A Focused Review on Advances in Risk Stratification of Malignant Polyps

Immunohistochemical insights into the pathogenesis of colonic sessile serrated lesions

BACKGROUND

Sessile serrated lesions (SSLs) are recognized as precursor lesions in the pathogenesis of colorectal cancer, particularly in the context of microsatellite instability (MSI). This study evaluates the role of immunohistochemical (IHC) markers in understanding the molecular and immunologic characteristics of SSLs.

MATERIALS AND METHODS

A retrospective analysis was performed on 45 colonic neoplastic lesions diagnosed as SSLs. An IHC staining panel was conducted, including MLH1, p53, CD44, CD3, CD8, MUC2, MUC5AC, MUC6, chromogranin and Ki67 antibodies.

RESULTS

MLH1 and p53 expressions showed correlations with dysplastic changes. Immunological markers CD3 and CD8 indicated a variable immune response, potentially reflecting the tumor's ability to evade immune surveillance in certain situations. CD44 was overexpressed in all SSLs. The number of neuroendocrine cells was overall reduced.

CONCLUSIONS

SSLs are heterogeneous lesions, exhibiting a wide range of histological and molecular features. Using IHC might enhance diagnostic accuracy, particularly in lesions with ambiguous histological features, when dysplasia develops. Accurate identification of SSLs and understanding their molecular characteristics are crucial for assessing their malignant potential.

Polyclonal-to-monoclonal transition in colorectal precancerous evolution

Unravelling the origin and evolution of precancerous lesions is crucial for effectively preventing malignant transformation, yet our current knowledge remains limited1-3. Here we used a base editor-enabled DNA barcoding system4 to comprehensively map single-cell phylogenies in mouse models of intestinal tumorigenesis induced by inflammation or loss of the Apc gene. Through quantitative analysis of high-resolution phylogenies including 260,922 single cells from normal, inflamed and neoplastic intestinal tissues, we identified tens of independent cell lineages undergoing parallel clonal expansions within each lesion. We also found polyclonal origins of human sporadic colorectal polyps through bulk whole-exome sequencing and single-gland whole-genome sequencing. Genomic and clinical data support a model of polyclonal-to-monoclonal transition, with monoclonal lesions representing a more advanced stage. Single-cell RNA sequencing revealed extensive intercellular interactions in early polyclonal lesions, but there was significant loss of interactions during monoclonal transition. Therefore, our data suggest that colorectal precancer is often founded by many different lineages and highlight their cooperative interactions in the earliest stages of cancer formation. These findings provide insights into opportunities for earlier intervention in colorectal cancer.

My approach to assessing for colorectal polyp cancer

Assessing a locally excised colorectal adenoma for malignancy is a common but often challenging scenario. This article outlines a simple, stepwise approach to this diagnostic assessment. The first steps are to assess for high-grade dysplasia and, if present, to determine whether any neoplastic glands lie within the submucosa. If so, a distinction must then be made between epithelial misplacement and adenocarcinoma; this process is aided by certain clinical and endoscopic data together with assessment of six key histological features. If adenocarcinoma is diagnosed, a final step is to report the presence/absence of high-risk features of polyp cancers because this will then determine if further surgical resection is required for that malignancy. Caveats, uncertainties and newly introduced concepts exist at several steps of the assessment pathway presented and are therefore discussed in detail throughout the article.

Advances in microRNAs as Emerging Biomarkers for Colorectal Cancer Early Detection and Diagnosis

Colorectal cancer (CRC) remains the second most common cause of cancer-related mortality worldwide, necessitating advancements in early detection and innovative treatment strategies. MicroRNAs (miRNAs), small non-coding RNAs involved in gene regulation, have emerged as crucial players in the pathogenesis of CRC. This review synthesizes the latest findings on miRNA deregulated in precancerous lesions and in CRC. By examining the deregulation patterns of miRNAs across different stages of CRC development, this review highlights their potential as diagnostic tools. We specifically analyse the roles and diagnostic relevance of four miRNAs-miR-15b, miR-21, miR-31, and miR-146a-that consistently exhibit altered expression in CRC. The current knowledge of their role in key oncogenic pathways, drug resistance, and clinical relevance is discussed. Despite challenges posed by the heterogeneity of the research findings on miRNA deregulation and their role in CRC, integrating miRNA diagnostics into current screening methods holds promise for enhancing personalized medicine approaches. This review emphasizes the transformative potential of miRNAs in CRC diagnosis, paving the way for improved patient outcomes and novel therapeutic paradigms.

Colorectal polypectomy and endoscopic mucosal resection: European Society of Gastrointestinal Endoscopy (ESGE) Guideline - Update 2024

1:  ESGE recommends cold snare polypectomy (CSP), to include a clear margin of normal tissue (1-2 mm) surrounding the polyp, for the removal of diminutive polyps (≤ 5 mm).Strong recommendation, high quality of evidence. 2:  ESGE recommends against the use of cold biopsy forceps excision because of its high rate of incomplete resection.Strong recommendation, moderate quality of evidence. 3:  ESGE recommends CSP, to include a clear margin of normal tissue (1-2 mm) surrounding the polyp, for the removal of small polyps (6-9 mm).Strong recommendation, high quality of evidence. 4:  ESGE recommends hot snare polypectomy for the removal of nonpedunculated adenomatous polyps of 10-19 mm in size.Strong recommendation, high quality of evidence. 5:  ESGE recommends conventional (diathermy-based) endoscopic mucosal resection (EMR) for large (≥ 20 mm) nonpedunculated adenomatous polyps (LNPCPs).Strong recommendation, high quality of evidence. 6:  ESGE suggests that underwater EMR can be considered an alternative to conventional hot EMR for the treatment of adenomatous LNPCPs.Weak recommendation, moderate quality of evidence. 7:  Endoscopic submucosal dissection (ESD) may also be suggested as an alternative for removal of LNPCPs of ≥ 20 mm in selected cases and in high-volume centers.Weak recommendation, low quality evidence. 8:  ESGE recommends that, after piecemeal EMR of LNPCPs by hot snare, the resection margins should be treated by thermal ablation using snare-tip soft coagulation to prevent adenoma recurrence.Strong recommendation, high quality of evidence. 9:  ESGE recommends (piecemeal) cold snare polypectomy or cold EMR for SSLs of all sizes without suspected dysplasia.Strong recommendation, moderate quality of evidence. 10:  ESGE recommends prophylactic endoscopic clip closure of the mucosal defect after EMR of LNPCPs in the right colon to reduce to reduce the risk of delayed bleeding.Strong recommendation, high quality of evidence. 11:  ESGE recommends that en bloc resection techniques, such as en bloc EMR, ESD, endoscopic intermuscular dissection, endoscopic full-thickness resection, or surgery should be the techniques of choice in cases with suspected superficial invasive carcinoma, which otherwise cannot be removed en bloc by standard polypectomy or EMR.Strong recommendation, moderate quality of evidence.

Lymph Node Molecular Analysis with OSNA Enables the Identification of pT1 CRC Patients at Risk of Recurrence: A Multicentre Study

Early-stage colorectal carcinoma (CRC)-pT1-is a therapeutic challenge and presents some histological features related to lymph node metastasis (LNM). A significant proportion of pT1 CRCs are treated surgically, resulting in a non-negligible surgical-associated mortality rate of 1.5-2%. Among these cases, approximately 6-16% exhibit LNM, but the impact on survival is unclear. Therefore, there is an unmet need to establish an objective and reliable lymph node (LN) staging method to optimise the therapeutic management of pT1 CRC patients and to avoid overtreating or undertreating them. In this multicentre study, 89 patients with pT1 CRC were included. All histological features associated with LNM were evaluated. LNs were assessed using two methods, One-Step Nucleic Acid Amplification (OSNA) and the conventional FFPE plus haematoxylin and eosin (H&E) staining. OSNA is an RT-PCR-based method for amplifying CK19 mRNA. Our aim was to assess the performance of OSNA and H&E in evaluating LNs to identify patients at risk of recurrence and to optimise their clinical management. We observed an 80.9% concordance in LN assessment using the two methods. In 9% of cases, LNs were found to be positive using H&E, and in 24.7% of cases, LNs were found to be positive using OSNA. The OSNA results are provided as the total tumour load (TTL), defined as the total tumour burden present in all the LNs of a surgical specimen. In CRC, a TTL ≥ 6000 CK19 m-RNA copies/µL is associated with poor prognosis. Three patients had TTL > 6000 copies/μL, which was associated with higher tumour budding. The discrepancies observed between the OSNA and H&E results were mostly attributed to tumour allocation bias. We concluded that LN assessment with OSNA enables the identification of pT1 CRC patients at some risk of recurrence and helps to optimise their clinical management.

Management of malignant T1 colorectal cancer polyps: results from a 10-year prospective observational study

AIM

The recurrence risk associated with residual malignant cells (bowel wall/regional nodes) following T1 colorectal cancer (CRC) polypectomy must be weighed against operative morbidity. Our aim was to describe the management and outcomes of a large prospective cohort of T1 CRCs.

METHOD

All T1 CRCs diagnosed between March 2007 and March 2017 at the Glasgow Royal Infirmary were included. Patients were grouped by polypectomy, rectal local excision and formal resection status. χ2 testing, multivariate binary logistic and Cox regression were performed.

RESULTS

Of 236 patients, 90 (38.1%) underwent polypectomy only, six (2.6%) polypectomy and then rectal excision, 57 (24.2%) polypectomy and then resection, 14 (5.9%) rectal excision only and 69 (29.2%) primary resection. Polypectomy only correlated with male sex (P = 0.028), older age (P < 0.001), distal CRCs (P < 0.001) and pedunculated polyps (P < 0.001); primary resection with larger polyps (P < 0.001); polypectomy then resection with piecemeal excision (P = 0.002) and involved polypectomy margin (P < 0.001). Poor differentiation (OR 7.860, 95% CI 1.117-55.328; P = 0.038) independently predicted lymph node involvement. Submucosal venous invasion (hazard ratio [HR] 10.154, 95% CI 2.087-49.396; P = 0.004) and mucinous subtype (HR 7.779, 95% CI 1.566-38.625; P = 0.012) independently predicted recurrence. Submucosal venous invasion (HR 5.792, 95% CI 1.056-31.754; P = 0.043) predicted CRC-specific survival. Although 64.4% of polypectomy-only patients had margin involvement/other risk factors, none developed recurrence. Of 94 with polypectomy margin involvement, five (5.3%) had confirmed residual tumour. Overall, lymph node metastases (7.1%), recurrence (4.2%) and cancer-specific mortality (3.0%) were rare. Cancer-specific 5-year survival was high: polypectomy only (100%), polypectomy and then resection (98.2%), primary resection (100%).

CONCLUSION

Surveillance may be safe for more T1 CRC polyp patients. Multidisciplinary team discussion and informed patient choice are critical.

Colorectal malignant polyps: a modern approach

Colorectal malignant polyps (MP) are polyps with invasive cancer into the submucosa harboring a variable risk of lymph node involvement, which can be estimated through evaluation of morphological, endoscopic, and histologic features. The recent advances in imaging endoscopic techniques have led to the possibility of performing an optical diagnosis of T1 colorectal cancer, allowing the selection of the best therapeutic modality to optimize outcomes for the patient. When MP are diagnosed after endoscopic removal, their management can be challenging. Differentiating low- and high-risk histologic features that influence the possibility of residual tumor, the risk of recurrence and the risk of lymph node metastasis, is crucial to further optimize treatment and surveillance plans. While the presence of high-risk features indicates a need for surgery in the majority of cases, location, comorbidities and the patient’s preference should be taken in account when making the final decision. This is a particularly important issue in the management of low rectal MP presenting with high-risk features, where chemoradiotherapy followed by a watch-and-wait strategy has demonstrated promising results. In this review we discuss the important prognostic features of MP and the most modern approaches regarding their management.

Endoscopic management of colorectal polyps: From benign to malignant polyps

Colorectal cancer (CRC) is the third most common cancer worldwide and the second leading cause of cancer related death in the world. The early detection and removal of CRC precursor lesions has been shown to reduce the incidence of CRC and cancer-related mortality. Endoscopic resection has become the first-line treatment for the removal of most precursor benign colorectal lesions and selected malignant polyps. Detailed lesion assessment is the first critical step in the evaluation and management of colorectal polyps. Polyp size, location and both macro- and micro- features provide important information regarding histological grade and endoscopic resectability. Benign polyps and even malignant polyps with superficial submucosal invasion and favorable histological features can be adequately removed endoscopically. When compared to surgery, endoscopic resection is associated with lower morbidity, mortality, and higher patient quality of life. Conversely, malignant polyps with deep submucosal invasion and/or high risk for lymph node metastasis will require surgery. From a practical standpoint, the most appropriate strategy for each patient will need to be individualized, based not only on polyp- and patient-related characteristics, but also on local resources and expertise availability. In this review, we provide a broad overview and present a potential decision tree algorithm for the evaluation and management of colorectal polyps that can be widely adopted into clinical practice.