Morphologic reappraisal of serrated colorectal polyps

Colorectal advanced neoplasms occur through dual carcinogenesis pathways in individuals with coexisting serrated polyps

Background

Individuals with serrated polyps (SP) are at higher risk for synchronous colorectal advanced neoplasms (AN) and cancers. However, it remains unclear whether there is a unique involvement of the serrated pathway and/or the classical adenoma-carcinoma sequence in this setting.

Methods

Colorectal ANs, which include tubular adenomas ≥10 mm, adenomas with villous histology, high-grade intraepithelial neoplasms, and cancers, were collected retrospectively. The groups included ANs with (AN+SP) or without (AN-only) coexisting SPs. Clinicopathological findings were compared between groups. BRAF and KRAS mutations in ANs and SPs, and methylation levels at long interspersed element-1 (LINE-1) in adjacent mucosa were determined by pyrosequencing.

Results

Seventy-five ANs from 40 patients in the AN+SP group, and 179 ANs from 119 patients in the AN-only group were analyzed. There were no significant differences in clinicopathological findings between the two groups, except that intraepithelial neoplasia in the AN+SP group was more likely to be located in the right colon (P = 0.018). BRAF mutations were significantly more frequent in the AN+SP group (P = 0.003), while KRAS mutations showed no significant differences between groups (P = 0.142). The majority of high-grade intraepithelial neoplasms in both groups showed a contiguous component of conventional adenoma. Individuals with large and right-sided SPs had significantly more conventional adenomas compared to those without such SPs (P = 0.027 and P = 0.031, respectively). Adjacent mucosa from individuals with multiple and large SPs showed significantly lower methylation levels at LINE-1 compared to individuals without such associated SPs (P = 0.049 and P = 0.015, respectively).

Conclusion

Our data suggest that both the adenoma-carcinoma sequence and the serrated pathway are operational in individuals with coexisting ANs and SPs. The reduced methylation levels at LINE-1 in the background mucosa suggest the possibility of an underlying ‘field defect’.

A pathologist's survey on the reporting of sessile serrated adenomas/polyps

AIM

The purpose of this survey was to ascertain reporting habits of pathologists towards sessile serrated adenomas/polyps (SSA/P).

METHODS

A questionnaire designed to highlight diagnostic criteria, approach and clinical implications of SSA/P was circulated electronically to 45 pathologists in the UK and North America.

RESULTS

Forty-three of 45 pathologists agreed to participate. The vast majority (88%) had a special interest in gastrointestinal (GI) pathology, had great exposure to GI polyps in general with 40% diagnosing SSA/P at least once a week if not more, abnormal architecture was thought by all participants to be histologically diagnostic, and 11% would make the diagnosis if a single diagnostic histological feature was present in one crypt only, while a further 19% would diagnose SSA/P in one crypt if more than one diagnostic feature was present. The vast majority agreed that deeper sections were useful and 88% did not feel proliferation markers were useful. More than one-third did not know whether, or did not feel that, their clinicians were aware of the implications of SSA/P.

CONCLUSIONS

98% of pathologists surveyed are aware that SSA/P is a precursor lesion to colorectal cancer, the majority agree on diagnostic criteria, and a significant number feel that there needs to be greater communication and awareness among pathologists and gastroenterologists about SSA/P.

Pathological features of the sessile serrated adenoma/polyp with special references of its carcinogenesis

The sessile serrated adenoma/polyp (SSA/P) has been thought as the relatively new precursor for the colorectal cancer. In the current review, the well-known pathological features including the histological definition of the SSA/P are described using the previous reports. Although the SSA/P is thought one of pre-cancerous lesions of the colorectal carcinoma, the decisive or documentary lesion like "carcinoma in adenoma" is very rare. In this review, the strict case of the carcinoma derived from the SSA/P is demonstrated using our cases. Although the genetic investigations of the SSA/P have shown the new pathway of colorectal carcinogenesis and these concepts are thought to be almost right, the verification for them should be performed using "the carcinoma in SSA/P" like the present case.

The CIMP Phenotype in BRAF Mutant Serrated Polyps from a Prospective Colonoscopy Patient Cohort

Colorectal cancers arising via the serrated pathway are often associated with BRAF V600E mutation, CpG island methylator phenotype (CIMP), and microsatellite instability. Previous studies have shown a strong association between BRAF V600E mutation and serrated polyps. This study aims to evaluate CIMP status of all the serrated polyp subtypes and its association with functionally important genes such as MLH1, p16, and IGFBP7. CIMP status and methylation were evaluated using the real-time based MethyLight assay in 154 serrated polyps and 63 conventional adenomas. Results showed that CIMP-high serrated polyps were strongly associated with BRAF mutation and proximal colon. CIMP-high was uncommon in conventional adenomas (1.59%), occurred in 8.25% of hyperplastic polyps (HPs), and became common in sessile serrated adenomas (SSAs) (51.43%). MLH1 methylation was mainly observed in the proximal colon and was significantly associated with BRAF mutation and CIMP-high. The number of samples methylated for p16 and IGFBP7 was the highest in SSAs. The methylation panel we used to detect CIMP is highly specific for CIMP-high cancers. With this panel, we demonstrate that CIMP-high is much more common in SSAs than HPs. This suggests that CIMP-high correlates with increased risk of malignant transformation which was also observed in methylation of functionally important genes.

Critical appraisal of the diagnosis of the sessile serrated adenoma

The sessile serrated adenoma (SSA) is a relatively recently described polyp that can present diagnostic difficulties for the practicing pathologist. The frequency of SSA diagnoses varies dramatically in the reported literature. In addition, the histologic interface between the microvesicular hyperplastic polyp (MVHP) and the SSA continues to be a diagnostic problem. The trend in recent years has been toward a lower threshold for SSA diagnosis. Herein, we have performed a cross-sectional study of 6340 colorectal polyps received at a high-volume community-based pathology practice over a 3-month period. After central review, with strict application of the diagnostic criteria outlined in the 2010 edition of the World Health Organization Classification of Tumours of the Digestive Tract, we found that SSAs represented 12.1% of all polyps. In addition, we developed novel diagnostic subcategories in an attempt to determine the most appropriate cutoff for the interface between the MVHP and the SSA. We found that serrated polyps (MVHPs or SSAs) with any SSA-like crypts had clinical features more in common with the SSA than the MVHP and that this diagnostic cutoff showed good reproducibility between pathologists. This supports the position of a recent consensus publication proposing that polyps with as few as 1 SSA-type crypt should be diagnosed as an SSA. Applying these criteria to our cohort yields an overall SSA rate of 14.7%. In summary, we believe that SSAs continue to be underdiagnosed in pathologic practice and that this may result in inadequate surveillance and thus contribute to interval colorectal carcinomas.

Serrated polyps detected during screening colonoscopies

AIM OF THE STUDY

It is estimated that between 15% and 35% of sporadic colorectal cancers (CRC) developing from adenomas come from serrated polyps. Currently, the most effective method used to prevent CRC is the removal of adenomas, including serrated polyps, during colonoscopy. The aim of this paper is to analyze the changes characterized as serrated polyps and detected during screening colonoscopies performed as part of the Screening Program for Early Colorectal Cancer Detection (SPED).

MATERIAL AND METHODS

In our center, as part of the nationwide SPED between 2000 and 2009, 1,442 screening colonoscopies were performed.

RESULTS

Serrated polyps were found in 11.9% of all patients and in 45.8% of patients who had polyps removed by endoscopy. In screening colonoscopy of the large intestine, the following polyps were found most frequently: hyperplastic, < 1 cm, without a stalk, multiple, located in the distal part of the large intestine, in men and in patients with a first-degree relative with a history of abdominal cancer. Detecting and removing polyps was facilitated by the fact that the cecum was intubated and the bowel preparation had been performed either very well or well. The detection rate of serrated polyps was not influenced by patients' place of residence or their age.

CONCLUSIONS

Serrated polyps constitute a frequent, and very frequent among removed polyps, abnormality detected during screening colonoscopy.

Endoscopic diagnosis of sessile serrated adenoma

Sessile serrated adenoma (SSA) is a special type of serrated adenoma, and recent studies have found that SSA has a malignant potential, progresses quickly and is closely related to right-sided colorectal cancer. SSA is usually located in the proximal colon, which is flat and sessile, and for this reason, SSA is difficult to find by conventional endoscopy and has a high rate of missed diagnosis. There is currently an urgent need to develop new endoscopic technologies to raise the diagnosis rate. In this paper, we will review recent progress in the diagnosis of sessile serrated adenoma using new endoscopic technologies.

Prevalence and molecular characterisation of the sessile serrated adenoma in a subset of the Chinese population

AIMS

The incidence and mortality rates from right-sided colorectal cancers (CRCs) have not decreased in recent years. It is very likely that a significant proportion of these cancers evolve from undetected sessile serrated adenomas (SSAs). The prevalence and molecular features of the SSAs in the Chinese population have seldom been investigated.

METHODS

We retrospectively reviewed the colonoscopy database and pathology archives in our medical centre. Adenomatous polyposis coli (APC) and β-catenin expressions were examined in 28 right hyperplastic polyps (RHPs) and 21 SSAs by immunohistochemical staining. The mutations of BRAF, KRAS, APC and β-CATENIN were analysed by direct sequencing. The methylation status of APC promoter in these polyps was analysed by methylation-specific PCR and bisulfite sequencing. Samples of left hyperplastic polyps, traditional adenomas and CRC were used as controls.

RESULTS

SSAs accounted for 4.9% of serrated polyps and 1.0% of all colorectal polyps. BRAF((V600E)) mutations were found in 14.3% of SSAs and 7.1% of RHPs. Nuclear accumulation of β-catenin was seen in 28.6% of SSAs and 17.9% of RHPs. APC mutations were detected in 57.1% of SSAs and 67.9% of RHPs. APC methylation was detected in 14.3% of RHPs and 23.8% of SSAs.

CONCLUSIONS

The prevalence of SSAs in a subset of the Chinese population is much lower than that in the Western population. BRAF((V600E)) mutation is not a frequent event in right colon serrated polyps in a subset of the Chinese population. APC mutation is possibly the main cause for the Wnt signalling activation in right colon serrated polyps.

RNA sequencing of sessile serrated colon polyps identifies differentially expressed genes and immunohistochemical markers

BACKGROUND

Sessile serrated adenomas/polyps (SSA/Ps) may account for 20-30% of colon cancers. Although large SSA/Ps are generally recognized phenotypically, small (<1 cm) or dysplastic SSA/Ps are difficult to differentiate from hyperplastic or small adenomatous polyps by endoscopy and histopathology. Our aim was to define the comprehensive gene expression phenotype of SSA/Ps to better define this cancer precursor.

RESULTS

RNA sequencing was performed on 5' capped RNA from seven SSA/Ps collected from patients with the serrated polyposis syndrome (SPS) versus eight controls. Highly expressed genes were analyzed by qPCR in additional SSA/Ps, adenomas and controls. The cellular localization and level of gene products were examined by immunohistochemistry in syndromic and sporadic SSA/Ps, adenomatous and hyperplastic polyps and controls. We identified 1,294 differentially expressed annotated genes, with 106 increased ≥10-fold, in SSA/Ps compared to controls. Comparing these genes with an array dataset for adenomatous polyps identified 30 protein coding genes uniquely expressed ≥10-fold in SSA/Ps. Biological pathways altered in SSA/Ps included mucosal integrity, cell adhesion, and cell development. Marked increased expression of MUC17, the cell junction protein genes VSIG1 and GJB5, and the antiapoptotic gene REG4 were found in SSA/Ps, relative to controls and adenomas, were verified by qPCR analysis of additional SSA/Ps (n = 21) and adenomas (n = 10). Immunohistochemical staining of syndromic (n≥11) and sporadic SSA/Ps (n≥17), adenomatous (n≥13) and hyperplastic (n≥10) polyps plus controls (n≥16) identified unique expression patterns for VSIG1 and MUC17 in SSA/Ps.

CONCLUSION

A subset of genes and pathways are uniquely increased in SSA/Ps, compared to adenomatous polyps, thus supporting the concept that cancer develops by different pathways in these phenotypically distinct polyps with markedly different gene expression profiles. Immunostaining for a subset of these genes differentiates both syndromic and sporadic SSA/Ps from adenomatous and hyperplastic polyps.

Competition in Colon Cancer Screening? What Is the Role of Colonoscopy?

BACKGROUND

Colorectal cancer (CRC) is one of the leading causes of cancer-related death in the Western world. The incidence could be reduced if this cancer were to be diagnosed at an early stage of disease. A competition has started between the existing screening methods to be the most efficient in detecting premalignant conditions. This review illustrates the current state of screening techniques for CRC.

METHOD

Pubmed was searched for meta-analyses and prospective studies on screening for CRC, with an emphasis on colonography, computed tomographic colonography (CTC), magnetic resonance colonography (MRC), stool DNA testing, and colon capsule endoscopy, and critical appraisal of the research was done by the reviewers.

RESULTS

The imaging techniques (CTC and MRC) had similar detection rates for bigger lesions (≥10 mm) as colonoscopy. High-definition colonoscopy showed better efficiency with smaller lesions. The techniques developing around colonoscopy such as the retro-viewing colonoscope, the balloon colonoscope, or the 330-degree viewing colonoscope try to enhance efficacy by reducing the adenoma miss rate in right-sided, non-polypoid lesions. Colon capsule endoscopy and the stool detection systems are limited to identifying cancer but not necessarily adenomas.

CONCLUSION

Colonoscopy is the preferred CRC screening strategy and the undisputed gold standard in terms of efficacy.

Contrast coating for the surface of flat polyps at CT colonography: a marker for detection

OBJECTIVES

To assess the frequency of oral contrast coating of flat polyps, which may promote detection, and influencing factors within a screening CT colonography (CTC) population.

METHODS

This was a retrospective, observational study performed at one institution. From 7,426 individuals, 123 patients with 160 flat polyps were extracted. Flat polyps were defined as plaque-like, raised at most 3 mm in height and reviewed for contrast coating. Factors including demographic variables such as age and sex, and polyp variables such as polyp size, location and histology were analysed for effect on coating.

RESULTS

Of 160 flat polyps (mean size 9.4 mm ± 3.6), 78.8 % demonstrated coating. Mean coat thickness was 1.5 mm ± 0.6; 23.8 % (n = 30) demonstrated a thin film of contrast. Large size (≥10 mm) and proximal colonic location (relative to splenic flexure) were predictive variables by univariate logistic regression [OR (odds ratio) 3.4 (CI 1.3-8.9; p = 0.011), 2.0 (CI 1.2-3.5; p = 0.011), respectively]. Adenomas (OR 0.37, CI 0.14-1.02; p = 0.054) and mucosal polyps or venous blebs (OR 0.07, CI 0.02-0.25; p < 0.001) were less likely to coat than serrated/hyperplastic lesions. Age and sex were not predictive for coating (p = 0.417, p = 0.499, respectively).

CONCLUSIONS

Surface contrast coating is common for flat polyps at CTC, promoted by large size, proximal location and serrated/hyperplastic histology. Given the difficulty in detection, recognition may aid in flat polyp identification.

KEY POINTS

• Oral contrast coats the surface of most flat colorectal polyps at CT colonography. • Large size, proximal colonic location and serrated/hyperplastic histology increase polyp coating. • Contrast coating increases diagnostic confidence for flat polyps. • Contrast coating may help in flat polyp detection at CTC.

Advanced imaging in colonoscopy and its impact on quality

Detecting and resecting colonic polyps during endoscopy has been shown to reduce CRC. At the same time, endoscopy has faced substantial technical improvements and continues to undergo major changes. Detection of colorectal neoplasias is facilitated by using high-definition endoscopy, and characterization of lesions is more accurate by using virtual CE. High-definition endoscopy has found widespread use, whereas virtual CE is still more often used in tertiary centers and for high-risk patient groups. Endomicroscopy has opened the door for in vivo histology and functional as well as molecular imaging. Thorough training of the endoscopists is necessary, and redefined reimbursement codes may help make these techniques available in the clinical arena for high-risk patients who are most probable to benefit from the more advanced diagnostic endoscopy techniques. Over recent years, there has also been an increasing push by healthcare payors and providers to improve the quality of healthcare services. The ultimate goal of monitoring quality measures is to improve the overall health of the population and, for colon cancer screening, to reduce the incidence and mortality of colon cancer. However, the development of an appropriate quality measure and ensuring the accuracy of the data on which we base our efforts are among the first challenges that we must meet (Table 1). The continued technologic advancements in colonoscopy and endoscopic imaging may result in improvements in the quality of colonoscopy and should lead to a decrease in the incidence and mortality from colon cancer.

Improved molecular classification of serrated lesions of the colon by immunohistochemical detection of BRAF V600E

BRAF V600E mutation in serrated lesions of the colon has been implicated as an important mutation and as a specific marker for the serrated carcinogenic pathway. Recent findings point to microvesicular hyperplastic polyps that have similar histologic and molecular features to sessile serrated adenomas/polyps, as potential colorectal carcinoma precursors. The aim of this study was to evaluate BRAF V600E mutation status by immunohistochemistry in serrated lesions of the colon with regard to histomorphology. We investigated 194 serrated lesions of the colon, comprising 42 sessile serrated adenomas/polyps, 16 traditional serrated adenomas, 136 hyperplastic polyps and 20 tubular/tubulovillous adenomas (conventional adenomas) with the novel BRAF V600E mutation-specific antibody VE1. In addition, BRAF exon 15 and KRAS exon 2 status was investigated by capillary sequencing in selected cases. All sessile serrated adenomas/polyps (42/42, 100%), 15/16 (94%) traditional serrated adenomas and 84/136 (62%) hyperplastic polyps were VE1+. None of the VE1- serrated lesions showed BRAF V600E mutation. Forty out of 42 (95%) sessile serrated adenomas/polyps displayed areas with microvesicular hyperplastic polyp-like features. In microvesicular hyperplastic polyps, VE1 positivity was significantly associated with nuclear atypia (P=0.003); however, nuclear atypia was also present in VE1- cases. Immunostaining with VE1 allows not only the detection of BRAF V600E mutation but also the correlation with histomorphology on a cellular level in serrated lesions. VE1 enables a subclassification of microvesicular hyperplastic polyps according to the mutation status. This improved classification of serrated lesions including immunohistochemical evaluation of BRAF V600E mutation may be the key to identify lesions with higher potential to progression into sessile serrated adenoma/polyp, and further to BRAF V600E-mutated colorectal cancer.

Detection rate of colorectal adenoma or cancer in unselected colonoscopy patients: Indonesian experience in a private hospital

BACKGROUND

Colorectal cancer is currently the third most common cancer in Indonesia, yet colonoscopy--the most accepted mode of screening to date--is not done routinely and national data are still lacking.

OBJECTIVE

To determine the detection rate of colorectal cancers and adenomas in unselected patients undergoing colonoscopy for various large bowel symptoms at the Digestive Disease and GI Oncology Centre, Medistra Hospital in Jakarta, Indonesia.

MATERIALS AND METHODS

Colonoscopy data from January 2009 to December 2012 were reviewed. New patients referred for colonoscopy were included. Data collected were patient demographic and significant colonoscopy findings such as the presence of hemorrhoids, colonic polyps, colonic diverticula, inflammation, and tumor mass. Histopathological data were obtained for specimens taken by biopsy. Associations between categorical variables were analyzed using chi-square test, while mean differences were tested using the t-test.

RESULTS

A total of, 1659 cases were included in this study, 889 (53.6%) of them being men. Polyps or masses were found in 495 (29.8%) patients while malignancy was confirmed in 74 (4.5%). Patients with a polyp or mass were significantly older (60.2 vs 50.8 years; p<0.001; t-test) and their presence was significantly associated with male gender (35.0% vs 23.9%; prevalent ratio [PR] 1.71; 95% confidence interval [CI] 1.38-2.12; p<0.001) and age>50 years (39.6% vs 16.6%; PR 3.29; 95% CI 2.59-4.12; p<0.001). Neoplastic lesions was found in 257 (16.1%), comprising 180 (11.3%) adenomas, 10 (0.6%) in situ carcinomas, and 67 (4.2%) carcinomas.

CONCLUSIONS

Polyps or masses were found in 30% of colonoscopy patients and malignancies in 16.1%. These figures do not represent the nation-wide demographic status of colorectal cancer, but may reflect a potentially increasing major health problem with colorectal cancer in Indonesia.

Advances in diagnostic and therapeutic colonoscopy

PURPOSE OF REVIEW

We review current studies on endoscopic and technologic advances for the detection and treatment of colorectal neoplasia.

RECENT FINDINGS

Improvements in adenoma detection have been shown to be possible with the use of high definition white light as well as water-related methods such as water exchange. Use of cap assist colonoscopy, when combined with water-related methods, has recently been shown to also improve the detection of adenomas. Narrow band imaging and confocal laser endomicroscopy may have an advantage of offering endoscopists the ability to make an 'optical diagnosis' with the possibility of discarding nonadenomatous tissue. Furthermore, educational interventions aimed at improving adenoma detection may have lasting effects on endoscopists' adenoma detection rates. Lastly, endoscopic mucosal resection and endoscopic submucosal dissection are being applied for the treatment of large colorectal polyps, obviating the need for surgery in most instances. However, further studies are needed to establish the optimal methods for polyp resection.

SUMMARY

Advances in endoscopic technology are being shown to enhance the detection of early cancers and precancerous lesions. However, these tools may be supplementary to a high-quality colonoscopy using excellent techniques, factors that are now being implemented in training programs.

Colonoscopic characteristics of serrated adenomas

AIM: To investigate the morphologic features of serrated adenomas (SA) by regular high-resolution colonoscopy with narrow band imaging (NBI).

METHODS: A retrospective analysis was performed of the imaging data for patients with colorectal SA who underwent colonoscopy between March 2010 and June 2013. A comparison of colonoscopic features was made between SA and hyperplastic polyps (HP) with comparable predicted diameter.

RESULTS: A total of 50 SA from 35 patients and 50 HP from 42 patients were included. More SA were located in the right colon than in the left colon (48% vs 36%, P > 0.05). Type IIa or laterally spreading tumors (LST) were more commonly seen in SA (P = 0.019) and II-O pit pattern was more commonly seen in HP (P = 0.000). SA more frequently showed the features of vague margins, irregular shape, cloud-like surface and dark bleeding spots in crypts (all P < 0.001). The sensitivities of II-O pit pattern, cloud-like surface, indistinct border, irregular shape and dark bleeding spots in the crypts for predicting SA were 44%, 92%, 30%, 66% and 76%, respectively, and the specificities were 98%, 98%, 98%, 94% and 92%, respectively. The sensitivity and specificity of the presence of three or more above characteristics for predicting SA were 80% and 100%, respectively.

CONCLUSION: SA have certain colonoscopic features, which can aid in differentiating SA from HP.

Optical biopsy of sessile serrated adenomas: do these lesions resemble hyperplastic polyps under narrow-band imaging?

BACKGROUND

Serrated colorectal lesions include hyperplastic polyps (HPs) and sessile serrated adenomas (SSAs). Optical biopsy could misclassify SSAs as unimportant if they resemble HPs.

OBJECTIVE

To explore the narrow-band imaging (NBI) features of SSAs. We hypothesized that SSAs resemble HPs under NBI.

DESIGN

Retrospective analysis of data from our prospective study of NBI in routine practice.

SETTING

Single specialty group.

PATIENTS

Patients undergoing colonoscopy.

INTERVENTION

Colonoscopy.

MAIN OUTCOME MEASUREMENTS

Polyp histology prediction by community gastroenterologists. Features of SSAs versus HPs and adenomas by using the Narrow-Band Imaging International Colorectal Endoscopic (NICE) Classification.

RESULTS

Among 2388 lesions, 141 were diagnosed on pathology as SSAs, 465 as HPs, and 1546 as adenomas. Each individual NICE feature of HPs was found in 38% to 42% of SSAs, 66% to 67% of HPs, and 15% to 20% of adenomas (P < .001 for each). Each individual NICE feature of adenomas was found in 57% to 62% of SSAs, 33% to 34% of HPs, and 80% to 84% of adenomas (P < .001 for each). Compared with HPs, SSAs were less likely (odds ratio [OR] 0.74; 95% confidence interval [CI], 0.69-0.79) and adenomas were even less likely (OR 0.62; 95% CI, 0.59-0.64) to have all 3 NICE features of HPs. SSAs >5 mm were more likely than smaller SSAs to have all 3 NICE features of adenomas. SSA location did not predict NBI features. Analyses restricted to high-confidence lesions showed similar results.

LIMITATIONS

The endoscopists were not NBI experts.

CONCLUSION

Community gastroenterologists observed a profile of NICE features among SSAs that was intermediate to the profiles observed for HPs and adenomas. These results require confirmation by NBI experts.

Traditional serrated adenoma of the colorectum: clinicopathologic implications and endoscopic findings of the precursor lesions

OBJECTIVES

To investigate the clinicopathologic and endoscopic features of precursor lesions associated with traditional serrated adenomas (TSAs).

METHODS

Mutation studies for BRAF, KRAS, PIK3CA, and EGFR and immunohistochemical staining for Ki-67 were performed on 107 TSAs from 104 patients.

RESULTS

Nondysplastic hyperplastic polyp (HP) or sessile serrated adenoma/polyp (SSA/P) precursor lesions were found in 56 (52.3%) TSAs, among which 32 (57.1%) cases showed a flat-elevated lesion with a type II pit pattern during endoscopy. TSAs with an SSA/P precursor lesion were usually found in the proximal colon, while TSAs with an HP or with no precursor lesion were mainly located in the distal colon and rectum (P < .001). TSAs with a precursor lesion showed a lower frequency of conventional epithelial dysplasia and KRAS mutation as well as a higher frequency of BRAF mutation compared with those with no precursor lesion (P = .002, P < .001, and P < .001, respectively).

CONCLUSIONS

A significant proportion of HP or SSA/P precursor lesions accompanied by TSAs can be detected by endoscopy based on both their flat-elevated growth and type II pit patterns. The heterogeneity of TSAs in terms of clinicopathologic and molecular features correlated with the status or type of precursor lesions.

Overexpression of regenerating gene Iα appears to reflect aberration of crypt cell compartmentalization in sessile serrated adenoma/polyps of the colon

Background

Colorectal sessile serrated adenoma/polyps (SSA/Ps) are characterized by asymmetrical distribution of Ki67-positive cells, which varies among crypts and involves the crypt length to a variable extent; the pattern has been designated as aberration of crypt cell compartmentalization. The regenerating gene (REG) Iα is a cell growth and/or anti-apoptotic factor and its overexpression might be associated with aberration of crypt cell compartmentalization in SSA/Ps. We investigated REG Iα expression in SSA/Ps in comparison to hyperplastic polyps (HPs).

Methods

A total of 64 cases of serrated polyps (≥10 mm in size), including 53 SSA/Ps and 11 HPs, were included in the present study. Immunostaining was performed using a labeled streptavidin-biotin method. REG Iα expression was classified as follows: (i) expression of endocrine cells: grade 0 (a few positive cells) to 3 (marked increase in positive cells); (ii) expression of goblet cells: grade 0 (negative) to 2 (positive for crypts and surface epithelial cells); (iii) staining intensity of goblet cells: grade 0 (negative) to 2 (strong); (iv) staining intensity of crypt (absorptive) cell membranes: grade 0 (negative) to 2 (strong). The presence of aberration of crypt cell compartmentalization was assessed using Ki67 immunostaining.

Results

With regard to the REG Iα expression of endocrine cells, 8 out of 11 HPs (73%) were grade 0, whereas 51 of 53 SSA/Ps (96%) were grade 1 or higher (p < 0.001). With regard to the distribution of REG Iα-immunoreactive goblet cells, 10 of 11 HPs (91%) were grade 1, whereas 50 of 53 SSA/Ps (94%) were grade 2 (p < 0.001). A similar trend was found in the staining intensity of goblet cells or crypt cell membranes (p = 0.011). Aberration of crypt cell compartmentalization was more frequently identified in SSA/Ps (72%) than in HPs (18%; p = 0.002). A significant association was observed between REG Iα overexpression and the aberration of crypt cell compartmentalization in serrated polyps (p = 0.037).

Conclusions

REG Iα overexpression is a characteristic of SSA/Ps, which appears to reflect aberration of crypt cell compartmentalization.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/7240956081100040

Activation of pro-oncogenic pathways in colorectal hyperplastic polyps

Background

In contrast to sessile serrated adenomas and traditional serrated adenomas which are associated with a significant cancer risk, the role of hyperplastic polyps (HP) in colorectal carcinogenesis as well as the molecular mechanisms underlying their development remain controversial and still need to be clarified. Several reports suggest that a subset of HP may represent precursor lesions of some colorectal cancers. However, biomarkers are needed to identify the subset of HP that may have a malignant potential. The hormone precursor, progastrin (PG) has been involved in colon carcinogenesis and is known to activate pro-oncogenic pathways such as the ERK or the STAT3 pathway. We therefore analyzed PG expression and the activation of these signaling factors in HP.

Methods

We retrospectively analyzed PG expression as well as the phosphorylation of ERK and STAT3 by immunohistochemistry in HP from 48 patients.

Results

Mean percentages of epithelial cells positive for PG or phospho-ERK were respectively, 31% and 33% in HP and were significantly higher in these lesions compared to normal colon (3%, p = 0.0021 and 7%, p = 0.0008, respectively). We found a significant correlation between PG and phospho-ERK expression in HP with ERK activation significantly stronger in lesions with high progastrin expression (p = 0.015). In contrast, STAT3 was not significantly activated in HP compared to normal colon and we did not observe a significant correlation with PG expression.

Conclusions

HP overexpressing PG that have the highest activation of the ERK pathway might reflect less latent lesions that might have a malignant potential.

Clinicopathologic features of hyperplastic/serrated polyposis syndrome in Japan

BACKGROUND AND AIM

Hyperplastic/serrated polyposis syndrome (HPS) is a condition characterized by multiple hyperplastic/serrated colorectal polyps. The risk of colorectal cancer (CRC) is increased in HPS. The clinicopathologic characteristics of HPS in Japanese patients are unknown. The aim of this study is to clarify the clinicopathologic features of HPS in Japanese patients.

METHODS

We retrieved records of patients diagnosed with HPS between April 2008 and March 2011 from the endoscopy database of Hiroshima University Hospital. In addition, we mailed a questionnaire to the hospital's 13 affiliated hospitals in July 2012. Data collected from the database and questionnaires included patient age, sex, number of hyperplastic/serrated polyps and tubular adenomas, size of the largest polyp, polyp location, resection for polyps, coexistence of HPS with CRC, and the diagnostic criterion met.

RESULTS

Of the 73,608 patients who underwent colonoscopy, 10 (0.014%) met the criteria for HPS. The mean age of these patients was 58.3 years, and 6 (60%) were men. No subjects had a first-degree relative with HPS. Four (40%) HPS patients had more than 30 hyperplastic/serrated polyps, and average size of the largest polyp was 19 mm. Three (30%) HPS patients had coexistence of HPS with CRC. In these 3 patients, polyps were observed throughout the colorectum.

CONCLUSIONS

Although HPS was a rare condition in the overall study population, patients with the disease may have high risk of CRC. HPS should be diagnosed correctly and followed up carefully.

Increased expression of α-methylacyl-coenzyme A racemase (AMACR; p504s) and p16 in distal hyperplastic polyps

Background

Hyperplastic polyps (HP) and sessile serrated adenomas (SSA) share morphological similarities. In this immunohistochemical study we chose a panel of potential relevant and promising biomarkers including α-methylacyl-coenzyme A racemase (AMACR; p504s), which is involved in the degradation of branched chained fatty acids derivates, and analysed a cohort of HPs and SSAs in order to identify different immunophenotypes in relation to lesion localisation.

Methods

154 specimen were carefully selected and a micro tissue array (TMA) was constructed. Immunohistochemistry of p16^Ink4a, Ki67, α-methylacyl-coenzyme A racemase (AMACR; p504s), BRAF, CK 20, MLH1 and β-catenin was performed and and immunoexpression was compared among proximal and distal HPs as well as SSAs.

Results

None of the markers revealed a differential expression among HPs and SSAs. However, the study demonstrates a significant overexpression of AMACR (p = 0.004) and p16^Ink4a (p = 0.028) in distal HPs compared to proximal HPs. In addition AMACR overexpression was associated with increased p16^Ink4a immunoexpression (p < 0.001).

Conclusions

In this study we describe differential AMACR and p16^Ink4a in HPs in relation to their localisation. Distal HPs were characterized by AMACR and p16^Ink4a overexpression in contrast to proximal HPs, although morphological identically. Thus AMACR overexpression points towards a pathobiological relevance of the protein in distal HPs. In context of recently published data this suggest distal HPs as potential precursor lesions of certain adenoma subtypes. However, at this point of time this finding remains speculative and needs to be confirmed by further studies.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1836116001066768

Gene expression profiling of serrated polyps identifies annexin A10 as a marker of a sessile serrated adenoma/polyp

Sessile serrated adenomas/polyps (SSA/Ps) are precursors of colon cancer, particularly those that exhibit microsatellite instability. Distinguishing SSA/Ps from the related, but innocuous, microvesicular hyperplastic polyp (MVHP) can be challenging. In this study seven gastrointestinal pathologists reviewed 109 serrated polyps and identified 60 polyps with histological consensus. Microarray analysis was performed on six distal consensus MVHPs < 9 mm, six proximal consensus SSA/Ps > 9 mm, and six normal colon biopsies (three proximal, three distal). Comparative gene expression analysis confirmed the close relationship between SSA/Ps and MVHPs as there was overlapping expression of many genes. However, the gene expression profile in SSA/Ps had stronger and more numerous associations with cancer-related genes compared with MVHPs. Three genes (TFF2, FABP6, and ANXA10) were identified as candidates whose expression can differentiate SSA/Ps from MVHPs, and the differences in expression were confirmed by quantitative RT-PCR. As ANXA10 showed the most promise in differentiating these polyps, the expression of ANXA10 was evaluated by immunohistochemistry in consensus SSA/Ps (n = 26), MVHPs (n = 21), and normal colon (n = 9). Immunohistochemical expression of ANXA10 was not identified in separate samples of normal colon or in the normal colonic epithelium adjacent to the serrated polyps. Consistent with the microarray and quantitative RT-PCR experiments, immunohistochemical expression of ANXA10 was markedly increased in SSA/Ps compared to MVHPs (p < 0.0001). An ANXA10 score ≥ 3 has a sensitivity of 73% and a specificity of 95% in the diagnosis of an SSA/P. In conclusion, we show that SSA/Ps and MVHPs have significant overlap in gene expression, but also important differences, particularly in cancer-related pathways. Expression of ANXA10 may be a potential marker of the serrated pathway to colon cancer.

Sessile serrated adenomas in the proximal colon are likely to be flat, large and occur in smokers

AIM

To examine the epidemiology and the morphology of the proximal sessile serrated adenomas (SSAs).

METHODS

We conducted a retrospective study to identify patients with SSAs using a university-based hospital pathology database query from January 2007 to April 2011. Data collected included: age, gender, ethnicity, body mass index, diabetes, smoking, family history of colorectal cancer, aspirin, and statin use. We collected data on morphology of SSAs including site (proximal or distal), size, and endoscopic appearance (flat or protuberant). We also compared proximal SSAs to proximal tubular adenomas detected during same time period.

RESULTS

One hundred and twenty patients with SSAs were identified: 61% were distal and 39% were proximal SSAs. Proximal SSAs were more likely to be flat than distal (100% vs 78% respectively; P = 0.0001). Proximal SSAs were more likely to occur in smokers (OR = 2.63; 95%CI: 1.17-5.90; P = 0.02) and in patients with family history of colorectal cancer (OR = 4.72; 95%CI: 1.43-15.55; P = 0.01) compared to distal. Proximal SSAs were statistically more likely to be ≥ 6 mm in size (OR = 2.94; P = 0.008), and also more likely to be large (≥ 1 cm) (OR = 4.55; P = 0.0005) compared to the distal lesions. Smokers were more likely to have proximal (P = 0.02), flat (P = 0.01) and large (P = 0.007) SSAs compared to non-smokers. Compared to proximal tubular adenomas, proximal SSAs were more likely to be large and occur in smokers.

CONCLUSION

Proximal SSAs which accounted for two-fifths of all SSAs were more likely to present as flat lesions, larger SSAs, and were more likely to occur in smokers and in patients with family history of colorectal cancer. Our data has implications for colorectal cancer screening.

Female-specific rectal carcinogenesis in cyclin D1b transgenic mice

Human cyclin D1 generates two major isoforms via alternative splicing: cyclin D1a and cyclin D1b. Cyclin D1b is hardly expressed in normal tissues but is frequently expressed in certain types of cancer tissues. To clarify the oncogenic potential of cyclin D1b variant, we developed cyclin D1b transgenic (Tg) mice and analyzed their phenotypes. We detected rectal tumors in 63% (15/24) of the female Tg mice. All rectal tumors had the histological characteristics similar to human sessile serrated adenoma/polyps (SSA/Ps). Adenocarcinomas were also found in 53% (8/15) of the rectal tumors, suggesting that these adenocarcinomas originated from the SSA/P-like lesions. No rectal tumors were found in the ovariectomized female cyclin D1b Tg mice (0/10), indicating that ovarian hormones played a critical role in rectal carcinogenesis in these Tg mice. Both phosphorylation of Erk, without activating MEK, and expression of estrogen receptor β were elevated in the rectal tumors of female cyclin D1b Tg mice compared with normal rectums of female wild-type mice. In addition, we established a cell line, D1bTgRT, derived from a rectal cancer of female Tg mouse. Small interfering RNA-induced cyclin D1b knockdown in this cell line suppressed Erk phosphorylation, anchorage-independent growth, cell invasiveness and tumorigenicity in nude mice. In humans, expression of cyclin D1b messenger RNA was detected in 17% (1/6) of colorectal cancer cell lines and 9.7% (3/31) of colorectal cancer tissues. Taken together, these results indicate that cyclin D1b expression contributes to the female- specific rectal carcinogenesis in mouse model.

Endoscopic features of colorectal serrated lesions using image-enhanced endoscopy with pathological analysis

OBJECTIVE

To clarify of the features of sessile serrated adenoma/polyp (SSA/P) observed with image-enhanced endoscopy using immunohistochemical staining.

MATERIALS AND METHODS

Twenty-five hyperplastic polyps (HP) and 46 SSA/P were studied with autofluorescence imaging (AFI) and magnifying endoscopy with narrow-band imaging (ME-NBI). AFI color change, capillary dilatation, existence of a mucous layer on the tumor surface, and pit dilatation under ME-NBI were examined retrospectively. Immunohistochemical staining was performed with the proliferation-associated antigen MIB-1 (Ki-67).

RESULTS

Using AFI, a magenta color was observed in 32% of HP and 44% of SSA/P. With NBI observation, capillary dilatation was observed in 4% of HP and 11% of SSA/P, a mucous cap was observed in 60% of HP and 94% of SSA/P, and pit dilatation was observed in 28% of HP and 80% of SSA/P. When magenta color, capillary dilatation, mucous cap, and pit dilatation were used for the differential diagnosis of SSA/P from HP, the sensitivity, specificity, and accuracy were 43, 68, and 52% for AFI, respectively, 10, 96, and, 41% for capillary dilatation, respectively, 94, 40, and 75% for mucous cap, respectively, and 80, 72, and 78% for pit dilatation, respectively. Compared with HP, MIB-1-positive cells were more frequently distributed in the gland's intermediate zone in SSA/P.

CONCLUSION

The biological malignant potential of SSA/P could be higher compared with HP as suggested by the MIB-1 stain. Therefore, endoscopic differentiation of SSA/P from HP is important, and the findings of a mucous cap and dilatated pit might be helpful for the differentiation of SSA/P from HP.

Relationship of colonoscopy-detected serrated polyps with synchronous advanced neoplasia in average-risk individuals

BACKGROUND

Serrated cancers account for 10% to 20% of all colorectal cancers (CRC) and more than 30% of interval cancers. The presence of proximal serrated polyps and large (≥10 mm) serrated polyps (LSP) has been correlated with colorectal neoplasia.

OBJECTIVE

To evaluate the prevalence of serrated polyps and their association with synchronous advanced neoplasia in a cohort of average-risk population and to assess the efficacy of one-time colonoscopy and a biennial fecal immunochemical test for reducing CRC-related mortality. This study focused on the sample of 5059 individuals belonging to the colonoscopy arm.

DESIGN

Multicenter, randomized, controlled trial.

SETTING

The ColonPrev study, a population-based, multicenter, nationwide, randomized, controlled trial.

PATIENTS

A total of 5059 asymptomatic men and women aged 50 to 69 years.

INTERVENTION

Colonoscopy.

MAIN OUTCOME MEASUREMENTS

Prevalence of serrated polyps and their association with synchronous advanced neoplasia.

RESULTS

Advanced neoplasia was detected in 520 individuals (10.3%) (CRC was detected in 27 [0.5%] and advanced adenomas in 493 [9.7%]). Serrated polyps were found in 1054 individuals (20.8%). A total of 329 individuals (6.5%) had proximal serrated polyps, and 90 (1.8%) had LSPs. Proximal serrated polyps or LSPs were associated with male sex (odds ratio [OR] 2.08, 95% confidence interval [CI], 1.76-4.45 and OR 1.65, 95% CI, 1.31-2.07, respectively). Also, LSPs were associated with advanced neoplasia (OR 2.49, 95% CI, 1.47-4.198), regardless of their proximal (OR 4.15, 95% CI, 1.69-10.15) or distal (OR 2.61, 95% CI, 1.48-4.58) locations. When we analyzed subtypes of serrated polyps, proximal hyperplasic polyps were related to advanced neoplasia (OR 1.61, 95% CI, 1.13-2.28), although no correlation with the location of the advanced neoplasia was observed.

LIMITATIONS

Pathology criteria for the diagnosis of serrated polyps were not centrally reviewed. The morphology of the hyperplasic polyps (protruded or flat) was not recorded. Finally, because of the characteristics of a population-based study carried out in average-risk patients, the proportion of patients with CRC was relatively small.

CONCLUSION

LSPs, but not proximal serrated polyps, are associated with the presence of synchronous advanced neoplasia. Further studies are needed to determine the risk of proximal hyperplastic polyps.

A genetic progression model of Braf(V600E)-induced intestinal tumorigenesis reveals targets for therapeutic intervention

We show that BRAF(V600E) initiates an alternative pathway to colorectal cancer (CRC), which progresses through a hyperplasia/adenoma/carcinoma sequence. This pathway underlies significant subsets of CRCs with distinctive pathomorphologic/genetic/epidemiologic/clinical characteristics. Genetic and functional analyses in mice revealed a series of stage-specific molecular alterations driving different phases of tumor evolution and uncovered mechanisms underlying this stage specificity. We further demonstrate dose-dependent effects of oncogenic signaling, with physiologic Braf(V600E) expression being sufficient for hyperplasia induction, but later stage intensified Mapk-signaling driving both tumor progression and activation of intrinsic tumor suppression. Such phenomena explain, for example, the inability of p53 to restrain tumor initiation as well as its importance in invasiveness control, and the late stage specificity of its somatic mutation. Finally, systematic drug screening revealed sensitivity of this CRC subtype to targeted therapeutics, including Mek or combinatorial PI3K/Braf inhibition.

Simple clinical risk score identifies patients with serrated polyps in routine practice

Large, proximal, or dysplastic (LPD) serrated polyps (SP) need accurate endoscopic recognition and removal as these might progress to colorectal cancer. Herewith, we examined the risk factors for having ≥1 LPD SP. We developed and validated a simple SP risk score as a potential tool for improving their detection. We reviewed clinical, endoscopic, and histologic features of serrated polyps in a study of patients undergoing elective colonoscopy (derivation cohort). A self-administered questionnaire was obtained. We conducted logistic regression analyses to identify independent risk factors for having ≥1 LPD SP and incorporated significant variables into a clinical score. We subsequently tested the performance of the SP score in a validation cohort. We examined 2,244 patients in the derivation and 2,402 patients in the validation cohort; 6.3% and 8.2% had ≥1 LPD SP, respectively. Independent risk factors for LPD SPs were age of more than 50 years [OR 2.2; 95% confidence interval (CI), 1.3-3.8; P = 0.004], personal history of serrated polyps (OR 2.6; 95% CI, 1.3-4.9; P = 0.005), current smoking (OR 2.2; 95% CI, 1.4-3.6; P = 0.001), and nondaily/no aspirin use (OR 1.8; 95% CI, 1.1-3.0; P = 0.016). In the validation cohort, a SP score ≥5 points was associated with a 3.0-fold increased odds for LPD SPs, compared with patients with a score <5 points. In the present study, age of more than 50 years, a personal history of serrated polyps, current smoking, and nondaily/no aspirin use were independent risk factors for having LPD SPs. The SP score might aid the endoscopist in the detection of such lesions.

Suppression of colon carcinogenesis by targeting Notch signaling

Recent studies have shown that aberrant Notch signaling contributes to the pathogenesis of colorectal cancer (CRC). However, the potential therapeutic benefits of Notch pathway inhibitors, including gamma-secretase inhibitors (GSIs) on colon carcinogenesis are still unclear. In this study, the effects of the GSI, N-[N-3,5-difluorophenacetyl]-L-alanyl-S-phenylglycine methyl ester (DAPM) on colon carcinogenesis were investigated. In vitro, DAPM suppressed cell proliferation and induced the expression of Krüppel-like factor 4 (KLF4) and p21 in human colon cancer cells. Interestingly, p21-null HCT 116 cells were largely resistant to the suppressive effects of DAPM on cell proliferation compared with the parental cells. To investigate the effects of DAPM in vivo, colonoscopy was performed to establish the presence of colon tumors 9 weeks after azoxymethane treatment. After tumors were identified, mice were injected intraperitoneally every other day with either DAPM or vehicle for 4 weeks. The frequency of both large (>4mm) and small (<1mm) colon tumors was significantly reduced by DAPM treatment. Colon tumors in the DAPM-treated mice displayed increased levels of KLF4 and p21, accompanied by reduced Ki-67 staining compared with controls. Notably, in human colon tumor biopsies, KLF4 and p21 expressions were present within hyperplastic polyps, but the levels of both proteins were markedly reduced in tubular adenomas. Our results suggest that inhibition of Notch signaling by DAPM provides a potential chemopreventive strategy for patients with tubular adenomas, in part via activation of the KLF4-p21 axis.

Expression of olfactomedin 4 and claudin-18 in serrated neoplasia of the colorectum: a characteristic pattern is associated with sessile serrated lesion

AIMS

Olfactomedin 4 is a useful marker for stem cells in the intestine and is an independent prognostic molecule for survival in patients with colorectal cancer (CRC). Claudin-18, a component of tight junctions, correlates with poor survival in patients with CRC and is associated with the gastric phenotype. We investigated the possible usefulness of these molecules in serrated neoplasia of the colorectum.

METHODS AND RESULTS

We performed immunohistochemical analysis of colorectal polyps, including hyperplastic polyps (HP), sessile serrated lesions (SSL), traditional serrated adenomas (TSA) and conventional adenomas (CA). We also investigated the association between expression of these molecules and clinicopathological parameters in serrated adenocarcinoma (SAC) and non-SAC of the colorectum. Olfactomedin 4 expression was not detected or was decreased in SSL compared with the other polyp types. Claudin-18 expression was higher in SSL than in the other types. Similarly, positivity for olfactomedin 4 in SAC was significantly lower than that in non-SAC, and positivity for claudin-18 in SAC was significantly higher than that in non-SAC. Furthermore, claudin-18-positive SAC showed more advanced N grade and stage than claudin-18-negative SAC.

CONCLUSIONS

Reduced expression of olfactomedin 4 and ectopic expression of claudin-18 might be useful markers in the differential diagnosis of serrated polyps.

Advanced precancerous lesions (APL) in the colonic mucosa

Colorectal cancer is a leading cause of cancer death worldwide. Most colorectal cancers are preventable. Surveillance colonoscopy is used to detect and remove precancerous lesions. Although the majority of precancerous lesions develop sporadically, some have an inherited component. In this review, we summarize the clinical, pathologic, and molecular features of advanced precancerous lesions of the colon. The most common and clinically important intestinal polyposis syndromes, and their genetics, are also discussed. Finally, current recommendations regarding the treatment and surveillance of precancerous lesions, both in the sporadic and in inherited setting, are reviewed.

Prevalence of adenomas and sessile serrated adenomas in Chinese compared with Caucasians

BACKGROUND AND AIMS

Colonic adenomas and sessile serrated adenomas (SSA) are the most common premalignant polyps identified at colonoscopy. This study compares the prevalence of neoplastic polyps in Chinese and Caucasians in a general gastroenterology outpatient practice in Australia.

METHODS

This study included consecutive unselected colonoscopies performed for standard clinical indications by a single endoscopist (JMH). All polyps detected were measured, resected, and sent for histopathology. The prevalence of adenomas, advanced adenomas, SSA, and cancer in the Chinese and Caucasian cohorts were compared. Advanced adenomas were defined as adenomas > 10 mm, villous histology, or high-grade dysplasia.

RESULTS

The study included 346 Chinese and 654 Caucasians. There was no significant difference in the baseline characteristics including age, gender, and indications of colonoscopy, although Chinese were more likely to present with rectal bleeding (22.8% vs 15.9%, P = 0.01). The prevalence of adenomatous polyps was similar in both Caucasians (34.3%) and Chinese (35.3%). However, advanced adenomas were more significantly common in Caucasians (11.3%) compared with Chinese (4.6%) (P < 0.001). SSA was rare in Chinese (2%) but present more frequently in Caucasians (7%) (P = 0.001). Multivariate analysis showed that Caucasian ethnicity (odds ratio 2.4, 95% confidence interval 1.6-3.6) and the presence of SSA (odds ratio 4.4, 95% confidence interval 2.3-8.6) were independent predictors for the detection of an advanced adenoma.

CONCLUSIONS

The prevalence of significant colorectal lesions, including advanced adenomas, large adenomas, and SSA, were lower in Chinese compared with Caucasians. These findings may influence the guidelines for colonic cancer screening in Chinese populations.

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.

Genomic aberrations occurring in subsets of serrated colorectal lesions but not conventional adenomas

A subset of aggressive colorectal cancers exhibit BRAF mutation, MLH1 methylation, and a CpG island methylator phenotype (CIMP), but precursors are poorly established. In this study, we determined the status of these markers in colorectal polyps and evaluated associated risk factors. The study included 771 polyp cases and 1,027 controls who were ages 24 to 80 years, part of a group health program, received a colonoscopy from 1998 to 2007, and completed a structured questionnaire assessing risk factors. Following standard pathology review, polyps were assayed for BRAF mutation (V600E) and tested for MLH1 and CIMP methylation, the latter including the genes, CACNA1G, IGF2, NEUROG1, RUNX3, and SOCS1. Polytomous logistic regression was used to estimate ORs and 95% confidence intervals for the association between molecularly defined subsets of polyps and potential risk factors. There were 580 conventional adenomas and 419 serrated lesions successfully assayed. For adenomas, the prevalence of each marker was ≤1%. In contrast, 55% of serrated lesions harbored mutant BRAF, 26% were CIMP-high, and 5% had methylated MLH1. In these lesions, the highest prevalence of markers was in sessile-serrated polyps (SSP) of ≥10 mm that were in the right-side/cecal regions of the colon. Risk factors for CIMP-high-serrated lesions included Caucasian race, current smoking status, and a history of polyps, whereas for serrated lesions with mutant BRAF, the significant risk factors were male sex, current smoking status, obesity, and a history of polyps. Our results suggest that SSPs and other large, right-sided serrated lesions have a unique molecular profile that is similar to CIMP-high, BRAF-mutated colorectal cancers.

Serrated polyps of the large intestine: current understanding of diagnosis, pathogenesis, and clinical management

Approximately 30% of colorectal carcinomas develop via the serrated neoplasia pathway characterized by widespread DNA methylation and frequent BRAF mutation. Serrated polyps represent a heterogeneous group of polyps which are the precursor lesions to serrated pathway colorectal carcinomas. The histological classification of serrated polyps has evolved over the last two decades to distinguish three separate entities: hyperplastic polyp, sessile serrated adenoma (SSA), and traditional serrated adenoma (TSA). The malignant potential of SSAs and TSAs has been clearly demonstrated. SSAs are more challenging to detect by colonoscopy and are likely to account for some interval carcinomas of the proximal colon. Serrated polyposis syndrome is now widely recognized as conferring a high risk of colorectal carcinoma although its cause remains elusive. The current understanding of the actual malignant potential of each serrated polyp subtype is still limited due to the lack of large-scale prospective studies. Patient management guidelines have been recently updated although high-level evidence to support them is still required.

The stem cell marker CD133 is highly expressed in sessile serrated adenoma and its borderline variant compared with hyperplastic polyp

Non-dysplastic serrated polyps (ND-SP) represent a heterogeneous group of colorectal lesions that comprise hyperplastic polyp (HP) and the non-dysplastic subset of sessile serrated adenoma/polyp/lesion (SSA/P/L) and its borderline variant (BSSA/P/L). Given the observer variation in their histological typing, the identification of reliable markers that assist in the characterisation is warranted. Most important is the identification of polyp qualities that may reflect the patients' risk of developing colorectal cancer. To address these issues, CD133 may represent a potential adjunct. Here we studied the discriminatory value of CD133 expression in the classification of ND-SPs and its distribution pattern in relation to synchronous colorectal carcinoma (SCRC). 39 SSA/P/Ls, 27 BSSA/P/Ls and 21 matched HPs were immunostained for CD133. The data were further correlated to the presence of SCRC and to polyp site and size. Ignoring SCRC status, CD133 was expressed more prominently in SSA/P/Ls than in HPs. The values for BSSA/P/Ls fell in between, yet closer to the SSA/P/L scorings. This observation was retained in the context of SCRC and for SSA/P/Ls not associated with SCRC. Right-sidedness and large size of the polyps more commonly associated with increased CD133 expression. CD133 expression was not a significant discriminator as to the SCRC status. BSSA/P/Ls are more closely aligned to SSA/P/L and further that SSA/P/L and BSSA/P/Ls fundamentally differ from HP by their CD133 immunoprofile, a notion that can be exploited in the diagnostic routine practice. Recorded data further indirectly support the idea that SSA/P/Ls are more prone to neoplastic progression than are HPs.

Serrated pathway: alternative route to colorectal cancer

Serrated polyps have been an area of intense focus for gastroenterologists over the past several years. Contrary to what was thought before, a growing body of literature indicates that these polyps can be precursors of colorectal cancer (CRC). Most of these lesions, particularly those in the proximal colon, have so far been under-recognized and missed during colonoscopy, qualifying these lesions to be the main cause of interval cancers. It is estimated that 10%-20% of CRCs evolve through this alternative, serrated pathway, with a distinct genetic and epigenetic profile. Aberrant DNA methylation plays a central role in the development of this CRC subtype. This characteristic molecular background is reflected in a unique pathological and clinical manifestation different from cancers arising via the traditional pathway. In this review we would like to highlight morphological, molecular and clinical features of this emerging pathway that are essential for gastroenterologists and may influence their everyday practice.

Incomplete polyp resection during colonoscopy-results of the complete adenoma resection (CARE) study

BACKGROUND & AIMS

Although the adenoma detection rate is used as a measure of colonoscopy quality, there are limited data on the quality of endoscopic resection of detected adenomas. We determined the rate of incompletely resected neoplastic polyps in clinical practice.

METHODS

We performed a prospective study on 1427 patients who underwent colonoscopy at 2 medical centers and had at least 1 nonpedunculated polyp (5-20 mm). After polyp removal was considered complete macroscopically, biopsies were obtained from the resection margin. The main outcome was the percentage of incompletely resected neoplastic polyps (incomplete resection rate [IRR]) determined by the presence of neoplastic tissue in post-polypectomy biopsies. Associations between IRR and polyp size, morphology, histology, and endoscopist were assessed by regression analysis.

RESULTS

Of 346 neoplastic polyps (269 patients; 84.0% men; mean age, 63.4 years) removed by 11 gastroenterologists, 10.1% were incompletely resected. IRR increased with polyp size and was significantly higher for large (10-20 mm) than small (5-9 mm) neoplastic polyps (17.3% vs 6.8%; relative risk = 2.1), and for sessile serrated adenomas/polyps than for conventional adenomas (31.0% vs 7.2%; relative risk = 3.7). The IRR for endoscopists with at least 20 polypectomies ranged from 6.5% to 22.7%; there was a 3.4-fold difference between the highest and lowest IRR after adjusting for size and sessile serrated histology.

CONCLUSIONS

Neoplastic polyps are often incompletely resected, and the rate of incomplete resection varies broadly among endoscopists. Incomplete resection might contribute to the development of colon cancers after colonoscopy (interval cancers). Efforts are needed to ensure complete resection, especially of larger lesions. ClinicalTrials.gov Number: NCT01224444.

Molecular Pathology of Gastrointestinal Cancer

The purpose of this review is to discuss important molecular changes that aid decision making in patient management and play a role in emerging treatment strategies for gastrointestinal malignancies. Although screening and surveillance practices have had an impact on the natural history of some tumor types, gastric carcinoma is a major cause of morbidity and mortality in high prevalence regions and colorectal carcinoma is still the fourth leading cause of cancer related death in the United States.