Search

Background: Colorectal cancer is the third most common tumour entity in the world and up to 50% of the patients develop liver metastases (CRLM) within five years. To improve and personalize therapeutic strategies, new diagnostic tools are urgently needed. For instance, biomechanical tumour properties measured by magnetic resonance elastography (MRE) could be implemented as such a diagnostic tool. We postulate that ex vivo MRE combined with histological and radiological evaluation of CRLM could provide biomechanics-based diagnostic markers for cell viability in tumours., Methods: 34 CRLM specimens from patients who had undergone hepatic resection were studied using ex vivo MRE in a frequency range from 500 Hz to 5300 Hz with increments of 400 Hz. Single frequency evaluation of shear wave speed and wave penetration rate as proxies for stiffness and viscosity was performed, along with rheological model fitting based on the spring-pot model and powerlaw exponent α, ranging between 0 (complete solid behaviour) and 1 (complete fluid behaviour). For histological analysis, samples were stained with H&E and categorized according to the degree of regression. Quantitative histologic analysis was performed to analyse nucleus size, aspect ratio, and density. Radiological response was assessed according to RECIST-criteria., Results: Five samples showed major response to chemotherapy, six samples partial response and 23 samples no response. For higher frequencies (> 2100 Hz), shear wave speed correlated significantly with the degree of regression (p ≤ 0.05) indicating stiffer properties with less viable tumour cells. Correspondingly, rheological analysis of α revealed more elastic-solid tissue properties at low cell viability and major response (α = 0.43 IQR 0.36, 0.47) than at higher cell viability and no response (α = 0.51 IQR 0.48, 0.55; p = 0.03). Quantitative histological analysis showed a decreased nuclear area and density as well as a higher nuclear aspect ratio in patients with major response to treatment compared to patients with no response (all p < 0.05)., Discussion: Our results suggest that MRE could be useful in the characterization of biomechanical property changes associated with cell viability in CRLM. In the future, MRE could be applied in clinical diagnosis to support individually tailored therapy plans for patients with CRLM., (© 2024. The Author(s).)

Background: β-catenin activation plays a crucial role for tumourigenesis in the large intestine but except for Lynch syndrome (LS) associated cancers stabilizing mutations of β-catenin gene (CTNNB1) are rare in colorectal cancer (CRC). Previous animal studies provide an explanation for this observation. They showed that CTNNB1 mutations induced transformation in the colon only when CTNNB1 was homozygously mutated or when membranous β-catenin binding was hampered by E-cadherin haploinsufficiency. We were interested, if these mechanisms are also found in human CTNNB1 mutated CRCs., Results: Among 869 CRCs stabilizing CTNNB1 mutations were found in 27 cases. Homo- or hemizygous CTNNB1 mutations were detected in 74% of CTNNB1 mutated CRCs (13 microsatellite instabile (MSI-H), 7 microsatellite stabile (MSS)) but only in 3% (1/33) of extracolonic CTNNB1 mutated cancers. In contrast to MSS CRC, CTNNB1 mutations at codon 41 or 45 were highly selected in MSI-H CRC. Of the examined three CRC cell lines, β-catenin and E-cadherin expression was similar in cell lines without or with hetereozygous CTNNB1 mutations (DLD1 and HCT116), while a reduced E-cadherin expression combined with cytoplasmic accumulation of β-catenin was found in a cell line with homozygous CTNNB1 mutation (LS180). Reduced expression of E-cadherin in human MSI-H CRC tissue was identified in 60% of investigated cancers, but no association with the CTNNB1 mutational status was found., Conclusions: In conclusion, this study shows that in contrast to extracolonic cancers stabilizing CTNNB1 mutations in CRC are commonly homo- or hemizygous indicating a higher threshold of β-catenin stabilization to be required for transformation in the colon as compared to extracolonic sites. Moreover, we found different mutational hotspots in CTNNB1 for MSI-H and MSS CRCs suggesting a selection of different effects on β-catenin stabilization according to the molecular pathway of tumourigenesis. Reduced E-cadherin expression in CRC may further contribute to higher levels of transcriptionally active β-catenin, but it is not directly linked to the CTNNB1 mutational status.

Background: Colorectal cancer (CRC) development is generally accepted as a sequential process, with genetic mutations determining phenotypic tumor progression. However, matching genetic profiles with histological transition requires the analyses of temporal samples from the same patient at key stages of progression., Results: Here, we compared the genetic profiles of 34 early carcinomas with their respective adenomatous precursors to assess timing and heterogeneity of driver alterations accompanying the switch from benign adenoma to malignant carcinoma. In almost half of the cases, driver mutations specific to the carcinoma stage were not observed. In samples where carcinoma-specific alterations were present, TP53 mutations and chromosome 20 copy gains commonly accompanied the switch from adenomatous tissue to carcinoma. Remarkably, 40% and 50% of high-grade adenomas shared TP53 mutations and chromosome 20 gains, respectively, with their matched carcinomas. In addition, multi-regional analyses revealed greater heterogeneity of driver mutations in adenomas compared to their matched carcinomas., Conclusion: Genetic alterations in TP53 and chromosome 20 occur at the earliest histological stage in colorectal carcinomas (pTis and pT1). However, high-grade adenomas can share these alterations despite their histological distinction. Based on the well-defined sequence of CRC development, we suggest that the timing of genetic changes during neoplastic progression is frequently uncoupled from histological progression.

Background: Competing molecular classification systems have been proposed to complement the TNM staging system for a better prediction of survival in colorectal cancer (CRC). However, validation studies are so far lacking. The aim of this study was to validate and extend previously published molecular classifications of CRC in a large independent cohort of CRC patients., Methods: CRC patients were recruited into a population-based cohort study (DACHS). Molecular subtypes were categorized based on three previously published classifications. Cox-proportional hazard models, based on the same set of patients and using the same confounders as reported by the original studies, were used to determine overall, cancer-specific, or relapse-free survival for each subtype. Hazard ratios and confidence intervals, as well as Kaplan-Meier plots were compared to those reported by the original studies., Results: We observed similar patterns of worse survival for the microsatellite stable (MSS)/BRAF-mutated and MSS/KRAS-mutated subtypes in our validation analyses, which were included in two of the validated classifications. Of the two MSI subtypes, one defined by additional presence of CIMP-high and BRAF-mutation and the other by tumors negative for CIMP, BRAF and KRAS-mutations, we could not confirm associations with better prognosis as suggested by one of the classifications. For two of the published classifications, we were able to provide results for additional subgroups not included in the original studies (men, other disease stages, other locations)., Conclusions: External validation of three previously proposed classifications confirmed findings of worse survival for CRC patients with MSS subtypes and BRAF or KRAS mutations. Regarding MSI subtypes, other patient characteristics such as stage of the tumor, may influence the potential survival benefit. Further integration of methylation, genetic, and immunological information is needed to develop and validate a comprehensive classification that will have relevance for use in clinical practice.

Pulmonary enteric adenocarcinoma is a rare non-small cell lung cancer subtype. It is poorly characterized and cannot be distinguished from metastatic colorectal or upper gastrointestinal adenocarcinomas by means of routine pathological methods. As DNA methylation patterns are known to be highly tissue specific, we aimed to develop a methylation-based algorithm to differentiate these entities. To this end, genome-wide methylation profiles of 600 primary pulmonary, colorectal, and upper gastrointestinal adenocarcinomas obtained from The Cancer Genome Atlas and the Gene Expression Omnibus database were used as a reference cohort to train a machine learning algorithm. The resulting classifier correctly classified all samples from a validation cohort consisting of 680 primary pulmonary, colorectal and upper gastrointestinal adenocarcinomas, demonstrating the ability of the algorithm to reliably distinguish these three entities. We then analyzed methylation data of 15 pulmonary enteric adenocarcinomas as well as four pulmonary metastases and four primary colorectal adenocarcinomas with the algorithm. All 15 pulmonary enteric adenocarcinomas were reliably classified as primary pulmonary tumors and all four metastases as well as all four primary colorectal cancer samples were identified as colorectal adenocarcinomas. In a t-distributed stochastic neighbor embedding analysis, the pulmonary enteric adenocarcinoma samples did not form a separate methylation subclass but rather diffusely intermixed with other pulmonary cancers. Additional characterization of the pulmonary enteric adenocarcinoma series using fluorescence in situ hybridization, next-generation sequencing and copy number analysis revealed KRAS mutations in nine of 15 samples (60%) and a high number of structural chromosomal changes. Except for an unusually high rate of chromosome 20 gain (67%), the molecular data was mostly reminiscent of standard pulmonary adenocarcinomas. In conclusion, we provide sound evidence of the pulmonary origin of pulmonary enteric adenocarcinomas and in addition provide a publicly available machine learning-based algorithm to reliably distinguish these tumors from metastatic colorectal cancer.

Background & Aims: Colorectal tumors with mutations in BRAF and microsatellite stability (MSS) have been associated with adverse outcomes of patients. Combined tests for microsatellite instability-high (MSI-H) and BRAF mutations might therefore be used in risk assessment, particularly for patients with stage II tumors. We investigate the stage-specific prognostic value of combined testing for MSI-H and BRAF for patients with colorectal cancer., Methods: We performed a retrospective analysis of colorectal tumor samples collected from 1995 patients at 22 hospitals in Germany, between 2003 and 2010. Samples were analyzed for MSI-H using an established mononucleotide marker panel; BRAF mutations (BRAFV600E) were detected by Sanger sequencing or in tissue microarray blocks using immunohistochemistry. Cancers were assigned to categories of having MSS without mutations in BRAF, MSS with mutant BRAF, MSI-H without mutations in BRAF, and MSI-H with mutant BRAF. We investigated the association between tumor categories with clinical and pathologic features and patient's overall, disease-specific, and recurrence-free survival (median follow-up time, 5.1 y)., Results: Tumors were stage I in 364 (18%), stage II in 678 (34%), stage III in 673 (34%), and stage IV (14%) in 280 patients. Sixty-three percent of tumors were located in the colon and 37% in the rectum. Most tumors (85%) had MSS without mutations in BRAF, 3% had MSS with mutant BRAF, 7% had MSI-H without mutations in BRAF, and 5% had MSI-H with mutant BRAF. In patients whose tumors were MSI-H, mutation of BRAF did not significantly affect survival time. Patients whose tumors had MSS with mutant BRAF had significantly reduced overall survival (hazard ratio [HR], 2.16; 95% CI, 1.54-3.04; P < .001), disease-specific survival (HR, 2.59; 95% CI, 1.77-3.79; P < .001), and recurrence-free survival (HR, 2.45; 95% CI, 1.70-3.52; P < .001) than patients whose tumors had MSS without BRAF mutation. Although BRAF mutations in tumors with MSS were associated with disease-specific survival of patients with stage III or IV tumors (P < .001), these features did not affect survival of patients with stage II tumors (P = .639)., Conclusions: In an analysis of almost 2000 patients with colorectal cancer, we found BRAF mutations to reduce survival of patients in stage III or IV (but not stage II) tumors with MSS. These findings do not support testing stage I or II colorectal tumors for BRAF mutations, although additional large studies are needed., (Copyright © 2019 AGA Institute. Published by Elsevier Inc. All rights reserved.)

The number of lymph nodes retrieved from colorectal cancer (CRC) resection specimens is crucial for adequate diagnosis and therapy. Previous studies indicate that in addition to the extent of surgical resection and the quality of pathological lymph node examination, non-modifiable tumour parameters like microsatellite instability (MSI) are associated with higher lymph node count. In order to study the potential influence of MSI on lymph node count, we analysed a previously MSI-typed population of CRC patients (n = 1196) to determine the relationship between MSI and the frequency with which at least 12 lymph nodes were retrieved, as well as the mean and median number of retrieved lymph nodes. MSI was associated with an increased frequency of 12-node retrieval, as well as a higher mean and median lymph node count in the overall analysis (p 0.004 and 0.001 for 12-node retrieval and lymph node count, respectively). However, when the analysis was restricted to cancers of the proximal colon, the main location of microsatellite unstable tumours (84% in our study), no association between MSI and 12-node retrieval was found. Subcategorisation by UICC stage of proximally located cancers showed a statistically significant increase in the lymph node count only in microsatellite unstable stage I tumours (p 0.010). In conclusion, our data shows that previously reported associations between MSI and higher lymph node count are mainly a consequence of the increased incidence of microsatellite unstable cancer in the proximal colon. Our finding that MSI is related to a significantly higher mean lymph node count in proximal stage I cancers may indicate that the immunogenicity of this molecular tumour type induces earlier lymph node activation.