Combined microsatellite instability and BRAF gene status as biomarkers for adjuvant chemotherapy in stage III colorectal cancer

Potent therapeutic strategy in gastric cancer with microsatellite instability-high and/or deficient mismatch repair

Gastric cancer (GC) is a common malignancy that presents challenges in patient care worldwide. The mismatch repair (MMR) system is a highly conserved DNA repair mechanism that protects genome integrity during replication. Deficient MMR (dMMR) results in an increased accumulation of genetic errors in microsatellite sequences, leading to the development of a microsatellite instability-high (MSI-H) phenotype. Most MSI-H/dMMR GCs arise sporadically, mainly due to MutL homolog 1 (MLH1) epigenetic silencing. Unlike microsatellite-stable (MSS)/proficient MMR (pMMR) GCs, MSI-H/dMMR GCs are relatively rare and represent a distinct subtype with genomic instability, a high somatic mutational burden, favorable immunogenicity, different responses to treatment, and prognosis. dMMR/MSI-H status is a robust predictive biomarker for treatment with immune checkpoint inhibitors (ICIs) due to high neoantigen load, prominent tumor-infiltrating lymphocytes, and programmed cell death ligand 1 (PD-L1) overexpression. However, a subset of MSI-H/dMMR GC patients does not benefit from immunotherapy, highlighting the need for further research into predictive biomarkers and resistance mechanisms. This review provides a comprehensive overview of the clinical, molecular, immunogenic, and therapeutic aspects of MSI-H/dMMR GC, with a focus on the impact of ICIs in immunotherapy and their potential as neoadjuvant therapies. Understanding the complexity and diversity of the molecular and immunological profiles of MSI-H/dMMR GC will drive the development of more effective therapeutic strategies and molecular targets for future precision medicine.

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 impact of molecular and mismatch repair status on the survival outcomes of surgically treated patients with colorectal peritoneal metastases

BACKGROUND

Stratification of patients with colorectal peritoneal metastases (CRPM) using RAS/BRAF mutational status may refine patient selection for cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). This study aimed to analyse the association of RAS/BRAF status and their variants, with clinicopathological variables and survival outcomes in patients who have undergone CRS ± HIPEC.

METHODS

A single centre, peritonectomy database was interrogated for patients with CRPM who underwent peritonectomy procedures between 2010 and 2020.

RESULTS

During the study period, 174 patients were included. Molecular status was obtained on 169 patients, with 68 (40.5%) KRAS, 25 (14.8%) BRAF and 6 (3.6%) NRAS mutations detected. Patients with BRAF mutations were more likely to be mismatch repair deficient (dMMR) (BRAF 20%, KRAS 4.4%, wild type 8.6%, p = 0.015). Most common BRAF and KRAS variants were, V600E (80%) and G12D (39.7%), respectively. BRAF V600E was independently associated with worse overall (median: 28 months, multivariate: HR 2.29, p = 0.026) and disease-free survival (median: 8 months, multivariate: HR 1.8, p = 0.047). KRAS G12V was a strong prognostic factor associated with disease-free survival (median: 9 months, HR 2.63, p = 0.016). dMMR patients (14/161, 8.7%) exhibited worse median overall survival compared to those with proficient MMR (dMMR 27 months, pMMR 29 months p = 0.025).

CONCLUSION

This study highlights the importance of molecular analysis in CRPM stratification. BRAF V600E mutations predict poor outcomes post CRS and HIPEC and may help refine patient selection for this procedure. Molecular analysis should be performed preoperatively to characterise prognosis and guide perioperative therapeutic options.

Survival benefit with adjuvant chemotherapy in stage III microsatellite-high/deficient mismatch repair colon cancer: a systematic review and meta-analysis

Clinical observations have demonstrated that microsatellite instability-high (MSI-H) and/or deficient MMR (dMMR) status are associated with favorable prognosis and no benefit from 5-Fluorouracil (5-FU)-based adjuvant chemotherapy in patients with resected stage II colorectal cancer (CRC). This study represents a systematic review and meta-analysis exploring the predictive role of MSI-H status in stage III CRC undergoing or not adjuvant chemotherapy. Published articles that evaluated the role of adjuvant chemotherapy in resected stage III CRC from inception to September 2020 were identified by searching the PubMed, EMBASE, and Cochrane Library databases. The random-effects model was conducted to estimate the pooled effect size of OS and DFS. The primary outcome of interest was OS. 21,590 patients with MSI-H/dMMR stage III CRC, from n = 17 retrospective studies, were analyzed. Overall, OS was improved with any adjuvant chemotherapy vs. any control arm (single-agent 5-FU or surgery alone): HR 0.42, 95% CI 0.26–0.66; P < 0.01. Conversely, DFS was not significantly improved (HR 0.7, 95% CI 0.45–1.09; P = 0.11). In patients with stage III MSI-H/dMMR CRC, adjuvant chemotherapy is associated with a significant OS improvement. Thus, MSI-H/dMMR status does represent a predictive factor for postoperative chemotherapy benefit in stage III CRC beyond its prognostic role.

Microsatellite and RAS/RAF Mutational Status as Prognostic Factors in Colorectal Peritoneal Metastases Treated with Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy (HIPEC)

BACKGROUND

Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) leads to prolonged survival for selected patients with colorectal (CRC) peritoneal metastases (PM). This study aimed to analyze the prognostic role of micro-satellite (MS) status and RAS/RAF mutations for patients treated with CRS.

METHODS

Data were collected from 13 Italian centers with PM expertise within a collaborative group of the Italian Society of Surgical Oncology. Clinical and pathologic variables and KRAS/NRAS/BRAF mutational and MS status were correlated with overall survival (OS) and disease-free survival (DFS).

RESULTS

The study enrolled 437 patients treated with CRS-HIPEC. The median OS was 42.3 months [95% confidence interval (CI), 33.4-51.2 months], and the median DFS was 13.6 months (95% CI, 12.3-14.9 months). The local (peritoneal) DFS was 20.5 months (95% CI, 16.4-24.6 months). In addition to the known clinical factors, KRAS mutations (p = 0.005), BRAF mutations (p = 0.01), and MS status (p = 0.04) were related to survival. The KRAS- and BRAF-mutated patients had a shorter survival than the wild-type (WT) patients (5-year OS, 29.4% and 26.8% vs 51.5%, respectively). The patients with micro-satellite instability (MSI) had a longer survival than the patients with micro-satellite stability (MSS) (5-year OS, 58.3% vs 36.7%). The MSI/WT patients had the best prognosis. The MSS/WT and MSI/mutated patients had similar survivals, whereas the MSS/mutated patients showed the worst prognosis (5-year OS, 70.6%, 48.1%, 23.4%; p = 0.0001). In the multivariable analysis, OS was related to the Peritoneal Cancer Index [hazard ratio (HR), 1.05 per point], completeness of cytoreduction (CC) score (HR, 2.8), N status (HR, 1.6), signet-ring (HR, 2.4), MSI/WT (HR, 0.5), and MSS/WT-MSI/mutation (HR, 0.4). Similar results were obtained for DFS.

CONCLUSION

For patients affected by CRC-PM who are eligible for CRS, clinical and pathologic criteria need to be integrated with molecular features (KRAS/BRAF mutation). Micro-satellite status should be strongly considered because MSI confers a survival advantage over MSS, even for mutated patients.

BRAF V600E potentially determines "Oncological Resectability" for "Technically Resectable" colorectal liver metastases

Despite reports on poor survival outcomes after hepatectomy for colorectal liver metastases (CRLM) with BRAF V600E mutation (mBRAF) exist, the role of mBRAF testing for technically resectable cases remains unclear. A single-center retrospective study was performed to investigate the survival outcomes of patients who underwent upfront hepatectomy for solitary resectable CRLM with mBRAF between January 2005 and December 2017 and to compare them with those of unresectable cases with mBRAF. Of 172 patients who underwent initial hepatectomy for solitary resectable CRLM, mBRAF, RAS mutations (mRAS), and wild-type RAS/BRAF (wtRAS/BRAF) were observed in 5 (2.9%), 73 (42.4%), and 93 (54.7%) patients, respectively. With a median follow-up period of 72.8 months, mBRAF was associated with a significantly shorter OS (median, 14.4 months) than wtRAS/BRAF (median, not reached [NR]) (hazard ratio [HR], 27.6; p < 0.001) and mRAS (median, NR) (HR, 9.9; p < 0.001), and mBRAF had the highest HR among all the indicators in the multivariable analysis (HR, 17.0; p < 0.001). The median OS after upfront hepatectomy for CRLM with mBRAF was identical to that of 28 unresectable CRLM with mBRAF that were treated with systemic chemotherapy (median, 17.2 months) (HR, 0.78; p = 0.65). When technically resectable CRLM are complicated with mBRAF, its survival outcome becomes as poor as unresectable cases; therefore, those with mBRAF should be considered as oncologically unresectable. Patients with CRLM should undergo pre-treatment mBRAF testing regardless of technical resectability. Clinical trial registration number: UMIN000034557.

Rate of dissemination and prognosis in early and advanced stage colorectal cancer based on microsatellite instability status: systematic review and meta-analysis

INTRODUCTION

For the past two decades, microsatellite instability (MSI) has been reported as a robust clinical biomarker associated with survival advantage attributed to its immunogenicity. However, MSI is also associated with high-risk adverse pathological features (poorly differentiated, mucinous, signet cell, higher grade) and exhibits a double-edged sword phenomenon. We performed a systematic review and meta-analysis to evaluate the rate of dissemination and the prognosis of early and advanced stage colorectal cancer based on MSI status.

METHODS

A systematic literature search of original studies was performed on Ovid searching MEDLINE, Embase, Cochrane Database of Systematic Reviews, American College of Physicians ACP Journal Club, Database of Abstracts of Reviews of Effects DARE, Clinical Trials databases from inception of database to June 2019. Colorectal cancer, microsatellite instability, genomic instability and DNA mismatch repair were used as key words or MeSH terms. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline was followed. Data were pooled using a random-effects model with odds ratio (OR) as the effect size. Statistical analysis was performed using RevMan ver 5.3 Cochrane Collaboration.

RESULTS

From 5288 studies, 136 met the inclusion criteria (n = 92,035; MSI-H 11,746 (13%)). Overall, MSI-H was associated with improved OS (OR, 0.81; 95% CI 0.73-0.90), DFS (OR, 0.73; 95% CI 0.66-0.81) and DSS (OR, 0.69; 95% CI 0.52-0.90). Importantly, MSI-H had a protective effect against dissemination with a significantly lower rate of lymph node and distant metastases. By stage, the protective effect of MSI-H in terms of OS and DFS was observed clearly in stage II and stage III. Survival in stage I CRC was excellent irrespective of MSI status. In stage IV CRC, without immunotherapy, MSI-H was not associated with any survival benefit.

CONCLUSIONS

MSI-H CRC was associated with an overall survival benefit with a lower rate of dissemination. Survival benefit was clearly evident in both stage II and III CRC, but MSI-H was neither a robust prognostic marker in stage I nor stage IV CRC without immunotherapy.

The role of molecular biomarkers in outcomes and patient selection for cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for peritoneal metastases of colorectal origin

BACKGROUND

Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is effective in select patients with peritoneal metastases of colorectal (CRC) origin. The impact of different biomarkers in predicting recurrence after CRS/HIPEC is unclear.

METHODS

Retrospective review of patients who underwent CRS/HIPEC for PC of CRC origin from 03/2007-08/2017. Molecular profile of the primary tumor was obtained from pathology reports, whenever available.

RESULTS

Overall, 100 patients underwent CRS/HIPEC for peritoneal metastases of CRC origin. Most patients presented high grade tumor histology (G2/G3, n = 97, 97%), and a majority showed mucinous features (n = 61, 61%). At a median follow-up of 18 months, median DFS for the overall population was 13 months (95% CI 9.6, 16.4). Data reporting at least one mutational analysis was available in 64 patients. Microsatellite stability was detected in 42/50 (84%) patients, mKRAS in 25/51 (49%), and mBRAF in 5/35 (14.3%). On Kaplan-Meier analysis, BRAF was the only mutation associated with poor DFS (16 months, CI 95% 11.7-43.3 vs. 7 months, CI 95% 2.1-11.9, p = .008). On multivariate analysis, mBRAF independently predicted earlier recurrence (p = .032).

CONCLUSIONS

In this analysis, mBRAF was independently associated with earlier recurrence in patients undergoing CRS/HIPEC for CRC, leading to dismal median DFS (7 months). Strict patient selection is advisable in these patients.

Microsatellite instability and sensitivity to fluoropyrimidine and oxaliplatin containing first-line chemotherapy in metastatic colorectal cancer

OBJECTIVES

To examine the effect of microsatellite instability (MSI) on the outcome of fluoropyrimidine and oxaliplatin containing first-line chemotherapy in metastatic colorectal cancer (mCRC).

METHODS

Patients with mCRC and treated with fluoropyrimidine/oxaliplatin first-line chemotherapy were included in our study. Demographic data, tumour characteristics, chemotherapy regimens, treatment responses and progression-free survival (PFS) were collected from medical records. The MSI analysis was performed using fluorescence-based PCR, and divided into MSI-high (MSI-H) and MSI-low (MSI-L)/microsatellite stable (MSS). Statistical analysis used Kaplan-Meier method, log-rank test and multivariate Cox model.

RESULTS

From 1 January 2015 to 1 May 2016, a total of 192 patients with mCRC were included in our study. Among these, 14 (7.29%) exhibited MSI-H and 178 (92.71%) were MSI-L/MSS. The objective response rate (p=0.79), disease control rate (p=0.22) and PFS (p=0.22) of fluoropyrimidine/oxaliplatin first-line chemotherapy were not significantly different between MSI-H and MSI-L/MSS tumours. But MSI-H tumours had a trend to better disease control rate (71.43% vs 54.49%) and PFS (6.50 m vs 5.40 m) than MSI-L/MSS tumours. Multivariate analysis indicated that MSI was not a predictive factor for PFS (p=0.18).

CONCLUSION

The effect of fluoropyrimidine/oxaliplatin first-line chemotherapy was not significantly different between MSI-H and MSI-L/MSS tumours. However, MSI-H tumours tended to have better disease control rate and PFS.

MSI status is associated with distinct clinicopathological features in BRAF mutation colorectal cancer: A systematic review and meta-analysis

BACKGROUND

Microsatellite stable (MSS) BRAF p.V600E mutation colorectal cancer (BRAF-CRC) has a poor prognosis, whereas microsatellite instability (MSI) in BRAF-CRC is associated with a favorable prognosis. Although usually considered a single clinical entity, the MSI BRAF-CRC subtype shows some distinct characteristics in comparison with the MSS BRAF-CRC subtype.

METHODS

We conducted a meta-analysis to investigate the influence of clinicopathological features on MSI status in BRAF-CRC. We searched publications up to March 2019 from PubMed, Embase, and the Cochrane Library. The effect of MSI status on outcome parameters was assessed using odds ratios (ORs) with 95% confidence intervals (CIs) and fixed- or random-effects models according to the heterogeneity.

RESULTS

After reviewing 2839 reports, 16 eligible studies including 1381 patients with BRAF-CRC met the criteria. The MSI BRAF-CRC subtype was associated with older age, female sex (OR = 1.70; 95% CI = 1.35-2.14; P < 0.00001), proximal tumor location (OR = 5.10; 95% CI = 3.70-7.03; P < 0.00001), early TNM stage (OR = 5.28; 95% CI = 3.93-7.09; P < 0.00001), and poor differentiation (OR = 2.29; 95% CI = 1.60-3.28; P < 0.00001).

CONCLUSIONS

MSI was significantly correlated with distinct favorable clinicopathological characteristics in BRAF-CRC. These results suggest that MSI status should be considered as a stratification factor for better management of the BRAF-CRC.

[Successful pembrolizumab therapy in metastasized adenosquamous carcinoma of the colon]

Adenosquamous carcinoma (ASqC) is an exceedingly rare subtype of colorectal cancer without any known special guidelines for treatment. The biological behaviour and molecular background are widely unknown, although a few case studies report a worse prognosis compared to ordinary colorectal adenocarcinoma. We herein report for the first time the successful immune checkpoint inhibitor therapy in a 40-year-old patient suffering from metastasized right-sided colonic ASqC with unique molecular features, after having previously progressed under standard chemotherapy.

Clinicopathological Significance of BRAFV600E Mutation in Colorectal Cancer: An Updated Meta-Analysis

Background and Aims: Numerous studies have identified BRAF^V600E mutation as a predictive factor of anti-EGFR antibodies in colorectal cancer (CRC). However, the association between BRAF^V600E mutation and clinicopathological features remains unclear. Therefore, we aimed to conduct an updated and comprehensive meta-analysis to evaluate the above issues. Methods: We performed a systematic literature search from PubMed, Web of Science, Embase, and PMC database examining the association between BRAF^V600E mutation and clinicopathological features in CRC patients. Odds ratio with 95% confidence interval were used to estimate the effects of BRAF^V600E mutation on each clinicopathological parameter with fixed-effect model or random-effect model. Results: Sixty-one studies published, including 32407 CRC patients from multiple countries, were included in the meta-analysis. The overall BRAF^V600E mutation rate was 11.38%, and BRAF^V600E mutation was positively related to high disease stage (OR=0.81; 95% CI=0.72-0.92; P=0.001), high T stage (OR=0.51; 95% CI=0.40-0.65; P<0.00001), proximal colon (OR=4.76; 95% CI=3.81-5.96; P<0.00001) or right colon (OR=5.15; 95% CI=4.35-6.10, P<0.00001) tumor location, poor tumor differentiation (OR=0.27; 95% CI=0.21-0.34; P<0.00001), mucinous histology (OR=2.97; 95% CI=2.37-3.72; P<0.00001), K-ras-wild type (OR=0.04; 95% CI=0.02-0.07; P<0.00001), TP53-wild type (OR=0.50; 95% CI=0.31-0.78; P=0.003), deficient DNA mismatch repair (OR=2.93; 95% CI=1.78-4.82; P<0.00001), high microsatellite instability (OR=11.15; 95% CI=8.51-14.61; P<0.00001) and high CpG island methylator phenotype (OR=0.04; 95% CI=0.03-0.08; P<0.00001). Conclusions: Our updated meta-analysis demonstrated that BRAF^V600E mutation was related to poor prognosis of CRC and associated with the distinct molecular phenotypes.

Evaluation of Long-Term Outcomes of Microsatellite Instability Status in an Asian Cohort of Sporadic Colorectal Cancers

PURPOSE

Microsatellite instability in colorectal cancer (CRC) and its long-term outcomes remains poorly studied in Asians. We investigate the prognostic significance of microsatellite instability in an Asian population and assess its clinical impact in patients who undergo adjuvant chemotherapy.

METHODS

Six hundred fifty-four consecutive CRC patients who underwent surgical resection between January 2010 and December 2012 were recruited. Survival was estimated using the Kaplan-Meier approach. Univariate Cox proportional hazard models were used to estimate the hazard ratios for variables associated with survival. A subgroup analyses was performed for stage III patients who underwent chemotherapy to evaluate the prognostic significance of microsatellite instability in this group.

RESULTS

Five hundred ninety-one (90.4%) patients were microsatellite stable (MSS) while 63 (9.6%) were microsatellite instable (MSI). Three years recurrence-free survival (RFS) and disease-specific survival (DSS) were 83.7 versus 73.7% (p = 0.295) and 87.1 versus 91.2% (p = 0.307) in MSS and MSI tumors, respectively. Among stage III patients who received adjuvant therapy, MSI status was found to be an adverse prognostic factor for RFS (HR 2.74 (95% CI 1.43-5.26), p = 0.002). This remained significant on multivariate analysis (HR 2.38 (95% CI 1.15-4.93), p = 0.018). Adjuvant chemotherapy was associated with survival benefit for patients with MSS tumors (HR 0.35, 95% CI 0.17-0.69, p = 0.002) but not MSI tumors (HR 0.67, 95% CI 0.08-8.15, p = 0.750).

CONCLUSIONS

MSI status is not a prognostic indicator in the general CRC population but appears to be an adverse prognostic indicator for RFS in stage III CRC patients who received adjuvant chemotherapy.

Prognostic value of the combination of microsatellite instability and BRAF mutation in colorectal cancer

Purpose

The aim of this study was to investigate the prognostic value of the combination of microsatellite instability (MSI) and BRAF V600E mutation in colorectal cancer (CRC).

Materials and methods

We compare the prognosis difference among CRC patients with four subtypes according to MSI and BRAF mutation, ie, microsatellite stable/BRAF wild type (MSS/BRAFwt), MSS/BRAF mutation (MSS/BRAFmut), MSI/BRAFwt, and MSI/BRAFmut, by pooling the previous related reports and public available data sets till December 2017 for the first time.

Results

Twenty-seven independent studies comprising 24,067 CRC patients were included. Meta-analysis suggested that, compared with MSS/BRAFwt subtype, MSS/BRAFmut was associated with shorter overall survival (OS) (N=25, HR = 2.018, 95% CI = 1.706-2.388, P=2.220E-16), while there was a trend of association of MSI/BRAFmut with OS (N=13, HR = 1.324, 95% CI = 0.938-1.868, P=1.096E-01) and no association of MSI/BRAFwt with OS (N=17, HR = 0.996, 95% CI = 0.801-1.240, P=9.761E-01). Compared with MSI/ BRAFwt subtype, MSI/BRAFmut was a poor factor for OS (N=22, HR = 1.470, 95% CI = 1.243-1.740, P=7.122E-06). Compared with MSS/BRAFmut subtype, both MSI/BRAFwt (N=11, HR = 0.560, 95% CI = 0.433-0.725, P=1.034E-05) and MSI/BRAFmut (N=16, HR = 0.741, 95% CI = 0.567-0.968, P=2.781E-02) were favorable for OS. Subgroup analysis revealed similar results in all subgroups except the subgroup of stage IV cancer, in which MSI showed poor effects on OS in BRAF wild-type patients (N=6, HR = 1.493, 95% CI = 1.187-1.879, P=6.262E-04) but not in BRAF-mutated patients (N=5, HR = 1.143, 95% CI = 0.789-1.655, P=4.839E-01). Meta-analysis regression and test of interaction revealed no interaction of MSI with BRAF mutation when evaluating the associations of MSI/BRAF mutation subtypes with OS in CRC.

Conclusion

Among the four subtypes according to MSI and BRAF mutation, MSS/BRAFmut was a poor prognostic factor, while MSS/BRAFwt and MSI/BRAFwt were comparable and favorable and MSI/BRAFmut was moderate in CRC. The combination of MSI/BRAF mutations could facilitate the planning of individualized treatment strategies and prognosis improvement in CRC.

Predictive model for high-frequency microsatellite instability in colorectal cancer patients over 50 years of age

Microsatellite instability (MSI) is an important biomarker for screening for Lynch syndrome, and also of response to immune checkpoint inhibitors. The aim of this study is to create a predictive model to determine which elderly patients with colorectal cancer (CRC) should undergo MSI and/or immunohistochemistry testing on the basis of clinicopathological data. We analyzed a test cohort of CRC patients aged ≥50 years (n = 2219) by multivariate logistic regression analyses to identify predictors of high‐frequency MSI (MSI‐H). The created prediction model was validated in an external cohort (n = 992). The frequency of MSI‐H was 5.5% among CRC patients aged ≥ 50 years. The following five predictors of MSI‐H were identified in the test cohort: female (1 point), mucinous component (2 points), tumor size ≥ 60 mm (2 points), location in proximal colon (3 points), and BRAF mutation (6 points). The area under curve (AUC) in the receiver‐operating characteristic (ROC) analysis of this prediction model was 0.832 (95% confidence interval: 0.790–0.874). The sensitivity and specificity were 74.4% and 77.7%, respectively, for a cut‐off score of 4 points. The receiver‐operating characteristic curve of the validation cohort also showed an AUC of 0.856 (95% CI: 0.806–0.905). This prediction model is useful to select elderly CRC patients who should undergo MSI testing, and who may benefit from treatment with 5‐FU‐based adjuvant chemotherapy and cancer immunotherapy.

Lymph Node Ratio as a Risk Factor for Recurrence After Adjuvant Chemotherapy in Stage III Colorectal Cancer

BACKGROUND

Although several markers, including the lymph node ratio (LNR), have been proposed as a clinically prognostic tool for colorectal cancer (CRC), it remains unclear which markers have the most relevance in determining recurrence following adjuvant chemotherapy for stage III CRC.

METHODS

Independent risk factors for recurrence-free survival (RFS) were retrospectively determined using the Cox proportional hazard model in 360 stage III CRC patients and validated using an independent cohort comprising 172 stage III CRC patients.

RESULTS

The LNR was independently associated with RFS (HR, 1.96; 95% CI, 1.11 to 3.28; P = 0.020). A higher LNR value was significantly associated with recurrence, microsatellite stable, and shorter time to recurrence. A combination of the LNR with pre-chemotherapy CEA and CA19-9, other independent risk factors, provided accurate risk stratification of RFS and conferred additional information on recurrence within each stage III CRC subgroup, which was then validated in an independent cohort. A beneficial effect in patients at risk of recurrence, and a reduced effect in patients at low risk, was exhibited by the addition of oxaliplatin to 5-fluorouracil-based adjuvant chemotherapy.

CONCLUSION

A higher LNR is one of the most aggressive phenotypes with recurrence risk following adjuvant chemotherapy for stage III CRC.

Clinical course and outcome of patients with high-level microsatellite instability cancers in a real-life setting: a retrospective analysis

BACKGROUND

The prognostic and predictive significance of the high-level microsatellite instability (MSI-H) phenotype in various malignancies is unclear. We describe the characteristics, clinical course, and outcomes of patients with MSI-H malignancies treated in a real-life hospital setting.

PATIENTS AND METHODS

A retrospective analysis of MSI-H cancer patient files was conducted. We analyzed the genetic data, clinical characteristics, and oncological treatments, including chemotherapy and surgical interventions.

RESULTS

Clinical data of 73 MSI-H cancer patients were available. Mean age at diagnosis of first malignancy was 52.3 years. Eight patients (11%) had more than four malignancies each. Most patients (76%) had colorectal cancer (CRC). Seventeen patients (23%) had only extracolonic malignancies. Eighteen women (36%) had gynecological malignancy. Nine women (18%) had breast cancer. Mean follow-up was 8.5 years. Five-year overall survival and disease-free survival of all MSI-H cancer patients from first malignancy were 86% and 74.6%, respectively. Five-year overall survival rates of stage 2, 3, and 4 MSI-H CRC patients were 89.5%, 58.4%, and 22.9%, respectively.

CONCLUSION

Although the overall prognosis of MSI-H cancer patients is favorable, this advantage may not be maintained in advanced MSI-H CRC patients.

Impact of microsatellite status on chemotherapy for colorectal cancer patients with KRAS or BRAF mutation

KRAS and BRAF mutations are frequently detected in cases of colorectal cancer (CRC). The microsatellite status of patients with CRC and mutated KRAS/BRAF is important when determining cancer therapy. In the present study, the microsatellite status and genetic polymorphisms of KRAS (codons 12 and 13) and BRAF (V600E) were characterized in CRC tissue. The mismatch repair activity and oncogenic potential of KRAS were assessed by immunoblots from two KRAS-mutated CRC cell lines, SW480 and HCT116, with different microsatellite statuses, following treatment with 5-fluorouracil (5-FU) and oxaliplatin. Of all the 205 patients with CRC enrolled in the present study, 31.2% (64 of 205) had a KRAS or BRAF mutation, and 79.7% (51 of 64) of these patients with a KRAS/BRAF mutation exhibited microsatellite stability (MSS), indicating that microsatellite status is correlated with KRAS/BRAF mutation (P=0.027). A higher proportion (39.0%, 41 of 105) of elderly patients (≥62.6 years) had mutated KRAS or BRAF than younger patients (<62.6 years; 23.0%, 23 of 100; P=0.013). In the subgroup of 154 patients with MSS, patients without the KRAS or BRAF mutation (n=110) had longer disease-specific survival rates (58.8±9.4%) than patients with KRAS or BRAF mutations (n=44; 50.6±11.0%; P=0.043). Cytoplasmic KRAS levels decreased whereas nuclear MutS protein homolog 2 (MSH2) levels increased slightly in CRC HCT116 cells that were microsatellite instable, following treatment with 76.9 µM 5-FU for 2 days. In microsatellite stable SW480 cells, MSH2 levels markedly increased in the nucleus following 150 µM oxaliplatin treatment for 3 days. However, no significant change was observed regarding KRAS distribution in these cells. The results of the present study suggest that it is important to identify patients with CRC who may benefit from adjuvant chemotherapy with 5-FU or oxaliplatin, particularly CRC patients with MSS and mutated KRAS or BRAF, who have poorer overall survival rates than patients with microsatellite instability. Knowledge of the microsatellite status of patients and whether they harbor KRAS or BRAF mutations may enable more effective therapeutic strategies to be developed. Further prospective studies are required to validate the findings of the current study.

Role of Deficient Mismatch Repair in the Personalized Management of Colorectal Cancer

Colorectal cancer (CRC) represents the third most common type of cancer in developed countries and one of the leading causes of cancer deaths worldwide. Personalized management of CRC has gained increasing attention since there are large inter-individual variations in the prognosis and response to drugs used to treat CRC owing to molecular heterogeneity. Approximately 15% of CRCs are caused by deficient mismatch repair (dMMR) characterized by microsatellite instability (MSI) phenotype. The present review is aimed at highlighting the role of MMR status in informing prognosis and personalized treatment of CRC including adjuvant chemotherapy, targeted therapy, and immune checkpoint inhibitor therapy to guide the individualized therapy of CRC.

Comparative Polymorphism of BAT-26 between Healthy Individuals and Cancer Patients and Its Cancer Risk Implication for Local Chinese

Purpose

BAT-26 is one of the representative markers for microsatellite instability evaluation and presents different polymorphisms in different ethnic populations. The current knowledge of its comparative polymorphism between healthy individuals and cancer patients in the Chinese population is insufficient. This study aims to analyze germline polymorphic variations of BAT-26 between healthy individuals and cancer patients in Chinese from Jiangsu province and the associated cancer risk implications.

Methods

The various BAT-26 alleles and their percentages in cervical cells from 500 healthy women were assessed by direct sequencing. Twenty of these samples were also analyzed by fragment analysis. BAT-26 of blood DNA from 24 healthy individuals and 247 cancer patients was analyzed by fragment analysis.

Results

Compared with the sequencing results, 122.6-122.9 bp, 123.4-123.8 bp and 124.1-124.8 bp corresponded to the A25, A26 and A27 alleles, respectively. The 524 healthy individuals showed 4.58%, 92.18% and 3.24% of A25, A26 and A27, respectively. The variant alleles A18, A24, A28, A29 and A32 were only found in cancer patients, accounting for 0.81%, 0.40%, 0.40%, 0.40% and 0.40%, respectively; the A25, A26 and A27 alleles in cancer patients accounted for 6.48%, 77.33% and 13.77%.

Conclusions

Healthy individuals had a stable BAT-26 profile within the quasimonomorphic variation range (QMVR), but cancer patients harbored variant alleles outside QMVR and showed a trend from quasimonomorph to polymonomorph, suggesting that variant alleles of BAT-26 in germline cells may be regarded as a potential marker of higher cancer risk in the Chinese population from Jiangsu province.

Prognostic Role of BRAF Mutation in Stage II/III Colorectal Cancer Receiving Curative Resection and Adjuvant Chemotherapy: A Meta-Analysis Based on Randomized Clinical Trials

Background and Objective

Studies examining the prognostic value of the BRAF mutation on relapse-free survival (RFS), disease-free survival (DFS) and overall survival (OS) in stage II/III colorectal cancer (CRC) patients receiving curative resection and adjuvant chemotherapy so far showed discrepant results. Therefore, a meta-analysis of relevant studies was performed for clarification.

Methods

Randomized trials of stage II/III colorectal cancer treated with curative resection followed by adjuvant chemotherapy were selected to conduct a meta-analysis. The necessary descriptive and statistical information such as hazard ratios (HRs) and 95% confidence intervals (CIs) were derived from published survival data.

Results

Seven phase III randomized clinical trials (RCTs) including 1,035 BRAF mutation stage II/III CRC patients receiving curative resection and adjuvant chemotherapy were analyzed. Overall, BRAF mutation resulted in poorer OS (HR = 1.42, 95% CI: 1.25–1.60; P < 0.00001), and poorer DFS (HR = 1.26, 95% CI: 1.07–1.48, P = 0.006) compared with BRAF wild-type CRC. The prognostic role on RFS could not be elucidated in the meta-analysis because of limited data.

Conclusions

BRAF mutation was significantly related with shorter DFS and OS among stage II/III CRC patients receiving adjuvant chemotherapy after curative resection. Its prognostic role for RFS needs to be further analyzed when more data is available.