Heterogeneity of colorectal adenomas, the serrated adenoma, and implications for screening and surveillance

Vector textures derived from higher order derivative domains for classification of colorectal polyps

Textures have become widely adopted as an essential tool for lesion detection and classification through analysis of the lesion heterogeneities. In this study, higher order derivative images are being employed to combat the challenge of the poor contrast across similar tissue types among certain imaging modalities. To make good use of the derivative information, a novel concept of vector texture is firstly introduced to construct and extract several types of polyp descriptors. Two widely used differential operators, i.e., the gradient operator and Hessian operator, are utilized to generate the first and second order derivative images. These derivative volumetric images are used to produce two angle-based and two vector-based (including both angle and magnitude) textures. Next, a vector-based co-occurrence matrix is proposed to extract texture features which are fed to a random forest classifier to perform polyp classifications. To evaluate the performance of our method, experiments are implemented over a private colorectal polyp dataset obtained from computed tomographic colonography. We compare our method with four existing state-of-the-art methods and find that our method can outperform those competing methods over 4%-13% evaluated by the area under the receiver operating characteristics curves.

Analysis of KRAS Mutation Status Prediction Model for Colorectal Cancer Based on Medical Imaging

This study retrospectively included some patients with colorectal cancer diagnosed by histopathology, to explore the feasibility of CT medical image texture analysis in predicting KRAS gene mutations in patients with colorectal cancer. Before any surgical procedure, all patients received an enhanced CT scan of the abdomen and pelvis, as well as genetic testing. To define patient groups, divide all patients into test and validation sets based on the order of patient enrollment. A radiologist took a look at the plain axial CT image of the tumor, as well as the portal vein CT image, at the corresponding level. The physician points the computer's cursor to the relevant area in the image, and TexRAD software programs together texture parameters based on various spatial scale factors, also known as total mean, total variance, statistical entropy, overall total average, mean total, positive mean, skewness value, kurtosis value, and general skewness. Using the same method again two weeks later, the observer and another physician measured the image of each patient again to see if the method was consistent between observers. With regard to clinical information, the KRAS gene mutation group and the wild group of participants in the test set and validation set each had values for the texture parameter. In a study of patients with colorectal cancer, the results demonstrated that CT texture parameters were correlated with the presence of the KRAS gene mutation. The best CT prediction model includes the values of the medium texture image's slope and the other CT fine texture image's value of entropy, the medium texture image's slope and kurtosis, and the medium texture image's mean and the other CT fine texture image's value of entropy. Regardless of the training set or the validation set, patients with and without KRAS gene mutations did not differ significantly in clinical characteristics. This method can be used to identify mutations in the KRAS gene in patients with colorectal cancer, making it practical to implement CT medical image texture analysis technology for that purpose.

Clinicopathological factors associated with BRAF-V600E mutation in colorectal serrated adenomas

Serrated adenomas are genetically heterogeneous, and the histological classification into sessile serrated (SSA) adenoma and traditional serrated adenoma (TSA) does not reflect the molecular landscape. The objective of this study was to assess clinical or pathological factors associated with BRAF-V600E mutation in serrated adenomas. Systematic review and meta-analysis was performed by searching electronic databases from January 2011 to January 2019 for studies assessing the association of BRAF-V600E mutation with clinical or pathological features of serrated adenomas. Odds ratio (OR) was calculated for each factor; a P-value <0.05 was considered significant. Forty studies assessing 3511 serrated adenomas (2375 SSAs and 1136 TSAs) were included. BRAF-V600E mutation was significantly associated with proximal localisation (OR = 2.71; P < 0.00001) and CIMP-H status (OR = 4.81; P < 0.0001) in both SSA and TSA, with polyp size <10 mm (OR = 0.41; P = 0.02) in TSA, and with endoscopic pit pattern II-O (OR = 13.11; P < 0.00001) and expression of MUC5A5 (OR = 4.43; P = 0.003) and MUC6 (OR = 2.28; P < 0.05) in SSA. Conversely, BRAF mutation was not associated with age <70 years (OR = 1.63; P = 0.34), age <60 years (OR = 0.86; P = 0.79), female sex (OR = 0.77; P = 0.12), flat morphology (OR = 1.52; P = 0.16), presence of any dysplasia (OR = 1.01; P = 0.59), serrated dysplasia (OR = 1.23; P = 0.72) and invasive cancer (OR = 0.67; P = 0.32), nuclear β-catenin expression (OR = 0.73; P = 0.21) and p53 overexpression (OR = 1.24; P = 0.82). In conclusion, BRAF-V600E mutation is associated with proximal localisation and CIMP-H status in both SSA and TSA, with size <10 mm only in TSA, and with expression of MUC5A5 and MUC6 and endoscopic pit pattern II-O at least in SSA. In serrated adenomas, BRAF-V600E mutation does not seem to be associated with age and sex, with the prevalence of dysplasia and cancer and with the morphology of the dysplastic component.

A randomized clinical prospective trial comparing split-dose picosulfate/ magnesium citrate and polyethylene glycol for colonoscopy preparation

Background

Colonoscopy remains the gold standard for the investigation of abnormalities within the colon. However, its success is highly dependent on the quality of bowel preparation. The objective of this study was to compare the bowel preparation efficacy of picosulfate/magnesium citrate (PMC) vs polyethylene glycol (PEG) in a one-day vs two-day split dose regimen.

Methods

A prospective, randomized, controlled trial was conducted at the Forzani & MacPhail Colon Cancer Screening Centre in Calgary, Canada. 171 colonoscopy outpatients were randomized to split-dose PMC or PEG lavage as well as into one-day split or two-day split regimens in blocks of eight. Bowel preparation quality was recorded in a blinded manner by the endoscopist using the Ottawa Bowel Preparation Scale (OBPS) prior to washing or suctioning. The scale results were analyzed using a two-factor analysis of variance.

Results

141 patients received complete colonoscopies (PMC-71; PEG-70). PEG was found to be superior to PMC (mean OBPS: 4.14 ± 2.64 vs 5.11 ± 3.44, p = 0.019), when adjusted for administration regimen, leading to significantly more adequate bowel preparations (79.7% vs 59.7%, p = 0.007). A two-day split dose was superior to a one-day split dose regimen (mean OBPS: 3.68± 2.82 vs 5.69 ± 3.06, p<0.001). Two-day split dosing also resulted in a better right colon cleanliness score (right bowel OBPS 1.27±0.11 vs 2.10±0.12 for one-day split, P<0.001).

Conclusions

Optimal bowel preparation was achieved with the use of PEG lavage when administered in a two-day split dose regimen. This trial is registered with ClinicalTrials.gov under identifier NCT01415687.

Precision Medicine for CRC Patients in the Veteran Population: State-of-the-Art, Challenges and Research Directions

Colorectal cancer (CRC) accounts for ~9% of all cancers in the Veteran population, a fact which has focused a great deal of the attention of the VA's research and development efforts. A field-based meeting of CRC experts was convened to discuss both challenges and opportunities in precision medicine for CRC. This group, designated as the VA Colorectal Cancer Cell-genomics Consortium (VA4C), discussed advances in CRC biology, biomarkers, and imaging for early detection and prevention. There was also a discussion of precision treatment involving fluorescence-guided surgery, targeted chemotherapies and immunotherapies, and personalized cancer treatment approaches. The overarching goal was to identify modalities that might ultimately lead to personalized cancer diagnosis and treatment. This review summarizes the findings of this VA field-based meeting, in which much of the current knowledge on CRC prescreening and treatment was discussed. It was concluded that there is a need and an opportunity to identify new targets for both the prevention of CRC and the development of effective therapies for advanced disease. Also, developing methods integrating genomic testing with tumoroid-based clinical drug response might lead to more accurate diagnosis and prognostication and more effective personalized treatment of CRC.

Split-Dose Polyethylene Glycol Is Superior to Single Dose for Colonoscopy Preparation: Results of a Randomized Controlled Trial

Background. The efficacy of colonoscopy in detecting abnormalities within the colon is highly dependent on the adequacy of the bowel preparation. The objective of this study was to compare the efficacy, safety, and tolerability of PEG lavage and split-dose PEG lavage with specific emphasis on the cleanliness of the right colon. Methods. The study was a prospective, randomized, two-arm, controlled trial of 237 patients. Patients between the age of 50 and 75 years were referred to an outpatient university screening clinic for colonoscopy. Patients were allocated to receive either a single 4 L PEG lavage or a split-dose PEG lavage. Results. Overall, the bowel preparation was superior in the split-dose group compared with the single-dose group (mean Ottawa score 3.50 ± 2.89 versus 5.96 ± 3.53; P < 0.05) and resulted in less overall fluid in the colon. This effect was observed across all segments of the colon assessed. Conclusions. The current study supports use of a split-dose PEG lavage over a single large volume lavage for superior bowel cleanliness, which may improve polyp detection. This trial is registered with ClinicalTrials.gov identifier NCT01610856.

Defined morphological criteria allow reliable diagnosis of colorectal serrated polyps and predict polyp genetics

Criteria for the diagnosis of serrated colorectal lesions (hyperplastic polyp, sessile serrated adenoma without or with dysplasia--which we called mixed polyp--and traditional serrated adenoma) for which consensus has been reached should be validated for applicability in daily practice in terms of inter-observer reproducibility and their association with clinical features and (epi)genetic events. A study set was created from a consecutive series of colorectal polyps (n = 1,926) by selecting all sessile serrated adenomas, traditional serrated adenomas and mixed polyps. We added consecutive series of hyperplastic polyps, classical adenomas and normal mucosa samples for a total of 200 specimens. With this series, we conducted an inter-observer study, encompassing ten pathologists with gastrointestinal pathology experience from five European countries, in three rounds in which all cases were microscopically evaluated. An assessment of single morphological criteria was included, and these were correlated with clinical parameters and the mutation status of KRAS, BRAF and PIK3CA and the methylation status of MLH1. Gender, age and localisation were significantly associated with certain types of lesions. Kappa statistics revealed moderate to good inter-observer agreement for polyp classification (κ = 0.56 to 0.63), but for single criteria, this varied considerably (κ = 0.06 to 0.82). BRAF mutations were frequently found in hyperplastic polyps (86 %, 62/72) and sessile serrated adenomas (80 %, 41/51). KRAS mutations occurred more frequently in traditional serrated adenomas (78 %, 7/9) and less so in classical adenomas (20 %, 10/51). Single morphological criteria for sessile serrated adenomas showed significant correlation with BRAF mutation (all p ≤ 0.001), and those for classical adenomas or traditional serrated adenoma correlated significantly with KRAS mutation (all p < 0.001). Therefore, single well-defined morphological criteria are predictive for genetic alterations in colorectal polyps.

Long-term follow-up of patients with malignant pedunculated colon polyps after colonoscopic polypectomy

BACKGROUND

Previously published studies have suggested that patients with resected colon cancer have an increased risk for early metachronous colon cancer. Current screening guidelines recommend intense surveillance by colonoscopy for the initial five years after the initial colon cancer has been resected. Information regarding endoscopically removed malignant polyps is limited.

METHODS

In the present study, 25 consecutive patients (14 male, 11 female) with malignant pedunculated colon polyps treated with snare cautery polypectomy were followed for more than one decade up to 20 years. Five patients required an additional resection to ensure that removal of the original cancer was complete. Annual colonoscopies were planned for five years. If an adenoma was detected in the fifth year, colonoscopy was performed annually until no adenomas were detected. Otherwise, colonoscopy was planned every three years after five years.

RESULTS

In the present study, there was no mortality from colon cancer and no patient developed either recurrent colon cancer or an early metachronous colon cancer during the initial five-year period of surveillance. Two patients (one male, one female) ultimately developed late cecal cancers almost one decade after the original colon cancers were resected. One had an early stage cancer that was resected, while the other had an infiltrating mucinous carcinoma complicating a small tubulovillous adenoma with extension to a single lymph node. After surgical removal and adjuvant chemotherapy, no further neoplastic disease has been detected.

CONCLUSIONS

Overall, patients with malignant pedunculated polyps do extremely well if appropriately managed at the time of the initial polypectomy. Short-term outcomes after removal of a malignant polyp(s) appear to be similar to those with a nonmalignant polyp. However, late metachronous colon cancer may still occur. Long-term follow-up should be considered in each patient, assuming reasonable life expectancy, because risk of additional adenomas and metachronous colon cancer persists even after the initial five years of currently recommended surveillance. Patients with resected malignant polyps may represent a special patient subgroup that requires surveillance for more extended periods than current guidelines have recommended.

Improving outcomes in colorectal cancer: where do we go from here?

Colorectal cancer (CRC) places a considerable burden on individuals and society in Europe, being the second most common cause of cancer-related death in the region. While earlier diagnosis and advances in treatment have considerably improved survival in recent years, further progress is needed. One of the greatest challenges associated with the treatment of CRC is the fact that current therapies for advanced disease are not curative, necessitating treatment for many years and placing a significant healthcare burden on society. To reduce the burden of CRC, care delivery must be more efficient and cost-effective. In particular, development of adequate screening programmes is needed, along with chemo-preventative strategies and newer, more active therapies. Further challenges include the lack of optimal selection of patients for adjuvant therapy, identification of the most appropriate target populations for current treatments and the optimum sequence for new molecular targeted agents. This article outlines current developments and unmet needs in CRC, and provides a detailed vision for improvements in the management of the disease. Implementation of some of these strategies will go some way to improving outcomes for patients with CRC.

Serrated polyps: new classifications highlight clinical importance

AIM

Many lesions previously classified as hyperplastic polyps and therefore thought to be innocuous have been reclassified as sessile serrated adenomas/polyps (SSA/Ps), establishing their place in the serrated pathway and underscoring their malignant potential. The clinical relevance of this new nomenclature is incompletely defined. This study examines the incidence and characteristics of colorectal SSA/Ps and describes other associated colorectal neoplasia.

METHOD

A single institution pathology database was searched for the diagnosis of SSA/Ps between January 2004 and October 2007. SSA/Ps found by colonoscopy were included. Patient demographics, SSA/P characteristics and associated colonoscopic findings were retrospectively recorded.

RESULTS

A total of 585 SSA/Ps were removed during 519 colonoscopies in 483 patients performed by 64 different endoscopists. This represented an overall incidence of SSA/Ps per colonoscopy of 2.1% in the 28,054 colonoscopies performed during the study period. The median SSA/P size was 0.8 cm (range 0.2-4.5) and 188 (69%) were ≥ 1.0 cm. Of the 585 SSA/Ps, 366 (63%) were right-sided, 129 (22%) were in the left colon and 90 (15%) were in the rectum. Also, 439 synchronous polyps of other histology (mainly adenomas and hyperplastic polyps) were found during the same 519 colonoscopies.

CONCLUSION

SSA/Ps are rare lesions found during colonoscopy that may coexist with small hyperplastic polyps. Because SSA/Ps are part of the serrated oncogenic pathway, all, even those appearing to be hyperplastic, should be removed or biopsied for diagnosis. Careful review of historical lesions with application of new definitions may redefine risk for malignancy.

Contribution of behavioral risk factors and obesity to socioeconomic differences in colorectal cancer incidence

BACKGROUND

Health behaviors are known risk factors for colorectal cancer and are more common in low socioeconomic status (SES) populations. We evaluated the extent to which behavioral risk factors and body mass index (BMI) explain SES disparities in colorectal cancer incidence, overall and by tumor location.

METHODS

We analyzed prospective National Institutes of Health-AARP Diet and Health Study data on 506 488 participants who were recruited in 1995-1996 from six US states and two metropolitan areas and followed through 2006. Detailed baseline data on risk factors for colorectal cancer, including health behaviors, were obtained using questionnaires. SES was measured by self-reported education and census-tract data. The outcome was primary incident invasive colorectal adenocarcinoma. Poisson regression was used to estimate the association between SES and risk of incident colorectal cancer, with adjustment for age, sex, race and ethnicity, family history, and state of residence. The model estimates were used to derive percentage mediation by behavioral risk factors; bias-corrected 95% confidence intervals were obtained through bootstrap techniques.

RESULTS

Seven-thousand six-hundred seventy-six participants developed colorectal cancer during follow-up. SES differences in prevalence of physical inactivity, unhealthy diet, smoking, and unhealthy weight each explained between 11.3% (BMI) and 21.6% (diet) of the association between education and risk of colorectal cancer and between 8.6% (smoking) and 15.3% (diet) of the association between neighborhood SES and risk of colorectal cancer. Health behaviors and BMI combined explained approximately 43.9% (95% CI = 35.1% to 57.9%) of the association of education and 36.2% (95% CI = 28.0% to 51.2%) of the association of neighborhood SES with risk of colorectal cancer. The percentage explained by all factors and BMI combined was largest for right colon cancers and smallest for rectal cancers.

CONCLUSION

A substantial proportion of the socioeconomic disparity in risk of new-onset colorectal cancer, and particularly of right colon cancers, may be attributable to the higher prevalence of adverse health behaviors in low-SES populations.

Socioeconomic status and the risk of colorectal cancer: an analysis of more than a half million adults in the National Institutes of Health-AARP Diet and Health Study

BACKGROUND

No previous prospective US study has examined whether the incidence of colorectal cancer (CRC) is disproportionately high in low socioeconomic status (SES) populations of both men and women. This study examined the relationship between both individual and area-level SES and CRC incidence, overall and by tumor location.

METHODS

Data were obtained from the ongoing prospective National Institutes of Health-AARP Diet and Health Study of persons (50-71 years old) who resided in 6 US states and 2 metropolitan areas at baseline in 1995-1996. Incident CRCs were ascertained from tumor registries through December 2006. SES was measured by self-reported education and census-tract socioeconomic deprivation. Baseline and follow-up questionnaires collected detailed information on individual-level CRC risk factors including family history and health behaviors.

RESULTS

Among 506,488 participants analyzed, 7676 were diagnosed with primary invasive colorectal adenocarcinomas: 44.6% [corrected] in the right colon, 26.7% in the left colon, and 25.9% in the rectum. The overall incidence of CRC was significantly higher among people who had low educational level or lived in low-SES neighborhoods, relative to respective highest-SES groups, even after accounting for other risk factors. These associations were stronger in the rectum than in left or right colon. In the right colon, there were no significant SES differences by either SES measure after accounting for covariates.

CONCLUSIONS

SES, assessed by either individual-level education or neighborhood measures, was associated with risk of CRC even after accounting for other risk factors. The relationship between SES and CRC was strongest in the rectum and weakest in the right colon.

[Histopathological diagnosis and differential diagnosis of colorectal serrated polys: findings of a consensus conference of the working group "gastroenterological pathology of the German Society of Pathology"]

Until recently, two major types of colorectal epithelial polyps were distinguished: the adenoma and the hyperplastic polyp. While adenomas - because of their cytological atypia - were recognized as precursor lesions for colorectal carcinoma, hyperplastic polyps were perceived as harmless lesions without any potential for malignant progression, mainly because hyperplastic polyps lack cytological atypia. Meanwhile, it is evident that the lesions formerly classified as hyperplastic represent a heterogeneous group of polyps, some of which exhibit a significant risk of neoplastic progression. These lesions show characteristic epigenetic alterations not commonly seen in colorectal adenomas and progress to colorectal carcinoma via the so-called serrated pathway (CIMP pathway). This group of polyps is comprised not only of hyperplastic polyps, but also of sessile serrated adenomas (SSA), traditional serrated adenomas (TSA) and mixed polyps, showing serrated and "classical" adenomatous features. In a consensus conference of the working group of gastroenterological pathology of the German Society of Pathology, standardization of nomenclature and diagnostic criteria as well as recommendations for clinical management of these serrated polyps were formulated and are presented herein.

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.

Serrated polyps of the colon and rectum (hyperplastic polyps, sessile serrated adenomas, traditional serrated adenomas, and mixed polyps)-proposal for diagnostic criteria

Until recently, two major types of colorectal epithelial polyps were distinguished: the adenoma and the hyperplastic polyp. While adenomas-because of their cytological atypia-were recognized as the precursor lesions for colorectal carcinoma, hyperplastic polyps were perceived as harmless lesions without any potential for malignant progression mainly because hyperplastic polyps are missing cytological atypia. Meanwhile, it is recognized that the lesions, formerly classified as hyperplastic, represent a heterogeneous group of polyps with characteristic serrated morphology some of which exhibit a significant risk of neoplastic progression. These serrated lesions show characteristic epigenetic alterations not commonly seen in colorectal adenomas and progress to colorectal carcinoma via the so-called serrated pathway (CpG-island-methylation-phenotype pathway). This group of polyps is comprised not only of hyperplastic polyps, but also of sessile serrated adenomas, traditional serrated adenomas and mixed polyps, showing serrated and "classical" adenomatous features. Diagnostic criteria and nomenclature for these lesions are not uniform and, therefore, somewhat confusing. In a consensus conference of the Working Group of Gastroenterological Pathology of the German Society of Pathology, standardization of nomenclature and diagnostic criteria as well as recommendations for clinical management of these serrated polyps were formulated and are presented herein.

Sessile serrated adenomas: prevalence of dysplasia and carcinoma in 2139 patients

BACKGROUND AND AIMS

Sessile serrated adenomas (SSAs) are recognised as precursors to microsatellite unstable adenocarcinomas. This study attempts to estimate the progression rate of SSAs based upon the epidemiology of a large cohort as well as identify relationships to other colorectal polyps.

METHODS

Pathological reports generated at Caris Diagnostics from 290 810 colonoscopic specimens on 179 111 patients were analysed using computerised algorithms.

RESULTS

SSAs with or without dysplasia/carcinoma (SSA+/-) were identified in 2416 specimens from 2139 patients (54% women). The distribution of SSA+/- was: right-sided (81.2%); left-sided (11.2%); both right- and left-sided (3.2%); not specified (4.3%). There were 1816 (85%) patients without dysplasia (SSA-), 257 (12%) with low-grade dysplasia (SSA-LD), 45 (2%) with high-grade dysplasia (SSA-HD) and 21 (1%) with adenocarcinoma (SSA-CA). The difference in median age between almost all groups was significant (SSA-=61 years versus SSA-LD=66 years (p<0.001) vs SSA-HD=72 years (p=0.002) vs SSA-CA=76 years (p=0.07, NS)). Women comprised 53% of the SSA- group (968/1816), 57% of the SSA-LD group (147/257), 69% of the SSA-HD group (31/45) and 76% of the SSA-CA group (16/21), being more likely to have high-grade dysplasia (OR 1.94, 95% CI 1.03 to 3.67) and adenocarcinoma (OR 2.80, 95% CI 1.02 to 7.68).

CONCLUSIONS

1.7% of patients with mucosal polyps had SSAs (with and without dysplasia), more commonly in women and primarily in the right colon. Dysplasia or carcinoma was identified in 15% of patients and significantly disproportionately among women. Based on significant age differences between groups, there appears to be a stepwise progression of dysplasia and carcinoma in SSAs over 10 to 15 years, a period two to three times longer than that for conventional adenomas.

Beta-catenin nuclear labeling is a common feature of sessile serrated adenomas and correlates with early neoplastic progression after BRAF activation

Recent observations indicate that some sessile serrated adenomas (SSAs) have aberrant beta-catenin nuclear labeling, implicating the Wnt pathway in the molecular progression of SSAs to colorectal carcinoma. We sought to expand upon this finding by characterizing beta-catenin expression in the full spectrum of serrated colorectal polyps, and correlating these findings with the genetic status of BRAF, KRAS and CTNNB1. Immunolabeling for beta-catenin confirmed the presence of abnormal nuclear accumulation in SSAs, with 35/54 (67%) SSAs showing nuclear labeling compared with 0/12 hyperplastic polyps. Abnormal nuclear labeling was also identified in 4/11 (36%) traditional serrated adenomas (TSAs) (P=0.00001). When SSAs were further analyzed with respect to the presence or absence of conventional epithelial dysplasia, nuclear beta-catenin labeling was seen in 8/27 (29%) SSAs without dysplasia (SSA) but in 27/27 (100%) of SSAs with dysplasia (P=0.000001). Sequencing of genomic DNA extracted from a subset of hyperplastic polyps, SSAs, SSAs with dysplasia, TSAs and tubular adenomas failed to identify any CTNNB1 mutations to account for abnormal beta-catenin nuclear labeling. However, abnormal nuclear labeling always occurred in the setting of a BRAF V600E mutation, indicating aberrant nuclear labeling occurs on a background of BRAF activation. Of interest, all 6 TSAs contained a KRAS mutation confirming that SSAs and TSAs are genetically distinct entities. These findings validate previous reports implicating activation of the Wnt signaling pathway in SSAs, and further indicate that Wnt pathway activation plays a role in the neoplastic progression of SSAs and TSAs to colonic carcinoma by mechanisms independent of CTNNB1 mutation.

[Role of mucinohistochemical analysis in verification of malignant potential of colorectal adenoma]

BACKGROUND/AIM

It is a general opinion that the biggest number of colorectal carcinoma (CRC) develops with the malignant alteration of colorectal adenomas (adenoma carcinoma sequence). Malignant potential of adenoma is in the function of its size, histological structure and the grade of dysplasia. An adequate analysis of colorectal adenomas helps their definition and timely removal, which significantly decreases carcinoma incidence. Mucin analysis can provide results which support the adenoma carcinoma sequence theory. The aim of the study was to present histochemical characteristics of adenomas and emphasize the significance of these analyses for the precise adenoma definition.

METHODS

This prospective study included analysis of 117 colorectal adenomas obtained by transcolonoscopic biopsy or polipectomy in 82 patients. The biopsy samples and the removed polyps were coloured by hematoxilin-eozin (HE) staining and histochemical stainings by Periodic Acid Schiff (AB-PAS) and High Iron Diamine/Alcian blue (HID-AB; pH = 2.5) to prove mucins.

RESULTS

Sulphomucins are more often found in adenomas of the left colon than of the right one (p < 0.001). Sialomucins are more reactive in adenomas of the right colon (p < 0.001). Sulphomucins are more reactive in adenomas of < 10 mm diameter (p < 0.05). The reactivity of all mucins is in negative correlation with the degree of dysplasia (p < 0.001). There is a significant difference in the reactivity of sialomucins in adenomas of the same histological type but different degree of dysplasia (chi2 = 25,743, df = 6, p < 0.001).

CONCLUSION

The difference in the presence of mucins between adenomas of the left and right colons supports the theory of adenoma carcinoma sequence, since adenomas of the right colon are more protected by sialomucins and therefore less malignantly altered, which is consistent with CRC topography. Histochemical analysis of colorectum is significant for more accurate gradation of dysplasia and confirmation of malignant alteration. The negative correlation between the degree of dysplasia and the production of mucin indicates the significance of the degree of dysplasia in malignant potential of colorectal adenomas.

An appendiceal neoplastic lesion: case report and implications for colonoscopic screening and surveillance

A 65-year-old man with a history of previously resected colonic adenomas had an apparent cecal lesion detected during colonoscopy. The polyp proved to be a tubulovillous adenoma with high-grade dysplasia involving most of the body of the appendix along with the base of the cecum. The appendiceal mucosa is biologically similar to the colonic mucosa, yet remains relatively 'hidden' in screening and surveillance studies, which suggests important implications for evolving detection strategies in the follow-up of patients with a previous colon polyp or cancer resections. Although endoscopic removal of the appendix has been reported, treatment of these localized appendiceal lesions requires a wide surgical excision.