Predictive and prognostic markers in colorectal cancer

Evaluation of the Immunohistochemical Scoring System of CDX2 Expression as a Prognostic Biomarker in Colon Cancer

Encoded by the CDX2 homeobox gene, the CDX2 protein assumes the role of a pivotal transcription factor localized within the nucleus of intestinal epithelial cells, orchestrating the delicate equilibrium of intestinal physiology while intricately guiding the precise development and differentiation of epithelial tissue. Emerging research has unveiled that positive immunohistochemical expression of this protein shows that the CDX2 gene exerts a potent suppressive impact on tumor advancement in colorectal cancer, impeding the proliferation and distant dissemination of tumor cells, while the inhibition or suppression of CDX2 frequently correlates with aggressive behavior in colorectal cancer. In this study, we conducted an immunohistochemical assessment of CDX2 expression on a cohort of 43 intraoperatively obtained tumor specimens from patients diagnosed with colon cancer at Colțea Clinical Hospital in Bucharest, between April 2019 and December 2023. Additionally, we shed light on the morphological diversity within colon tumors, uncovering varying differentiation grades within the same tumor, reflecting the variations in CDX2 expression as well as the genetic complexity underlying these tumors. Based on the findings, we developed an innovative immunohistochemical scoring system that addresses the heterogeneous nature of colon tumors. Comprehensive statistical analysis of CDX2 immunohistochemical expression unveiled significant correlations with known histopathological parameters such as tumor differentiation grades (p-value = 0.011) and tumor budding score (p-value = 0.002), providing intriguing insights into the complex involvement of the CDX2 gene in orchestrating tumor progression through modulation of differentiation processes, and highlighting its role in metastatic predisposition. The compelling correlation identified between CDX2 expression and conventional histopathological parameters emphasizes the prognostic significance of the CDX2 biomarker in colon cancer. Moreover, our novel immunohistochemical scoring system reveals a distinct subset of colon tumors exhibiting reserved prognostic outcomes, distinguished by their "mosaic" CDX2 expression pattern.

KRAS status predicted by pretreatment MRI radiomics was associated with lung metastasis in locally advanced rectal cancer patients

BACKGROUND

Mutated KRAS may indicate an invasive nature and predict prognosis in locally advanced rectal cancer (LARC). We aimed to establish a radiomic model using pretreatment T2W MRIs to predict KRAS status and explore the association between the KRAS status or model predictions and lung metastasis.

METHODS

In this retrospective multicentre study, LARC patients from two institutions between January 2012 and January 2019 were randomly divided into training and testing cohorts. Least absolute shrinkage and selection operator (LASSO) regression and the support vector machine (SVM) classifier were utilized to select significant radiomic features and establish a prediction model, which was validated by radiomic score distribution and decision curve analysis. The association between the model stratification and lung metastasis was investigated by Cox regression and Kaplan‒Meier survival analysis; the results were compared by the log-rank test.

RESULTS

Overall, 103 patients were enrolled (73 and 30 in the training and testing cohorts, respectively). The median follow-up was 38.1 months (interquartile range: 26.9, 49.4). The radiomic model had an area under the curve (AUC) of 0.983 in the training cohort and 0.814 in the testing cohort. Using a cut-off of 0.679 defined by the receiver operating characteristic (ROC) curve, patients with a high radiomic score (RS) had a higher risk for lung metastasis (HR 3.565, 95% CI 1.337, 9.505, p = 0.011), showing similar predictive performances for the mutant and wild-type KRAS groups (HR 3.225, 95% CI 1.249, 8.323, p = 0.016, IDI: 1.08%, p = 0.687; NRI 2.23%, p = 0.766).

CONCLUSIONS

We established and validated a radiomic model for predicting KRAS status in LARC. Patients with high RS experienced more lung metastases. The model could noninvasively detect KRAS status and may help individualize clinical decision-making.

Case Report: Long-term survival of a patient with advanced rectal cancer and multiple pelvic recurrences after seven surgeries

Background

Rectal cancer has a high risk of recurrence and metastasis, with median survival ranging from 24 months to 36 months. K-RAS mutation is a predictor of poor prognosis in rectal cancer. Advanced rectal cancer can be stopped in its tracks by pelvic exenteration.

Case summary

A 51-year-old woman was diagnosed with advanced rectal cancer (pT4bN2aM1b, stage IV) with the KRAS G12D mutation due to a change in bowel habits. The patient had experienced repeated recurrences of rectal cancer after initial radical resection, and the tumor had invaded the ovaries, sacrum, bladder, vagina and anus. Since the onset of the disease, the patient had undergone a total of seven surgeries and long-term FOLFIRI- or XELOX-based chemotherapy regimens, with the targeted agents bevacizumab and regorafenib. Fortunately, the patient was able to achieve intraoperative R0 resection in almost all surgical procedures and achieve tumor-free survival after pelvic exenteration. The patient has been alive for 86 months since her diagnosis.

Conclusions

Patients with advanced rectal cancer can achieve long-term survival through active multidisciplinary management and R0 surgery.

DNA Mismatch Repair Proteins and BRAF V600E Detection by Immunohistochemistry in Colorectal Cancer Demonstrates Concordance with Next Generation Sequencing

Background and Aims: Multiple laboratory methods are used to screen patients with colorectal cancer (CRC) for mismatch repair (MMR) protein deficiency to identify possible Lynch syndrome patients. The goal of this study was to compare the agreement between ready-to-use immunohistochemistry (IHC) assays for MLH-1, PMS-2, MSH-2, MSH-6, and mutated BRAF at V600E and molecular methods in CRC cases. The inclusion of the BRAF V600E mutation testing is important for the identification of patients with sporadic CRC, as the BRAF V600E mutation is very rarely observed in patients with Lynch syndrome tumors. Methods: CRC cases were analyzed by ColoSeqTM tumor sequencing assay and VENTANA MMR IHC Panel that included anti-MLH1, anti-PMS2, anti-MSH2, anti-MSH6, and anti-BRAF V600E antibodies. Additionally, CRC cases with MLH1 IHC loss were evaluated for MLH1 promoter hypermethylation. Results: One hundred and eighteen cases were analyzed. The overall percent agreement (OPA) for each evaluated marker status compared to next-generation sequencing (NGS) exceeded 96%. Twenty-three cases were positive for the BRAF V600E mutation by IHC and NGS, and twenty cases showed loss of MLH1 protein and were positive for MLH1 hypermethylation. Samples with loss of MMR protein expression by IHC demonstrated genetic and/or epigenetic alterations that were consistent with the observed protein expression patterns. Conclusions: The results of this study indicate that ready-to-use IHC assays can correctly identify the loss of MMR proteins and the presence of mutated BRAF V600E protein, supporting the utility of the VENTANA MMR IHC Panel as an aid to stratify patients with sporadic CRC vs. potential Lynch syndrome.

Pattern of Expression of CDX2 in Colorectal Cancer and its Role in Prognosis: An Ambispective Observational Study

Introduction Caudal-type homeobox 2 (CDX2), a nuclear protein, is essential for the proliferation and development of intestinal epithelial cells and is frequently downregulated during tumorigenesis. CDX2 inhibits cell growth as well as stimulates differentiation by activating intestinal specific genes, thus lack of CDX2 favors tumor growth and aggressiveness.

Objectives We aimed to evaluate the pattern of CDX2 expression in all stages of colorectal cancer (CRC) and study its association with baseline characteristics and prognosis.

Materials and Methods Study was conducted as an ambispective observational study, enrolling cases of CRC retrospectively from January 2014 to July 2016 (30 months), and prospectively during next 18-month period till January 2018. We performed CDX2 staining by immunohistochemistry on the available biopsy blocks of CRC patients during the study period. Total 286 patients were registered during the study period, of which only 110 biopsy blocks were available for staining. CDX2 scoring was done by a semiquantitative method on whole tissue section for the intensity and percentage of the cells showing positivity. Correlation of CDX2 expression was done with baseline clinical and histopathologic characteristics, and survival.

Results Of 110 patients, 77 (70%) constituted colon cancer and 33 (30%) were rectal cancer. The median age was 54.2 years, 62 (56.4%) being male and 48 (43.6%) female with male-to-female ratio 1.3:1. In the study cohort, 33 (30%) patients had stage II disease, 30 (27.3%) stage III, and 47 (42.7%) were stage IV. Seventy-three (66.4%) were positive for CDX2 and 37 (33.4%) were negative. Loss of CDX2 expression was significantly associated with advanced stage, rectal site, poor grade of differentiation, and presence of lymphovascular invasion (LVSI). With median follow-up of 16 months, progression-free survival (PFS) at 2 years was 30% for CDX2 negative patients compared with 67% for CDX2 positive (p = 0.009), while overall survival (OS) at 2 years was 46% for CDX2 negative versus 77% for positive patients (p = 0.01).

Conclusion Loss of CDX2 expression is associated with advanced stage, higher tumor grade, presence of LVSI, and worse PFS and OS and thereby functions as a poor prognostic factor in CRC.

Role of MRI‑based radiomics in locally advanced rectal cancer (Review)

Colorectal cancer is the third most common type of cancer, with high morbidity and mortality rates. In particular, locally advanced rectal cancer (LARC) is difficult to treat and has a high recurrence rate. Neoadjuvant chemoradiotherapy (NCRT) is one of the standard treatment programs of LARC. If the response to treatment and prognosis in patients with LARC can be predicted, it will guide clinical decision‑making. Radiomics is characterized by the extraction of high‑dimensional quantitative features from medical imaging data, followed by data analysis and model construction, which can be used for tumor diagnosis, staging, prediction of treatment response and prognosis. In recent years, a number of studies have assessed the role of radiomics in NCRT for LARC. MRI‑based radiomics provides valuable data and is expected to become an imaging biomarker for predicting treatment response and prognosis. The potential of radiomics to guide personalized medicine is widely recognized; however, current limitations and challenges prevent its application to clinical decision‑making. The present review summarizes the applications, limitations and prospects of MRI‑based radiomics in LARC.

KRAS mutation is predictive for poor prognosis in rectal cancer patients with neoadjuvant chemoradiotherapy: a systemic review and meta-analysis

PURPOSE

To investigate the association between KRAS mutation and prognosis in rectal cancer patients with neoadjuvant chemoradiotherapy.

METHODS

Literature was searched in the databases including Cochrane Library, EMBASE (Ovid), and MEDLINE (PubMed) from inception to December 16, 2020. The keywords "rectal cancer" or "rectal carcinoma" or "rectal adenocarcinoma" and "KRAS" and "neoadjuvant" were used for preliminary literature retrieval. Pooled odds ratios (ORs) and 95% confidence intervals (95%CIs) were calculated for the KRAS mutation and clinical outcomes including overall survival (OS), disease-free survival (DFS), pathologic complete remission (pCR), downstaging of T stages and tumor stages, as well as improvements in tumor regression grading (TRG). Publication bias was assessed by the funnel plots.

RESULTS

A total of 16 articles were included for eligibility. The total number of patients was 3674 cases, with an incidence of KRAS gene mutation of 36.6% (1346/3674). Meta-analysis showed that the pooled OR for KRAS mutation on OS was 1.33 (95%CI: 113-1.56). Consistently, results also indicated that the KRAS mutant was related to the poor DFS (pooled OR=1.55, 95%CI: 1.19-2.02). However, KRAS mutation is not related to the PCR (pooled OR= 0.71, 95%CI: 0.44-1.14), downstaging in T stages (pooled OR= 0.66, 95%CI: 0.42-1.06), tumor stages (pooled OR= 1.18, 95%CI: 0.78-1.78, I2=12.9%), as well as improvement in TRG grades (pooled OR= 0.84, 95%CI: 0.59-1.20).

CONCLUSION

KRAS mutation is a predictor for the poor prognosis of neoadjuvant chemoradiotherapy in patients with rectal cancer, but it is not related to the responses of tumors after treatment.

Prognostic impact of tumour sidedness in patients with stage II colon cancer: a single-centre retrospective study

BACKGROUND

The search for high-risk factors in stage II colon cancer (CC) is ongoing and several high-risk factors for stage II CC have been identified; however, the effects of tumour sidedness on prognosis are not clear. This study aims to determine whether tumour sidedness could be identified as another high-risk factor for stage II CC.

METHODS

We retrospectively analysed 189 patients with stage II CC and compared clinicopathological findings and long-term outcomes between the patients with right colonic cancer (RCC) and with left colonic cancer (LCC). Prognostic factors for survival were determined using univariate and Cox proportional regression analyses.

RESULTS

A total of 72 patients were diagnosed with RCC and 117 patients were diagnosed with LCC. Patients with RCC were significantly older (P < 0.001), and the number of harvested lymph nodes was greater in the RCC group (RCC: 25 versus LCC: 19; P = 0.003). The overall survival (OS) was worse in the RCC group than the OS in the LCC group (5-year survival rate - RCC: 81.3% versus LCC: 90.4%; P = 0.025). Cox proportional regression analysis showed that tumour sidedness was an independent prognostic factor for both OS (hazard ratio (HR) 3.78, 95% confidence interval (CI) 1.61-8.85, P = 0.022) and DFS (HR 2.58, 95% CI 1.33-4.99, P = 0.005).

CONCLUSION

Patients with RCC have more negative prognostic factors and worse long-term outcomes than those with LCC in stage II CC. Tumour sidedness is a high-risk factor in stage II CC patients.

Prognostic and Predictive Cross-Roads of Microsatellite Instability and Immune Response to Colon Cancer

Understanding molecular features of colon cancer has shed light on its pathogenesis and progression. Over time, some of these features acquired clinical dignity and were incorporated in decision making. Namely, microsatellite instability (MSI) due to mismatch repair of defects, which primarily was adopted for the diagnosis of Lynch syndrome, became recognized as the biomarker of a different disease type, showing a less aggressive behavior. MSI tumors harbor high amounts of tumor infiltrating lymphocytes (TILs) due to their peculiar load in neoantigens. However, microsatellite stable colon cancer may also show high amounts of TILs, and this feature is as well associated with better outcomes. High TIL loads are in general associated with a favorable prognosis, especially in stage II colon cancer, and therein identifies a patient subset with the lowest probability of relapse. With respect to post-surgical adjuvant treatment, particularly in stage III, TILs predictive ability seems to weaken along with the progression of the disease, being less evident in high risk patients. Moving from cohort studies to the analysis of a series from clinical trials contributed to increase the robustness of TILs as a biomarker. The employment of high TIL densities as an indicator of good prognosis in early-stage colon cancers is strongly advisable, while in late-stage colon cancers the employment as an indicator of good responsiveness to post-surgical therapy requires refinement. It remains to be clarified whether TILs could help in identifying those patients with node-positive cancers to whom adjuvant treatment could be spared, at least in low-risk groups as defined by the TNM staging system.

Association of Consensus Molecular Subtypes and Molecular Markers With Clinical Outcomes in Patients With Metastatic Colorectal Cancer: Biomarker Analyses From LUME-Colon 1

INTRODUCTION

LUME-Colon 1 (NCT02149108) was a global, placebo-controlled phase III study of nintedanib in advanced colorectal cancer (CRC). Pre-specified biomarker analyses investigated the association of CRC consensus molecular subtypes (CMS) and tumor genomic and circulating biomarkers with clinical outcomes.

MATERIALS AND METHODS

Archival tumor tissue, cell-free DNA (cfDNA), and plasma samples were collected for genomic, transcriptomic, and proteomic analyses to investigate potential associations between CRC CMS and other biomarkers with nintedanib response and clinical outcomes.

RESULTS

Of the 765 treated patients, 735, 245, and 192 patient samples were analyzed in the circulating protein, tumor tissue, and cfDNA datasets, respectively. Patients were classified as CMS1 (1.7%), CMS2 (27.7%), CMS3 (0.9%), CMS4 (51.5%), or unclassified (18.2%). Unclassified/mixed CMS was associated with longer overall survival (OS) with nintedanib vs. CMS2 or CMS4 (interaction P-value = .0086); no association was observed for CMS4. Gene expression-based pathway analysis revealed an association between vascular endothelial growth factor-related signaling and OS for nintedanib (P = .0498). The most frequently detected somatic mutations were APC (72.0% [tumor tissue] vs. 56.8% [cfDNA]), TP53 (47.1% vs. 34.9%), KRAS (40.8% vs. 28.6%), and PIK3CA (16.6% vs. 11.5%); concordance rates were > 80%. Median OS differences were observed for APC and TP53 mutations vs. wild-type in cfDNA, indicating a potential prognostic value. Circulating ANG-2, CA-9, CEACAM1, collagen-IV, IGFBP-1, ICAM-1, IL-8, and uPAR were potentially prognostic for both OS and progression-free survival.

CONCLUSION

We demonstrated the feasibility of large-scale biomarker analyses and CMS classification within a global clinical trial, and identified signals suggesting a potential for greater nintedanib treatment response in the unclassified/mixed CMS subgroup, despite these tumors showing heterogeneous patterns of CMS mixtures. Our results revealed a high degree of concordance in somatic mutations between tumor tissue and cfDNA. Associations with prognosis for cfDNA somatic mutations, as well as several protein-based biomarkers, may warrant further investigation in future trials.

TGFβ-induced SMAD4-dependent Apoptosis Proceeded by EMT in CRC

Colorectal cancer is one of the leading causes of cancer-related deaths worldwide. In Saudi Arabia, colorectal cancer is more aggressive and presents at younger age, warranting new treatment strategies. Role of TGFβ/Smad4 signaling pathway in initiation and progression of colorectal cancer is well documented. This study examined the role of TGFβ/Smad4 signaling pathway in a large cohort of Saudi patients with colorectal cancer, followed by in vitro analysis to dissect the dual role of TGFβ on inducing epithelial-to-mesenchymal transition (EMT) and apoptosis. Our study demonstrated high frequency of Smad4 alterations with low expression of Smad4 protein identifying a subgroup of aggressive colorectal cancer to be an independent marker for poor prognosis. Functional studies using colorectal cancer cells show that TGFβ induces Smad4-dependent EMT followed by apoptosis. Induction of mesenchymal transcriptional factors, Snail1 and Zeb1, was essential for TGFβ-induced apoptosis. Our results indicate that KLF5 acts as an oncogene in colorectal cancer cells regardless of Smad4 expression and inhibition of KLF5 is requisite for TGFβ-induced apoptosis. Furthermore, TGFβ/Smad4 signal inhibits the transcription of KLF5 that in turn switches Sox4 from tumor promoter to suppressor. A high incidence of Smad4 alterations were found in the Saudi patients with colorectal cancer. Functional study results indicate that TGFβ induces Smad4-dependent EMT followed by apoptosis in colorectal cancer cells.

Systematic Review of the Prognostic Role of the Immune System After Surgery of Colorectal Liver Metastases

Background: The current prognostication of patient survival after surgery for colorectal liver metastases is based on clinical characteristics, but low accuracy makes it difficult to guide treatment for the individual patient. Rapidly evolving technologies have led to the expectation that biomarkers will be able to outperform the current clinical scoring systems and provide more effective personalised treatment. Two main topics prevail in cancer treatment, namely the role of the immune system and the prediction and prognostication by application of high-throughput methodology. The aim of this review is to examine the evidence for prognostic immunological and molecular markers studied in tumour tissue obtained at surgical resection for colorectal liver metastases.

Methods: First we analysed immunophenotypical protein markers, that are mainly studied by immunohistochemistry. Second, we review molecular markers by analysing high-throughput studies on tumour mRNA and microRNA expression.

Results: CD3, CD4, and CD8 are the most frequently studied protein markers. High intra-tumoural CD3+ T cell infiltration and low CXCR4 expression have the best association with favourable patient survival. Studies that analysed microRNA or mRNA expression data showed very little overlap in prognostic genes.

Conclusions: Patient prognostication after surgery for colorectal liver metastases by analysing the immune system remains difficult. Current data are based on diverse and heterogeneous patient populations which prohibits drawing firm conclusions.

Survival marker genes of colorectal cancer derived from consistent transcriptomic profiling

Background

Identification of biomarkers associated with the prognosis of different cancer subtypes is critical to achieve better therapeutic assistance. In colorectal cancer (CRC) the discovery of stable and consistent survival markers remains a challenge due to the high heterogeneity of this class of tumors. In this work, we identified a new set of gene markers for CRC associated to prognosis and risk using a large unified cohort of patients with transcriptomic profiles and survival information.

Results

We built an integrated dataset with 1273 human colorectal samples, which provides a homogeneous robust framework to analyse genome-wide expression and survival data. Using this dataset we identified two sets of genes that are candidate prognostic markers for CRC in stages III and IV, showing either up-regulation correlated with poor prognosis or up-regulation correlated with good prognosis. The top 10 up-regulated genes found as survival markers of poor prognosis (i.e. low survival) were: DCBLD2, PTPN14, LAMP5, TM4SF1, NPR3, LEMD1, LCA5, CSGALNACT2, SLC2A3 and GADD45B. The stability and robustness of the gene survival markers was assessed by cross-validation, and the best-ranked genes were also validated with two external independent cohorts: one of microarrays with 482 samples; another of RNA-seq with 269 samples. Up-regulation of the top genes was also proved in a comparison with normal colorectal tissue samples. Finally, the set of top 100 genes that showed overexpression correlated with low survival was used to build a CRC risk predictor applying a multivariate Cox proportional hazards regression analysis. This risk predictor yielded an optimal separation of the individual patients of the cohort according to their survival, with a p-value of 8.25e-14 and Hazard Ratio 2.14 (95% CI: 1.75–2.61).

Conclusions

The results presented in this work provide a solid rationale for the prognostic utility of a new set of genes in CRC, demonstrating their potential to predict colorectal tumor progression and evolution towards poor survival stages. Our study does not provide a fixed gene signature for prognosis and risk prediction, but instead proposes a robust set of genes ranked according to their predictive power that can be selected for additional tests with other CRC clinical cohorts.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5193-9) contains supplementary material, which is available to authorized users.

Primary tumor sidedness is an independent prognostic marker for survival in metastatic colorectal cancer: Results from a large retrospective cohort with mutational analysis

Recent reports demonstrate inferior outcomes associated with primary right‐sided vs left‐sided colorectal tumors in patients with metastatic colorectal cancer (mCRC). We sought to describe our experience with mCRC patients on whom we have molecular data to determine whether primary tumor sidedness was an independent prognostic marker for overall survival (OS). mCRC patients with documented primary tumor sidedness who received mutational profiling between 2009 and 2014 were identified (n = 367, median follow‐up 30.4 months). Mutational profiling for >150 mutations across commonly mutated cancer genes including RAS, PIK3CA, BRAF, and PTEN as well as treatment data, including receipt of a biologic agent, were collected. Univariable/multivariable models were used to analyze relationships between collected data and OS. Among 367 patients, sidedness breakdown was as follows: 234 left (64%), 133 right (36%). 56% were male, with a median age at diagnosis of 57 (range 24‐89). A total of 143 patients had RAS mutations. Five‐year OS was 41%, median OS was 54 months (range 1‐149). Five‐year OS for left‐ vs right‐sided tumors was 46% vs 24% (P < .0001). On univariable analysis, among both RAS wildtype and mutant tumors, left‐sided tumors continued to have improved OS vs right‐sided tumors (HR: 0.49, 95% CI: 0.34‐0.69 RAS wildtype; HR: 0.61, 95% CI: 0.40‐0.95 RAS mutant). Left‐sidedness was an important prognostic factor for OS among RAS wildtype patients despite treatment with or without a biologic agent (P < .05). Left‐sidedness remained significant for improved OS on multivariable analysis (P < .0001). Left‐sided primary tumor remained most important prognostic factor for OS, even when adjusting for mutational status and receipt of biologic agent.

SHP-2 phosphatase contributes to KRAS-driven intestinal oncogenesis but prevents colitis-associated cancer development

A major risk factor of developing colorectal cancer (CRC) is the presence of chronic inflammation in the colon. In order to understand how inflammation contributes to CRC development, the present study focused on SHP-2, a tyrosine phosphatase encoded by PTPN11 gene in which polymorphisms have been shown to be markers of colitis susceptibility. Conversely, gain-of-function mutations in PTPN11 gene (E76 residue) have been found in certain sporadic CRC. Results shown herein demonstrate that SHP-2 expression was markedly increased in sporadic human adenomas but not in advanced colorectal tumors. SHP-2 silencing inhibited proliferative, invasive and tumoral properties of both intestinal epithelial cells (IECs) transformed by oncogenic KRAS and of human CRC cells. IEC-specific expression of a SHP-2^E76K activated mutant in mice was not sufficient to induce tumorigenesis but markedly promoted tumor growth under the Apc^Min/+ background. Conversely, mice with a conditional deletion of SHP-2 in IECs developed colitis-associated adenocarcinomas with age, associated with sustained activation of Wnt/β-catenin, NFκB and STAT3 signalings in the colonic mucosae. Moreover, SHP-2 epithelial deficiency considerably increased tumor load in Apc^Min/+ mice, shifting tumor incidence toward the colon. Overall, these results reveal that SHP-2 can exert opposing functions in the large intestine: it can promote or inhibit tumorigenesis depending of the inflammatory context.

Evolving notions on immune response in colorectal cancer and their implications for biomarker development

INTRODUCTION

Colorectal cancer (CRC) still represents the third most commonly diagnosed type of cancer in men and women worldwide. CRC is acknowledged as a heterogeneous disease that develops through a multi-step sequence of events driven by clonal selections; this observation is sustained by the fact that histologically similar tumors may have completely different outcomes, including a varied response to therapy.

METHODS

In "early" and "intermediate" stage of CRC (stages II and III, respectively) there is a compelling need for new biomarkers fit to assess the metastatic potential of their disease, selecting patients with aggressive disease that might benefit from adjuvant and targeted therapies. Therefore, we review the actual notions on immune response in colorectal cancer and their implications for biomarker development.

RESULTS

The recognition of the key role of immune cells in human cancer progression has recently drawn attention on the tumor immune microenvironment, as a source of new indicators of tumor outcome and response to therapy. Thus, beside consolidated histopathological biomarkers, immune endpoints are now emerging as potential biomarkers.

CONCLUSIONS

The introduction of immune signatures and cellular and molecular components of the immune system as biomarkers is particularly important considering the increasing use of immune-based cancer therapies as therapeutic strategies for cancer patients.

Tumor-infiltrating lymphocyte as a prognostic biomarker in stage IV colorectal cancer should take into account the metastatic status and operation modality

BACKGROUND

Although tumor-infiltrating lymphocytes (TILs) have been understood for years as a favorable prognostic factor for colorectal cancers (CRCs) after complete surgical resection, its prognostic role in metastatic CRC (mCRC) remains poorly defined, and it is largely unknown how this prognostic benefit relates to the metastatic status and operation modality.

MATERIALS AND METHODS

After reviewing 2215 consecutive cases of surgically resected CRC, 332 patients newly diagnosed with stage IV CRC and treated at the Sun Yat-Sen University Cancer Center between 2009 and 2014 were included. H&E-stained (HES) slides from surgical specimens were evaluated for the extent of TILs. The primary end point was overall survival (OS). Cox proportional hazards regression was conducted to determine the prognostic significance of TILs. All statistical tests were 2-sided.

RESULTS

HES slides from primary tumor samples were evaluable for 302 of the 332 included cases. Among the 302 patients, 105 patients (34.8%) were classified as high TIL, the remaining 197 (65.2%) were defined as low TIL. In the univariate analysis, TILs were significantly associated with better OS (P=0.015). Multivariable analysis confirmed that high TIL strongly predicted better survival (hazard ratio =0.62, 95% CI: 0.44-0.89, P=0.008), independent of other patients' clinicopathological characteristics. Stratified analysis revealed a prognostic benefit of high TIL for patients in the subgroup with non-oligometastatic disease (P=0.002), ≥2 metastatic organs (P=0.006), and non-metastasectomy (P=0.005). By contrast, oligometastatic disease, 1 metastatic organ, or metastasectomy fully abrogated the prognostic effect of TIL.

CONCLUSION

Our findings indicate that the level of TILs can be used to predict the outcome for patients with mCRC; however, the operation modality and the metastatic status of patients should also be taken into account.

Luminally expressed gastrointestinal biomarkers

A biomarker is a measurable indicator of normal biologic processes, pathogenic processes or pharmacological responses. The identification of a useful biomarker is challenging, with several hurdles to overcome before clinical adoption. This review gives a general overview of a range of biomarkers associated with inflammatory bowel disease or colorectal cancer along the gastrointestinal tract. Areas covered: These markers include those that are already clinically accepted, such as inflammatory markers such as faecal calprotectin, S100A12 (Calgranulin C), Fatty Acid Binding Proteins (FABP), malignancy markers such as Faecal Occult Blood, Mucins, Stool DNA, Faecal microRNA (miRNA), other markers such as Faecal Elastase, Faecal alpha-1-antitrypsin, Alpha2-macroglobulin and possible future markers such as microbiota, volatile organic compounds and pH. Expert commentary: There are currently a few biomarkers that have been sufficiently validated for routine clinical use at present such as FC. However, many of these biomarkers continue to be limited in sensitivity and specificity for various GI diseases. Emerging biomarkers have the potential to improve diagnosis and monitoring but further study is required to determine efficacy and validate clinical utility.

The Prognostic Value of Tyrosine Kinase SRC Expression in Locally Advanced Rectal Cancer

The cellular sarcoma gene (SRC) is a proto-oncogene encoding for a tyrosine kinase. SRC expression was determined in locally advanced rectal adenocarcinoma tissue from pretreatment biopsies and resection specimens. The expression level was correlated with clinicopathological parameters to evaluate the predictive and prognostic capacity.

For this monocentric analysis 186 patients with locally advanced rectal cancer (median: 63.7 years; 130 men (69.9%), 56 women (30.1%)) were included. Patients with a carcinoma of the upper third of the rectum were treated with primary tumor resection (n=27; 14.5%). All other patients received a preoperative chemoradiotherapy (CRT) with 50.4 Gy and concomitant 5-fluorouracil (5-FU) or 5-FU+oxaliplatin followed by postoperative chemotherapy with 5-FU or 5-FU+oxaliplatin. SRC expression was determined with immunohistochemical staining from pretreatment biopsies (n=152) and residual tumor tissue from the resection specimens (n=163). The results were correlated with clinicopathological parameters and long-term follow-up.

The expression of SRC was determined in pretherapeutic biopsies (mean H-Score: 229) and resection specimens (mean H-Score: 254). High SRC expression in pretherapeutic tumor samples significantly correlated with a negative postoperative nodal status (p=0.005). Furthermore an increased protein expression in residual tumor tissue was associated with fewer distant metastases (p=0.04). The overexpression of SRC in pretreatment tumor biopsies showed also a trend for a longer cancer-specific survival (CSS; p=0.05) and fewer local relapses (p=0.06) during long-term follow-up.

High SRC expression in rectal cancer seems to be associated with a better long-term outcome. This finding could help in the future to stratify patients for a recurrence risk adapted postoperative treatment.

Ku70, Ku80, and sClusterin: A Cluster of Predicting Factors for Response to Neoadjuvant Chemoradiation Therapy in Patients With Locally Advanced Rectal Cancer

PURPOSE

The identification of predictive biomarkers for neoadjuvant chemoradiation therapy (CRT) is a current clinical need. The heterodimer Ku70/80 plays a critical role in DNA repair and cell death induction after damage. The aberrant expression and localization of these proteins fail to control DNA repair and apoptosis. sClusterin is the Ku70 partner that sterically inhibits Bax-dependent cell death after damage in some pathologic conditions. This study sought to evaluate the molecular relevance of Ku70-Ku80-Clu as a molecular cluster predicting the response to neoadjuvant CRT in patients with locally advanced rectal cancer (LARC).

METHODS AND MATERIALS

Patients enrolled in this study underwent preoperative CRT followed by surgical excision. A retrospective study based on individual response, evaluated by computed tomography and diffusion-weighted magnetic resonance imaging, identified responder (56%) and no-responder patients (44%). Ku70/80 and Clu expression were observed in biopsy specimens obtained before and after treatment with neoadjuvant CRT from the same LARC patients. In vitro studies before and after irradiation were also performed on radioresistant (SW480) and radiosensitive (SW620) colorectal cancer cell lines, mimicking sensitive or resistant tumor behavior.

RESULTS

We found a conventional nuclear localization of Ku70/80 in pretherapeutic tumor biopsies of responder patients, in agreement with their role in DNA repair and regulating apoptosis. By contrast, in the no-responder population we observed an unconventional overexpression of Ku70 in the cytoplasm (P<.001). In this context we also overexpression of sClu in the cytoplasm, which accorded with its role in stabilizing of Bax-Ku70 complex, inhibiting Bax-dependent apoptosis. Strikingly, Ku80 in these tumor tissues was lost (P<.005). In vitro testing of colon cancer cells finally confirmed the results observed in tumor biopsy specimens, proving that Ku70/80-Clu deregulation is extensively involved in the resistance mechanism.

CONCLUSION

These results strongly suggest a potential role of these proteins as a new prognostic tool to predict the response to chemoradiation in LARC.

KRAS Mutation Status Predicts Site-Specific Recurrence and Survival After Resection of Colorectal Liver Metastases Irrespective of Location of the Primary Lesion

BACKGROUND

The KRAS mutation status is reportedly correlated with poor survival outcome in patients with colorectal liver metastases (CLM); however, its true prognostic impact and the reason for the poor prognosis remain unclear.

METHODS

Data on 163 patients with a known KRAS mutation status who underwent curative resection for CLM were retrospectively reviewed. The long-term survival and site-specific incidence of recurrence were then compared between patients with a KRAS mutation (mtKRAS) and those without a mutation (wtKRAS).

RESULTS

The mtKRAS group had a poorer 3-year disease-specific survival (DSS) rate (59.8 vs. 83.6 %, p = 0.016), 3-year recurrence-free survival (RFS) rate (0 vs. 20.2 %, p = 0.069), and median time to surgical failure (TSF) [18.8 vs. 39.7 months, p = 0.001] than the wtKRAS group. The cumulative incidences of liver recurrence and lung recurrence at 3 years were also higher in the mtKRAS group (76.2 vs. 54.7 %, p = 0.060; and 71.9 vs. 37.3 %, p < 0.001, respectively). A multivariate analysis confirmed that an mtKRAS status had a significant effect on the DSS rate (hazard ratio [HR] 2.9, p = 0.006), RFS (HR 2.0, p = 0.004), TSF (HR 2.4, p < 0.001), liver recurrence (HR 1.7, p < 0.001), and lung recurrence (HR 2.6, p < 0.001). Lung-related unresectable recurrences were more frequent (41 vs. 18 %, p = 0.048) and were associated with an earlier TSF (9.6 vs. 14.0 months, p = 0.14) in the mtKRAS group, regardless of the location of the primary lesions.

CONCLUSIONS

mtKRAS is associated with poor survival outcome after CLM resection because of a relatively high incidence of lung recurrence and a relatively short TSF.

Association Between Specific Mutations in KRAS Codon 12 and Colorectal Liver Metastasis

IMPORTANCE

Currently, one of the most commonly available biomarkers in the treatment of patients with colorectal liver metastases (CRLM) is the Kirsten rat sarcoma viral oncogene homolog (KRAS); however, the prognostic implications of specific mutations of the KRAS gene are still not well defined.

OBJECTIVE

To investigate the prognostic impact of specific KRAS mutations on patients undergoing liver resection for CRLM.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective single-center study was conducted from January 1, 2003, to December 31, 2013. Data about specific KRAS mutations for 331 patients who underwent hepatic resection for CRLM at Johns Hopkins Hospital between 2003 and 2013 were analyzed. Clinicopathological characteristics, perioperative details, and outcomes were stratified by specific KRAS mutation at codons 12 and 13.

INTERVENTION

Resection of CRLM.

MAIN OUTCOMES AND MEASURES

Overall survival (OS) and recurrence-free survival.

RESULTS

A mutated KRAS (mtKRAS) was identified in 91 patients (27.5%). At a median follow-up of 27.4 months, recurrence was observed in 48 patients (52.7%) with mtKRAS and 130 patients (54.2%) with wild-type KRAS (wtKRAS) (P = .82). Median and 5-year survival among patients with mtKRAS was 32.4 months and 32.7%, respectively, vs 58.5 months and 46.9%, respectively, for patients with wtKRAS (P = .02). Patients with KRAS codon 12 mutations had worse OS (hazard ratio [HR], 1.54; 95% CI, 1.05-2.27; P = .03) vs those with wtKRAS, whereas a KRAS codon 13 mutation was not associated with prognosis (HR, 1.47; 95% CI, 0.83-2.62; P = .19). Among the 6 most common mutations in codons 12 and 13, only G12V (HR, 1.78; 95% CI, 1.00-3.17; P = .05) and G12S (HR, 3.33; 95% CI, 1.22-9.10; P = .02) were associated with worse OS compared with patients with wtKRAS (both P < .05). Among patients who recurred, G12V (HR, 2.96; 95% CI, 1.32-6.61; P = .01), G12C (HR, 6.74; 95% CI, 2.05-22.2; P = .002), and G12S mutations (HR, 4.91; 95% CI, 1.52-15.8; P = .01) were associated with worse OS (both P < .05).

CONCLUSIONS AND RELEVANCE

G12V and G12S mutations of codon 12 were independent prognostic factors of worse OS. Among patients who recurred after resection of CRLM, G12V, G12C, and G12S mutations were associated with worse OS. Information on specific KRAS mutations may help individualize therapeutic and surveillance strategies for patients with resected CRLM.

Primary tumor location as a prognostic factor in metastatic colorectal cancer

BACKGROUND

We sought to clarify the prognostic impact of primary tumor location in metastatic colorectal cancer (mCRC).

METHODS

We evaluated the association between tumor location and survival parameters in patients with previously untreated mCRC receiving first-line chemotherapy ± bevacizumab in three independent cohorts: a prospective pharmacogenetic study (PROVETTA) and two randomized phase III trials, AVF2107g and NO16966. Cancers proximal or distal of the splenic flexure were classified as right-sided or left-sided, respectively. The primary end point was overall survival (OS). Data were analyzed with Cox proportional hazards and logistic regression models. All statistical tests were two-sided.

RESULTS

Among evaluable patients in the PROVETTA (n = 200), AVF2107g (n = 559), and NO16966 (n = 1268) studies, 72.0%, 63.1%, and 73.7% had left-sided tumors, respectively. In PROVETTA, patients with left-sided tumors had superior OS (left-sided vs right-sided: hazard ratio [HR] = .44, 95% confidence interval [CI] = .28 to .70, P < .001) and progression-free survival (HR = .52, 95% CI = .36 to .75, P < .001) outcomes. Multivariable analyses confirmed right-sided location as a negative prognostic variable, independent of mucinous histology and BRAF mutational status. Data from the AVF2107g (HR for OS = .55, 95% CI = .43 to .70) and NO16966 trials (HR for OS = .71, 95% CI = .62 to .82 both P < .001) also showed favorable outcomes in patients with left-sided tumors. In both randomized studies, the efficacy of bevacizumab was independent of tumor location.

CONCLUSIONS

These data demonstrate that primary tumor location is an important prognostic factor in previously untreated mCRC. Given the consistency across an exploratory set and two confirmatory phase III studies, side of tumor origin should be considered for stratification in randomized trials.

Biomarker signatures correlate with clinical outcome in refractory metastatic colorectal cancer patients receiving bevacizumab and everolimus

A novel combination of bevacizumab and everolimus was evaluated in refractory colorectal cancer patients in a phase II trial. In this retrospective analysis, plasma samples from 49 patients were tested for over 40 biomarkers at baseline and after one or two cycles of drug administration. Analyte levels at baseline and change on-treatment were correlated with progression-free survival (PFS) and overall survival (OS) using univariate Cox proportional hazard modeling. Multivariable analyses were conducted using Cox modeling. Significant changes in multiple markers were observed following bevacizumab and everolimus treatment. Baseline levels of six markers significantly correlated with PFS and OS, including CRP, Gro-α, IGFBP-1, TF, ICAM-1, and TSP-2 (P < 0.05). At C2D1, changes of IGFBP-3, TGFβ-R3, and IGFBP-2 correlated with PFS and OS. Prognostic models were developed for OS and PFS (P = 0.0002 and 0.004, respectively). The baseline model for OS consisted of CRP, Gro-α, and TF, while the on-treatment model at C2D1 included IGFBP-2, IGFBP-3, and TGFβ-R3. These data demonstrated that multiple biomarkers were significantly modulated in response to bevacizumab and everolimus. Several markers correlated with both PFS and OS. Interestingly, these markers are known to be associated with inflammation and IGF signaling, key modulators of mTOR biology.

Stromal expression of miR-21 in T3-4a colorectal cancer is an independent predictor of early tumor relapse

BACKGROUND

MicroRNA-21 (miR-21) is an oncogenic microRNA that regulates the expression of multiple cancer-related target genes. miR-21 has been associated with progression of some types of cancer. Metastasis-associated protein1 expression and loss of E-cadherin expression are correlated with cancer progression and metastasis in many cancer types. In advanced colorectal cancer, the clinical significance of miR-21 expression remains unclear. We aimed to investigate the impact of miR-21 expression in advanced colorectal cancer and its correlation with target proteins associated with colorectal cancer progression.

METHODS

From 2004 to 2007, 277 consecutive patients with T3-4a colorectal cancer treated with R0 surgical resection were included. Patients with neoadjuvant therapy and distant metastasis at presentation were excluded. The expression of miR-21 was investigated by in situ hybridization. Immunohistochemistry was used to detect E-cadherin and metastasis-associated protein1 expression.

RESULTS

High stromal expression of miR-21 was found in 76 of 277 (27.4%) colorectal cancer samples and was correlated with low E-cadherin expression (P = 0.019) and high metastasis-associated protein1 expression (P = 0.004). T3-4a colorectal cancer patients with high miR-21 expression had significantly shorter recurrence-free survival than those with low miR-21 expression. When analyzing colon and rectal cancer separately, high expression of miR-21 was an independent prognostic factor of unfavorable recurrence-free survival in T3-4a colon cancer patients (P = 0.038, HR = 2.45; 95% CI = 1.05-5.72) but not in T3-4a rectal cancer patients. In a sub-classification analysis, high miR-21 expression was associated with shorter recurrence-free survival in the stage II cancer (P = 0.001) but not in the stage III subgroup (P = 0.267).

CONCLUSIONS

Stromal miR-21 expression is related to the expression of E-cadherin and metastasis-associated protein1 in colorectal cancer. Stage II colorectal cancer patients with high levels of miR-21 are at higher risk for tumor recurrence and should be considered for more intensive treatment.

Predictive impact of genetic polymorphisms in DNA repair genes on susceptibility and therapeutic outcomes to colorectal cancer patients

Several hereditary syndromes characterized by defective DNA repair are associated with high risk of colorectal cancer (CRC). To explore whether common polymorphisms in DNA repair genes affect risk and prognosis of CRC, we evaluated the association between single nucleotide polymorphisms (SNPs) in XPG, XPC, and WRN gene and susceptibility of CRC, and clinical outcomes in a population-based case-control study. A total of 890 CRC cases and 910 controls recruited into the study provided a biologic sample. Individuals with variant genotypes of XPC Ala499Val appeared to be associated with the increased risk of CRC. WRN Cys1367Arg variants carriers showed an increased susceptibility for CRC. More importantly, the risk of CRC increased further in a combined analysis of multiple polymorphisms. Furthermore, stratified analyses revealed that XPG Arg1104His polymorphism was associated with tumor differentiation of CRC patients (P = 0.043). Log-rank test and adjusted multivariate Cox regression analysis verified that XPG Arg1104His variants were associated with a longer disease-free survival (DFS) [CG genotype: adjusted HR (95% confidence interval (CI)) = 0.163 (0.107-0.248), P < 0.001; CC genotype: adjusted HR (95% CI) = 0.333 (0.235-0.470), P < 0.001; CG/CC genotype: adjusted HR (95% CI) = 0.333 (0.235-0.470)] in patients with oxaliplatin-based chemotherapy (N = 718). Moreover, XPC Ala499Val CT genotype showed a significant impact on DFS [CC genotype: adjusted HR (95% CI) = 0.691 (0.528-0.904), P = 0.007; CT/CC genotype: adjusted HR (95% CI) = 0.602 (0.389-0.934), P = 0.024]. However, no correlation was found between WRN Cys1367Arg polymorphism and prognosis in CRC patients. Our findings will add to the literature on the impact of genetic variation in DNA repair genes involved in susceptibility for CRC and therapeutic outcomes in response to oxaliplatin-based chemotherapy.

FBXL20 acts as an invasion inducer and mediates E-cadherin in colorectal adenocarcinoma

The mechanisms eliciting colorectal adenocarcinoma are not well understood and the FBXL20 gene is problematic as it exhibits an abnormal expression in colorectal cancer cells. In the present study a recombinant plasmid, pReceiver-M03-FBL20 expression plasmid was constructed, which overexpressed FBXL20; this was transfected into Lovo cells to form Lovo-FBL20 cells. The FBXL20 expression level was examined by quantitative polymerase chain reaction (qPCR) and western blot analysis. The cell viability and invasion capacity were measured using cell counting kit 8, Transwell chamber and wound healing assays, respectively. The associated genes, including E-cadherin, β-catenin, c-Myc, SET nuclear oncogene, protein phosphatase-2A, Axin, p53 and caspase 3, were detected by qPCR and western blotting. It was demonstrated that the FBXL20 expression level was markedly upregulated in the Lovo-FBL20 cells transfected with pReceiver-M03-FBL20 expression plasmid, compared with that of the Lovo cells. In addition, the cell viability and invasion capacity of the Lovo-FBL20 cells were significantly increased. These increases correlated with a significant upregulation in the expression level of β-catenin and c-Myc, and a downregulated expression level of E-cadherin. The results of the present study indicate that FBXL20 may mediate the ubiquitin degradation of E-cadherin resulting in an increased invasive ability of malignant cells.

The expression and prognostic significance of retinoic acid metabolising enzymes in colorectal cancer

Colorectal cancer is one of the most common types of cancer with over fifty percent of patients presenting at an advanced stage. Retinoic acid is a metabolite of vitamin A and is essential for normal cell growth and aberrant retinoic acid metabolism is implicated in tumourigenesis. This study has profiled the expression of retinoic acid metabolising enzymes using a well characterised colorectal cancer tissue microarray containing 650 primary colorectal cancers, 285 lymph node metastasis and 50 normal colonic mucosal samples. Immunohistochemistry was performed on the tissue microarray using monoclonal antibodies which we have developed to the retinoic acid metabolising enzymes CYP26A1, CYP26B1, CYP26C1 and lecithin retinol acyl transferase (LRAT) using a semi-quantitative scoring scheme to assess expression. Moderate or strong expression of CYP26A1was observed in 32.5% of cancers compared to 10% of normal colonic epithelium samples (p<0.001). CYP26B1 was moderately or strongly expressed in 25.2% of tumours and was significantly less expressed in normal colonic epithelium (p<0.001). CYP26C1 was not expressed in any sample. LRAT also showed significantly increased expression in primary colorectal cancers compared with normal colonic epithelium (p<0.001). Strong CYP26B1 expression was significantly associated with poor prognosis (HR = 1.239, 95%CI = 1.104-1.390, χ(2) = 15.063, p = 0.002). Strong LRAT was also associated with poorer outcome (HR = 1.321, 95%CI = 1.034-1.688, χ(2) = 5.039, p = 0.025). In mismatch repair proficient tumours strong CYP26B1 (HR = 1.330, 95%CI = 1.173-1.509, χ(2)= 21.493, p<0.001) and strong LRAT (HR = 1.464, 95%CI = 1.110-1.930, χ(2) = 7.425, p = 0.006) were also associated with poorer prognosis. This study has shown that the retinoic acid metabolising enzymes CYP26A1, CYP26B1 and LRAT are significantly overexpressed in colorectal cancer and that CYP26B1 and LRAT are significantly associated with prognosis both in the total cohort and in those tumours which are mismatch repair proficient. CYP26B1 was independently prognostic in a multivariate model both in the whole patient cohort (HR = 1.177, 95%CI = 1.020-1.216, p = 0.026) and in mismatch repair proficient tumours (HR = 1.255, 95%CI = 1.073-1.467, p = 0.004).

RAS mutation status predicts survival and patterns of recurrence in patients undergoing hepatectomy for colorectal liver metastases

OBJECTIVE

To determine the impact of RAS mutation status on survival and patterns of recurrence in patients undergoing curative resection of colorectal liver metastases (CLM) after preoperative modern chemotherapy.

BACKGROUND

RAS mutation has been reported to be associated with aggressive tumor biology. However, the effect of RAS mutation on survival and patterns of recurrence after resection of CLM remains unclear.

METHODS

Somatic mutations were analyzed using mass spectroscopy in 193 patients who underwent single-regimen modern chemotherapy before resection of CLM. The relationship between RAS mutation status and survival outcomes was investigated.

RESULTS

Detected somatic mutations included RAS (KRAS/NRAS) in 34 (18%), PIK3CA in 13 (7%), and BRAF in 2 (1%) patients. At a median follow-up of 33 months, 3-year overall survival (OS) rates were 81% in patients with wild-type versus 52.2% in patients with mutant RAS (P = 0.002); 3-year recurrence-free survival (RFS) rates were 33.5% with wild-type versus 13.5% with mutant RAS (P = 0.001). Liver and lung recurrences were observed in 89 and 83 patients, respectively. Patients with RAS mutation had a lower 3-year lung RFS rate (34.6% vs 59.3%, P < 0.001) but not a lower 3-year liver RFS rate (43.8% vs 50.2%, P = 0.181). In multivariate analyses, RAS mutation predicted worse OS [hazard ratio (HR) = 2.3, P = 0.002), overall RFS (HR = 1.9, P = 0.005), and lung RFS (HR = 2.0, P = 0.01), but not liver RFS (P = 0.181).

CONCLUSIONS

RAS mutation predicts early lung recurrence and worse survival after curative resection of CLM. This information may be used to individualize systemic and local tumor-directed therapies and follow-up strategies.

Mast cells as a potential prognostic marker in prostate cancer

Despite years of intensive investigation that has been made in understanding prostate cancer, it remains one of the major men's health issues and the leading cause of death worldwide. It is now ascertained that prostate cancer emerges from multiple spontaneous and/or inherited alterations that induce changes in expression patterns of genes and proteins that function in complex networks controlling critical cellular events. It is now accepted that several innate and adaptive immune cells, including T- and B-lymphocytes, macrophages, natural killer cells, dendritic cells, neutrophils, eosinophils, and mast cells (MCs), infiltrate the prostate cancer. All of these cells are irregularly scattered within the tumor and loaded with an assorted array of cytokines, chemokines, and inflammatory and cytotoxic mediators. This complex framework reflects the diversity in tumor biology and tumor-host interactions. MCs are well-established effector cells in Immunoglobulin-E (Ig-E) associated immune responses and potent effector cells of the innate immune system; however, their clinical significance in prostate cancer is still debated. Here, these controversies are summarized, focusing on the implications of these findings in understanding the roles of MCs in primary prostate cancer.

Biomarkers in precision therapy in colorectal cancer

Colorectal cancer (CRC) is the most commonly diagnosed cancer in Europe. Because CRC is also a major cause of cancer-related deaths worldwide, a lot of research has been focused on the discovery and development of biomarkers to improve the diagnostic process and to predict treatment outcomes. Up till now only a few biomarkers are recommended by expert panels. Current TNM criteria, however, cause substantial under- and overtreatment of CRC patients. Consequently, there is a growing need for new and efficient biomarkers to ensure optimal treatment allocation. An ideal biomarker should be easily translated into clinical practice, to identify patients who can be spared from treatment or benefit from therapy, ultimately resulting in precision medicine in the future. In this review we aim to provide an overview of a number of frequently studied biomarkers in CRC and, at the same time, we will emphasize the challenges and controversies that withhold the clinical introduction of these biomarkers. We will discuss both prognostic and predictive markers of chemotherapy, aspirin therapy as well as overall therapy toxicity. Currently, only mutant KRAS, mutant BRAF, MSI and the Oncotype DX® Colon Cancer Assay are used in clinical practice. Other biomarker studies showed insufficient evidence to be introduced into clinical practice. Divergent patient selection criteria, absence of validation studies and a large number of single biomarker studies are possibly responsible. We therefore recommend that future studies focus on combining key markers, rather than analysing single markers, standardizing study protocols, and validate the results in independent study cohorts, followed by prospective clinical trials.

Prognostic relevance of KRAS and BRAF mutations in Japanese patients with colorectal cancer

BACKGROUND

Mutations of the KRAS or BRAF genes are now recognized as prognostic markers for colorectal cancer (CRC). They are also important predictive markers for resistance to the monoclonal antibodies that target the epidermal growth factor receptor.

METHODS

In this retrospective study, KRAS and BRAF mutations were analyzed using a direct sequence method in 254 Japanese CRC patients, and the associations between KRAS or BRAF mutations and clinicopathological characteristics or outcome were evaluated.

RESULTS

KRAS and BRAF mutations were detected in 33.5 and 6.7 % of all patients, respectively. Consistent with previous reports, BRAF mutations were significantly correlated with the anatomical site of the tumor (P < 0.001), tumor grade (P = 0.001) and high frequency of microsatellite instability (P < 0.001). BRAF mutations were correlated with poor overall survival in the full patient cohort (P = 0.009). KRAS mutations were significantly correlated with poor recurrence-free survival (P = 0.03), particularly in patients with stage II CRC (P = 0.007). Cox regression analysis showed that KRAS mutations were a negative predictor of recurrence-free survival in patients with stage II CRC.

CONCLUSION

KRAS mutation status could be a novel biomarker for predicting disease recurrence in Japanese patients with stage II CRC.

Clinical value of prognosis gene expression signatures in colorectal cancer: a systematic review

Introduction

The traditional staging system is inadequate to identify those patients with stage II colorectal cancer (CRC) at high risk of recurrence or with stage III CRC at low risk. A number of gene expression signatures to predict CRC prognosis have been proposed, but none is routinely used in the clinic. The aim of this work was to assess the prediction ability and potential clinical usefulness of these signatures in a series of independent datasets.

Methods

A literature review identified 31 gene expression signatures that used gene expression data to predict prognosis in CRC tissue. The search was based on the PubMed database and was restricted to papers published from January 2004 to December 2011. Eleven CRC gene expression datasets with outcome information were identified and downloaded from public repositories. Random Forest classifier was used to build predictors from the gene lists. Matthews correlation coefficient was chosen as a measure of classification accuracy and its associated p-value was used to assess association with prognosis. For clinical usefulness evaluation, positive and negative post-tests probabilities were computed in stage II and III samples.

Results

Five gene signatures showed significant association with prognosis and provided reasonable prediction accuracy in their own training datasets. Nevertheless, all signatures showed low reproducibility in independent data. Stratified analyses by stage or microsatellite instability status showed significant association but limited discrimination ability, especially in stage II tumors. From a clinical perspective, the most predictive signatures showed a minor but significant improvement over the classical staging system.

Conclusions

The published signatures show low prediction accuracy but moderate clinical usefulness. Although gene expression data may inform prognosis, better strategies for signature validation are needed to encourage their widespread use in the clinic.

Functional, genetic, and epigenetic aspects of base and nucleotide excision repair in colorectal carcinomas

PURPOSE

DNA repair capacity (DRC) is a determinant not only of cancer development but also of individual response to therapy. Previously, altered base and nucleotide excision repair (BER and NER) have been described in lymphocytes of patients with sporadic colorectal cancer. We, for the first time, evaluate both excision repair capacities in human colon biopsies to study their participation in colorectal tumorigenesis.

EXPERIMENTAL DESIGN

Seventy pairs of tumor and adjacent healthy tissues were analyzed for BER- and NER-specific DRC by a comet repair assay. Tissue pairs were further compared for expression levels of a panel of 25 BER and NER genes complemented by their promoter methylation status.

RESULTS

We observed a moderate increase of NER-DRC (P = 0.019), but not of BER-DRC in tumors. There was a strong correlation between both tissues for all investigated parameters (P < 0.001). However, 4 NER (CSB, CCNH, XPA, XPD) and 4 BER (NEIL1, APEX1, OGG1, PARP1) genes showed a 1.08- to 1.28-fold change difference in expression in tumors (P < 0.05). Individual gene expression levels did not correlate with overall DRC, and we did not detect any aberrant methylation of the investigated genes.

CONCLUSIONS

Our complex analysis showed that tumor cells are not deficient in BER and NER, but rather follow patterns characteristic for each individual and are comparable with adjacent tissue. Alteration of excision repair pathways is not a pronounced event in colorectal carcinogenesis. This study shows the feasibility of DRC evaluation in human solid tissues, representing a complex marker of multigene DNA repair processes.

Promoter CpG island methylation markers in colorectal cancer: the road ahead

Despite increasing knowledge on the biology, detection and treatment of colorectal cancer (CRC), the disease is still a major health problem. Hypermethylation of promoter regions of genes has been studied extensively as a contributor in CRC carcinogenesis. In addition, it is the topic of many studies focusing on biomarkers for the early detection, prediction of prognosis and treatment outcome. Methylation markers may be preferred over current screening and test methods as they are stable and easy to detect. However, almost no methylation marker is currently being used in clinical practice, often due to a lack of sensitivity, specificity, or validation of the results. This review summarizes the current knowledge of hypermethylation biomarkers for CRC detection, progression and treatment outcome.

Analysis of colorectal cancer morphology in relation to sex, age, location, and family history

BACKGROUND

Studies of colorectal cancer (CRC) have suggested different mechanisms of carcinogenesis in men and women, young and old patients, right- and left sided tumors, and sporadic and familial tumors. These differences might be reflected in morphology.

METHODS

CRCs from 1613 patients operated on in 2004-2006 in Sweden were histologically reviewed. Morphology was examined in relation to sex, age groups, location, and family history.

RESULTS

Tumors in the right colon were larger, of higher stage, more often poorly differentiated, more mucin-producing, more often had a peritumoral lymphocytic infiltrate and a high level of tumor-infiltrating lymphocytes (TILs), and more seldom had an infiltrating margin than tumors in the left colon and rectum (p < 0.0001 for most features). Young patients (<60 years) more seldom had multiple tumors but more often had perineural invasion, an infiltrative tumor margin, and high-stage tumors. Three features, TILs, medullary tumors, and invasive tumor margin, were related to sex. Only vascular invasion was related to familiality.

CONCLUSION

Location is the factor that has the most influence on tumor morphology. The results support the idea that different carcinogenic mechanisms may be involved in the right and left colon. Age is the most important determinant for the presence of multiple tumors and is a crucial factor for the aggressiveness of the disease.

Complex patterns of altered MicroRNA expression during the adenoma-adenocarcinoma sequence for microsatellite-stable colorectal cancer

PURPOSE

MicroRNAs are short noncoding RNAs that regulate gene expression and are over- or underexpressed in most tumors, including colorectal adenocarcinoma. MicroRNAs are potential biomarkers and therapeutic targets and agents, but limited information on microRNAome alterations during progression in the well-known adenoma-adenocarcinoma sequence is available to guide their usage.

EXPERIMENTAL DESIGN

We profiled 866 human microRNAs by microarray analysis in 69 matched specimens of microsatellite-stable adenocarcinomas, adjoining precursor adenomas including areas of high- and low-grade dysplasia, and nonneoplastic mucosa.

RESULTS

We found 230 microRNAs that were significantly differentially expressed during progression, including 19 not reported previously. Altered microRNAs clustered into two major patterns of early (type I) and late (type II) differential expression. The largest number (n = 108) was altered at the earliest step from mucosa to low-grade dysplasia (subtype IA) prior to major nuclear localization of β-catenin, including 36 microRNAs that had persistent differential expression throughout the entire sequence to adenocarcinoma. Twenty microRNAs were intermittently altered (subtype IB), and six were transiently altered (subtype IC). In contrast, 33 microRNAs were altered late in high-grade dysplasia and adenocarcinoma (subtype IIA), and 63 in adenocarcinoma only (subtype IIB). Predicted targets in 12 molecular pathways were identified for highly altered microRNAs, including the Wnt signaling pathway leading to low-grade dysplasia. β-catenin expression correlated with downregulated microRNAs.

CONCLUSIONS

Our findings suggest that numerous microRNAs play roles in the sequence of molecular events, especially early events, resulting in colorectal adenocarcinoma. The temporal patterns and complexity of microRNAome alterations during progression will influence the efficacy of microRNAs for clinical purposes.