma (83% vs. 72%), adenomas (55% vs. 50%), inflammatory bowel disease (52% vs. 48%) and hyperplastic polyps (48% vs. 25%). The sensitivity of the PNA test and Hemolex for colorectal neoplasia was 69% vs. 59% and specificity 68% vs. 86% (p=0.002). SDS-PAGE and PNA-overlay showed some commonly expressed PNA-binding proteins in both normal mucosa and colorectal cancer and a higher and even selective expression of 160 kD PNA-binding protein in colorectal cancer.

CONCLUSIONS

A single PNA test in its present form is as sensitive an indicator of colorectal neoplasia as Hemolex completed over three days, but lacks specificity. The 160 kD cancer-associated antigen we have identified is under further characterization for development of a more specific PNA test.

Pathologic features and biologic importance of colorectal serrated polyps

Serrated polyps of the large intestine comprise a heterogeneous group of mucosal lesions that includes nondysplastic polyps, such as hyperplastic polyps and sessile serrated polyps, and polyps that show overt cytologic dysplasia, namely serrated adenomas and mixed hyperplastic/adenomatous polyps. These polyps have received increased recognition over the past 2 decades, as emerging evidence suggests that a subset may be precursors to colorectal carcinomas that lack chromosomal instability. Several investigators have proposed the concept of the "serrated neoplastic pathway" according to which nondysplastic serrated lesions develop progressively severe dysplasia culminating in the development of microsatellite unstable carcinomas that show DNA hypermethylation and BRAF mutations. A subset of hyperplastic polyps and sessile serrated polyps show mutations in the BRAF gene and abnormal DNA methylation, which can, ultimately, affect the promoter regions of key DNA-repair and tumor suppressor genes, such as MLH1 and MGMT, leading to their decreased transcription and microsatellite instability. On the basis of this hypothesis, many authors have proposed that sessile serrated polyps should be treated and surveilled similar to conventional adenomas, although prospective data are lacking. This review describes the clinicopathologic and molecular features of serrated polyps and discusses the current data regarding their biologic significance.

Hyperplastic polyps and the risk of adenoma recurrence in the polyp prevention trial

BACKGROUND AND AIMS

Recent studies have suggested that some hyperplastic polyps may be associated with an increased risk of colorectal cancer. Prospective information on the risk of adenoma recurrence associated with hyperplastic polyps is limited. We sought to investigate whether the coexistence of hyperplastic polyps with adenomas increases the risk of adenoma recurrence.

METHODS

We used unconditional logistic regression models to examine the association between baseline hyperplastic polyps and subsequent adenoma recurrence during a 3-year follow-up evaluation, among 1637 participants in the Polyp Prevention Trial.

RESULTS

A total of 437 participants (26.7%) had hyperplastic polyps coexisting with adenomas at baseline. Of these, 132 (30.2%) had at least one hyperplastic polyp in the proximal colon, whereas 305 (69.8%) had only distal hyperplastic polyps. When compared with subjects without any hyperplastic polyps at baseline, there was no statistically significant association between the presence of baseline hyperplastic polyps and recurrence of any adenoma (odds ratio [OR], 1.19; 95% confidence interval [CI], 0.94-1.51) or advanced adenoma (OR, 1.25; 95% CI, 0.78-2.03). Also, there was no association between hyperplastic polyp location and adenoma recurrence (OR, 1.01; 95% CI, 0.69-1.48) for any proximal hyperplastic polyp (OR, 1.26; 95% CI, 0.96-1.65) and for distal hyperplastic polyps.

CONCLUSIONS

The coexistence of hyperplastic polyps with adenomas, irrespective of location, does not confer an increased risk of adenoma recurrence beyond that of adenomas alone within 3 years of follow-up evaluation. Prospective long-term studies on adenoma recurrence risk associated with hyperplastic polyps in screening populations are needed.

Ethnicity and risk for colorectal cancers showing somatic BRAF V600E mutation or CpG island methylator phenotype

Colorectal cancers arising from serrated polyps are characterized by the CpG island methylator phenotype (CIMP) and somatic mutation (V600E) in the BRAF proto-oncogene. Few epidemiologic studies have investigated risk factors for these tumors. We conducted a cohort study of 41,328 residents of Melbourne, Australia that included 9,939 participants of southern European origin and 31,389 of Anglo-Celtic origin. Colorectal adenocarcinomas were identified from population-based cancer registries. BRAF V600E mutation in tumors was determined using a PCR-based allelic discrimination method. Tumors were classified as CIMP positive when at least three of five markers (RUNX3, CACNA1G, SOCS1, NEUROG1, and IGF2) were methylated according to MethyLight analysis. Hazard ratios (HR) and 95% confidence intervals (95% CI) were estimated by Cox regression with adjustment for risk factors for colorectal cancer. During follow-up, 718 participants were diagnosed with colorectal cancer. CIMP assays were done for 579 and BRAF V600E mutation testing for 582. After adjustment for other risk factors, when compared with people of Anglo-Celtic origin, those of southern European origin had lower incidence of colorectal cancer that had CIMP (HR, 0.32; 95% CI, 0.16-0.67) or BRAF mutations (HR, 0.30; 95% CI, 0.16-0.58) but similar incidence of colorectal cancer without CIMP (HR, 0.86; 95% CI, 0.70-1.05) or BRAF (HR, 0.90; 95% CI, 0.74-1.11). People of southern European origin had lower risk of colorectal cancers with CIMP and BRAF mutation than people of Anglo-Celtic origin, which may in part be due to genetic factors that are less common in people of southern European origin.

Findings on optical colonoscopy after positive CT colonography exam

BACKGROUND & AIMS

The aim of this study is to evaluate the findings on optical colonoscopy (OC) after a positive CT colonography (CTC) exam and characterize the type of polyps seen on OC but not reported by CTC.

METHODS

Over an 18-month period a total of 159 asymptomatic adults had polyps seen on computed tomography colonography examination and subsequently underwent planned therapeutic optical colonoscopy. The colonoscopists were aware of the findings on CT colonography prior to further evaluation of the colon. Characteristics of polyps and adenomas seen on subsequent optical colonoscopy but not seen or reported on CT colonography were examined.

RESULTS

The adenoma miss rate for CT colonography overall was 18.9% (25/132) including 6.2% (4/65) for polyps >9 mm and 18.2% (8/44) for polyps 6-9 mm. Three of the adenomas >9 mm not seen on CTC were sessile, and two were found in patients with technically difficult CT colonography studies due to poor colonic distention. No adenomas with advanced pathology <6 mm were found on optical colonoscopy but not reported on CT colonography. False-positive CTC referral where no polyp was seen on colonoscopy was 5.0%.

CONCLUSIONS

CT colonography has adenoma miss rates similar to miss rates historically found with optical colonoscopy, with most missed adenomas being <10 mm and sessile in shape.

COX-2 expression in sporadic colorectal adenomatous polyps is linked to adenoma characteristics

AIMS

To assess cyclooxygenase-2 (COX-2) expression in sporadic colonic adenomas and to explore the association of COX-2 positivity with adenoma characteristics linked to increased risk of malignant transformation.

METHODS AND RESULTS

COX-2 expression and localization were assessed in 64 colorectal adenomas and 35 paired adjacent normal colonic mucosal biopsy specimens. The number of adenoma specimens was then extended to include polyps exhibiting an increasing degree of epithelial dysplasia. Forty colonic hyperplastic polyps were also identified from the pathology diagnostic database and included in the analysis. Immunohistochemistry was performed with the Envision+ peroxidase-linked biotin-free system incorporating a signal amplification step. There was a statistically significant increase in COX-2 expression in colonic polyps compared with paired adjacent normal mucosa, chi(2) = 40.1, P = 0.001. The probability of COX-2 expression increased along with increasing adenoma size and increasing degree of epithelial dysplasia. Fifty-five per cent of the hyperplastic polyp specimens expressed COX-2.

CONCLUSIONS

This study associates COX-2 epithelial expression with a number of adenoma characteristics that convey an increased risk of malignant transformation. This is in keeping with a positive role for COX-2 in early colorectal carcinogenesis.

Anthropometric risk factors for colorectal polyps in African-American women

OBJECTIVE

Colorectal adenomas are thought to be precursor lesions to colorectal cancer, a leading cause of cancer incidence and mortality in African-American women. Studies suggest that obesity is associated with risk of adenomas in white women, but little is known about the relation in African-American women. We prospectively examined the association between selected anthropometric factors and colorectal polyps in African-American women.

METHODS AND PROCEDURES

Data were obtained from the Black Women's Health Study (BWHS), a prospective cohort study of African-American women. From 1997 to 2003, we followed 33,403 women aged > or =30 years with no prior diagnosis of cancer or polyps. Cox regression was used to estimate incidence rate ratios (IRRs) and 95% confidence intervals (CIs) for risk of polyps, with adjustment for potential confounders.

RESULTS

After 211,797 person-years of follow-up, 1,189 cases of colorectal polyps were reported. The IRR comparing women with a current BMI > or =35 to <25 kg/m(2) was 1.35 (95% CI = 1.12-1.62), after adjustment for covariates including waist-to-hip ratio (WHR). Women who gained > or =30 kg since age 18 were 1.76 times as likely as those who gained <5 kg to report polyps (95% CI = 1.33-2.33). The IRR comparing the highest (>or =0.87) to lowest (<0.71) quintiles of WHR was 1.26 (95% CI = 1.04-1.54), after adjustment for covariates including BMI. BMI at age 18, adult height, and waist circumference (BMI-adjusted) were not materially associated with risk. Results were similar among women with a recent endoscopy.

DISCUSSION

Weight gain and obesity in adulthood may increase the risk of colorectal polyps in African-American women.

Sessile serrated adenoma: challenging discrimination from other serrated colonic polyps

Sessile serrated adenoma (SSA) is the proposed precursor for microsatellite unstable colorectal carcinomas and some authorities recommend that SSAs should be managed similar to adenomas. The aim of our study was to determine whether serrated polyps can be classified with sufficient consistency to support current treatment recommendations. One hundred eighty-five serrated polyps were classified as hyperplastic polyp (HP), SSA, or traditional serrated adenoma (TSA) by 5 pathologists blinded to clinical data. The observers documented which histologic features they considered most helpful in reaching their diagnosis in each case. In a second round, the observers were provided with polyp site and size. After reaching a consensus on minimum criteria for SSA and TSA, the pathologists classified another set of 50 polyps. The interobserver concordance was calculated using kappa statistics. In the first round, the overall interobserver agreement was moderate (kappa=0.55). Concordance for HP and SSA was moderate whereas it was nearly perfect for TSA. In the second round, there was no improvement in the concordance. All observers relied more often on architectural features than on cytologic ones to distinguish SSA from HP and agreement was reached that architectural features should provide the basis for the diagnosis of SSA. Subsequently, interobserver concordance was slightly improved but remained moderate (kappa=0.58). Interobserver agreement for the diagnosis of serrated polyps is moderate. However, this level of variability is acceptable because the presence of SSA indicates increased risk of developing additional serrated polyps and carcinoma, and surveillance is appropriate.

Long-term use of proton pump inhibitors does not affect the frequency, growth, or histologic characteristics of colon adenomas

BACKGROUND

The clinical significance of the trophic effects of long-term proton pump inhibitors (PPI)-related hypergastrinemia on colon polyps remains unknown.

AIM

To study the frequency, growth, and histology of colon polyps in patients on chronic PPI therapy (cases), compared to those not receiving acid suppression (controls).

METHODS

Medical records of 2868 consecutive patients who underwent two or more colonoscopies, performed 3 or more months apart were reviewed. Cases (116) that used PPIs between the two colonoscopies were then compared to controls (194).

RESULTS

Demographics and risk factors for colon cancer were comparable between the two groups. At baseline the mean frequency and size of adenomatous polyps were similar in cases and controls (P > 0.05) and at follow-up, these were 0.89 and 1.18 (P > 0.05; 95% CI of -0.08 to 0.66) and 4.09 mm and 4.00 mm (P > 0.05; 95% CI -2.29 to 2.11), respectively with no significant change. However, control group had a higher mean frequency and size of hyperplastic polyps at baseline as well as at follow-up colonoscopy (P < 0.05).

CONCLUSIONS

The long-term use of PPI does not influence the frequency, growth, or histology of adenomatous polyps, but is associated with a reduction in both baseline and interval development of hyperplastic polyps.

The impact of new screening protocol on individuals at increased risk of colorectal cancer

OBJECTIVE

Screening colonoscopy has been shown to reduce mortality and cancer stage in hereditary nonpolyposis colorectal cancer (HNPCC) individuals. However, the benefit of screening in intermediate risk groups is unknown. The most recent national guidelines have recommended a reduction of screening frequency for the intermediate risk group. Therefore, this study aims to compare the results of colonoscopic screening in HNPCC and intermediate risk groups and assess the effect of the most recent screening protocol recommendations.

METHOD

A total of 244 individuals; 108 from HNPCC families (28 mismatch repair gene carriers) and 136 from intermediate risk families were referred for regular colonoscopic screening by the Regional Genetics Service. Findings from 417 colonoscopies performed between 1992 and 2003 were evaluated.

RESULTS

A total of three cancers, 39 adenomas and 41 hyperplastic polyps were found in the HNPCC group compared with one cancer, 22 adenomas and 19 hyperplasic polyps in the intermediate risk group. If the recent screening guidelines for the intermediate group were applied, then 89 (44%) fewer colonoscopies would have been performed. Although no cancers would have been missed, six adenomas (mean size = 5.7 mm, range 2-10 mm) with two graded as severely dysplasic and six hyperplastic polyps would not have been detected.

CONCLUSION

The detection rate and distribution of adenomas were similar in both groups. If the new colonoscopic screening recommendations for the intermediate risk group had been applied, a small number of significant lesions would have been missed.

The case for a genetic predisposition to serrated neoplasia in the colorectum: hypothesis and review of the literature

In recent years, an alternative pathway of colorectal cancer development has been described in which serrated polyps replace the traditional adenoma as the precursor lesion. Importantly, serrated polyps and a subset of colorectal cancer show largely nonoverlapping mutation profiles to those found in adenomas and the majority of colorectal cancer. These genetic alterations include activating mutation of the BRAF proto-oncogene and widespread gene promoter hypermethylation (CpG island methylator phenotype or CIMP). Up to 15% of colorectal cancer is likely to develop on the basis of a strong genetic predisposition. The two most well-characterized syndromes, familial adenomatous polyposis and hereditary nonpolyposis colorectal cancer (Lynch syndrome), both develop via the adenoma-carcinoma pathway and together account for approximately one third of familial colorectal cancer. We have recently described 11 families in which there is evidence that the genetic predisposition to autosomal dominant colorectal cancer is linked to the serrated pathway. This condition, serrated pathway syndrome, and the related condition, hyperplastic polyposis, the presentation of which suggests a recessive mode of inheritance, represent two syndromes in which BRAF mutation and methylation co-occur within serrated precursor lesions. Further, CIMP is observed in the normal colonic mucosa of individuals with hyperplastic polyposis consistent with a field defect in epigenetic regulation. The spectrum of serrated neoplasia may also implicate the apparently sporadic and later onset subset of colorectal cancer with high levels of microsatellite instability. The tendency for these lesions to be multiple, associated with smoking, and to show frequent BRAF mutation and CIMP points to a defect that may result from interactions between the environment and a weakly penetrant genetic alteration.

Serrated polyps of the colorectum: is sessile serrated adenoma distinguishable from hyperplastic polyp in a daily practice?

The distinction between serrated polyps of the colon is complex, particularly between hyperplastic polyps (HP) and sessile serrated adenomas (SSA). Recent data show that SSA might be the precursors of serrated colonic cancers, underlining the necessity of identifying them. We characterized the demographic and pathologic characteristics of 102 serrated lesions among 321 polyps of the colorectum and determined if SSA can be microscopically distinguished from HP in biopsy material of a daily practice. There were 81 HP (79%) and 7 SSA (7%) of which one displayed low-grade dysplasia. Only six serrated polyps (6%) could not be correctly classified. The main architectural criteria for distinguishing SSA from HP is the serrated feature along the crypt axis and the rarity of undifferentiated cells in the lower third of the crypts. SSA was significantly more often located in the right colon and larger (median, 11 vs 4 mm) than HP. SSA are rare serrated polyps that can be distinguished from HP based on their morphology, location in the right colon, and larger size. One SSA of our series showed low-grade dysplasia supporting the concept that this lesion might be a precursor of serrated adenocarcinoma.

Tobacco smoking and colorectal hyperplastic and adenomatous polyps

Colorectal adenomas and possibly some hyperplastic polyps are precursors of colorectal cancer. Tobacco use is associated in epidemiologic studies with these polyps, although links between smoking and colorectal cancer are less consistent. To characterize the role of tobacco in early colorectal carcinogenesis, we compared tobacco use among 4,383 subjects with histologically verified benign (hyperplastic or adenomatous) polyps of the distal colon (descending colon, sigmoid, and rectum) with tobacco use among 33,667 subjects who were endoscopy negative for distal colon tumors, in the screening arm of the Prostate, Lung, Colorectal, and Ovarian Trial, a randomized trial of flexible sigmoidoscopy. Risks, estimated by the odds ratio (OR), associated with current cigarette use were OR = 4.4 [95% confidence interval (95% CI), 3.7-5.2] for hyperplastic polyps only, OR = 1.8 (95% CI, 1.5-2.1) for adenomas only, and OR = 6.2 (95% CI, 4.7-8.3) for subjects with both hyperplastic and adenomatous polyps concurrently. Effects were weaker among ex smokers; the smoking-associated ORs remained consistently higher for hyperplastic polyps. This pattern was also seen in relation to cigarettes smoked per day, smoking duration, and pack-years. Tobacco-associated risks for multiple polyps were also stronger when hyperplastic disease was involved. In conclusion, tobacco use, particularly recent use, increases risk for both adenomatous and hyperplastic polyps, but the risks are substantially greater for hyperplastic lesions.

Regulation of hMSH2 and hMLH1 expression in the human colon cancer cell line SW1116 by DNA methyltransferase 1

Aberrant DNA methylation is now recognized as an important epigenetic alteration occurring early in human cancer. To directly study the role of DNA methyltransferase 1 (DNMT1) in the regulation of expression of tumor-related genes in human colon cancer cells, we stably transfected expression constructs containing sense or antisense DNMT1 into the human colon cancer cell line, SW1116. The expression level of mismatch repair genes (MMR), human mut-L homologue 1 (hMLH1) and human Mut S homologue 2 (hMSH2), was monitored by real-time RT-PCR. The methylation status of hMLH1 and hMSH2 promoters was determined by bisulfite modification and methylation-specific PCR (MSP). The protein levels of DNMT1, hMSH2 and hMLH1 were determined by Western analysis. The results show that DNMT1 protein expression was increased or decreased in transfected cell lines containing sense or antisense DNMT1 constructs, respectively. In cells expressing the sense DNMT1 construct, the expression of hMLH1 and hMSH2 was down-regulated through hypermethylation of their respective promoters. Furthermore, antisense DNMT1 expression induced promoter demethylation and up-regulated transcription of hMSH2 (P<0.05) and hMLH1 (P=0.064) in SW1116 cells.

The Association Between Cigarette Smoking and Colorectal Polyp Recurrence (United States)

OBJECTIVE

Although evidence exists linking smoking to precancerous colorectal adenomatous polyps, few studies have examined the association between cigarette smoking and recurrence of colorectal polyps. This association was investigated prospectively with data from the Polyp Prevention Trial.

METHODS

Cigarette smoking data were collected through baseline interviews. The study was completed by 1872 men and women with presence of adenomas at baseline colonoscopy. Multiple logistic regression analysis was used to examine the association between cigarette smoking and polyp recurrence (adenomatous and hyperplastic) up to four years from baseline.

RESULTS

Adenoma recurrence was not related to cigarette smoking. Current smokers had increased odds of hyperplastic polyps at follow-up compared to never smokers (OR 2.88, 95% CI 2.06-4.01). Current smoking was associated with subsequent distal (OR 3.44, 95% CI 2.38-4.95) and rectal (OR 3.53, 95% CI 2.15-5.78) hyperplastic polyps, but not subsequent proximal hyperplastic polyps. Cigarette smoking was associated with subsequent multiple and small size (4 mm) hyperplastic polyps. Significant linear trends were observed between development of subsequent hyperplastic polyps and all smoking variables.

CONCLUSIONS

Although no association with recurrent adenomas was observed, cigarette smoking was significantly associated with hyperplastic polyp development, except for those in the proximal colon. This prospective study confirms that cigarette smoking has a significant effect on the development of hyperplastic colorectal polyps.

Etiologic aspects and management of acromegaly

Acromegaly is a systemic disease with various etiologies. It can occur as a sporadic or, more rarely, as a familial disease. Numerous complications such as endocrine, cardiovascular, respiratory, metabolic, osteoarticular and neoplastic disturbances occur and must be taken into account when establishing a therapeutic strategy. For this reason, the decision as to a treatment modality of acromegaly must be followed by a thorough evaluation of the patient and once the diagnosis of complications is settled, adequate treatment should be instituted. Follow up of the patients requires periodical re-assessment of complications’ status.

Distribution and prevalence of colorectal hyperplastic polyps using magnifying pan-mucosal chromoendoscopy and its relationship with synchronous colorectal cancer: prospective study

BACKGROUND AND AIM

Patients with multiple (hyperplastic polyposis) or large hyperplastic polyps (HPs) predominantly in the right-sided colon, have been reported to have an increased risk of colorectal cancer (CRC). This prospective study was conducted to clarify the distribution of various sized HPs using magnifying pan-mucosal chromoendoscopy and its relationship with synchronous CRC.

METHODS

Patients eligible for this study had an initial total colonoscopy. Indigo carmine dye was sprayed throughout the whole colon and rectum, and diagnoses were made using magnifying colonoscopy.

RESULTS

A total of 263 patients were enrolled, and a total of 3060 HPs were observed in 226 (86%) patients. The prevalence of patients with intermediate size (> or = 6 mm) HPs was 8.7% (n = 23) and that of patients with large HPs (> or = 10 mm) was 0.8% (n = 2). Of 3060 HPs, the numbers of diminutive (< 6 mm), intermediate size and large HPs were 3020, 38 and two, respectively, and 5.0%, 42.1% and 100% of these were located in the right-sided colon, respectively. Synchronous CRC was observed in 64 (24%) of 263 patients. Compared to patients without HPs, patients with intermediate size HPs showed a significant increase in odds ratio (OR) for synchronous CRC (OR = 4.9: 95% CI [1.3-18.2]), but there was no significant association between synchronous CRC and patients with diminutive or large HPs.

CONCLUSIONS

Compared to diminutive HPs, intermediate size and large HPs were predominantly located in the right-side colon. Moreover, intermediate size HPs were significantly correlated with synchronous CRC.

Association between adenomas of rectosigmoid colon and metabolic syndrome features in a Chinese population

BACKGROUND AND AIMS

Metabolic syndrome (MS) consists of a cluster of diseases, including obesity, dyslipidemia, hyperglycemia and high blood pressure. The purpose of the present study was to assess the association of MS with adenomas of the rectosigmoid colon, a well-established precancerous lesion.

METHODS

A total of 4938 Taiwanese patients (2891 men and 2047 women with a mean age of 50.1 years), who had a physical examination at our hospital between January 2001 and October 2002, were enrolled in this study. All patients underwent a sigmoidoscopic examination to 60 cm from the anus. A modified National Cholesterol Education Program (NCEP) definition of MS was used in this study, in which body mass index (BMI) was substituted for the waist circumference measurement.

RESULTS

Overall, 14% of patients had an elevated fasting glucose, 27% had high blood pressure, 14% had an increased triglyceride (TG) level, 8% had low high density lipoprotein (HDL) cholesterol, and 18% were obese. Rectosigmoid polyps were present in 17% of patients, among whom 568 received polypectomy. Pathological findings were hyperplastic in 138 subjects, adenomas in 341, carcinomas in 10, and other benign lesions in 79. In patients without polyps, the adjusted mean TG level and calculated BMI level were lower than those in patients with adenomas. No such difference existed, however, between patients without polyps and those with hyperplastic polyps. The odds ratio of adenomas in situ as compared to either a polyp-free state or the presence of hyperplastic polyps increased significantly with the number of MS diagnostic criteria the patient exhibited.

CONCLUSION

Our study shows that MS is associated with rectosigmoid adenomas in a Chinese population. In patients with rectosigmoid polyps, the coexistence of MS may portend an increased risk of adenomas.

The human tumor suppressor CEACAM1 modulates apoptosis and is implicated in early colorectal tumorigenesis

Defects in the adenomatous polyposis coli (APC) tumor suppressor pathway are sufficient for neoplastic transformation as the initiating step in colorectal carcinogenesis. In contrast, hyperplastic tumors possess normal APC function, and it is unclear whether they represent significant precursor lesion in cancer development. CEACAM1 is a tumor suppressor whose expression is known to be lost in the great majority of early adenomas and carcinomas. We found that loss of CEACAM1 expression is more common in neoplastic tumors than APC mutations. While APC function was normal in hyperplastic aberrant cypt foci and hyperplastic polyps, loss of CEACAM1 was observed as frequently as in the neoplasias. Moreover, the presence or absence of CEACAM1 expression in the hyperplastic tumors correlates with normal or reduced apoptosis, respectively. In vitro, CEACAM1 acts as a regulator of apoptosis in CEACAM1-transfected Jurkat cells. Finally, in human HT29 colon cancer cells, apoptosis can be specifically restored by induction of CEACAM1 expression. These data suggest an oncodevelopmental link between neoplasia and hyperplasia and demonstrate that CEACAM1 acts as a regulator of apoptosis in the colonic epithelium. Thus, failure of the maturing colon cell to express CEACAM1 is likely to contribute to the development of hyperplastic lesions, which may eventually pave the way to neoplastic transformation and colon cancer development.

From Colonic Polyps to Colon Cancer: Pathophysiology, Clinical Presentation, and Diagnosis

Epidemiologists, basic researchers, clinicians, and public health administrators unite! Develop and implement a simple, safe, and effective preventive and screening test for colon cancer. The public will willingly and enthusiastically accept such a test. Many thousands of lives are at stake every year.

The pathophysiology, clinical presentation, and diagnosis of colon cancer and adenomatous polyps

A review of the pathophysiology, clinical presentation, and diagnosis of colon cancer and colonic polyps is important and timely. This field is rapidly changing because of breakthroughs in the molecular basis of carcinogenesis and in the technology for colon cancer detection and treatment. This article reviews colon cancer and colonic polyps, with a focus on recent dramatic advances, to help the pri-mary care physician and internist appropriately refer patients for screening colonoscopy and intelligently evaluate colonoscopic findings to reduce the mortality from this cancer.

Hyperplastic polyps and serrated adenomas: colonoscopic surveillance?

Hyperplastic polyps are not thought to carry a malignant potential. They are, therefore, not regularly screened by the majority of clinicians. We present two case reports of serrated adenomas that add to a small but expanding body of clinical and histological evidence that suggests a hyperplastic to neoplastic pathway. Regular colonoscopic surveillance may be indicated in at least some cases of hyperplastic polyposis

Comparative molecular pathology of sporadic hyperplastic polyps and neoplastic lesions from the same individual

AIM

The biology of colorectal hyperplastic polyps is of considerable relevance, because recent evidence suggests that under certain circumstances hyperplastic polyps may be precursors of neoplasms. The aim of this study was to assess and compare the clinical and molecular characteristics of hyperplastic polyps and neoplastic lesions removed from patients without the hyperplastic polyposis syndrome.

METHODS

One hundred and twenty six patients were identified through a series of genetic epidemiological studies. Each patient had at least one neoplastic lesion and one hyperplastic polyp; there was a total of 147 hyperplastic polyps. All lesions were evaluated for K-ras mutations, loss of heterozygosity (LOH) of the adenomatous polyposis coli (APC) gene, and microsatellite instability.

RESULTS

K-ras mutation was detected in 15 (10%) hyperplastic polyps, all from the rectosigmoid colon. No hyperplastic polyp had APC LOH or microsatellite instability. Patients with adenomas or carcinomas showing K-ras mutations were not more likely to have hyperplastic polyps with K-ras mutations. The average number of adenomas did not differ between those patients with hyperplastic polyps with K-ras mutations and those without K-ras mutations. There was no association between the hyperplastic polyp and the adenoma regarding the colon segments from which the two lesions were removed.

CONCLUSIONS

The sporadic hyperplastic polyp is a lesion with limited molecular change and no relation to patients' neoplastic lesions.

Hyperplastic polyposis and the risk of colorectal cancer

PURPOSE

Hyperplastic polyps are usually considered to be an innocent finding with little or no potential to progress to colorectal cancer. However, recent literature suggests that some of these polyps may be morphologically and genetically distinct and lead to microsatellite unstable colorectal cancers. The purpose of this study was to define the cancer risk associated with hyperplastic polyposis.

METHODS

All patients with hyperplastic polyposis diagnosed by a single colorectal surgeon at a university hospital were followed prospectively. The diagnosis of hyperplastic polyposis was made by the presence of more than 20 hyperplastic polyps distributed throughout the colon and/or a hyperplastic polyp at least 1 cm in size in diameter in the right colon. Patient demographics, family history, size, location, and distribution of polyps and the development of colorectal cancer were noted.

RESULTS

Thirteen patients who met the criteria for hyperplastic polyposis were identified and followed prospectively. All of these patients had at least 30 polyps distributed throughout the colon, often > 100. Nine of 13 also had a hyperplastic polyp at least 1 cm in size, usually in the right colon. Of particular note, 7 of 13 patients (54 percent) were diagnosed with colorectal cancer during the study period. Four had cancer on initial diagnosis and three patients developed cancer despite frequent colonoscopic surveillance. Five of seven colorectal cancers were located in the right colon.

CONCLUSIONS

Patients with hyperplastic polyposis are at high risk for colorectal cancer. Failure to identify this subset of patients could have dire consequences.

Defective mismatch repair in the pathogenesis of low-grade appendiceal mucinous neoplasms and adenocarcinomas

Defective DNA mismatch repair has been proposed as a second pathway for colonic carcinogenesis, particularly in tumors arising in the right colon. We investigated whether tumors arising in the appendix are associated with defective DNA mismatch repair using immunohistochemistry for mismatch repair enzymes hMLH-1, hMSH-2, hMSH-6, and hPMS-2. These immunoassays have been shown to be highly sensitive and specific for defective DNA mismatch repair in sporadic and familial adenocarcinomas. Sporadic adenocarcinomas with defective DNA mismatch repair essentially always show loss of hMLH-1, while loss of hMSH-2, hMSH-6, or hPMS-2 is almost always due to germline mutation. In all, 35 cases of appendiceal epithelial neoplasms were evaluated, comprising 18 low-grade appendiceal mucinous neoplasms confined to the appendix; eight low-grade appendiceal mucinous neoplasms with extra-appendiceal spread (five peritoneum and ovaries, two peritoneum, one ovaries only); and nine invasive adenocarcinomas (three with metastatic disease). All immunohistochemical slides were reviewed by two pathologists. One (11%) invasive adenocarcinoma showed absent expression of hMSH-2 and hMSH-6, but preserved hMLH-1 and hPMS-2 expression. This case was a 26-year-old female with a history of synovial sarcoma who presented with acute appendicitis and appendiceal perforation (median age for other invasive carcinomas, 62 years; range 38-76 years). The appendiceal tumor was a moderately differentiated, colonic-type adenocarcinoma without significant extracellular mucin or tumor-infiltrating lymphocytes. The remaining invasive carcinomas and low-grade appendiceal mucinous neoplasms demonstrated preserved expression of all mismatch repair enzymes, including the seven cases in which extra-appendiceal tumor was also evaluated. We conclude that defective DNA mismatch repair does not play a role in the pathogenesis of low-grade appendiceal mucinous neoplasms. Defective DNA mismatch was found in 11% of invasive carcinomas, likely due to a germline mutation. These findings suggest that sporadic appendiceal neoplasia rarely arises through the defective DNA mismatch repair (mutator) pathway.

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Flat Colorectal Lesions: Colonoscopic Detection Without Dye Spray or Magnification and Clinical Significance

OBJECTIVE

The detection of flat colorectal lesions with possible malignant potential has been described by Japanese endoscopists. This study looks at the detection of flat lesions using standard colonoscopic techniques and examines the clinical significance of these lesions.

METHODS

The records of patients who underwent complete colonoscopy by a single colorectal surgeon in an outpatient setting over a 4-year period were reviewed. The site and number of flat lesions and their histology were noted. Patients with incomplete intubation of the colon were excluded.

RESULTS

A total of 491 patients underwent 593 colonoscopic examinations. There were 236 flat lesions identified in 91 patients: 24% (56/236) were adenomas showing mild or moderate dysplasia, and 63% (148/236) were hyperplastic.

CONCLUSIONS

Flat colorectal lesions are common and can be detected without the aid of dye spray and magnification. One-quarter of these lesions are adenomatous and we recommend routine hot biopsy or polypectomy of these lesions.

Proximal versus distal hyperplastic polyps of the colorectum: different lesions or a biological spectrum?

BACKGROUND

Because of their suggested link with microsatellite instability high colorectal cancers, right sided hyperplastic polyps (HPs) may differ from their distally located counterparts. This is highlighted by the recognition of a variant HP, termed sessile serrated adenoma (SSA), which predominates in the proximal colon. HPs displaying the morphological features now associated with SSAs have been shown to have altered expression of "cancer associated" markers, but no studies have investigated whether this is dependent on anatomical location of the polyps.

AIMS

To evaluate morphological and functional features in right versus left sided HPs from patients without colorectal cancer with the aim of identifying distinguishing characteristics.

METHODS

HPs originating in the proximal and distal colorectum were histochemically and immunohistochemically stained to evaluate a panel of markers related to proliferation and differentiation. In addition, a series of morphological features was evaluated for each polyp.

RESULTS

Crypt serration, crypt dilatation, and horizontal crypt growth were more common among HPs from the right side, whereas histochemical factors including mucin changes, global methylation status, and expression of carcinoembryonic antigen were not significantly different. An age disparity was also seen between patients with right versus left sided lesions, with patients with right sided lesions being an average of more than 10 years younger than those with left sided lesions.

CONCLUSIONS

These findings suggest that right and left sided HPs differ mainly in terms of growth regulation rather than cellular differentiation, implying that these lesions belong to a continuous spectrum of serrated polyps that differ quantitatively rather than qualitatively.

Simple and complex genetics of colorectal cancer susceptibility

There are several hereditary conditions associated with an increased risk of colorectal cancer (CRC). These include well-characterized autosomal dominant syndromes, such as familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC). A novel autosomal recessive form of FAP, caused by mutations in the base excision repair gene MYH, has recently been recognized. This discovery has provided further evidence for the importance of DNA repair mechanisms in CRC development, already documented by the involvement of the mismatch repair in HNPCC. Additional CRC-predisposing conditions, such as hyperplastic polyposis and hereditary mixed polyposis syndrome, are being outlined. Heterogeneity of genetic mechanisms has important consequences for counseling and surveillance in hereditary CRC. Nevertheless, classical mendelian conditions represent only a minor share of the total CRC population burden. Alleles of the same genes that are involved in hereditary syndromes might also act as low penetrance variants, as shown for APC 1307K in the Ashkenazi. However, the level of complexity of multifactorial CRC is such that current tools appear inadequate to pinpoint all the involved components. A combination of different strategies, including careful clinical observation, analysis of homogeneous patient populations, and critical evaluation of data derived from experimental models, along with methodological improvements in nucleic acid analysis, will probably be necessary to unravel the basis of nonmendelian CRC. Once this is achieved, it will be possible to realize the ultimate goal of targeted CRC prevention, with the adoption of measures tailored according to individual risk levels. .

Laminin 5 gamma 2 chain expression: a marker of early invasiveness in colorectal adenomas

AIM

Polyps of the colon and rectum are considered to be premalignant lesions in the development of colorectal cancer. However, knowledge of how normal epithelial cells gain invasive properties is limited. Laminin 5 gamma 2 chain expression was investigated to determine the role of laminin 5 as a marker of potential invasiveness in colorectal polyps.

MATERIAL/METHODS

Sixty seven polyps of different types (15 hyperplastic polyps, 12 serrated adenomas, 16 tubular adenomas, and 24 adenomas with a villous component) were assessed for gamma 2 chain expression of laminin 5 by immunohistochemistry on archival, paraffin wax embedded sections.

RESULTS

Ten polyps stained positive and the number of polyps expressing the laminin 5 gamma 2 chain increased significantly as the phenotype of the adenomas became more atypical: none of the 15 hyperplastic polyps, two of the 16 tubular adenomas (12.5%), and six of the 24 adenomas with a villous component (25%) were positive. Two of 12 (17%) serrated adenomas, regarded as a distinct form of colorectal neoplasia, showed gamma 2 chain expression. Furthermore, laminin 5 gamma 2 chain expression correlated with lesion size. Polyps smaller than 10 mm expressed the gamma 2 chain less frequently than did those equal to or larger than 10 mm.

CONCLUSION

Laminin 5 gamma 2 chain expression was found to increase progressively towards a more atypical phenotype of adenoma. The results suggest that, in the future, laminin 5 gamma 2 chain expression may be used as an indicator of incipient malignant transformation of a benign colorectal adenoma.