BRAF mutation in colorectal carcinomas with signet ring cell component

Molecular characteristics of patients with colorectal signet-ring cell carcinoma with different ABO blood groups

Background

Colorectal signet-ring cell carcinoma (SRCC) is a rare subtype of malignant adenocarcinoma, accounting for approximately 1 % of colorectal cancer (CRC) cases. Its biomarkers and molecular characteristics remain controversial, and there are no specific therapeutic targets or strategies for its clinical treatment.

Methods

A retrospective study was conducted between January 2010 and December 2021. 1058 colorectal cancer cases from the Sun Yat-sen University Cancer Center and 489 cases from the Tumor Genome Atlas Project were included in the analysis, of which 64 were SRCC. Data extraction included patient demographics, blood types and risk factors, including clinical variables and genomics (either a 19-gene panel NGS or 1021-gene panel NGS). Univariate analyses were performed to identify factors significantly associated with overall survival.

Results

The blood groups of 27 (42.2 %), 18 (28.1 %), 12 (18.8 %), and seven (10.9 %) patients were classified as O, A, B, and AB, respectively. We found that O was a unique blood group characterized by a low frequency of KRAS mutations, a high frequency of heterozygosity at each HLA class I locus, and a high tumor mutational burden (TMB). Patients in blood group A with high-frequency KRAS mutations and those in blood group B with anemia and metabolic abnormalities required targeted treatment. Furthermore, genetic alterations in SRCC differed from those in adenocarcinoma and mucinous adenocarcinoma.

Conclusions

Our study revealed genomic changes in SRCC patients across different blood groups, which could advance the understanding and precise treatment of colorectal SRCC.

Development and validation of a nomogram for predicting metachronous peritoneal metastasis in colorectal cancer: A retrospective study

BACKGROUND

Peritoneal metastasis (PM) after primary surgery for colorectal cancer (CRC) has the worst prognosis. Prediction and early detection of metachronous PM (m-PM) have an important role in improving postoperative prognosis of CRC. However, commonly used imaging methods have limited sensitivity to detect PM early. We aimed to establish a nomogram model to evaluate the individual probability of m-PM to facilitate early interventions for high-risk patients.

AIM

To establish and validate a nomogram model for predicting the occurrence of m-PM in CRC within 3 years after surgery.

METHODS

We used the clinical data of 878 patients at the Second Hospital of Jilin University, between January 1, 2014 and January 31, 2019. The patients were randomly divided into training and validation cohorts at a ratio of 2:1. The least absolute shrinkage and selection operator (LASSO) regression was performed to identify the variables with nonzero coefficients to predict the risk of m-PM. Multivariate logistic regression was used to verify the selected variables and to develop the predictive nomogram model. Harrell’s concordance index, receiver operating characteristic curve, Brier score, and decision curve analysis (DCA) were used to evaluate discrimination, distinctiveness, validity, and clinical utility of this nomogram model. The model was verified internally using bootstrapping method and verified externally using validation cohort.

RESULTS

LASSO regression analysis identified six potential risk factors with nonzero coefficients. Multivariate logistic regression confirmed the risk factors to be independent. Based on the results of two regression analyses, a nomogram model was established. The nomogram included six predictors: Tumor site, histological type, pathological T stage, carbohydrate antigen 125, v-raf murine sarcoma viral oncogene homolog B mutation and microsatellite instability status. The model achieved good predictive accuracy on both the training and validation datasets. The C-index, area under the curve, and Brier scores were 0.796, 0.796 [95% confidence interval (CI) 0.735-0.856], and 0.081 for the training cohort and 0.782, 0.782 (95%CI 0.690-0.874), and 0.089 for the validation cohort, respectively. DCA showed that when the threshold probability was between 0.01 and 0.90, using this model to predict m-PM achieved a net clinical benefit.

CONCLUSION

We have established and validated a nomogram model to predict m-PM in patients undergoing curative surgery, which shows good discrimination and high accuracy.

The Molecular Associations of Signet-Ring Cell Carcinoma in Colorectum: Meta-Analysis and System Review

Background: Signet ring cell carcinoma (SC) accounts for 1% of total colorectal cancer (CRC) cases and is associated with aggressive behaviors, such as lymphatic invasion and distant metastases, resulting in poor prognosis. To date, there is still a lack of consensus on the genetic etiology underpinning this cancer subtype. This study aimed to clarify the molecular associations of SC by using meta-analysis and a systematic review. Methods: PubMed, Embase, and Cochrane Library were searched for studies evaluating the KRAS, BRAF, P53 statuses, and microsatellite instability (MSI) in CRC patients with different histological subtypes, including SC. The diagnosis of SC is defined as the signet ring cells comprising ≥50 percent of the tumor mass. By dividing the studies into subgroups based on the composition of control groups, such as classic adenocarcinoma (AC; no SC components) and non-SC (including those with SC components < 50%), the relative risk (RR) of molecular alterations for SC in each study were pooled using a random-effects model. Two reviewers identified trials for inclusion, assessed quality, and extracted data independently. Results: Data from 29 studies consisting of 9366 patients were included in this analysis. SC was associated positively with MSI (RR 1.78, 95% CI 1.34 to 2.37; 95% CI 0.77 to 4.15; p = 0.0005), BRAF mutation (RR 1.99, 95% CI 1.21 to 3.26; 95%CI 0.68 to 5.82; p = 0.0146), and negatively with KRAS mutation (RR 0.48, 95% CI 0.29 to 0.78; 95% CI 0.09 to 2.49; p = 0.0062). No association was found between SC and P53 expression (RR 0.92, 95% CI 0.76 to 1.13; 95%CI 0.61 to 1.39; p = 0.3790). Moreover, it was associated negatively with P53 gene mutations (RR 0.92, 95% CI 0.77 to 1.09; 95% CI 0.46 to 1.82; p = 0.1568), and P53 protein (RR 0.93, 95% CI 0.58 to 1.49; 95% CI 0.40 to 2.17; p = 0.6885). Conclusions: The molecular etiology of SC may be associated with the BRAF and MSI pathways. Its features, such as the high frequency of BRAF mutation, could partly explain its less favorable outcomes and limited effects of traditional chemotherapy.

Signet ring cell carcinoma of the gastrointestinal tract: National trends on treatment effects and prognostic outcomes

BACKGROUND

Signet ring cell carcinoma (SRCC) is a distinct malignancy occurring across the tubular gastrointestinal tract (tGIT). We comprehensively examined the outcomes of patients diagnosed with SRCC across tGIT.

METHODS

SRCC and not-otherwise-specified adenocarcinoma (NOS) patients reported to the National Cancer Database from 2004 to 2015 were included. Baseline characteristics, outcomes and site-specific adjusted hazard ratios (aHR) derived from Cox models of SRCC patients were compared to those of NOS patients. Overall survival (OS) was primary endpoint.

RESULTS

A total of 41,686 SRCC (4.6%) and 871,373 NOS patients (95.4%) were included. SRCC patients were younger (63.1 ± 14.7 vs. 67.0 ± 13.4 y, p < 0.001) and more likely to present with Stage IV disease than NOS patients (42.5% vs. 24.5%, p < 0.001). Stomach (n = 24,433) and colon (n = 9,914) contributed highest frequency of SRCC. SRCC histology was associated with shorter OS (aHR = 1.377, p < 0.001) in multivariate model. There was an interaction between SRCC and chemotherapy effects on risk of death (interaction aHR = 1.072, p_interaction< 0.001) and between SRCC histology and disease site, suggesting that the effect of SRCC on OS is site-dependent, with a higher increased risk of death in patients with rectal SRCC (aHR = 2.378, p_interaction< 0.001).

CONCLUSION

Significant negative prognostic effect associated with SRCC is site-dependent across the GIT. Surgical and or systemic therapy was associated with improved OS among SRCC patients, but remained lower than NOS patients. Further understanding of gastrointestinal SRCC molecular profile is needed to better inform future treatment strategies.

Clinicopathological and Molecular Characteristics of Colorectal Signet Ring Cell Carcinoma: A Review

Colorectal signet ring cell carcinoma (SRCC) is a rare subtype of colorectal cancer (CRC) with unique characteristics. Due to the limited researches on it, a comprehensive and in-depth understanding of this subtype is still lacking. In this article, we summarize the clinicopathological features and molecular characteristics of colorectal SRCC based on a literature review. Clinically, SRCC has been associated with young age, proximal site preference, advanced tumor stage, high histological grade, high rate of lymph node involvement, frequent peritoneal metastasis, and a significantly poor prognosis. Regarding molecular characteristics, in SRCC, the mutation burden of the classic signaling pathways that include WNT/β-catenin, RAS/RAF/MAPK, and PI3K/AKT/mTOR signaling pathways are generally reduced. In contrast, some genes related to the “epithelial-mesenchymal transition (EMT) process” and the “stem cell properties”, including RNF43, CDH1, and SMAD4, as well as the related TGF-β signaling pathway have been observed more frequently altered in SRCC than in conventional adenocarcinoma (AC). In many studies but not in others, SRCC showed a higher frequency of BRAF mutation, microsatellite instability-high (MSI-H) and CpG island methylator phenotype (CIMP) positive status compared to AC. It has been proposed that colorectal SRCC consists of two subtypes, in which the MSI⁺/CIMP⁺/BRAF⁺/CD3⁺/PD-L1⁺ hypermethylated genotype is more common in the proximal colon, and may represent the potential candidate for immunotherapy. Understanding the special molecular mechanisms related to the aggressive biology of SRCC is of great importance, which may provide a theoretical basis for the development of more targeted and effective treatments for this refractory disease.

Investigation of clinicopathological characters and gene expression features in colorectal signet-ring cell carcinoma utilizing CMS classification

Signet ring cell carcinoma (SRCC) is a rare pathological type of colorectal cancer, of which the clinicopathological features and genetic background have not yet been fully investigated. Previous research has focused on the optimization of colorectal cancer treatment utilizing consensus molecular subtyping (CMS). However, it is not known what type of CMS would be designated to SRCC treatment. In the current study, of 1,350 patients diagnosed with colorectal cancer who underwent surgery, 14 were diagnosed with SRCC. The case-control cohort that fit the clinical background of the SRCC case was constructed. Statistical comparison between the SRCC group and the case-control cohort was performed among clinicopathological variables. SRCC and well to moderately adenocarcinoma case mRNA were submitted to microarray analysis and CMS analysis. Compared with the case-control cohort, the SRCC group was located more in the right-sided colon, the lymphatic invasion was more severe and the peritoneal dissemination was more frequent. The cancer-specific survival and the progression-free survival were significantly worse in the SRCC group compared with the case-control cohort. Microarray and CMS analysis identified that one SRCC case was significantly well assigned in the CMS 4 group and the other case was assigned in the CMS 1 group. Gene set analysis revealed the upregulation of EMT related genes and the downregulation of fatty acid, glycolysis, differentiation, MYC, HNF4A, DNA repair genes. In conclusion, the clinical characteristics of SRCC are severe but there is a possibility of the presence of different phenotypes according to CMS analysis.

Clinicopathological Characteristics and Mutation Spectrum of Colorectal Adenocarcinoma With Mucinous Component in a Chinese Cohort: Comparison With Classical Adenocarcinoma

Background: Colorectal adenocarcinoma with mucinous component (AWMC) is a special entity of colorectal cancer. The study is aimed at analyzing the clinicopathological characteristics, mutation spectrum, and prognosis of AWMC and comparing it with classical adenocarcinoma (AC) in a Chinese cohort. Methods: One hundred eight AMWC and 204 AC patients were included. Targeted next-generation sequencing (NGS) was performed on formalin-fixed paraffin-embedded (FFPE) tissues. AWMC was further divided into two groups: AWMC with signet ring cell component and AWMC without signet ring cell component. Clinicopathological features, mismatch repair protein (MMR) status, genetic alterations, and survival outcomes were analyzed after tumor location was taken into consideration. Results: AWMC had larger tumor size (p = 0.014) and showed predilection for proximal colon (p < 0.001) compared with AC. Regardless of primary sites, AWMC was associated with less metastasis (p < 0.001) and earlier AJCC stage (p < 0.001). Mismatch repair protein deficiency (dMMR) was more commonly detected in AWMC than in AC for right-sided colon (p < 0.001), but the difference was not significant for left-sided colon (p = 0.081). The five most commonly mutated genes in AWMC were KRAS (45.4%), TP53 (39.8%), APC (22.2%), PIK3CA (22.2%), and SMAD4 (10.2%). AWMC showed a significantly lower mutation rate of TP53 than AC, both in right-sided colon and in left-sided colon (p < 0.001 and p = 0.033, respectively). In left-sided colon, AWMC with signet ring cell component had a significantly smaller size than tumors with signet ring cell component (p = 0.034). No dMMR cases were detected in AWMC with signet ring cell component (n = 7). Moreover, AWMC with signet ring cell component had a significantly lower KRAS mutation rate than AWMC without signet ring cell component, both in right-sided colon and in left-sided colon (p = 0.036 and p = 0.012, respectively). The disease-specific survival (DSS) for AWMC and AC were not statistically different (p = 0.0587). Multivariate analysis showed that AWMC was not an independent predictor of prognosis. Conclusion: Regardless of primary sites, AWMC demonstrates less metastasis, earlier stages, more frequent dMMR, and lower TP53 mutation rate than AC. Our results indicate that different molecular pathogenesis might underlie mucinous morphology in colorectal carcinoma. Mucinous component is not an independent factor of outcome.

Signet ring cell colorectal cancer: genomic insights into a rare subpopulation of colorectal adenocarcinoma

Background

Signet ring cell carcinoma (SRCC) is a rare subtype of colorectal cancer (CRC). The aim of this study was to characterise the genomic alterations and outcomes of SRCC.

Methods

Medical records of metastatic CRC (mCRC) patients whose tumours were evaluated by NGS analysis were reviewed. SC-mCRC were classified into two groups: SRCC (>50% signet ring cells) and adenocarcinoma (AC) with SC component (≤50% signet ring cells).

Results

Six hundred and sixty-five mCRC patients were included. Of the 93 mCRC cases with SC features, 63 had slides for review. Of those 63 cases, 35 were confirmed SRCC, and 28 were AC with SC component. Compared with AC group, KRAS and PIK3CA mutations (mts) were found in only 11% (OR: 0.13) and 3% (OR: 0.15) of SRCC cases, respectively. In contrast to the 44% rate of APC mts in AC group, only 3% of SRCC patients had APC mts (OR = 0.04).

Conclusions

SRCC has distinct molecular features, including low rates of KRAS, PIK3CA and APC mts. Further study to identify activation pathways and potential therapeutic targets are needed.

Genomic alterations in signet ring and mucinous patterned colorectal carcinoma

BACKGROUND

The genetic alterations (GAs) in two specific histological subtypes of colorectal cancer (CRC), signet ring cell colorectal carcinoma (SRC) and mucinous colorectal carcinoma (MC), are not well known. In the present study, we employed next-generation sequencing to perform genetic profiling of SRC and MC, and compared the spectrum of GAs with the alterations found in conventional type colorectal cancer (CON).

MATERIALS AND METHODS

We selected 46 CRCs comprising 17 SRCs and mucinous carcinoma with signet ring cell component (SRCCs), 17 MCs, and 12 CONs with microsatellite stability or microsatellite instability-low. Deep sequencing was performed using a targeted cancer panel composed of 171 cancer-related genes. SMAD4 protein expression was evaluated by immunohistochemical staining.

RESULTS

We detected 108 mutations in 18 different genes. Overall, 2.34 GAs were detected per tumor (range, 0-14). The overall frequency of GA and alteration in targetable genes was less prevalent in SRC/SRCC compared to the frequency of alteration in MC/CON (p = 0.040 and p < 0.001, respectively). The GA profile of SRC/SRCC included TP53 (8/17, 47.1%), SMAD4 (5/17, 29.4%), KRAS (4/17.23.5%), APC (4/17.23.5%), PIK3CA, ATM, BRAF, and PIK3R1 (1/17, 5.9%, each). KRAS mutation was significantly less prevalent in SRC/SRCC compared to the number of KRAS mutations in MC (12/17, 70.6%) and CON (9/12, 75.0%) (p = 0.015 and 0.01, respectively). Compared to the 152 non-hypermutated CONs from TCGA database, SMAD4 alteration was predominant in SRC/SRCC (p = 0.045) with aberrant loss of SMAD4 expression (13/17, 76.5%) compared to the SMAD4 alterations in CON (5/15, 33.3%) (p = 0.031). Accordingly, KRAS (12/17, 70.6%), APC (6/17, 35.3%), SMAD4, TP53 (4/17, 23.5%, each), PIK3CA (3/17, 17.6%), AKT1, ATM, BRAF, EGFR, and EZH2 (1/17, 5.9%, each) were altered in MC. APC and TP53 mutations were less frequent in MC compared to those in TCGA-CON (p < 0.001 and 0.003, respectively) whereas KRAS mutation was prevalent (p = 0.041).

CONCLUSION

Alterations of known cancer associated genes and targetable genes in SRC/SRCC are infrequent. The profile of GAs in SRC/SRCC and MC differs from the GA profile of CON. Specifically, SMAD4 mutation and loss of SMAD4 expression is frequently found in SRC/SRCC. The genetic profiles revealed in the present study may aid in developing precision medicine for CRC treatment based on histological subtype.

Molecular Profiling of Appendiceal Adenocarcinoma and Comparison with Right-sided and Left-sided Colorectal Cancer

PURPOSE

The natural history and prognosis of appendiceal adenocarcinomas differ from those of adenocarcinomas arising in other large bowel sites. We aimed to compare the molecular profiles exhibited by appendiceal adenocarcinomas and colorectal cancers, or between the histopathologic subtypes of appendiceal adenocarcinoma.

EXPERIMENTAL DESIGN

A total of 183 samples from appendiceal adenocarcinoma [46 adenocarcinoma, not otherwise specified (NOS), 66 pseudomyxoma peritonei (PMP), 44 mucinous adenocarcinoma (MU), and 27 signet ring cell carcinoma (SR)], 994 from right-sided colorectal cancer (R-CRC), and 1,080 from left-sided CRC (L-CRC) were analyzed by next-generation sequencing (NGS) and IHC markers. Microsatellite instability (MSI) and tumor mutational burden (TMB) were tested by NGS, and programmed death ligand 1 (PD-L1) by IHC.

RESULTS

We observed high mutation rates in appendiceal adenocarcinoma samples for KRAS (55%), TP53 (40%), GNAS (31%), SMAD4 (16%), and APC (10%). Appendiceal adenocarcinoma exhibited higher mutation rates in KRAS and GNAS, and lower mutation rates in TP53, APC, and PIK3CA (6%) than colorectal cancers. PMP exhibited much higher mutation rates in KRAS (74%) and GNAS (63%), and much lower mutation rates in TP53 (23%), APC (2%), and PIK3CA (2%) than NOS. Alterations associated with immune checkpoint inhibitor response (MSI-high, TMB-high, PD-L1 expression) showed similar frequency in appendiceal adenocarcinoma compared with L-CRC, but not R-CRC, and those of NOS were higher than other subtypes of appendiceal adenocarcinoma and L-CRC.

CONCLUSIONS

Molecular profiling of appendiceal adenocarcinoma revealed different molecular characteristics than noted in R-CRC and L-CRC, and molecular heterogeneity among the histopathologic subtypes of appendiceal adenocarcinoma. Our findings may be critical to developing an individualized approach to appendiceal adenocarcinoma treatment.

Mutations of key driver genes in colorectal cancer progression and metastasis

The association between mutations of key driver genes and colorectal cancer (CRC) metastasis has been investigated by many studies. However, the results of these studies have been contradictory. Here, we perform a comprehensive analysis to screen key driver genes from the TCGA database and validate the roles of these mutations in CRC metastasis. Using bioinformatics analysis, we identified six key driver genes, namely APC, KRAS, BRAF, PIK3CA, SMAD4 and p53. Through a systematic search, 120 articles published by November 30, 2017, were included, which all showed roles for these gene mutations in CRC metastasis. A meta-analysis showed that KRAS mutations (combined OR 1.18, 95% CI 1.05-1.33) and p53 mutations (combined OR 1.49, 95% CI 1.23-1.80) were associated with CRC metastasis, including lymphatic and distant metastases. Moreover, CRC patients with a KRAS mutation (combined OR 1.29, 95% CI 1.13-1.47), p53 mutation (combined OR 1.35, 95% CI 1.06-1.72) or SMAD4 mutation (combined OR 2.04, 95% CI 1.41-2.95) were at a higher risk of distant metastasis. Subgroup analysis stratified by ethnic populations indicated that the BRAF mutation was related to CRC metastasis (combined OR 1.42, 95% CI 1.18-1.71) and distant metastasis (combined OR 1.51, 95% CI 1.20-1.91) in an Asian population. No significant association was found between mutations of APC or PIK3CA and CRC metastasis. In conclusion, mutations of KRAS, p53, SMAD4 and BRAF play significant roles in CRC metastasis and may be both potential biomarkers of CRC metastasis as well as therapeutic targets.

Colorectal cancer: genetic abnormalities, tumor progression, tumor heterogeneity, clonal evolution and tumor-initiating cells

Colon cancer is the third most common cancer worldwide. Most colorectal cancer occurrences are sporadic, not related to genetic predisposition or family history; however, 20-30% of patients with colorectal cancer have a family history of colorectal cancer and 5% of these tumors arise in the setting of a Mendelian inheritance syndrome. In many patients, the development of a colorectal cancer is preceded by a benign neoplastic lesion: either an adenomatous polyp or a serrated polyp. Studies carried out in the last years have characterized the main molecular alterations occurring in colorectal cancers, showing that the tumor of each patient displays from two to eight driver mutations. The ensemble of molecular studies, including gene expression studies, has led to two proposed classifications of colorectal cancers, with the identification of four/five non-overlapping groups. The homeostasis of the rapidly renewing intestinal epithelium is ensured by few stem cells present at the level of the base of intestinal crypts. Various experimental evidence suggests that colorectal cancers may derive from the malignant transformation of intestinal stem cells or of intestinal cells that acquire stem cell properties following malignant transformation. Colon cancer stem cells seem to be involved in tumor chemoresistance, radioresistance and relapse.