[Molecular pathology of colorectal cancer]

[Colon polyps-nomenclature, histology, and molecular pathology]

Polyps are macroscopically visible protrusions of the mucosa in hollow organs. In the colon, epithelial neoplasms deriving from the mucosa dominate. These can be classified based on their morphology into classic and serrated adenomas and show different degrees of epithelial dysplasia. The histological subtypes show various molecular alterations and can be assigned to different pathways of carcinogenesis. These must be separated from hamartomatous polyps of the colon mucosa, which can occur sporadically or as part of hereditary syndromes.

Five-year follow-up study of stage I-IV rectal cancer including EGFR immunoexpression and p21 immunoactivity

Introduction

Both environmental and genetic factors increase the likelihood of developing rectal cancer.

Aim

To assess the EGFR and p21 immunoreactivity in rectal cancer and to assess its relationship with the clinical outcome.

Material and methods

Applying exclusion criteria, 102 patients with stage I–IV rectal cancer, who had undergone scheduled surgery during the period 2005–2011, were included in the study. There was a follow-up study with a span of 5 years from the date of the surgery. Immunohistochemistry using epidermal growth factor receptor (EGFR Ab10, Clone111.6) and antibodies against p21 (p21^WAF1 (Clone H252)) was performed to detect overexpression of the targeted receptor. Digital analysis of positive reactions of membranes and nuclei was performed utilizing Visiopharm.

Results

The degree of EGFR intensity (log OR = 0.854, OR = 2.35, 95% CI: 1.14–4.85, p = 0.021) is a significant factor in the prognosis of death within 2 years after surgery. The OS curve showed a significant decrease after 40 months from the date of surgery in the cases where EGFR had high expression. The ROC curve for cancer stage, according to the UICC classification and EGFR expression, in order to predict 2-year RFS, reached a high specificity value (ROC = 0.81, p = 0.0408). The analysis showed no statistically significant differences in the survival curves of patients in groups with immunoreactivity of p21 protein at 0, 1, 2, 3 (p = 0.6453 in the log-rank test). Also, it is not a significant risk factor for death (HR = 0.915, p = 0.7842) or for tumor dissemination (HR = 0.94, p = 0.9426).

Conclusions

The determination of EGFR immunoreactivity is important in the monitoring and treatment of patients with rectal cancer, as opposed to p21.

Artificial Intelligence in Pathology

BACKGROUND

Increasing digitalization enables the use of artificial intelligence (AI) and machine learning in pathology. However, these technologies have only just begun to be implemented, and no randomized prospective trials have yet shown a benefit of AI-based diagnosis. In this review, we present current concepts, illustrate them with examples from representative publications, and discuss the possibilities and limitations of their use.

METHODS

This article is based on the results of a search in PubMed for articles published between January 1950 and January 2020 containing the searching terms "artificial intelligence," "deep learning," and "digital pathology," as well as the authors' own research findings.

RESULTS

Current research on AI in pathology focuses on supporting routine diagnosis and on prognostication, particularly for patients with cancer. Initial data indicate that pathologists can arrive at a diagnosis faster and more accurately with the aid of a computer. In a pilot study on the diagnosis of breast cancer, involving 70 patients, sensitivity for the detection of micrometastases rose from 83.3% (by a pathologist alone) to 91.2% (by a pathologist combined with a computer algorithm). The evidence likewise suggests that AI applied to histomorphological properties of cells during microscopy may enable the inference of certain genetic properties, such as mutations in key genes and deoxyribonucleic acid (DNA) methylation profiles.

CONCLUSION

Initial proof-of-concept studies for AI in pathology are now available. Randomized, prospective studies are now needed so that these early findings can be confirmed or falsified.

P21 is not a prognostic marker for rectal cancer - five-year follow up study of rectal cancer in stages I-IV

The p21 participates in the regulation of DNA repair and replication, and modulation of apoptosis as well. After DNA damage, the p53-dependent induction of p21 results in cell cycle arrest or could trigger cell apoptosis. The objective of the study was the assessment of p21 immunoreactivity in rectal cancer and the estimation of relationships with clinical outcome especially as predictor of poor outcome. While applying the ruling in and out criteria, 102 patients were incorporated to the study, with stage I–IV rectal cancer who had undergone surgery in a planned mode during 2005–2011. The follow-up covered 5 years period from surgery date. Conventional immunohistochemistry were performed using antibody against p21 (p21WAF1 (Clone H252) to detect overexpression targeted receptor. The analysis showed no statistically significant differences in the survival curves of patients in groups with immunoreactivity of p21 protein at 0; 1; 2; 3 (p = 0.6453 in the log-rank test), also is not a significant risk factor for death (HR = 0.915, p = 0.7842) and for tumor dissemination (HR = 0.94, p = 0.9426). Our study leads to the conclusion that the probability of survival does not depend on p21 expression and do not authorize the importance of p21 immunoreactivity in the detection and monitoring of rectal cancer treatment.

Budding, tumor-infiltrating lymphocytes, gland formation: scoring leads to new prognostic groups in World Health Organization low-grade colorectal cancer with impact on survival

Grading for colorectal carcinoma (CRC) is traditionally based on the percentage of gland formation. In recent years, high-grade CRC has become subject to more precise molecular grading strategies. Most, however, are low-grade cases according to the World Health Organization (WHO) with inhomogenous outcomes due to still insufficient characterization. On the other hand, budding and tumor-infiltrating lymphocytes have developed as interesting additive prognostic factors in CRC. Especially budding has been very well defined by the International Tumor Budding Consensus Conference recently. We analyzed a large collective of 576 WHO low-grade CRC cases, stages I to IV, diagnosed between 2005 and 2016 in terms of gland formation, budding, and tumor-infiltrating lymphocytes and developed a new, morphology-based risk score, taking into account each of the 3 parameters. For each parameter, 1 to 2 points were given, resulting in a sum score, dividing the CRC cases into a low-, an intermediate-, and a high-risk group. By our score, 179 (34.9%) of the cases were grouped as low risk, 241 (53.5) as intermediate risk, and 92 (35.5%) as high risk. The 3 groups differed significantly in pT, pN, and M as well as tumor stages, lymphatic vessel invasion, venous invasion, and overall survival (0.;P < .001 for low risk versus high risk, P = .038 for low versus intermediate risk, and P = .036 for intermediate versus high risk; log rank: median, 94.0 months [95% confidence interval {CI}, 74.9-113.1] for low risk; median, 63.0 months [95% CI, 44.0-82.0] for intermediate risk; and median, 40.0 months [95% CI, 23.4-56.7] for high risk) in Kaplan-Meier-analysis. Our proposed Bayreuth score enables separating the large group of WHO low-grade CRC cases into subgroups, which differ significantly in outcome.

Budding and tumor-infiltrating lymphocytes - combination of both parameters predicts survival in colorectal cancer and leads to new prognostic subgroups

Tumor budding is an independent prognostic factor in colorectal cancer (CRC) and has recently been well defined by the International Concensus Conference on Tumor Budding (ITBCC). Tumor-infiltrating lymphocytes (TILs) are also an issue in different human cancers and correlate with prognosis in CRC. Here we evaluate the combination of budding and TILs in CRC with regard to prognosis. Hematoxylin and eosin (H&E)-stained slides of 501 CRC patients, diagnosed between 2005 and 2010, were reevaluated for tumor budding according to the ITBCC criteria. Low (n = 331) was compared to intermediate/high budding (n = 170). The percentage of TILs was also assessed, and the following four groups were established: low budding + TILs >5% (n = 162), low budding + TILS ≤5% (n = 169), high budding + TILS >5% (n = 68), high budding + TILs ≤5% (n = 93). The combination of both markers revealed highly significant differences in overall survival (OS) between the four groups (P = .001). The low budding/>5% TILs group showed longest OS, followed by high budding/>5% TILs cases, followed by tumors with low budding/≤5% TILs. OS was worst for the high budding/≤ 5% TILs group. The combined score also correlated with T, N, M, L, Vstaging, development of disease relapse and distant metastasis. Our study shows that - even in the age of molecular pathology - it is still important to pay special attention to tumor morphology for additional information on tumor behavior and prognosis. Combining different morphological parameters of tumor and tumor environment can help to further subdivide CRC into new prognostic groups.

Clinical Aspects of Microsatellite Instability Testing in Colorectal Cancer

Microsatellite instability (MSI) is a molecular hallmark for some colorectal cancers (CRCs) in which short tandem repeats are prone to mutations along with DNA sequences. It is due to DNA-mismatch-repair system deficiency because of a germline/somatic mutation in mismatch-repair (MMR) genes. The germline mutations lead to Lynch syndrome (LS) while epigenetic gene silencing results in sporadic CRC tumors. We discuss in our paper the most important clinical aspects of MSI testing in CRCs. We reviewed the most reliable relevant studies and clinical trials according to their high-quality methods, particularly within two recent decades. MSI testing is used to classify CRC tumors as MSI-high (MSI-H), MSI-low, and microsatellite stable tumors. MSI-H or MMR deficient tumors have shown the best prognosis among all CRCs, so MSI testing is considered as a good prognostic marker. Moreover, it is used to identify LS among familial CRC patients. There is a diagnostic mutation in BRAF gene (V600E) by which sporadic CRCs could be distinguished from LS associated CRCs, due to its concordance with sporadic CRCs not LS. Although, some previous studies had demonstrated a predictive role for MSI testing in chemotherapy process, emerging some controversial findings in recent studies has not convinced many authors to recommend it as a routine examination to evaluate therapeutic response. Though emerging new molecular findings have opened novel windows to develop clinical management of CRC, MSI testing has remained as an excellent prognostic and diagnostic tool for CRC tumors.

The effect of the primary tumor location on the survival of colorectal cancer patients after radical surgery

Background and Objectives: Colorectal cancer is one of the most common cancers and the leading cause of cancer-related death worldwide. The impact of the primary tumor location on the prognosis of patients with colorectal cancer has long been a concern, but studies have led to conflicting conclusions. Methods: In total, 465 colorectal cancer patients who received radical surgery were reviewed in this study. Enrolled patients were divided into two groups according to the tumor location. Disease-free survival (DFS) and overall survival (OS) were analyzed via the Kaplan-Meier method. A Cox regression model was employed to evaluate the independent prognostic factors for DFS and OS. Results: The right colorectal cancer (RCC) and left colorectal cancer (LCC) groups comprised 202 and 140 patients, respectively. Univariate and multivariate analyses revealed that the tumor location and TNM stage were independent predictors of DFS and OS. Subgroup analyses by stage demonstrated that there were significant differences in DFS and OS between patients with stage II and III RCC and LCC, but not for those with stage I colorectal cancer. Conclusions: Patients with stage II and III LCC had better survival than those with RCC. However, this improvement in DFS and OS was not observed in patients with stage I colorectal cancer.