Colorectal carcinoma associated with serrated adenoma--prevalence, histological features, and prognosis

Nonconventional Dysplasia is Frequently Associated With Goblet Cell Deficient and Serrated Variants of Colonic Adenocarcinoma in Inflammatory Bowel Disease

Various subtypes of nonconventional dysplasia have been recently described in inflammatory bowel disease (IBD). We hypothesized that goblet cell deficient dysplasia and serrated dysplasia may be the primary precursor lesions for goblet cell deficient (GCDAC) and serrated (SAC) variants of colonic adenocarcinoma, respectively. Clinicopathologic features of 23 GCDAC and 10 SAC colectomy cases were analyzed. All dysplastic lesions found adjacent to the colorectal cancers (n = 22 for GCDACs and n = 10 for SACs) were subtyped as conventional, nonconventional, or mixed-type dysplasia. As controls, 12 IBD colectomy cases with well to moderately differentiated adenocarcinoma that lacked any mucinous, signet ring cell, low-grade tubuloglandular, or serrated features while retaining goblet cells throughout the tumor (at least 50% of the tumor) were evaluated. The cohort consisted of 19 (58%) men and 14 (42%) women, with a mean age of 53 years and a long history of IBD (mean duration: 18 y). Twenty-seven (82%) patients had ulcerative colitis. GCDACs (57%) were more often flat or invisible than SACs (10%) and controls (25%; P = 0.023). The GCDAC and SAC groups were more likely to show lymphovascular invasion (GCDAC group: 52%, SAC group: 50%, control group: 0%, P = 0.001) and lymph node metastasis (GCDAC group: 39%, SAC group: 50%, control group: 0%, P = 0.009) than the control group. Notably, GCDACs and SACs were more frequently associated with nonconventional dysplasia than controls (GCDAC group: 77%, SAC group: 40%, control group: 0%, P < 0.001). Goblet cell deficient dysplasia (73%) was the most prevalent dysplastic subtype associated with GCDACs ( P = 0.049), whereas dysplasias featuring a serrated component (60%) were most often associated with SACs ( P = 0.001). The GCDAC group (75%) had a higher rate of macroscopically flat or invisible synchronous dysplasia compared with the SAC (20%) and control (33%) groups ( P = 0.045). Synchronous dysplasia demonstrated nonconventional dysplastic features more frequently in the GCDAC (69%) and SAC (40%) groups compared with the control group (0%; P = 0.016). In conclusion, goblet cell deficient dysplasia and dysplasias featuring a serrated component could potentially serve as high-risk markers for GCDACs and SACs, respectively.

Emerging and under-recognised patterns of colorectal carcinoma morphologies: a comprehensive review

While the overwhelming majority of colorectal carcinomas (CRC) are diagnosed as adenocarcinoma not otherwise specified, there are numerous under-recognised morphologic patterns of CRC. These patterns are recognised by the WHO, appear in reporting manuals for the American Joint Committee of Cancer, and/or are listed on synoptic reports, while many other variants have either fallen out of favour or are emerging as future bona fide patterns. Herein, we discuss 13 variants: serrated adenocarcinoma, micropapillary adenocarcinoma, medullary carcinoma, neuroendocrine carcinoma, mucinous adenocarcinoma, signet-ring cell carcinoma, adenosquamous carcinoma, adenoma-like adenocarcinoma, lymphoglandular complex-like CRC, carcinoma with sarcomatoid components, cribriform-comedo-type adenocarcinoma, undifferentiated carcinoma and low-grade tubuloglandular adenocarcinoma. The purpose of this review is to scrutinise these variants by assessing their clinical characteristics, morphologic cues, as well as pitfalls, and address their prognostic significance. Our analysis aims to bring clarity and updated understanding to these variants, offering valuable insights for pathologists. This contributes to more nuanced CRC diagnosis and treatment strategies, highlighting the importance of recognising a broad spectrum of morphologic patterns in CRC.

Serrated adenocarcinoma of sigmoid colon with mismatch repair protein-proficient phenotype: Histopathological recognition of a new subtype of colorectal adenocarcinoma

Serrated adenocarcinoma is a distinct subtype of colorectal carcinoma characterized by unique histological and molecular features. Here we present a case study of a 58-year-old female patient who presented with generalized weakness, abdominal discomfort, and per-rectal bleeding. This case report highlights the importance of understanding the histopathological features of serrated adenocarcinoma for accurate diagnosis which has impact on further management.

Detection of colorectal adenomas with texture and color enhancement imaging: Multicenter observational study

OBJECTIVES

We aimed to evaluate the efficacy of texture and color enhancement imaging (TXI), which allows the acquisition of brighter images with enhanced color and surface structure in colorectal polyp detection compared to white light imaging.

METHODS

Patients who underwent colonoscopy with repeated ascending colon observation using TXI and white light imaging between August 2020 and January 2021 were identified in three institutions. The outcomes included the mean number of adenomas detected per procedure (MAP), adenoma detection rate (ADR), and ascending colonic adenoma miss rate (Ac-AMR). Logistic regression was used to determine the effects of the variables on the outcomes.

RESULTS

We included 1043 lesions from 470 patients in the analysis. The MAP, ADR, flat polyp detection rate, and Ac-AMR in TXI and white light imaging were 1.5% (95% confidence interval 1.3-1.6%) vs. 1.0% (0.9-1.1%), 58.2% (51.7-64.6%) vs. 46.8% (40.2-53.4%), 66.2% (59.8-72.2%) vs. 49.8% (43.2-56.4%), and 17.9% (12.1-25.2%) vs. 28.2% (20.0-37.6%), respectively. TXI, age, withdrawal time, and endoscopy type were identified as significant factors affecting the MAP and the ADR using multivariate regression analysis.

CONCLUSIONS

Our study indicates that TXI improve the detection of colorectal neoplastic lesions. However, prospective randomized trials are required to confirm these findings.

Clinical, Pathologic, Genetics and Intratumoral Immune Milieu of Serrated Adenocarcinoma of the Colon

BACKGROUND

Serrated adenocarcinoma (SAC), a recognized WHO variant of colonic adenocarcinoma, is the purported end-product of serrated neoplasia. Yet, the diagnosis of SAC is infrequently rendered, and little is known about its prognosis, immune microenvironment, and molecular alterations.

MATERIALS AND METHODS

We assessed 903 consecutive colon carcinomas and recognized tumors with ≥5% (n=77) serrated pattern, and ≥50% serrated pattern (n=13). We assessed precursor polyps and synchronous polyps. We recorded demographic/clinical parameters, histological features, and MMR status. We performed immunohistochemistry and quantification on tissue microarray for HLA class I/II proteins, beta-2-microglobulin (B2MG), CD8, CD163, LAG3, PD-L1, FoxP3, PD-L1and BRAF V600E.

RESULTS

We identified ≥ 5% epithelial serration prevalence in 8.5% of cases, and ≥50% epithelial serration prevalence in 1.4% of cases. Precursor lesions were present in 21.4% of cases; these were mostly tubular adenomas with two traditional serrated adenoma identified. SAC with ≥ 5% serrations exhibited lower numbers of CD8 positive lymphocytes (p=0.002) and lower B2MG expression (p=0.048), although neither value was significant at ≥50% serration threshold. There was no difference in HLA class I/II, or PD-L1 expression on tumor cells and no difference in PD-L1, LAG3, FOXP3 and CD163 expression on immune cells. There was no association with MMR status, or BRAFV600E relative to conventional adenocarcinoma. There was improved disease-specific survival on univariate (but not multivariate) analysis between carcinomas with serrated pattern and non-mucinous conventional colonic carcinomas at ≥5% epithelial serrations (p=0.04).

CONCLUSION

SAC category shows a limited impact on survival, and this phenotype may harbor a unique immunologic milieu.

Sarcopenia and Myosteatosis Are Associated with Neutrophil to Lymphocyte Ratio but Not Glasgow Prognostic Score in Colorectal Cancer Patients

Cancer patients commonly present sarcopenia, myosteatosis, and systemic inflammation, which are risk factors of poor survival. In this study, sarcopenia and myosteatosis were defined from preoperative body computed tomography scans of 222 colorectal cancer (CRC) patients and analyzed in relation to tumor and patient characteristics, markers of systemic inflammation (modified Glasgow prognostic score (mGPS), neutrophil−lymphocyte ratio (NLR), serum levels of C-reactive protein (CRP), albumin, and 13 cytokines, and survival. Of the systemic inflammation markers, sarcopenia and/or myosteatosis associated with elevated NLR (p = 0.005) and low albumin levels (≤35 g/L) (p = 0.018), but not with mGPS or serum cytokine levels. In addition, myosteatosis was associated with a proximal tumor location (p = 0.039), serrated tumor subtype (p < 0.001), and severe comorbidities (p = 0.004). Multivariable analyses revealed that severe comorbidities and serrated histology were independent predictors of myosteatosis, and older age and elevated NLR were independent indicators of sarcopenia. Myosteatosis associated with shorter overall survival in univariable analysis (HR 1.959, 95% CI 1.24−3.10, p = 0.004) but not in multivariable analysis (p = 0.075). We conclude that sarcopenia and myosteatosis were associated with inflammatory marker NLR, but not with mGPS. Moreover, patients with serrated CRC may have an increased risk of myosteatosis. Myosteatosis or sarcopenia were not independent predictors of patient survival.

Clinicopathological characteristics of colorectal serrated polyposis syndrome (SPS): results of a multicenter study by the SPS Study Group in Japan

BACKGROUND

Serrated polyposis syndrome (SPS), a type of colorectal polyposis characterized by multiple serrated polyps, is associated with a high risk of colorectal carcinoma (CRC). This study aimed to clarify the clinicopathological characteristics of SPS in Japan.

METHODS

We investigated the clinicopathological characteristics of patients with SPS from the "Multicenter Study on Clinicopathological Characteristics of SPS (UMIN 000032138)" by the Colorectal Serrated Polyposis Syndrome (SPS) Study Group. In this study, patients were diagnosed with SPS based on the 2019 World Health Organization (WHO) SPS diagnostic criteria.

RESULTS

Ninety-four patients were diagnosed with SPS in 10 institutions between January 2001 and December 2017. The mean number (± standard deviation [SD]) of resected lesions per patient was 11.3 ± 13.8. The mean age at diagnosis of SPS was 63.3 ± 11.6 years, and 58 patients (61.7%) were male. Eighty-seven (92.6%) and 16 (17.0%) patients satisfied WHO diagnostic criteria I and II, respectively. Nine patients (9.6%) satisfied both criteria I and II. Carcinoma (T1-T4) were observed in 21 patients (22.3%) and 24 lesions. Of the 21 patients with CRC, 19 (90.4%) satisfied diagnostic criterion I, 1 (4.8%) satisfied diagnostic criterion II, and 1 (4.8%) satisfied diagnostic criteria I and II. There was no notable difference in the prevalence of CRC among patients who met diagnostic criterion I, II, and both I and II.

CONCLUSIONS

Patients with SPS have a high risk of CRC and should undergo regular surveillance colonoscopy. Raising awareness of this syndrome is crucial.

Tribbles Gene Expression Profiles in Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of death due to cancer in the world. Therefore, the identification of novel druggable targets is urgently needed. Tribbles proteins belong to a pseudokinase family, previously recognized in CRC as oncogenes and potential therapeutic targets. Here, we analyzed the expression of TRIB1, TRIB2, and TRIB3 simultaneously in 33 data sets from CRC based on available GEO profiles. We show that all three Tribbles genes are overrepresented in CRC cell lines and primary tumors, though depending on specific features of the CRC samples. Higher expression of TRIB2 in the tumor microenvironment and TRIB3 overexpression in an early stage of CRC development, unveil a potential and unexplored role for these proteins in the context of CRC. Differential Tribbles expression was also explored in diverse cellular experimental conditions where either genetic or pharmacological approaches were used, providing novel hints for future research. This comprehensive bioinformatic analysis provides new insights into Tribbles gene expression and transcript regulation in CRC.

Tribbles Gene Expression Profiles in Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of death due to cancer in the world. Therefore, the identification of novel druggable targets is urgently needed. Tribbles proteins belong to a pseudokinase family, previously recognized in CRC as oncogenes and potential therapeutic targets. Here, we analyzed the expression of TRIB1, TRIB2, and TRIB3 simultaneously in 33 data sets from CRC based on available GEO profiles. We show that all three Tribbles genes are overrepresented in CRC cell lines and primary tumors, though depending on specific features of the CRC samples. Higher expression of TRIB2 in the tumor microenvironment and TRIB3 overexpression in an early stage of CRC development, unveil a potential and unexplored role for these proteins in the context of CRC. Differential Tribbles expression was also explored in diverse cellular experimental conditions where either genetic or pharmacological approaches were used, providing novel hints for future research. This comprehensive bioinformatic analysis provides new insights into Tribbles gene expression and transcript regulation in CRC.

ETV4 plays a role on the primary events during the adenoma-adenocarcinoma progression in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is one of the most common cancers worldwide; it is the fourth leading cause of death in the world and the third in Brazil. Mutations in the APC, DCC, KRAS and TP53 genes have been associated with the progression of sporadic CRC, occurring at defined pathological stages of the tumor progression and consequently modulating several genes in the corresponding signaling pathways. Therefore, the identification of gene signatures that occur at each stage during the CRC progression is critical and can present an impact on the diagnosis and prognosis of the patient. In this study, our main goal was to determine these signatures, by evaluating the gene expression of paired colorectal adenoma and adenocarcinoma samples to identify novel genetic markers in association to the adenoma-adenocarcinoma stage transition.

METHODS

Ten paired adenoma and adenocarcinoma colorectal samples were subjected to microarray gene expression analysis. In addition, mutations in APC, KRAS and TP53 genes were investigated by DNA sequencing in paired samples of adenoma, adenocarcinoma, normal tissue, and peripheral blood from ten patients.

RESULTS

Gene expression analysis revealed a signature of 689 differentially expressed genes (DEG) (fold-change> 2, p< 0.05), between the adenoma and adenocarcinoma paired samples analyzed. Gene pathway analysis using the 689 DEG identified important cancer pathways such as remodeling of the extracellular matrix and epithelial-mesenchymal transition. Among these DEG, the ETV4 stood out as one of the most expressed in the adenocarcinoma samples, further confirmed in the adenocarcinoma set of samples from the TCGA database. Subsequent in vitro siRNA assays against ETV4 resulted in the decrease of cell proliferation, colony formation and cell migration in the HT29 and SW480 colorectal cell lines. DNA sequencing analysis revealed KRAS and TP53 gene pathogenic mutations, exclusively in the adenocarcinomas samples.

CONCLUSION

Our study identified a set of genes with high potential to be used as biomarkers in CRC, with a special emphasis on the ETV4 gene, which demonstrated involvement in proliferation and migration.

Postmenopausal Hormone Therapy and Colorectal Cancer Risk by Molecularly Defined Subtypes and Tumor Location

BACKGROUND

Postmenopausal hormone therapy (HT) is associated with a decreased colorectal cancer (CRC) risk. As CRC is a heterogeneous disease, we evaluated whether the association of HT and CRC differs across etiologically relevant, molecularly defined tumor subtypes and tumor location.

METHODS

We pooled data on tumor subtypes (microsatellite instability status, CpG island methylator phenotype status, BRAF and KRAS mutations, pathway: adenoma-carcinoma, alternate, serrated), tumor location (proximal colon, distal colon, rectum), and HT use among 8220 postmenopausal women (3898 CRC cases and 4322 controls) from 8 observational studies. We used multinomial logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CIs) for the association of ever vs never HT use with each tumor subtype compared with controls. Models were adjusted for study, age, body mass index, smoking status, and CRC family history. All statistical tests were 2-sided.

RESULTS

Among postmenopausal women, ever HT use was associated with a 38% reduction in overall CRC risk (OR =0.62, 95% CI = 0.56 to 0.69). This association was similar according to microsatellite instability, CpG island methylator phenotype and BRAF or KRAS status. However, the association was attenuated for tumors arising through the serrated pathway (OR = 0.81, 95% CI = 0.66 to 1.01) compared with the adenoma-carcinoma pathway (OR = 0.63, 95% CI = 0.55 to 0.73; P het =.04) and alternate pathway (OR = 0.61, 95% CI = 0.51 to 0.72). Additionally, proximal colon tumors had a weaker association (OR = 0.71, 95% CI = 0.62 to 0.80) compared with rectal (OR = 0.54, 95% CI = 0.46 to 0.63) and distal colon (OR = 0.57, 95% CI = 0.49 to 0.66; P het =.01) tumors.

CONCLUSIONS

We observed a strong inverse association between HT use and overall CRC risk, which may predominantly reflect a benefit of HT use for tumors arising through the adenoma-carcinoma and alternate pathways as well as distal colon and rectal tumors.

Expression of the Serrated Markers Annexin A10 or Gremlin1 in Colonic Adenocarcinomas: Morphology and Prognostic Values

Describe clinical, histological and molecular charatcteristics and prognosis values of the serrated candidate markers AnnexinA10 and Gremlin1 in colon adenocarcinomas. Immunohistochemical expression of AnnexinA10 and Gremlin1 was evaluated on 346 colonic adenocarcinomas. Clinicopathological, molecular features and prognostic characteristics were then evaluated. A total of 40 colonic adenocarcinomas expressed AnnexinA10 (11.6%) and, 115 expressed Gremlin1 (40.4%). AnnexinA10 expression was significantly associated, on univariate analyses, with female gender (p = 0.03), right tumor location (p < 0.001), differentiation grade 3 (p < 0.001), serrated adenocarcinoma subtype (p < 0.001), serrated (p < 0.001), medullary (p = 0.005), and mucinous component (p = 0.004), cytoplasmic eosinophilia (p < 0.001), discernible nuclei (p = 0.001), preserved polarity (p < 0.001), lymphatic invasion (p = 0.01), BRAFV600E mutation (p < 0.001), MSI-H status (p < 0.001) and CIMP-H status (p = 0.019). Multivariate analyses revealed that mucinous component (p = 0.002), lymphatic invasion (p = 0.02) and BRAFV600E mutation (p < 0.001) were independently associated with AnnexinA10 expression. In addition, AnnexinA10 was an indicator of poorer overall survival (OS) in UICC stage IV adenocarcinomas (p = 0.01) only. Gremlin1 expression was neither associated with serrated adenocarcinoma subtype (p = 0.51) nor with AnnexinA10 expression (p = 0,31), but was significantly associated, in univariate analysis with male gender (p = 0.002), younger age (p = 0.002), left tumor location (p = 0.04), and MSS status (p = 0.03). Gremlin1 expression was associated with better OS only in UICC stage III colon adenocarcinomas (p = 0.006). Colon adenocarcinomas expressing AnnexinA10 have distinct clinico-pathological and molecular features. AnnexinA10 expression is an indicator of poorer OS in UICC stage IV patients. Gremlin1 expression is not associated with serrated adenocarcinomas subtype. Its expression was associated with better OS in UICC Stage III patients.

Traditional Serrated Pathway-associated Colorectal Carcinoma: Morphologic Reappraisal of Serrated Morphology, Tumor Budding, and Identification of Frequent PTEN Alterations

The phenotypic characteristics of traditional serrated adenoma (TSA)-associated malignancies remain obscure. This study was a morphologic reappraisal of 27 colorectal carcinomas arising from TSA (TSA-CRCs) and 53 BRAF-mutated/microsatellite-stable colorectal carcinomas (BRAF-mut/MSS CRCs). Makinen's criteria for serrated adenocarcinoma were applied to assess the morphologic similarity of the 2 entities. Tumor budding, another histologic feature of serrated adenocarcinoma, was also evaluated. Phosphatase and tensin homologue deleted on chromosome 10 (PTEN), a commonly mutated gene in the serrated pathway, was assessed with immunohistochemistry. Tumors with aberrant PTEN expression were subjected to molecular analysis using quantitative methylation assay, exon sequencing, and fluorescence in situ hybridization. Most cases (>90%) of TSA-CRCs and BRAF-mut/MSS CRCs exhibited a constellation of serrated morphology, including epithelial serrations, abundant eosinophilic cytoplasm, and discernible/vesicular nuclei. A majority (65%) of them qualified for the diagnosis of serrated adenocarcinoma. High-grade tumor budding was closely associated with serrated morphology and was a significant independent factor for poor patient survival in multivariate analysis (P=0.008). Aberrant PTEN expression was detected in nearly half of the cases of both entities (P=0.501). Among the 44 samples with aberrant PTEN expression, 8 harbored PTEN somatic mutations, which were characterized by random distribution without hotspot clustering, 12 had promoter hypermethylation, and 14 had deleted alleles. These findings support a unique model of colorectal carcinogenesis that is similar between TSA-CRCs and BRAF-mut/MSS CRCs. Both entities exhibited common histologic patterns and similar molecular alterations and may well constitute the TSA pathway.

Serrated Colorectal Cancer: The Road Less Travelled?

Studies of colorectal cancer (CRC) originating through the conventional adenoma-carcinoma sequence have provided insight into the molecular mechanisms controlling its initiation and progression. Less is known about the alternative 'serrated' pathway, which has been associated with BRAF mutation and microsatellite instability. Recent transcriptomics approaches to classify human CRC revealed that mesenchymal and/or desmoplastic features combined with an immunosuppressive microenvironment are key determinants of CRC with the poorest prognosis. Importantly, these aggressive CRCs harbor the characteristics of serrated tumors, suggesting that initiation through this alternative pathway determines how aggressive the CRC becomes. Here, we review recent evidence on how serrated carcinogenesis contributes to the subtype of CRC with the poorest prognosis.

Morphology and Molecular Features of Rare Colorectal Carcinoma Histotypes

Several histopathological variants of colorectal carcinoma can be distinguished, some associated with specific molecular profiles. However, in routine practice, ninety/ninety-five percent of all large bowel tumors are diagnosed as conventional adenocarcinoma, even though they are a heterogeneous group including rare histotypes, which are often under-recognized. Indeed, colorectal cancer exhibits differences in incidence, location of tumor, pathogenesis, molecular pathways and outcome depending on histotype. The aim is therefore to review the morphological and molecular features of these rare variants of intestinal carcinomas which may hold the key to differences in prognosis and treatment.

The association between colorectal sessile serrated adenomas/polyps and subsequent advanced colorectal neoplasia

PURPOSE

Colorectal cancer (CRC) screening guidelines recommend increased surveillance of individuals with sessile serrated adenomas/polyps (SSA/Ps), but there is uncertainty about the risk associated with SSA/Ps. We aimed to determine the association between SSA/Ps and subsequent advanced colorectal neoplasia.

METHODS

This case-control study included Kaiser Permanente Washington (KPWA) members who received an index colonoscopy between 1/1/1998 and 12/31/2007, and had hyperplastic polyps (HPs) or SSA/Ps but no conventional adenomas according to study pathologist histologic review. Subsequent pathology reports and biopsies through 1/1/2013 were reviewed for advanced colorectal neoplasia. We linked to the Seattle-Puget Sound Surveillance Epidemiology and End Results (SEER) registry to identify additional CRC cases. We used generalized estimating equations with a logit link to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for advanced colorectal neoplasia, comparing those with SSA/Ps to those with HPs.

RESULTS

There were 161 individuals with index SSA/Ps, 548 with HPs, and 918 subsequent endoscopies included in analyses. Of those with index SSA/Ps, 19 had subsequent advanced colorectal neoplasia; 39 with HPs had subsequent advanced colorectal neoplasia. Compared to those with HPs, those with SSA/Ps were not statistically significantly more likely to have subsequent advanced colorectal neoplasia (adjusted OR 1.79; CI 0.98-3.28). Polyp size ≥ 10 mm, right colon location, and the presence of multiple serrated polyps were also not associated with advanced colorectal neoplasia.

CONCLUSIONS

Our results suggest that there is not a strong association between SSA/Ps and subsequent advanced colorectal neoplasia during the 5 years following SSA/P removal.

Can the rate and location of sessile serrated polyps be part of colorectal Cancer disparity in African Americans?

BACKGROUND

Up to 30% of colorectal cancers develop through the serrated pathway. African Americans (AAs) suffer a disproportionate burden of colorectal cancer. The aim of this study was to evaluate clinicopathological features of AA patients diagnosed with sessile serrated polyps (SSPs).

METHODS

We conducted a retrospective study of all colonoscopies (n = 12,085) performed at Howard University Hospital, from January 1st, 2010 to December 31st, 2015, of which 83% were in AA patients, (n = 10,027). Among AAs, pathology reports confirmed 4070 patients with polyps including 252 with SSPs. Demographic and clinical variables (i.e. sex, age, BMI, anatomic location, clinical symptoms, polyp size, and clinical indications were collected at colonoscopy.

RESULTS

In the AA population, the median age was 56 with interquartile range (IQR) of 51 to 62 years, 54% were female, and 48% had a BMI > 30. The most common reason for colonoscopy was screening (53%), whereas the prevalent reasons for diagnostic colonoscopies were changes in bowel habits (18%) and gastrointestinal bleeding (17%). The total number of SSPs among the 252 AA (diagnosed with SSPs) was 338. Of these, 9% (n = 29/338) had some degree of cytological dysplasia, primarily in the ascending colon (n = 6/42, 14%), Transverse colon (n = 2/16, 13%) and rectosigmoid (n = 19/233, 8%). About 24% of patients had more than 2 polyps. Most patients (76%) had distal SSPs (rectal and rectosigmoid), in comparison to 14% of proximal polyps and 10% of bilateral locations. Median SSA/P size for all locations was 0.6 cm.

CONCLUSION

The prevalence of SSPs accounts for 6% of all polyps in AA patients and was diagnosed in 2.5% of all colonoscopies (n = 252/10,027), which is higher than Caucasians in the US. SSPs were predominantly located in the left side, as compared to published literature showing the predominance in the right side of the colon. Screening of CRC will have the chance to detect high risk SSA/P in this population.

Early-stage serrated adenocarcinomas are divided into several molecularly distinct subtypes

Serrated adenocarcinoma (SAC) is considered the end stage of the serrated neoplasia pathway. Although SAC prognosis is not widely recognized, the serrated pathway-associated subtype consistently exhibits unfavorable prognosis in genetic studies. Herein, we classified molecularly distinct subtypes of serrated adenocarcinomas and clarified their associated clinicopathological characteristics and genetic changes. We examined 38 early-stage colorectal SACs. Of these, 24 were classified into three molecularly distinct groups by colon cancer subtyping (CCS). The clinicopathological characteristics, Ki 67 labeling index (LI), and SAC epithelial serration were assessed. The DNA from carcinomas and normal tissue/adenoma was extracted by laser microdissection and sequenced by next-generation sequencing, and mutation numbers and patterns of a 15-oncogene panel were determined. The CCS groups included CCS1 (CDX2+, HTR2B-, FRMD6-, ZEB1-, and microsatellite instable-low [MSI-L]/microsatellite stable [MSS]; 14 cases), CCS2 (microsatellite instable-high [MSI-H], 5 cases), and CCS3 (CDX2-, HTR2B+, FRMD6+, ZEB1+, and MSI-L/MSS; 5 cases). Invasive cancer was significantly more frequent in CCS3 than in CCS1 (5/5 versus 3/14, respectively). Ki67 LI and epithelial serration were higher in CCS3 than in CCS1 (83.0 ± 5.8 versus 65.4 ± 4.0 and 5/5 versus 3/14, respectively; p = 0.031 and 0.0048). CCS2 showed the highest mutation number, whereas KRAS and BRAF mutation numbers were higher in CCS3 than in CCS1. Early-stage SACs were classified into three molecularly distinct subtypes with different clinicopathological and genetic characteristics.

Identification of risk factors for sessile and traditional serrated adenomas of the colon by using big data analysis

BACKGROUND AND AIM

Little is known about the risk factors associated with serrated polyps, because the early studies, which occurred before the new World Health Organization classification was introduced, included mixtures of serrated polyps. This study aimed to evaluate the risk factors associated with the presence of sessile serrated adenomas (SSAs) and traditional serrated adenomas (TSAs) using big data analytics.

METHODS

Using a case-control design, we evaluated the risk factors associated with the presence of SSAs and TSAs. Subjects who underwent colonoscopies from 2002 to 2012 as part of the comprehensive health screening programs undertaken at the Samsung Medical Center, Korea, participated in this study.

RESULTS

Of the 48 677 individuals who underwent colonoscopies, 183 (0.4%) had SSAs and 212 (0.4%) had TSAs. The multivariate analysis determined that being aged ≥ 50 years (odds ratio [OR] 1.91, 95% confidential interval [CI] 1.27-2.90, P = 0.002) and a history of colorectal cancer among first-degree relatives (OR 3.14, 95% CI 1.57-6.27, P = 0.001) were significant risk factors associated with the presence of SSAs and that being aged ≥ 50 years (OR 2.61, 95% CI 1.79-3.80, P < 0.001), obesity (OR 1.63, 95% CI 1.12-2.36, P = 0.010), and a higher triglyceride level (OR 1.63, 95% CI 1.12-2.36, P = 0.010) were independent risk factors associated with the presence of TSAs.

CONCLUSIONS

We used big data analytics to determine the risk factors associated with the presence of specific polyp subgroups, and individuals who have these risk factors should be carefully scrutinized for the presence of SSAs or TSAs during screening colonoscopies.

Update on Sporadic Colorectal Cancer Genetics

Our understanding of the genetics of colorectal cancer has changed dramatically over recent years. Colorectal cancer can be classified in multiple different ways. Along with the advent of whole-exome sequencing, we have gained an understanding of the scale of the genetic changes found in sporadic colorectal cancer. We now know that there are multiple pathways that are commonly involved in the evolution of colorectal cancer including Wnt/β-catenin, RAS, EGFR, and PIK3 kinase. Another recent leap in our understanding of colorectal cancer genetics is the recognition that many, if not all tumors, are actually genetically heterogeneous within individual tumors and also between tumors. Recent research has revealed the prognostic and possibly therapeutic implications of various specific mutations, including specific mutations in BRAF and KRAS . There is increasing interest in the use of mutation testing for screening and surveillance through stool and circulating DNA testing. Recent advances in translational research in colorectal cancer genetics are dramatically changing our understanding of colorectal cancer and will likely change therapy and surveillance in the near future.

Clinicopathologic and outcome study of sessile serrated adenomas/polyps with serrated versus intestinal dysplasia

It is believed that sessile serrated adenomas/polyps lead to the development of microsatellite unstable cancer via a dysplasia-carcinoma sequence. Little is known regarding the morphologic and biologic features, and outcome of sessile serrated adenomas/polyps with dysplasia, or of its specific dysplasia subtypes (intestinal versus serrated). The aims of this study were to analyze and compare the clinical, pathologic, and outcome characteristics of sessile serrated adenomas/polyps with serrated versus intestinal dysplasia. The study included 86 patients with sessile serrated adenomas/polyps with dysplasia (50 serrated dysplasia, 22 intestinal dysplasia, 14 mixed serrated and intestinal dysplasia). The clinical and pathologic features, and the prevalence rate of prior, concurrent, and future neoplastic lesions, were compared between sessile serrated adenomas/polyps with intestinal versus serrated dysplasia and with matched control patients with ≥1 conventional adenoma. The mean age of the patients, polyp size, and prevalence of adenocarcinoma within the polyps were significantly higher in sessile serrated adenomas/polyps with high versus low-grade dysplasia. Sessile serrated adenomas/polyps with intestinal dysplasia showed a significantly higher rate of adenocarcinoma (23%) compared with those with serrated dysplasia (6%, P=0.05), and the high-grade lesions occurred at a significantly younger age in the former compared with the latter (65 versus 76 years, P=0.05). Compared with patients with conventional adenomas, patients with sessile serrated adenomas/polyps with dysplasia showed a significantly higher rate of invasive carcinoma within the polyps (12 versus 0%, P=0.01) and a significantly lower association with prior or future conventional adenomas. Sessile serrated adenomas/polyps with dysplasia should be considered high-risk neoplastic precursor lesions, particularly those with intestinal dysplasia. Cancer may develop from sessile serrated adenomas/polyps with either type of dysplasia.

Expression of doublecortin and CaM kinase-like-1 protein in serrated neoplasia of the colorectum

The adenoma-carcinoma sequence (ACS) and the serrated pathway are two distinct developmental routes leading to the formation of colorectal carcinoma. Recently, the doublecortin and CaM kinase-like-1 protein (DCLK1) has been reported to serve as an intestinal cancer stem cell marker and has been demonstrated to be overexpressed through the ACS; however, there is a lack of reports on the role of DCLK1 in the serrated pathway. To clarify the correlation between DCLK1 protein expression and clinicopathological characteristics of the serrated tumorigenic pathway, the present study used immunohistochemistry to examine the expression of DCLK1 in endoscopically resected samples of 62 serrated polyps [20 hyperplastic polyps (HPs), 16 traditional serrated adenomas (TSAs) and 26 sessile serrated adenoma-polyps (SSA/Ps)], as well as 20 non-serrated adenomas, 20 carcinoma in adenomas (CIAs) and 18 early pure colorectal carcinomas without any adenoma component (EPCs). Based on immunostaining score, high DCLK1 expression was detected in 20.0% of HPs (23.1% of microvesicular HPs and 14.3% of goblet cell HPs), 37.5% of TSAs, 7.7% of SSA/Ps, 80.0% of non-serrated adenomas, 75.0% of CIAs and 50.0% of EPCs. Negative or low DCLK1 expression was frequently observed in TSAs (P<0.005), SSA/Ps (P<0.00001) and EPCs (P<0.04) compared with non-serrated adenomas and CIAs. In addition, negative or low DCLK1 expression was significantly more frequent in SSA/Ps (92.3%) compared with TSAs (62.5%; P<0.05). Thus, the expression pattern of DCLK1 between the serrated pathway and ACS differed, indicating that DCLK1 expression may perform a secondary role in serrated tumorigenesis. In addition, the data indicates that EPCs may contain tumors derived from the serrated pathway as well as the ACS.

Clinicopathologic and endoscopic features of early-stage colorectal serrated adenocarcinoma

Background

Serrated adenocarcinoma (SAC) is a distinct colorectal carcinoma variant that accounts for approximately 7.5% of all advanced colorectal carcinomas. While its prognosis is worse than conventional carcinoma, its early-stage clinicopathologic features are unclear. We therefore aimed to clarify the clinicopathologic and endoscopic characteristics of early-stage SACs.

Methods

Forty consecutive early-stage SAC patients at Hiroshima University Hospital were enrolled; SACs were classified into epithelial serration (Group A, n = 17) and non-epithelial serration (Group B, n = 23) groups. Additionally, we classified serrated adenoma into 4 types: sessile serrated adenoma (SSA), traditional serrated adenoma (TSA), unclassified, and non-serrated adenoma type.

Results

There were significant differences between Groups A and B in terms of tumor size (27.6 vs. 43.1 mm), incidences of T1 carcinoma (71% vs. 13%), and having the same color as normal mucosa (47% vs. 17%), respectively (p <0.01). In SACs >20 mm, the incidence of T1 carcinoma in Group A (70%) was significantly greater than that in Group B (13%) (p <0.05). There were significant differences in ‘Japan NBI Expert Team’ type 3 and type V pit pattern classifications between the 2 groups. The average TSA-type tumor size (42.6 mm) was significantly larger than that of the SSA (17.2 mm) and non-serrated component types (18.3 mm). The incidences of submucosal invasion in SSA- (80%), unclassified- (100%), and non-serrated-type (100%) tumors were significantly higher than that in the TSA type (11%).

Conclusions

Epithelial serration in the cancerous area and a non-TSA background indicated aggressive behavior in early-stage SACs.

Protein expression of Fragile Histidine Triad and cyclooxgenase-2 in serrated neoplasia of the colorectum

The adenoma-carcinoma sequence (ACS) and the serrated pathway are two distinct developmental routes leading to the formation of colorectal carcinoma (CRC). However, the mechanism triggered by the serrated pathway remains unclear. Therefore, to clarify the molecular and clinicopathological characteristics of the serrated tumorigenic pathway, immunohistochemistry was used to examine the expression of Fragile Histidine Triad (FHIT), cyclooxygenase-2 (COX-2), MutL homolog 1 (MLH1), MutS protein homolog 2 (MSH2) and P53 in endoscopically resected samples of 62 serrated polyps. These samples included 20 hyperplastic polyps (HPs), 16 traditional serrated adenomas (TSAs), 26 sessile serrated adenoma/polyps (SSA/Ps), 20 non-serrated adenomas, 20 carcinoma in adenomas (CIAs) and 18 early pure CRCs without any adenoma component (EPCs). FHIT expression was markedly reduced or absent in 50% of TSA samples, 92.3% of SSA/Ps and 44% of EPCs, but only rarely in HPs, non-serrated adenomas and CIAs. COX-2 expression was more common in non-serrated adenomas compared with in serrated polyps, and was present in 25 and 3.2% of the cases respectively (P<0.01). Furthermore, COX-2 expression was more frequent in CIAs (60%) compared with in EPCs (22.2%; P<0.05). The incidence of negative COX-2 expression was higher in FHIT-negative SSA/Ps compared with in FHIT-positive SSA/Ps (P=0.08). A total of 16.7% of EPC samples and 11.5% of SSA/Ps demonstrated a loss of MLH1/MSH2 expression, but none of the other tumor types did. P53 overexpression was significantly increased in EPC (77.8%) and CIA (60%) samples compared with in HP (0%), TSA (6.6%), SSA/P (0%) and non-serrated adenoma (10%) samples (P<0.01). These findings demonstrated that there are different expression patterns between the serrated pathway and ACS, indicating that aberrant FHIT and inhibited COX-2 expression may be associated with serrated tumorigenesis. In addition, this data indicated that EPC may contain tumors derived from the serrated pathway as well as ACS.

CpG Island Methylator Phenotype-High Colorectal Cancers and Their Prognostic Implications and Relationships with the Serrated Neoplasia Pathway

The concept of a CpG island methylator phenotype (CIMP) was first introduced by Toyota and Issa to describe a subset of colorectal cancers (CRCs) with concurrent hypermethylation of multiple CpG island loci. The concept of CIMP as a molecular carcinogenesis mechanism was consolidated by the identification of the serrated neoplasia pathway, in which CIMP participates in the initiation and progression of serrated adenomas. Distinct clinicopathological and molecular features of CIMP-high (CIMP-H) CRCs have been characterized, including proximal colon location, older age of onset, female preponderance, and frequent associations of high-level microsatellite instability and BRAF mutations. CIMP-H CRCs arise in sessile or traditional serrated adenomas and thus tend to display the morphological characteristics of serrated adenomas, including epithelial serration, vesicular nuclei, and abundant cytoplasm. Both the frequent association of CIMP and poor prognosis and different responses of CRCs to adjuvant therapy depending on CIMP status indicate clinical implications. In this review, we present an overview of the literature documenting the relevant findings of CIMP-H CRCs and their relationships with the serrated neoplasia pathway.

Bilateral blockade of MEK- and PI3K-mediated pathways downstream of mutant KRAS as a treatment approach for peritoneal mucinous malignancies

Mucinous colorectal adenocarcinomas (MCAs) are clinically and morphologically distinct from nonmucinous colorectal cancers (CRCs), show a distinct spectrum of genetic alterations (higher KRAS mutations, lower p53, high MUC2), exhibit more aggressive behavior (more prone to peritoneal dissemination and lymph node involvement) and are associated with poorer response to chemotherapy with limited treatment options. Here, we report the effectiveness of combinatorial targeting of two KRAS-mediated parallel pathways in reducing MUC2 production and mucinous tumor growth in vitro and in vivo. By knockdown of mutant KRAS we show that, mutant KRAS (a) is necessary for MUC2 production in vitro and (b) synergistically engages PI3K/AKT and MEK/ERK pathways to maintain MUC2 expression in MCA cells. These results define a novel and a previously undescribed role for oncogenic KRAS in mucinous cancers. MCA cells were sensitive to MEK inhibition suggesting cellular dependence (‘addiction’) of KRAS-mutant MCA cells on hyperactivation of the MEK-driven pathway. Interestingly, MCA cells, though initially sensitive, were later resistant to PI3K single agent inhibition. Our studies suggest that this resistance involves dynamic rewiring of signaling circuits mediated through relief of RTK inhibition and MEK-ERK rebound activation. This resistance however, could be overcome by co-targeting of PI3K and MEK. Our studies thus provide a rational basis for MEK- and PI3K-targeted combination therapy for not only KRAS mutant MCA but also for other related mucinous neoplasms that overproduce MUC2 and have a high rate of KRAS mutations such as pseudomyxoma peritonei.

The clinical impact of serrated colorectal polyps

Serrated polyps (SPs) of the colorectum pose a novel challenge to practicing gastroenterologists. Previously thought benign and unimportant, there is now compelling evidence that SPs are responsible for a significant percentage of incident colorectal cancer worldwide. In contrast to conventional adenomas, which tend to be slow growing and polypoid, SPs have unique features that undermine current screening and surveillance practices. For example, sessile serrated polyps (SSPs) are flat, predominately right-sided, and thought to have the potential for rapid growth. Moreover, SSPs are subject to wide variations in endoscopic detection and pathologic interpretation. Unfortunately, little is known about the natural history of SPs, and current guidelines are based largely on expert opinion. In this review, we outline the current taxonomy, epidemiology, and management of SPs with an emphasis on the clinical and public health impact of these lesions.

Molecular Subtypes of Colorectal Cancer and Their Clinicopathologic Features, With an Emphasis on the Serrated Neoplasia Pathway

CONTEXT

-Colorectal cancer is a heterogeneous disease entity with 3 molecular carcinogenesis pathways and 2 morphologic multistep pathways. Right-sided colon cancers and left-sided colon and rectal cancers exhibit differences in their incidence rates according to geographic region, age, and sex. A linear tendency toward increasing frequencies of microsatellite instability-high or CpG island methylator phenotype-high cancers in subsites along the bowel from the rectum to the cecum or the ascending colon accounts for the differences in tumor phenotypes associated with these subsites. The molecular subtypes of colorectal cancers exhibit different responses to adjuvant therapy, which might be responsible for differences in subtype-specific survival.

OBJECTIVES

-To review the clinicopathologic and molecular features of the molecular subtypes of colorectal cancer generated by combined CpG island methylator phenotype and microsatellite statuses, to integrate these features with the most recent findings in the context of the prognostic implications of molecular subtypes, and to emphasize the necessity of developing molecular markers that enable the identification of adenocarcinomas involving the serrated neoplasia pathway.

DATA SOURCES

-Based on the authors' own experimental data and a review of the pertinent literature.

CONCLUSIONS

-Because colorectal cancers arise from 2 different morphologic multistep carcinogenesis pathways with varying contributions from 3 different molecular carcinogenesis pathways, colorectal cancer is a heterogeneous and complex disease. Thus, molecular subtyping of colorectal cancers is an important approach to characterizing their heterogeneity with respect to not only prognosis and therapeutic response but also biology and natural history.

BRAFV600E cooperates with CDX2 inactivation to promote serrated colorectal tumorigenesis

While 20–30% of colorectal cancers (CRCs) may arise from precursors with serrated glands, only 8–10% of CRCs manifest serrated morphology at diagnosis. Markers for distinguishing CRCs arising from ‘serrated’ versus ‘conventional adenoma’ precursors are lacking. We studied 36 human serrated CRCs and found CDX2 loss or BRAF mutations in ~60% of cases and often together (p=0.04). CDX2^Null/BRAF^V600E expression in adult mouse intestinal epithelium led to serrated morphology tumors (including carcinomas) and BRAF^V600E potently interacted with CDX2 silencing to alter gene expression. Like human serrated lesions, CDX2^Null/BRAF^V600E-mutant epithelium expressed gastric markers. Organoids from CDX2^Null/BRAF^V600E–mutant colon epithelium showed serrated features, and partially recapitulated the gene expression pattern in mouse colon tissues. We present a novel mouse tumor model based on signature defects seen in many human serrated CRCs – CDX2 loss and BRAF^V600E. The mouse intestinal tumors show significant phenotypic similarities to human serrated CRCs and inform about serrated CRC pathogenesis.

DOI:http://dx.doi.org/10.7554/eLife.20331.001

Colorectal cancer anatomic distribution patterns remain the same after sessile serrated adenoma/polyp considered cancer precursor: a 9-year comparison study from community-based endoscopy centers

BACKGROUND

The overall incidence of colorectal cancer (CRC) in the United States has steadily decreased. However, the incidence of right-sided CRC remains unchanged for the past two decades. The serrated neoplastic pathway (sessile serrated adenoma/polyp, SSA/P) has been considered an important pathway of colorectal carcinogenesis, especially in the right-sided CRC. The aim of this study was to compare CRC anatomic distribution patterns in a 9-year interval in the general population before and after SSA/P was recognized and treated as a CRC precursor.

METHODS

The Miraca Life Sciences (MLS) pathology database was queried for all primary CRCs diagnosed between 8/3/2000 to 12/31/2005 (control group) and 1/1/2014 to 12/31/2014 (current group). Patients' demographics, clinical information, and pathology reports were collected and analyzed.

RESULTS

A total of 5,602 patients with 5,685 CRCs were identified, of which 2,728 patients with 2,765 CRCs in current group and 2,874 patients with 2,920 CRCs in control group. Overall, there were no statistical differences in the current group in regards to the anatomical distribution patterns of CRCs in the proximal, right-sided, distal, and left-sided colon or genders compared with the control group (all P>0.05). Among the current group, there were 33 (1.2%) patients with 38 (1.4%) CRCs arising in SSA/Ps [serrated carcinomas (SCAs)], of which 33 (86.8%) were in the right-sided colon and 5 (13.2%) in the left-sided colon. Twenty-three (69.7%) SCA patients were female with significant advanced age than male (76.4 vs. 69.6, P=0.023).

CONCLUSIONS

The overall current CRC anatomic distribution patterns after SSA/Ps managed as CRC precursor remain the same in the patients' population from the community-based endoscopy centers in the U.S. It is suggested that the current SSA/P management might need to be further modified.

Gremlin1 expression associates with serrated pathway and favourable prognosis in colorectal cancer

AIMS

Gremlin1 is a bone morphogenetic protein (BMP) antagonist with a suggested role in colorectal cancer (CRC) progression. We have analysed Gremlin1 protein expression in CRC and assessed its correlation with clinicopathological characteristics, including developmental pathway and prognosis.

METHODS AND RESULTS

Material included a non-selected series of 148 surgically treated CRC cases. The tumour-node-metastasis (TNM) stage, histological grade and inflammatory infiltrate at the invasive margin were assessed, and tumours were classified to serrated or non-serrated types. Immunohistochemistry was conducted to evaluate Gremlin1 expression. Prognosis (60-month follow-up) was analysed by Kaplan-Meier methods and Cox regression analysis. Gremlin1 expression was detected in epithelial cells both in normal mucosa and in carcinomas. Abundant expression in carcinomas associated with low TNM stage (P = 0.044), low histological grade (P = 0.044), serrated histology (P = 0.033 or P = 0.053 depending on the classification cut-off) and intensive inflammatory infiltrate at the invasive margin (P = 0.044), and was a stage independent indicator of extended survival (P = 0.029).

CONCLUSIONS

Gremlin1 protein expression in CRC associates with low tumour stage and extended survival independently of tumour stage, suggesting that it represents a relevant prognostic indicator in CRC. High expression in carcinomas with serrated histology suggests a potential role for Gremlin1 in the serrated pathway of CRC.

The frequency of early colorectal cancer derived from sessile serrated adenoma/polyps among 1858 serrated polyps from a single institution

BACKGROUND AND AIM

Sessile serrated adenoma/polyps (SSAPs) are suspected to have a high malignant potential, although few reports have evaluated the incidence of carcinomas derived from SSAPs using the new classification for serrated polyps (SPs). The aim of study was to compare the frequency of cancer coexisting with the various SP subtypes including mixed polyps (MIXs) and conventional adenomas (CADs).

METHODS

A total of 18,667 CADs were identified between April 2005 and December 2011, and 1858 SPs (re-classified as SSAP, hyperplastic polyp (HP), traditional serrated adenoma (TSA), or MIX) were removed via snare polypectomy, endoscopic mucosal resection, or endoscopic sub-mucosal dissection.

RESULTS

Among 1160 HP lesions, 1 (0.1%) coexisting sub-mucosal invasive carcinoma (T1) was detected. Among 430 SSAP lesions, 3 (0.7%) high-grade dysplasia (HGD/Tis) and 1 (0.2%) T1 were detected. All of the lesions were detected in the proximal colon, with a mean tumor diameter of 18 mm (SD 9 mm). Among 212 TSA lesions, 3 (1%) HGD/Tis were detected but no T1 cancer. Among 56 MIX lesions, 9 (16%) HGD/Tis and 1 (2%) T1 cancers were detected, and among 18,677 CAD lesions, 964 (5%) HGD/Tis and 166 (1%) T1 cancers were identified.

CONCLUSIONS

Among the resected lesions that were detected during endoscopic examination, a smaller proportion (1%) of SSAPs harbored HGD or coexisting cancer, compared to CAD or MIX lesions. Therefore, more attention should be paid to accurately identifying lesions endoscopically for intentional resection and the surveillance of each SP subtype.

[Serrated lesions of the large intestine: Prevalence analysis and clinical and morphologic characteristics]

OBJECTIVE

to retrospectively estimate the prevalence of serrated lesions of the large intestine and to reveal the features of dis- tribution of serrated lesions in the previously diagnosed classical adenomas and hyperplastic polyps.

MATERIAL AND METHODS

A continuous sampling method was used to take biopsy specimens from the archive material of 440 polypoid lesions of the large intestine, which had entered in 2012-2013, and which were be morphologically reexamined by three experts. The mor- phological criteria for diagnosing different types of serrated lesions were taken according to the 2010 WHO classification of premalignant lesions of the large intestine and to the recommendations from an expert panel (Am J of Gastroenterology 2012).

RESULTS

A group of serrated lesions included tubular (13.7%), tubulovillous adenomas (12.5%), and villous (50%) adenomas. The reexamination revealed 121 serrated lesions, including hyperplastic polyps (n = 55 (45.5%)), sessile serrated adenomas/ polyps (SSA/P) (n = 24 (19.8%)), out of which there were those with dysplasia (n=6 (5%)), traditional serrated adenomas (TSAs) (n = 20 (16.5%)), out of which there were those with dysplasia (n = 1 4 (11.6%)), and unclassified serrated polyps (n =22 (18.2%)). Most hyperplastic polyps (89%) and SSA/P (71%) were located distal to the splenic flexure of the colon; TSAs were equally distributed between the proximal and distal portions of the large intestine. The proportion of serrated lesions with dysplasia was 16.5%; that among SSA/P and TSAs was 25 and 70%, respectively. Serrated lesions with dysplasia were more often located proximally and were larger in size than those without dysplasia.

CONCLUSION

Serrated lesions of the large intestine are its more common abnormalities than previously thought. The reexamination has revealed that serrated lesions occur in both the preexisting group of hyperplastic polyps and all groups of classical adenomas, suggesting the need for widespread introduction of the current classification intO everyday diagnostic practice.

Serrated tubulovillous adenoma of the large intestine

AIMS

Most colorectal polyps are classified readily, but a subset of tubulovillous adenomas (TVA) with prominent serrated architecture causes diagnostic confusion. We aimed to (i) identify histological features that separate serrated TVAs from both conventional TVAs and traditional serrated adenomas (TSA) and (ii) perform a clinicopathological and molecular analysis to determine if the serrated TVA has unique features.

METHODS AND RESULTS

We collected 48 serrated TVAs, 50 conventional TVAs and 66 BRAF wild-type TSAs for analysis. For each polyp we performed a clinicopathological assessment, BRAF and KRAS mutation profiling, cytosine-phosphate-guanosine (CpG) island methylator phenotype status, MGMT methylation and immunohistochemical assessment of seven markers [MutL homologue 1 (MLH1), p16, p53, β-catenin, Ki67, CK7 and CK20]. We found that serrated TVAs can be diagnosed reliably, and have features distinct from both conventional TVAs and TSAs. Compared to conventional TVAs, serrated TVAs are larger, more often proximal, more histologically advanced, show more CpG island methylation and more frequent KRAS mutation. Compared to TSAs they are more often proximal, show less CpG island methylation, more frequent MGMT methylation and more frequent nuclear staining for β-catenin.

CONCLUSIONS

The serrated TVA can be diagnosed reliably and has unique features. It represents a precursor of KRAS mutated, microsatellite stable colorectal carcinoma.

The Increasing Relevance of Tumour Histology in Determining Oncological Outcomes in Colorectal Cancer

Colorectal cancer is not just one type of cancer. Differences in outcome and reaction to treatment can at least be partly explained by different histological and molecular subtypes. Recognition of these differences may influence treatment decisions. However, there is huge variation in the amount of information that is available. Several tumour types such as mucinous carcinoma, signet ring cell carcinoma, neuroendocrine carcinoma and adenosquamous carcinoma have such a distinct phenotype that they are readily recognised. However, due to the rarity of signet ring cell carcinoma and adenosquamous carcinoma, limited data are available. More recently defined subtypes, like medullary carcinoma, serrated adenocarcinoma and micropapillary carcinoma, are not adequately diagnosed, which limits research possibilities using large-scale data from registries. In the current review, we systematically describe the histologic subtypes with the clinical and molecular background. We evaluate their prognosis compared to adenocarcinoma not otherwise specified and speculate about the clinical relevance.

A clinicopathological and molecular analysis of 200 traditional serrated adenomas

The traditional serrated adenoma is the least common colorectal serrated polyp. The clinicopathological features and molecular drivers of these polyps require further investigation. We have prospectively collected a cohort of 200 ordinary and advanced traditional serrated adenomas and performed BRAF and KRAS mutational profiling, CpG island methylator phenotype analysis, and immunohistochemistry for a panel of 7 antibodies (MLH1, β-catenin, p53, p16, Ki67, CK7, and CK20) on all cases. The mean age of the patients was 64 years and 50% were female. Of the polyps, 71% were distal. Advanced histology (overt dysplasia or carcinoma) was present in 19% of cases. BRAF mutation was present in 67% and KRAS mutation in 22%. BRAF mutant traditional serrated adenomas were more frequently proximal (39% versus 2%; P≤0.0001), were exclusively associated with a precursor polyp (57% versus 0%; P≤0.0001), and were more frequently CpG island methylator phenotype high (60% versus 16%; P≤0.0001) than KRAS mutant traditional serrated adenomas. Advanced traditional serrated adenomas retained MLH1 expression in 97%, showed strong p53 staining in 55%, and nuclear β-catenin staining in 40%. P16 staining was lost in the advanced areas of 55% of BRAF mutant traditional serrated adenomas compared with 10% of the advanced areas of KRAS mutant or BRAF/KRAS wild-type traditional serrated adenomas. BRAF and KRAS mutant traditional serrated adenomas are morphologically related but biologically disparate polyps with distinctive clinicopathological and molecular features. The overwhelming majority of traditional serrated adenomas retain mismatch repair enzyme function indicating a microsatellite-stable phenotype. Malignant progression occurs via TP53 mutation and Wnt pathway activation regardless of mutation status. However, CDKN2A (encoding the p16 protein) is silenced nearly exclusively in the advanced areas of the BRAF mutant traditional serrated adenomas. Thus, the BRAF mutant traditional serrated adenoma represents an important precursor of the aggressive BRAF mutant, microsatellite-stable subtype of colorectal carcinoma.

[Serrated lesions of the large bowel]

The 2010 WHO classification identifies a new group of pretumor lesions of the large bowel--serrated masses, which includes hyperplastic polyps (HPs), sessile serrated adenomas/polyps (SSA/P), and traditional serrated adenomas (TSA). Serrated masses are a heterogeneous group characterized by serrated gland lumens and, in most cases, without dysplasia. An enlarged proliferative zone, elongated crypts, and no cytological atypia in addition to a serrated lumen are typical of HPs. SSA/P is characterized by the migration of the proliferative zone to the crypt walls, giving rise to specific architectural disorders, such as expanded and horizontally growing basal gland segments along the lamina muscularis mucosae. TSA is typified by short ectopic crypts that cannot reach the lamina muscularis and by epithelial eosinophilic changes. SSA/P and TSA have peculiar molecular genetic profiles and proven malignant potential.

Smoking-associated risks of conventional adenomas and serrated polyps in the colorectum

Purpose

Prior studies suggest cigarette smoking is associated with 1.5- to twofold increased risk of colorectal adenomas and possibly a higher risk of serrated polyps. Further clarification of risk differences between adenomas and serrated polyps is needed with regard to co-occurrence and polyp location.

Methods

We conducted a combined analysis of conventional adenoma and serrated polyp occurrence using individual-level data from 2,915 patients participating in three colonoscopy-based clinical trials. All participants had ≥1 adenomas removed at baseline and were followed for up to 4 years. Smoking habits and other lifestyle factors were collected at baseline using questionnaires. We used generalized linear regression to estimate risk ratios and 95 % confidence intervals.

Results

Smokers were at slightly increased risk of adenomas compared to never smokers [current: RR 1.29 (95 % CI 1.11–1.49) and former: RR 1.18 (1.05–1.32)]. Smoking was associated with greater risk of serrated polyps [current: RR 2.01 (1.66–2.44); former: RR 1.42 (1.20–1.68)], particularly in the left colorectum. Associations between current smoking and occurrence of serrated polyps only [RR 2.33 (1.76–3.07)] and both adenomas and serrated polyps [RR 2.27 (1.68–3.06)] were more pronounced than for adenomas only [RR 1.31 (1.08–1.58)]. Results were similar for other smoking variables and did not differ by gender or for advanced adenomas.

Conclusions

Cigarette smoking has only a weak association with adenomas, but is associated with a significantly increased risk of serrated polyps, particularly in the left colorectum. Since a minority of left-sided serrated polyps is thought to have malignant potential, the role of smoking in initiation phases of carcinogenesis is uncertain.

Annexin A10 is a marker for the serrated pathway of colorectal carcinoma

Serrated adenocarcinoma (SAC), representing at least 10 % of colorectal carcinomas (CRC), differs from conventional carcinomas not only by its histology, but also by its molecular basis. However, the diagnosis of SAC in poorly differentiated cases and without an adjacent serrated adenoma can be challenging. In this study, we utilized previously described expression data and identified annexin A10 (ANXA10) as a potential marker for SAC. We conducted ANXA10 immunohistochemistry in groups of 146 CRC patients and 131 serrated and conventional polyps. In CRC cases, ANXA10 expression associated with serrated histology (sensitivity 42 % and specificity 98 %). BRAF V600E mutation correlated with ANXA10 expression but also seven BRAF wild-type tumors (5 %) were positive for ANXA10. Immunoreactivity for either ANXA10 or BRAF V600E was an accurate predictor of serrated histology (sensitivity 55 % and specificity 97 %). ANXA10 expression did not associate with tumor stage or grade. Of the 131 colorectal polyps, 30/30 of sessile serrated adenomas, 6/11 traditional serrated adenomas, 20/32 hyperplastic polyps, and 2/27 tubulovillous adenomas were positive for ANXA10, while 31/31 tubular adenomas were negative. In conclusion, the results suggest that ANXA10 is a marker with high specificity for the serrated pathway of CRC.

Annexin A10 is a marker for the serrated pathway of colorectal carcinoma

Serrated adenocarcinoma (SAC), representing at least 10 % of colorectal carcinomas (CRC), differs from conventional carcinomas not only by its histology, but also by its molecular basis. However, the diagnosis of SAC in poorly differentiated cases and without an adjacent serrated adenoma can be challenging. In this study, we utilized previously described expression data and identified annexin A10 (ANXA10) as a potential marker for SAC. We conducted ANXA10 immunohistochemistry in groups of 146 CRC patients and 131 serrated and conventional polyps. In CRC cases, ANXA10 expression associated with serrated histology (sensitivity 42 % and specificity 98 %). BRAF V600E mutation correlated with ANXA10 expression but also seven BRAF wild-type tumors (5 %) were positive for ANXA10. Immunoreactivity for either ANXA10 or BRAF V600E was an accurate predictor of serrated histology (sensitivity 55 % and specificity 97 %). ANXA10 expression did not associate with tumor stage or grade. Of the 131 colorectal polyps, 30/30 of sessile serrated adenomas, 6/11 traditional serrated adenomas, 20/32 hyperplastic polyps, and 2/27 tubulovillous adenomas were positive for ANXA10, while 31/31 tubular adenomas were negative. In conclusion, the results suggest that ANXA10 is a marker with high specificity for the serrated pathway of CRC.

Serrated neoplasia of the colon: what do we really know?

Colonoscopy offers incomplete protection from colorectal cancer, particularly in the right colon. Part of this inadequacy may be related to serrated neoplasia. Serrated polyps of the colorectum are now understood to be a heterogeneous group of polyps, some of which are cancer precursors, such as the sessile serrated adenoma (SSA) and the traditional serrated adenoma (TSA). In contrast to conventional adenomas, there is limited published literature on the epidemiology and natural history of these lesions. Furthermore, existing guidelines regarding screening and surveillance practices for these polyps are based largely on expert opinion without firm evidence. In this review, we describe the current understanding of the molecular biology, histopathology, and endoscopic features of serrated neoplasia of the colorectum, with an emphasis on aspects relevant to the practicing gastroenterologist.

Traditional serrated adenoma has two pathways of neoplastic progression that are distinct from the sessile serrated pathway of colorectal carcinogenesis

Traditional serrated adenoma is one type of colorectal serrated neoplasm and a precursor of colorectal cancer. We evaluated the pathologic and molecular features of 60 traditional serrated adenomas with cytologic dysplasia and/or invasive carcinoma. On the basis of morphological features, 16 cases (27%) were categorized as traditional serrated adenoma with serrated dysplasia and 25 cases (42%) as traditional serrated adenoma with conventional adenomatous dysplasia. In addition, 19 cases (31%) showed an overall tubulovillous adenomatous structure but with focal serrated feature. Traditional serrated adenoma with serrated dysplasia had a significantly higher frequency of BRAF mutation than traditional serrated adenoma with conventional adenomatous dysplasia and tubulovillous adenoma with serrated feature (P=0.006), whereas traditional serrated adenoma with conventional adenomatous dysplasia and tubulovillous adenoma with serrated feature had higher frequencies of KRAS mutation than traditional serrated adenoma with serrated dysplasia (P<0.0001). Only traditional serrated adenoma with serrated dysplasia showed sessile serrated adenoma-like lesions at the periphery (n=3) and developed invasive carcinomas when the lesions were <15 mm in size. Abnormal nuclear accumulation of β-catenin was detected in traditional serrated adenoma with conventional adenomatous dysplasia and tubulovillous adenoma with serrated feature but not in traditional serrated adenoma with serrated dysplasia. The frequency of the positive CpG island methylator phenotype was similar among the three dysplastic subtypes, and immunostaining of four mismatch repair proteins in the nucleus was retained in all traditional serrated adenomas and associated invasive malignancies. Traditional serrated adenoma-associated adenocarcinomas (n=28) displayed distinctive morphological features: oval cell nuclei, serrated glands, infiltrating borders, rare occurrences of necrosis and mucinous differentiation. Overexpression of p53 was detected only in high-grade dysplasia and invasive adenocarcinoma. Our findings indicate that traditional serrated adenoma is a heterogeneous neoplasm with two pathways of neoplastic progression, which are distinct from the sessile serrated pathway of colorectal carcinogenesis.

Distinct profile of HIF1α, PTCH, EphB2, or DNA repair protein expression and BRAF mutation in colorectal serrated adenoma

BACKGROUND AND AIMS

The serrated colorectal carcinoma (CRC) as proposed to arise from serrated adenoma (SA) is characterized by upregulation of HIF1α, suppression of PTCH or EphB2, loss of DNA repair proteins, and BRAF mutation. The aim of this study was to evaluate alterations of these candidates involved in the serrated pathway in colorectal polyps.

METHODS

We analyzed immunoreactivity of these proteins, methylation of PTCH and EphB2, and mutation of BRAF and Kras in sessile SAs (SSAs; n = 32), traditional SAs (n = 28), hyperplastic polyps (HPs; n = 24), and conventional adenomas (ADs; n = 21).

RESULTS

Increase of nuclear HIF1α expression was more frequent in SA than HP, but less frequent in SA than AD (P < 0.001). Increase of PTCH expression was not found in SSA or HP, but was evident in about half of traditional SA and all AD (P < 0.001). Decrease of EphB2 expression was more prominent in SA than HP or AD (P ≤ 0.005). Loss of hMLH1 and MGMT expression were most frequent in SSA (P < 0.001). Loss of hMSH2 showed more pronounced in SA and HP than AD (P ≤ 0.004). Methylations of PTCH and EphB2 were rare in all categories. BRAF mutation harbored frequently in SA, but not AD; only AD harbored Kras mutation.

CONCLUSIONS

This work provides evidence of similarity of HIF1α, EphB2 or DNA repair proteins expression, and BRAF mutation in serrated CRCs and their precursors, especially SSA, compared with AD and HP.

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.

Characteristics of missed or interval colorectal cancer and patient survival: a population-based study

BACKGROUND & AIMS

Colorectal cancers (CRCs) diagnosed within a few years after an index colonoscopy can arise from missed lesions or the development of a new tumor. We investigated the proportion, characteristics, and factors that predict interval CRCs that develop within 6-60 months of colonoscopy.

METHODS

We performed a population-based cohort study of Utah residents who underwent colonoscopy examinations from 1995 through 2009 at Intermountain Healthcare or the University of Utah Health System, which provide care to more than 85% of state residents. Colonoscopy results were linked with cancer histories from the Utah Population Database to identify patients who underwent colonoscopy 6-60 months before a diagnosis of CRC (interval cancer). Logistic regression was performed to identify risk factors associated with interval cancers.

RESULTS

Of 126,851 patients who underwent colonoscopies, 2659 were diagnosed with CRC; 6% of these CRCs (159 of 2659) developed within 6 to 60 months of a colonoscopy. Sex and age were not associated with interval CRCs. A higher percentage of patients with interval CRC were found to have adenomas at their index colonoscopy (57.2%), compared with patients found to have CRC detected at colonoscopy (36%) or patients who did not develop cancer (26%) (P < .001). Interval CRCs tended to be earlier-stage tumors than those detected at index colonoscopy, and to be proximally located (odds ratio, 2.24; P < .001). Patients with interval CRC were more likely to have a family history of CRC (odds ratio, 2.27; P = .008) and had a lower risk of death than patients found to have CRC at their index colonoscopy (hazard ratio, 0.63; P < .001).

CONCLUSIONS

In a population-based study in Utah, 6% of all patients with CRC had interval cancers (cancer that developed within 6 to 60 months of a colonoscopy). Interval CRCs were associated with the proximal colon, earlier-stage cancer, lower risk of death, higher rate of adenoma, and family history of CRC. These findings indicate that interval colorectal tumors may arise as the result of distinct biologic features and/or suboptimal management of polyps at colonoscopy.

Lynch syndrome-associated neoplasms: a discussion on histopathology and immunohistochemistry

It was a century ago that Warthin, a pathologist, first described the clinical condition now known as Lynch syndrome. One hundred years later, our understanding of this syndrome has advanced significantly. Much of the progress took place over the last 25 years and was marked by a series of interacting developments from the disciplines of clinical oncology, pathology, and molecular genetics, with each development serving to guide or enhance the next. The advancement of our understanding about the pathology of Lynch syndrome associated tumors exemplifies such intimate interplay among disciplines. Today, accumulative knowledge has enabled surgical pathologists to detect tumors that are likely to be associated with Lynch syndrome, and the pathologist is playing an increasingly more important role in the care of these patients. The pathologist's ability is afforded primarily by information gained from tumor histopathology and by DNA mismatch repair protein immunohistochemistry. It is therefore pertinent both for the pathologists to accurately ascertain this morphologic information, and for all that are involved in the care of these patients to thoroughly understand the implications of such information. This article provides an overview of the development of histopathology and immunohistochemistry in Lynch syndrome-associated tumors, particularly in colorectal and endometrial cancers, and outlines the issues and current status of these specific pathologic aspects in not only the major tumors but also those less commonly seen or only newly reported in Lynch syndrome patients.

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.