KRAS and BRAF somatic mutations in colonic polyps and the risk of metachronous neoplasia

Prediction of metachronous advanced colorectal neoplasia by KRAS mutation in polyps

BACKGROUND

The potential of molecular markers in the removed polys as reliable predictors of metachronous lesions is still uncertain.

AIM

Our aim was to evaluate the role of somatic mutations in KRAS in polyps of patients with high-risk adenomas to predict the risk of advanced polyps or colorectal cancer (CRC) within 3 years.

METHODS

A total of 518 patients were prospectively enrolled. The included patients had adenomas ≥10 mm, high-grade dysplasia, villous component or ≥3 more adenomas at baseline and were scheduled to undergo surveillance colonoscopy at 3 years ± 6 months. Somatic KRAS mutation was performed on 1189 polyps collected from these patients. At surveillance, advanced lesions were defined as adenomas with a size of ≥10 mm. High-grade dysplasia or villous component, serrated polyps ≥10 mm or with dysplasia or CRC.

RESULTS

At baseline, 81 patients (15.6%) had KRAS mutations in at least one polyp. Patients with KRAS mutated polyps had more frequent villous histological lesions and size ≥20 mm. In the multivariate analysis, adjusted for age and sex, only age (odds ratios [OR], 1.06; 95% confidence interval [CI], 1.02-1.09; p < 0.001), ≥5 adenomas (OR, 3.92; 95% CI, 1.96-7.82), and KRAS mutation (OR, 2.54; 95% CI, 1.48-4.34; p < 0.01) were independently associated with the development of advanced lesions at surveillance.

CONCLUSIONS

Our results show that, in patients with high-risk adenomas, the presence of somatic mutations in KRAS is an independent risk factor for the development of advanced metachronous polyps.

Pre-malignant conditions diagnosed following a positive cancer signal from a multi-cancer early detection test

Blood-based tests for multi-cancer early detection (MCED) are being developed to facilitate the detection of various cancer types. The Detecting cancers Earlier Through Elective mutation-based blood Collection and Testing study (DETECT-A) study evaluated an MCED test in 9,911 women, age 65-75, without personal history of cancer. In a post-hoc analysis, we report on the detection of precancerous neoplasms consequent to MCED testing and follow-up. Participants with positive baseline and confirmatory MCED testing underwent 2-deoxy-2[fluorine-18] fluoro-D-glucose positron emission tomography-computed tomography (PET-CT) and diagnostic evaluation as indicated by PET-CT results. We reviewed the electronic health records of participants with a precancerous neoplasm and summarized their clinical course. MCED results were positive in 134 participants. Clinically significant pre-malignant conditions were identified in three of these participants: A 71-year-old with an ovarian mucinous cystadenoma, a 67-year-old with an appendiceal mucinous neoplasm, and a 70-year-old with colon adenomas displaying high-grade dysplasia. All three participants underwent surgical treatment and remain alive and cancer-free as of last follow up. The diagnostic evaluation of a positive MCED test may occasionally reveal clinically significant pre-cancerous conditions amenable to interventions. The frequency of such findings and their clinical impact warrants further study.

Surveillance after colorectal polyp resection

Post-polypectomy surveillance has proven to reduce colorectal cancer (CRC) incidence in patients with high-risk polyps, but it implies a major burden on colonoscopy units. Therefore, it should be targeted to individuals with a higher risk. Different societies have published guidelines on surveillance after resection of polyps, with notable discrepancies among them, and many recommendations come from low-quality evidence based on surrogate measures, such as risk of advanced adenoma, and not CRC risk. In this review, we aimed to summarize the evidence supporting post-polypectomy surveillance, compare the recently updated major guidelines, and discuss the existing discrepancies on this topic. Briefly, patients with adenomas ≥10 mm or high-grade dysplasia and patients with serrated polyps ≥10 mm or dysplasia are generally considered to have an increased risk of metachronous CRC and require surveillance, whereas the indication of surveillance is not clearly established in patients without these high-risk features.

KRAS mutations and their associations with clinicopathological features and survival in Vietnamese non‑polyp colon cancer patients

The aim of the present study was to determine Kirsten Ras sarcoma virus (KRAS) mutations and the associations of KRAS mutations with clinicopathological features and treatment outcomes in Vietnamese non-polyp colon cancer (NPCC) patients. The data in the present study covered 194 patients with non-polyp colon cancers at stages II or III, according to the 8th edition of the American Joint Committee on Cancer staging system, in northern Vietnam from January 2016 to August 2020. All patients underwent radical surgery and adjuvant therapy with FOLFOX4 or XELOX. Subsequently, the recruited patients were followed-up with scheduled hospital exams for diagnosing recurrence. Genomic DNA samples were prepared from dissected tumors and specific sequences of the KRAS gene were amplified by polymerase chain reactions (PCR). The mutations at codons 12, 13, 59, 60, 61, 117 and 146 of the gene were determined. Possible associations of the KRAS mutations with clinicopathological properties and the survival of patients were analysed. The KRAS mutation rate was 47.9% in Vietnamese patients with NPCC, of those, mutations in exon 2 accounted for 91.4% of all detected mutations. The mutated-KRAS patients exhibited a significantly higher rate of anemia. Moreover, the KRAS mutation rate was higher in females (57.1%) than in males (39.8%). The KRAS mutation rate was also higher in patients with right colon cancers. Furthermore, KRAS mutations were an independent prognosis for poor disease-free survival (DFS) and overall survival (OS) in stage II patients. Among left-sided colon patients, mutated KRAS was a significant predictive factor for poor DFS but not for OS. The present study revealed a very high mutation rate of KRAS in Vietnamese patients with NPCC. The data of the present study indicated that the mutation status was associated with female patients and right-sided tumors. The KRAS mutations were a negative factor for the survival of patients with stage II NPCC and patients with left-sided colon cancer.

Patterns of Somatic Variants in Colorectal Adenoma and Carcinoma Tissue and Matched Plasma Samples from the Hungarian Oncogenome Program

Analysis of circulating cell-free DNA (cfDNA) of colorectal adenoma (AD) and cancer (CRC) patients provides a minimally invasive approach that is able to explore genetic alterations. It is unknown whether there are specific genetic variants that could explain the high prevalence of CRC in Hungary. Whole-exome sequencing (WES) was performed on colon tissues (27 AD, 51 CRC) and matched cfDNAs (17 AD, 33 CRC); furthermore, targeted panel sequencing was performed on a subset of cfDNA samples. The most frequently mutated genes were APC, KRAS, and FBN3 in AD, while APC, TP53, TTN, and KRAS were the most frequently mutated in CRC tissue. Variants in KRAS codons 12 (AD: 8/27, CRC: 11/51 (0.216)) and 13 (CRC: 3/51 (0.06)) were the most frequent in our sample set, with G12V (5/27) dominance in ADs and G12D (5/51 (0.098)) in CRCs. In terms of the cfDNA WES results, tumor somatic variants were found in 6/33 of CRC cases. Panel sequencing revealed somatic variants in 8 out of the 12 enrolled patients, identifying 12/20 tumor somatic variants falling on its targeted regions, while WES recovered only 20% in the respective regions in cfDNA of the same patients. In liquid biopsy analyses, WES is less efficient compared to the targeted panel sequencing with a higher coverage depth that can hold a relevant clinical potential to be applied in everyday practice in the future.

A review on mechanobiology of cell adhesion networks in different stages of sporadic colorectal cancer to explain its tumorigenesis

Sporadic colorectal cancer (CRC) is strongly linked to extraneous factors, like poor diet and lifestyle, but not to inherent factors like familial genetics. The changes at the epigenomics and signalling pathways are known across the sporadic CRC stages. The catch is that temporal information of the onset, the feedback loop, and the crosstalk of signalling and noise are still unclear. This makes it challenging to diagnose and treat colon cancer effectively with no relapse. Various microbial cells and native cells of the colon, contribute to sporadic CRC development. These cells secrete autocrine and paracrine for their bioenergetics and communications with other cell types. Imbalances of the biochemicals affect the epithelial lining of colon. One side of this epithelial lining is interfacing the dense colon tissue, while the other side is exposed to microbiota and excrement from the lumen. Hence, the epithelial lining is prone to tumorigenesis due to the influence of both biochemical and mechanical cues from its complex surrounding. The role of physical transformations in tumorigenesis have been limitedly discussed. In this context, cellular and tissue structures, and force transductions are heavily regulated by cell adhesion networks. These networks include cell anchoring mechanism to the surrounding, cell structural integrity mechanism, and cell effector molecules. This review will focus on the progression of the sporadic CRC stages that are governed by the underlaying cell adhesion networks within the epithelial cells. Additionally, current and potential technologies and therapeutics that target cell adhesion networks for treatments of sporadic CRC will be incorporated.

Somatic Mutations in Exon 7 of the TP53 Gene in Index Colorectal Lesions Are Associated with the Early Occurrence of Metachronous Adenoma

Simple Summary

Identifying patients with an increased risk of early recurrence of colorectal lesions is still a problem. In our study, we focused on improving this identification by determining the mutation profile of index lesions. We found a statistically significant association between the mutation in exon 7 of the TP53 gene in the index lesion and the risk of early metachronous adenoma.

Abstract

(1) Background: this prospective study was focused on detailed analysis of the mutation heterogeneity in colorectal lesions removed during baseline (index) colonoscopy to identify patients at high risk of early occurrence of metachronous adenomas. (2) Methods: a total of 120 patients after endoscopic therapy of advanced colorectal neoplasia size ≥10 mm (index lesion) with subsequent surveillance colonoscopy after 10–18 months were included. In total, 143 index lesions and 84 synchronous lesions in paraffin blocks were divided into up to 30 samples. In each of them, the detection of somatic mutations in 11 hot spot gene loci was performed. Statistical analysis to correlate the mutation profiles and the degree of heterogeneity of the lesions with the risk of metachronous adenoma occurrence was undertaken. (3) Results: mutation in exon 7 of the TP53 gene found in the index lesion significantly correlated with the early occurrence of metachronous adenoma (log-rank test p = 0.003, hazard ratio 2.73, 95% confidence interval 1.14–6.56). We did not find an association between the risk of metachronous adenomas and other markers monitored. (4) Conclusions: the findings of this study could lead to an adjustment of existing recommendations for surveillance colonoscopies in a specific group of patients with mutations in exon 7 of the TP53 gene in an index lesion, where a shortening of surveillance interval may be warranted.

Validation of a Liquid Biopsy Protocol for Canine BRAFV595E Variant Detection in Dog Urine and Its Evaluation as a Diagnostic Test Complementary to Cytology

A significant proportion of canine urothelial carcinomas carry the driver valine to glutamic acid variation (V595E) in BRAF kinase. The detection of V595E may prove suitable to guide molecularly targeted therapies and support non-invasive diagnosis of the urogenital system by means of a liquid biopsy approach using urine. Three cohorts and a control group were included in this multi-step validation study which included setting up a digital PCR assay. This was followed by investigation of preanalytical factors and two alternative PCR techniques on a liquid biopsy protocol. Finally, a blind study using urine as diagnostic sample has been carried out to verify its suitability as diagnostic test to complement cytology. The digital PCR (dPCR) assay proved consistently specific, sensitive, and linear. Using the dPCR assay, the prevalence of V595E in 22 urothelial carcinomas was 90.9%. When compared with histopathology as gold standard in the blind-label cases, the diagnostic accuracy of using the canine BRAF (cBRAF) variation as a surrogate assay against the histologic diagnosis was 85.7% with 92.3% positive predictive value and 80.0% negative predictive value. In all the cases, in which both biopsy tissue and the associated urine were assayed, the findings matched completely. Finally, when combined with urine sediment cytology examination in blind-label cases with clinical suspicion of malignancy, the dPCR assay significantly improved the overall diagnostic accuracy. A liquid biopsy approach on urine using the digital PCR may be a valuable breakthrough in the diagnostic of urothelial carcinomas in dogs.

Genomic profiling of intestinal/mixed-type superficial non-ampullary duodenal epithelial tumors

Background and Aim

The mechanism underlying carcinogenesis and the genomic features of superficial non‐ampullary duodenal epithelial tumors (SNADETs) have not been elucidated in detail. In this study, we examined the genomic features of incipient SNADETs, such as small lesions resected via endoscopic treatment, using next‐generation sequencing (NGS).

Methods

Twenty consecutive patients who underwent endoscopic treatment for SNADETs of less than 20 mm between January and December 2017 were enrolled. Targeted genomic sequencing was performed through NGS using a panel of 160 cancer‐related genes. Furthermore, the alteration/mutation frequencies in SNADETs were examined.

Results

The maximum size of the SNADETs examined in this study was 12 mm in diameter. Five SNADETs were classified as low‐grade dysplasia (LGD) tumors, while 14 SNADETs were classified as high‐grade dysplasia tumors. Only one carcinoma in situ was detected. NGS data for 16 samples were obtained. APC alterations were detected in 81% of samples (13/16). KRAS, BRAF, and TP53 alterations were detected in 25% (4/16), 18.8% (3/16), and 6.3% (1/16) of cases, respectively.

Conclusion

We detected APC alterations in most small SNADETs resected via endoscopic treatment, from LGD to carcinoma samples. Even in SNADETs classified as small LGD exhibited KRAS and BRAF alterations.

A Diffusion-like Process Accommodates New Crypts During Clonal Expansion in Human Colonic Epithelium

BACKGROUND & AIMS

Colorectal cancer (CRC) is thought to arise when the cumulative mutational burden within colonic crypts exceeds a certain threshold that leads to clonal expansion and ultimately neoplastic transformation. Therefore, quantification of the fixation and subsequent expansion of somatic mutations in normal epithelium is key to understanding colorectal cancer initiation. The aim of the present study was to determine how advantaged expansions can be accommodated in the human colon.

METHODS

Immunohistochemistry was used to visualize loss of the cancer driver KDM6A in formalin-fixed paraffin-embedded (FFPE) normal human colonic epithelium. Combining microscopy with neural network-based image analysis, we determined the frequencies of KDM6A-mutant crypts and fission/fusion intermediates as well as the spatial distribution of clones. Mathematical modeling then defined the dynamics of their fixation and expansion.

RESULTS

Interpretation of the age-related behavior of KDM6A-negative clones revealed significant competitive advantage in intracrypt dynamics as well as a 5-fold increase in crypt fission rate. This was not accompanied by an increase in crypt fusion. Mathematical modeling of crypt spacing identifies evidence for a crypt diffusion process. We define the threshold fission rate at which diffusion fails to accommodate new crypts, which can be exceeded by KRAS activating mutations.

CONCLUSIONS

Advantaged gene mutations in KDM6A expand dramatically by crypt fission but not fusion. The crypt diffusion process enables accommodation of the additional crypts up to a threshold value, beyond which polyp growth may occur. The fission rate associated with KRAS mutations offers a potential explanation for KRAS-initiated polyps.

Novel Methods of Risk Stratifying Patients for Metachronous, Pre-Malignant Colorectal Polyps: A Systematic Review

INTRODUCTION

Despite conventional measures of future polyp risk (histology, dysplasia, size, number), surveillance places a burden on patients and colonoscopy services. We aimed to review novel risk stratification techniques.

METHODS

A systematic literature review was performed for studies using genomics, transcriptomics, IHC or microbiome as markers of metachronous polyp risk.

RESULTS

4165 papers underwent title, 303 abstract and 215 full paper review. 25 papers were included. 49 mutations/ SNPs/ haplotypes in 23 genes/ chromosomal regions (KRAS, APC, EGFR, COX1/2, IL23R, DRD2, CYP2C9/24A1/7A1, UGT1A6, ODC, ALOX12/15, PGDH, SRC, IGSF5, KCNS3, EPHB1/ KY, FAM188b, 3p24.1, 9q33.2, 13q33.2) correlated with metachronous adenoma / advanced adenoma risk. Expression levels of 6 proteins correlated with metachronous adenoma (p53, β-catenin, COX2, Adnab-9, ALDH1A1) or sessile serrated polyp (ANXA10) risk.

CONCLUSION

Although genomic and IHC markers correlated with metachronous polyp risk, it seems likely that a panel of novel markers will be required to refine this risk.

Distinct Mutational Profile of Lynch Syndrome Colorectal Cancers Diagnosed under Regular Colonoscopy Surveillance

Regular colonoscopy even with short intervals does not prevent all colorectal cancers (CRC) in Lynch syndrome (LS). In the present study, we asked whether cancers detected under regular colonoscopy surveillance (incident cancers) are phenotypically different from cancers detected at first colonoscopy (prevalent cancers). We analyzed clinical, histological, immunological and mutational characteristics, including panel sequencing and high-throughput coding microsatellite (cMS) analysis, in 28 incident and 67 prevalent LS CRCs (n total = 95). Incident cancers presented with lower UICC and T stage compared to prevalent cancers (p < 0.0005). The majority of incident cancers (21/28) were detected after previous colonoscopy without any pathological findings. On the molecular level, incident cancers presented with a significantly lower KRAS codon 12/13 (1/23, 4.3% vs. 11/21, 52%; p = 0.0005) and pathogenic TP53 mutation frequency (0/17, 0% vs. 7/21, 33.3%; p = 0.0108,) compared to prevalent cancers; 10/17 (58.8%) incident cancers harbored one or more truncating APC mutations, all showing mutational signatures of mismatch repair (MMR) deficiency. The proportion of MMR deficiency-related mutational events was significantly higher in incident compared to prevalent CRC (p = 0.018). In conclusion, our study identifies a set of features indicative of biological differences between incident and prevalent cancers in LS, which should further be monitored in prospective LS screening studies to guide towards optimized prevention protocols.

Constitutive activation of mitogen-activated protein kinase kinase (MEK1) in ileal enterocytes leads to dysplasia and a predisposition to cancer

Activation of mitogen-activated protein kinases (MAPKs) is a key factor in the pathogenesis of cancer, although the specific role of mitogen-activated protein kinase kinase (MEK1) is not well understood. Villin promoter-driven Cre expression was used to excise a floxed stop cassette from a phosphomimetically constitutively activated MEK1 (caMEK1) expression construct in the intestine of C57BL/6 mice. Zygosity status of caMEK1 afforded assessment of the dose dependence of the effect. The expected mendelian distribution of genotypes and sex was observed in 443 progenies. Between 21 and 63 days of life, caMEK1 had no effect on body weight in male mice, but reduced body weight in female mice homozygous for caMEK1. At 10 wk of age, the ileum of caMEK1-expressing mice was characterized by the finding of dysplasia and profound changes in overall architecture. Paneth cells were nearly absent in caMEK1 homozygotes. Targeted proteomic profiling via reverse phase protein array analyses with confirmatory Western blotting revealed significant changes in protein and phosphoprotein expression, including upregulation of proteins downstream of MEK1, associated with enhanced markers of proliferation, diminished apoptosis, alterations in cell-fate determination, cell-cell interactions, and tight junctions. Long-term viability of caMEK1 homozygous mice was reduced with no survival beyond 1 yr. Invasive adenocarcinoma developed in three of ten older mice [15 wk (homozygous), 26 wk (homozygous), and 35 wk (heterozygous) of age]. Expression of caMEK1 in enterocytes leads to marked derangements in the intestinal epithelium, which is associated with a predisposition to the development of invasive cancer.NEW & NOTEWORTHY The ileum of mice with constitutive expression of activated MEK1 (via phosphomimetic changes) in enterocytes is markedly abnormal with architectural distortion and cytologic atypia, which evolves into an adenoma invasive carcinoma sequence. Phosphoproteomic analysis reveals upregulation of proteins downstream of MEK1, associated with enhanced markers of proliferation, diminished apoptosis, alterations in cell-fate determination, cell-cell interactions, and tight junctions. This novel model provides new insights into intestinal homeostasis and carcinogenesis.

Identifying modules of cooperating cancer drivers

Identifying cooperating modules of driver alterations can provide insights into cancer etiology and advance the development of effective personalized treatments. We present Cancer Rule Set Optimization (CRSO) for inferring the combinations of alterations that cooperate to drive tumor formation in individual patients. Application to 19 TCGA cancer types revealed a mean of 11 core driver combinations per cancer, comprising 2-6 alterations per combination and accounting for a mean of 70% of samples per cancer type. CRSO is distinct from methods based on statistical co-occurrence, which we demonstrate is a suboptimal criterion for investigating driver cooperation. CRSO identified well-studied driver combinations that were not detected by other approaches and nominated novel combinations that correlate with clinical outcomes in multiple cancer types. Novel synergies were identified in NRAS-mutant melanomas that may be therapeutically relevant. Core driver combinations involving NFE2L2 mutations were identified in four cancer types, supporting the therapeutic potential of NRF2 pathway inhibition. CRSO is available at https://github.com/mikekleinsgit/CRSO/.

Predictors of Metachronous Risk Polyps After Index Colonoscopy

INTRODUCTION

Guidelines for surveillance after polypectomy are lacking in strong evidence. Our aim was to identify some precursors of colorectal cancer lesions at 3 years after polypectomy to improve stratification and surveillance programs.

METHODS

We included patients with high-risk lesions (HRLs), defined as advanced adenoma (AA), large serrated polyps (SPs), and multiplicity (≥3 of any adenomas/SPs). Data on age, sex, cardiovascular risk factors, pharmacological treatment, and the histological characteristics in each individual, and mutations in genes involved in the most advanced index polyp, were collected. Parameters independently associated with a metachronous HRL diagnosis were evaluated through univariate and multivariate analyses. The results are reported as odds ratios and 95% confidence intervals along with P values.

RESULTS

A total of 537 cases (median age: 60.7 years; 66% male) were included. Dyslipidemia and smoking correlated with metachronous HRLs. Multivariate logistic regression analysis showed that the presence of multiplicity with ≥3 polyps on the index colonoscopy was significantly associated with metachronous HRL, AA, proximal AA, and ≥3 polyps at 3 years. In addition, independent predictors of metachronous proximal AA were increasing age, female sex, and the loss of expression of the MLH1 protein.

DISCUSSION

Multiplicity was a strong predictor of HRLs at 3 years, although the inclusion of other clinical variables (age, sex, smoking status, and dyslipidemia) improves surveillance recommendations. Without these risk factors, the surveillance could be extended to 5 years; we propose examining the somatic expression of MHL1 in all patients.

Effects of Somatic Methylation in Colonic Polyps on Risk of Developing Metachronous Advanced Colorectal Lesions

The utility of molecular markers for predicting the risk of metachronous advanced colorectal lesions (MACLs) remains poorly investigated. We examined the relationship between somatic hypermethylation in polyps at baseline and the risk of developing MACL. This retrospective cohort study included 281 consecutive patients with colonic polyps who were enrolled between 2007 and 2009 and followed-up until 2014. MACLs were defined as adenomas of ≥10 mm, high-grade dysplasia, or with a villous component; and serrated lesions of ≥10 mm or with dysplasia. In total, 595 polyps were removed at baseline colonoscopy and analyzed for pathological characteristics and CpG island methylator phenotype (CIMP) using the MS-MLPA (Methylation-Specific -- Multiplex Ligation-dependent Probe Amplification) technique. Forty-five patients (16.0%) showed at least one CIMP+ polyp. MACL risk was higher in patients with CIMP+ polyps (odds ratio (OR), 4.50; 95% CI, 1.78-11.4; p = 0.002). Patients with CIMP+ polyps also exhibited shorter time to MACL development (33.8 months vs. 50.1 months; p < 0.001), even with adjustment for polyp size and number (OR, 2.40; 95% CI, 1.33-4.34). Adding CIMP analysis improved the sensitivity (57.0% to 70.9%), negative predictive value (71.1% to 77.3%), and overall accuracy (49.8% to 52.0%) for MACL risk estimation. These results highlight that CIMP may be a useful marker for endoscopic surveillance.

Associations between molecular characteristics of colorectal serrated polyps and subsequent advanced colorectal neoplasia

PURPOSE

BRAF mutation and DNA hypermethylation have linked sessile serrated adenomas/polyps (SSA/Ps) to serrated colorectal cancer (CRC) in cross-sectional studies, but they have not been evaluated in a longitudinal study. We aimed to evaluate the associations between molecular markers of serrated polyps and subsequent advanced colorectal neoplasia.

METHODS

Study subjects included Kaiser Permanente Washington members aged 20-75 years who received an index colonoscopy between 1/1/1998 and 12/31/2007 and had hyperplastic polyps (HPs) or SSA/Ps according to study pathology review. Polyps from index colonoscopies were removed and assayed for BRAF mutation, CpG island methylator phenotype (CIMP), and MLH1 methylation. Pathology reports and biopsies from the subsequent lower gastrointestinal endoscopy through 1/1/2013 were reviewed for advanced colorectal neoplasia. We identified additional incident CRC cases through linkage to the Seattle-Puget Sound Surveillance Epidemiology and End Results registry. We used generalized estimating equations to calculate adjusted odds ratios (OR) and 95% confidence intervals (CI) for subsequent advanced colorectal neoplasia, comparing index serrated polyps with different molecular markers.

RESULTS

We included 553 individuals with index serrated polyps (420 HPs and 133 SSA/Ps) and 795 subsequent endoscopies. The prevalence of BRAF-mutant, CIMP-high, and MLH1-methylated serrated polyps were 51%, 4%, and 2%, respectively. BRAF and CIMP were not associated with subsequent advanced colorectal neoplasia. MLH1-methylated SSP/As were significantly more likely to have subsequent advanced neoplasia (OR = 4.66, 95% CI 1.06-20.51).

CONCLUSION

Our results suggest that BRAF-mutant and CIMP-high serrated polyps are not associated with subsequent advanced colorectal neoplasia. Among SSA/Ps, MLH1 methylation may be an important marker to identify high-risk CRC precursors.

Patterns of polyp histology: predictors of peril in the mucosa

BACKGROUND

Precursor colonic polyps of varied subtypes correlate with the known neoplastic pathways. When patients present with synchronous pre-malignant polyps of multiple histologies, multiple genetic mechanisms are likely to be active, potentially resulting in a more unstable, tumourigenic mucosa.

METHODS

We hypothesized that patients with a combination of sessile serrated adenomas/polyps (SSA/Ps), hyperplastic (HP) polyps and adenomas would be at highest risk of developing dysplasia/cancer compared to SSA/Ps alone, due to the synergistic effect of multiple active carcinogenic pathways. A prospective colonoscopy database was examined for patients with a history of SSA/P. Patients were placed into four groups based on patterns of polyp histology as follows: (i) only SSA/Ps; (ii) SSA/P + HP; (iii) SSA/Ps + adenomas; and (iv) SSA/Ps + HP + adenomas. These groups were compared in terms of the numbers, size, location and histology of polyps and personal or family history of colorectal cancer.

RESULTS

A total of 374 patients were included. The average age was 70 years (range 21-88), and 43% were male. There was a trend towards the most aggressive neoplastic pattern in group 4, associated with a tendency to larger SSA/Ps, more villous architecture in the adenomas and more high-grade dysplasia in both types of polyps. It was also associated with multiplicity of both SSA/Ps and adenomas. No SSA/Ps existing in the absence of adenomas had cytological dysplasia.

CONCLUSION

The combination of SSA/Ps, HP and adenomas in the colorectal epithelium seems to be a marker for aggressive carcinogenesis and suggests that accurate and effective surveillance is important to manage this risk.

Mutations of RAS genes in endometrial polyps

Endometrial polyps are common, yet the molecular mechanisms underlying their formation and progression remain unclear. We examined gene mutations possibly related to the pathogenesis of endometrial polyps, as well as to their clinical features. Four premenopausal patients with endometrial polyps, who were not under drug treatment, were recruited. Whole exomes of endometrial polyps and peripheral blood lymphocytes were analyzed by next‑generation sequencing, and somatic mutations were derived by subtraction. Then, 35 samples of endometrial polyps and 12 samples of atypical polypoid adenomyoma were newly recruited to validate the identified mutations by polymerase chain reaction‑reverse sequence specific oligonucleotide method. The mutations were also analyzed in separate stromal and glandular components of the polyps after laser‑capture microdissection. Whole exome sequencing revealed that KRAS mutations were the only type of mutation detectable in multiple cases (2/4). Targeted mutation analysis revealed that 16 of 35 samples (45.7%) of endometrial polyps harbored RAS mutations. Mutation‑positive cases exhibited a significantly higher number of endometrial polyps (3.25±2.70 vs. 1.74±0.87, P=0.045). Laser‑capture microdissection in NRAS‑mutated endometrial polyps revealed that both stromal and glandular components harbored RAS mutations. There was no RAS mutation in 12 samples of atypical polypoid adenomyoma. This is the first report demonstrating that pathogenic RAS mutations are frequent in non‑treated endometrial polyps. RAS mutations may have an important role in tumorigenesis and in the formation of multiple endometrial polyps.

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.

Tubulovillous Adenoma of Vagina With Both KRAS and APC Mutations: Case Report

Adenomatous polyps of the vulva and vagina are extremely rare. We report a case of a 74-yr-old women with a tubulovillous adenoma occurring in the vagina, and a second one occurring later in the vulva. Tumor cells in both lesions were CK7, CK20, CDX-2, and showed intact mismatch-repair proteins. A G13D (c.38G>A, p.Gly13Asp) mutation in the KRAS gene was identified in both masses. As well, a novel frameshift truncating mutation (c.4320delA, p.Pro1441fsTer32) in the APC gene was detected only in the vaginal mass, ruling out the possibility that the vulvar mass was a local recurrence of the vaginal mass. This is the first identification of KRAS and APC gene mutations in adenomatous polyps involving the female lower genital tract.

Integrative analysis of exogenous, endogenous, tumour and immune factors for precision medicine

Immunotherapy strategies targeting immune checkpoints such as the CTLA4 and CD274 (programmed cell death 1 ligand 1, PD-L1)/PDCD1 (programmed cell death 1, PD-1) T-cell coreceptor pathways are revolutionising oncology. The approval of pembrolizumab use for solid tumours with high-level microsatellite instability or mismatch repair deficiency by the US Food and Drug Administration highlights promise of precision immuno-oncology. However, despite evidence indicating influences of exogenous and endogenous factors such as diet, nutrients, alcohol, smoking, obesity, lifestyle, environmental exposures and microbiome on tumour-immune interactions, integrative analyses of those factors and immunity lag behind. Immune cell analyses in the tumour microenvironment have not adequately been integrated into large-scale studies. Addressing this gap, the transdisciplinary field of molecular pathological epidemiology (MPE) offers research frameworks to integrate tumour immunology into population health sciences, and link the exposures and germline genetics (eg, HLA genotypes) to tumour and immune characteristics. Multilevel research using bioinformatics, in vivo pathology and omics (genomics, epigenomics, transcriptomics, proteomics and metabolomics) technologies is possible with use of tissue, peripheral blood circulating cells, cell-free plasma, stool, sputum, urine and other body fluids. This immunology-MPE model can synergise with experimental immunology, microbiology and systems biology. GI neoplasms represent exemplary diseases for the immunology-MPE model, given rich microbiota and immune tissues of intestines, and the well-established carcinogenic role of intestinal inflammation. Proof-of-principle studies on colorectal cancer provided insights into immunomodulating effects of aspirin, vitamin D, inflammatory diets and omega-3 polyunsaturated fatty acids. The integrated immunology-MPE model can contribute to better understanding of environment-tumour-immune interactions, and effective immunoprevention and immunotherapy strategies for precision medicine.