The role of epithelial mesenchymal transition and resistance to neoadjuvant therapy in locally advanced rectal cancer

Pulmonary sarcomatoid carcinoma: A rare case report, diagnostic dilemma and review of literature

RATIONALE

Pulmonary sarcomatoid carcinoma (PSC), a rare tumor, comprises 0.1% to 0.4% of all malignant lung tumors. Given the rarity of PSC, its clinical course, therapeutic guidelines, and patient outcomes remain largely unknown. Therefore, it is imperative to alert clinicians to this extremely rare and instructive early-onset cancer.

PATIENT CONCERNS

This report describes a 28-year-old woman with PSC, who was initially misdiagnosed with Whipple's disease. A conclusive diagnosis of PSC was made following careful clinical examination, imaging, and histopathological evaluation of the patient's biopsy sample. Radiological imaging revealed multiple nodules and mass formations in the left upper lobe of the patient's lung, with the largest measuring of 5.4 × 3.2 cm.

DIAGNOSIS

Histopathological examination indicated the presence of a malignant neoplasm associated with necrosis suggestive of sarcoma, which was pathologically staged as cT4N1M1.

INTERVENTIONS AND OUTCOMES

A regimen of doxorubicin and ifosfamide was administered therapeutically, resulting in a stable disease state.

LESSONS

The rarity and tumor origin challenge the diagnosis, which emphasizes the imperative role of histological examination, immunohistochemistry, and flow cytometry in achieving an accurate diagnosis. This report summarizes the existing publications to provide a comprehensive overview of PSC, including its clinical manifestations, radiographic imaging, pathologic features, diagnostic challenges, treatment strategies, and prognosis, and aims to improve the understanding of PSC.

Update on Epithelial-Mesenchymal Plasticity in Cancer Progression

Epithelial-mesenchymal transition (EMT) is a cellular process by which epithelial cells lose their characteristics and acquire mesenchymal traits to promote cell movement. This program is aberrantly activated in human cancers and endows tumor cells with increased abilities in tumor initiation, cell migration, invasion, metastasis, and therapy resistance. The EMT program in tumors is rarely binary and often leads to a series of gradual or intermediate epithelial-mesenchymal states. Functionally, epithelial-mesenchymal plasticity (EMP) improves the fitness of cancer cells during tumor progression and in response to therapies. Here, we discuss the most recent advances in our understanding of the diverse roles of EMP in tumor initiation, progression, metastasis, and therapy resistance and address major clinical challenges due to EMP-driven phenotypic heterogeneity in cancer. Uncovering novel molecular markers and key regulators of EMP in cancer will aid the development of new therapeutic strategies to prevent cancer recurrence and overcome therapy resistance.

E-Cadherin Expression Varies Depending on the Location within the Primary Tumor and Is Higher in Colorectal Cancer with Lymphoid Follicles

Reliable indicators of cancer advancement have actively been sought recently. The detection of colorectal cancer progression markers is essential in improving diagnostic and therapeutic protocols. The aim of the study was to investigate the profile of E-cadherin expression in colorectal cancer tissue depending on the TNM staging and its correlation with several clinical and histopathological features. The study included 55 colorectal cancer patients admitted to the surgical ward for elective surgery. Tissue samples were obtained from resected specimens. Different distributions of E-cadherin expression within tumors were observed; the highest percentage of positive E-cadherin expression was found in the invasive front and in the tumor center. Additionally, the different cellular distribution of E-cadherin expression was noticed; weak membranous E-cadherin expression was the highest in the invasive front and in the budding sites, but a strong membranous pattern was most frequent in the tumor center. Various distributions of E-cadherin expression depending on cancer progression were also found; E-cadherin expression in node-positive patients was lower in the tumor center and in the tumor invasive front, whereas, in patients with distant metastases, the expression of E-Cadherin was lower in the budding sites. In patients with higher TNM stages, E-cadherin expression was lower within the tumor (in the budding sites, tumor center, and invasive front). In tumors with lymphoid follicles, E-cadherin expression was higher in all localizations within the primary tumor. E-cadherin expression in the tumor center was also lower in tumors with some higher tumor budding parameters (areas of poorly differentiated components and poorly differentiated clusters). E-cadherin expression was found to be lower at the tumor center in younger individuals, at the budding sites in men, and at the surrounding lymph nodes in rectal tumors. Low E-cadherin expression appears to be a reliable indicator of higher cancer staging and progression. When assessing the advancement of cancer, apart from the TNM classification, it is beneficial to also consider the expression of E-cadherin. High tumor budding, the poverty of lymphoid follicles, and low E-cadherin expression analyzed simultaneously may contribute to a reliable assessment of colorectal cancer staging. These three histopathological features complement each other, and their investigation, together with conventional tumor staging and grading, may be very helpful in predicting the prognosis of colorectal cancer patients and qualifying them for the best treatment. The role of E-cadherin in the diagnosis and treatment of colorectal cancer, as a part of a personalized medicine strategy, still requires comprehensive, prospective clinical evaluations to precisely target the optimal therapies for the right patients at the right time.

Significance of Wnt/β-Catenin Signal Activation for Resistance to Neoadjuvant Chemoradiotherapy in Rectal Cancer

Although a therapeutic response to neoadjuvant chemoradiotherapy (NACRT) is important to improve oncological outcomes after surgery in patients with locally advanced rectal cancer, there is no reliable predictor for this. The Wnt/β-catenin signal is known to be crucial for the tumorigenesis of colorectal cancer. This study aimed to investigate the association of Wnt/β-catenin signal activation with a pathological response to NACRT. The immunohistochemical expression of nuclear and membranous β-catenin was analyzed in biopsy samples obtained from 60 patients with locally advanced rectal cancer who received curative surgery following NACRT. The association of Wnt/β-catenin signal activation with their clinical outcomes was investigated. Notably, the body mass index of these patients was significantly higher in the low nuclear β-catenin expression group. Moreover, patients in the high nuclear β-catenin expression group tended to have more advanced disease and a higher rate of positive vascular invasion than those in the low expression group. Furthermore, the rate of good histological responses was significantly higher in the low nuclear β-catenin expression group (72% vs. 37.1%, p < 0.01). Overall, relapse-free survival tended to be better in patients with low nuclear/high membranous β-catenin expression (n = 9) than in other individuals (n = 51) (p = 0.093 and p = 0.214, respectively). Activation of the Wnt/β-catenin signal pathway represented by nuclear β-catenin accumulation was significantly associated with a poor response to NACRT in patients with rectal cancer. Analysis of nuclear β-catenin accumulation before starting treatment might help predict the therapeutic response to NACRT.

Predicting neoadjuvant chemoradiotherapy response with functional imaging and liquid biomarkers in locally advanced rectal cancer

INTRODUCTION

Non-invasive predictive quantitative biomarkers are required to guide treatment individualization in patients with locally advanced rectal cancer (LARC) in order to maximise therapeutic outcomes and minimise treatment toxicity. Magnetic resonance imaging (MRI), positron emission tomography (PET) and blood biomarkers have the potential to predict chemoradiotherapy (CRT) response in LARC.

AREAS COVERED

This review examines the value of functional imaging (MRI and PET) and liquid biomarkers (circulating tumor cells (CTCs) and circulating tumor nucleic acid (ctNA)) in the prediction of CRT response in LARC. Selected imaging and liquid biomarker studies are presented and the current status of the most promising imaging (apparent diffusion co-efficient (ADC), K^trans, SUV_max, metabolic tumor volume (MTV) and total lesion glycolysis (TLG) and liquid biomarkers (circulating tumor cells (CTCs), circulating tumor nucleic acid (ctNA)) is discussed. The potential applications of imaging and liquid biomarkers for treatment stratification and a pathway to clinical translation are presented.

EXPERT OPINION

Functional imaging and liquid biomarkers provide novel ways of predicting CRT response. The clinical and technical validation of the most promising imaging and liquid biopsy biomarkers in multi-centre studies with harmonised acquisition techniques is required. This will enable clinical trials to investigate treatment escalation or de-escalation pathways in rectal cancer.

The Roles of Non-Coding RNAs in Radiotherapy of Gastrointestinal Carcinoma

Radiotherapy (RT), or radiation therapy, has been widely used in clinical practice for the treatment of local advanced gastrointestinal carcinoma. RT causes DNA double-strand breaks leading to cell cytotoxicity and indirectly damages tumor cells by activating downstream genes. Non-coding RNA (including microRNAs, long non-coding RNAs (ncRNAs), and circular RNAs) is a type of RNA that does not encode a protein. As the field of ncRNAs increasingly expands, new complex roles have gradually emerged for ncRNAs in RT. It has been shown that ncRNAs can act as radiosensitivity regulators in gastrointestinal carcinoma by affecting DNA damage repair, cell cycle arrest, irradiation-induced apoptosis, cell autophagy, stemness, EMT, and cell pyroptosis. Here, we review the complex roles of ncRNAs in RT and gastrointestinal carcinoma. We also discuss the potential clinical significance and predictive value of ncRNAs in response to RT for guiding the individualized treatment of patients. This review can serve as a guide for the application of ncRNAs as radiosensitivity enhancers, radioresistance inducers, and predictors of response in RT of gastrointestinal carcinoma.

Nucleic acid-based markers of response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer

The progress that has been made in the treatment of rectal cancer has mostly resulted from multimodality strategy approach that combines surgery, chemotherapy and radiotherapy. In locally advanced rectal cancer (LARC), surgery remains the primary treatment, while neoadjuvant chemoradiotherapy (nCRT) is used to downsize or downstage the tumor before surgical resection. Highly variable response to nCRT observed in LARC patients raises the need for biomarkers to enable prediction and evaluation of treatment response in a more efficient and timely manner than currently available tools. The search for predictive biomarkers continues beyond blood proteins, which have failed in subsequent validation studies. This review presents nucleic acids-based markers and their predictive potential in LARC patients. Most of the candidate biomarkers come from relatively small single-institution studies. The only candidate biomarker that emerged as relevant in more than a single study was elevated levels of Fusobacterium nucleatum nucleic acids in tumor tissue. Considering that this marker is easily accessible through non-invasive analysis of faecal samples, its predictive potential is worth further validation. The other candidate nucleic acid-based biomarkers require more consistent studies on larger cohorts before they can be considered for use in clinical setting.

ceRNA Networks: The Backbone Role in Neoadjuvant Chemoradiotherapy Resistance/Sensitivity of Locally Advanced Rectal Cancer

Approximately 40% of rectal cancers during initial diagnosis are identified as locally advanced rectal cancers (LARCs), for which the standardized treatment scenario is total mesorectal excision following neoadjuvant chemoradiotherapy (nCRT). nCRT can lead to discernible reductions in local relapse rate and distant metastasis rate in LARC patients, in whom previously inoperable tumors may potentially be surgically removed. However, only 4% to 20% cases can attain pathological complete response, and the remaining patients who are unresponsive to nCRT have to suffer from the side effects plus toxicities and may encounter poor survival outcomes due to the late surgical intervention. As such, employing potential biomarkers to differentiate responders from nonresponders before nCRT implementation appears to be the overarching goal. Well-defined competing endogenous RNA (ceRNA) networks include long noncoding RNA (lncRNA)-microRNA (miRNA)-mRNA and circRNA-miRNA-mRNA networks. As ceRNAs, lncRNAs, and circRNAs sponge miRNAs to indirectly suppress miRNAs downstream of oncogenic mRNAs or tumor-suppressive mRNAs. The abnormal expression of mRNAs regulates the nCRT-induced DNA damage repair process through pluralistic carcinogenic signaling pathways, thereby bringing about alterations in the nCRT resistance/sensitivity of tumors. Moreover, many molecular mechanisms relevant to cell proliferation, metastasis, or apoptosis of cancers (eg, epithelial-mesenchymal transition and caspase-9-caspase-3 pathway) are influenced by ceRNA networks. Herein, we reviewed a large group of abnormally expressed mRNAs and noncoding RNAs that are associated with nCRT resistance/sensitivity in LARC patients and ultimately pinpointed the backbone role of ceRNA networks in the molecular mechanisms of nCRT resistance/sensitivity.

Increased Expression of Long Non-coding RNA H19 is Associated With Colon Cancer Recurrence

BACKGROUND

Colon cancer is a leading cause of cancer-related death. Long non-coding (Lnc) RNAs are critical mediators of tumor biology. H19 is a well-characterized lncRNA involved in p53 regulation and cancer progression. A specific colon cancer data set was utilized to determine if tumor H19 expression is associated with recurrence-free and overall survival.

METHODS

Clinical patient data from The Cancer Genome Atlas colon adenocarcinoma data set was downloaded using FirebrowseR and normalized H19 expression from the associated RNA-seq data set downloaded using cBioportal. Univariable and multivariable Cox proportional regression analyses were used to identify an association between H19 expression in colon cancer tissue and recurrence-free, and overall survival.

RESULTS

Three hundred eight patients were studied. Median age was 68 years (interquartile range: 58-77 years) and 156 patients (51%) were men. Increased H19 expression was associated with KRAS mutation status (P= 0.016). There was no difference in overall survival between the low and high H19 expression groups (log rank = 0.481); however, increased H19 expression was associated with reduced recurrence-free survival (Log-Rank = 0.012). On multivariable regression analysis, increased H19 expression (Hazard ratio  = 1.83, 95%CI: 1.02-3.27, P= 0.042), and stage III or IV disease (Hazard ratio  = 2.39, 95%CI: 1.34-4.27, P= 0.003) were risk factors for reduced recurrence-free survival.

CONCLUSIONS

Colon cancer H19 expression is associated with advanced stage of tumor disease and is a significant risk factor for reduced recurrence-free survival. Tumor expression of H19 may have potential for both prognostic and therapeutic uses in the future.

Prognostic and Predictive Value of Tumor Budding in Colorectal Cancer

BACKGROUND

Tumor budding (TB) is an adverse prognostic factor in colorectal cancer (CRC). International consensus on a standardized assessment method has led to its wider reporting. However, uncertainty regarding its clinical value persists. This study aimed to (1) confirm the prognostic significance of TB, particularly in stage II CRC; (2) to determine optimum thresholds for TB risk grouping; and (3) to determine whether TB influences responsiveness to chemotherapy.

METHODS

TB was assessed in CRC sections from 1575 QUASAR trial patients randomized between adjuvant chemotherapy and observation. Optimal risk group cutoffs were determined by maximum likelihood methods, with their influence on recurrence and mortality investigated in stratified log-rank analyses on exploratory (n = 504), hypothesis-testing (n = 478), and final (n = 593) data sets.

RESULTS

The optimal threshold for high-grade TB (HGTB) was ≥ 10 buds per 1.23 mm². High-grade TB tumors had significantly worse outcomes than those with lower TB: 10-year recurrence 36% versus 22% (risk ratio, 2.00 [95% CI, 1.62-2.45]; 2P < .0001) and 10-year mortality 50% vs. 37% (risk ratio, 1.53 [95% CI, 1.34-1.76]; 2P < .0001). The prognostic significance remained equally strong after allowance for other pathological risk factors, including stage, grade, lymphovascular invasion, and mismatch repair status. There was a nonsignificant trend toward increasing chemotherapy efficacy with increasing bud counts.

CONCLUSIONS

TB is a strong independent predictor of recurrence. Chemotherapy efficacy is comparable in patients with higher and lower TB; hence, absolute reductions in recurrence and death with chemotherapy should be about twice as large in patients with ≥ 10 than < 10 TB counts.

The histopathological and molecular features of breast carcinoma with tumour budding-a systematic review and meta-analysis

PURPOSE

Tumour budding (TB) is an adverse histological feature in many epithelial cancers. It is thought to represent epithelial-mesenchymal transition, a key step in the metastatic process. The significance of TB in breast carcinoma (BC) remains unclear. The aim of this study is to investigate the relationship between TB and other histological and molecular features of BC.

METHODS

A systematic search was performed to identify studies that compared features of BC based on the presence or absence of high-grade TB. Dichotomous variables were pooled as odds ratios (OR) using the Der Simonian-Laird method. Quality assessment of the included studies was performed using the Newcastle-Ottawa scale (NOS).

RESULTS

Seven studies with a total of 1040 patients (high-grade TB n = 519, 49.9%; low-grade/absent TB n = 521, 50.1%) were included. A moderate to high risk of bias was noted. The median NOS was 7 (range 6-8). High-grade TB was significantly associated with lymph node metastasis (OR 2.32, 95% c.i. 1.77 to 3.03, P < 0.001) and lymphovascular invasion (OR 3.08, 95% c.i. 2.13 to 4.47, P < 0.001). With regard to molecular subtypes, there was an increased likelihood of high-grade TB in oestrogen (OR 1.66, 95% c.i. 1.21 to 2.29, P = 0.002) and progesterone receptor-positive (OR 1.48, 95% c.i. 1.09 to 2.02, P = 0.01) tumours. In contrast, triple-negative breast cancer had a reduced incidence of high-grade TB (OR 0.46, 95% c.i. 0.30 to 0.72, P = 0.0006).

CONCLUSION

High-grade TB is enriched in hormone receptor-positive BC and is associated with known adverse prognostic variables. TB may offer new insights into the metastatic process of BC.

Unintended consequences of treating early rectal cancers for complete clinical response with chemoradiotherapy

The aim was to examine the current trend in rectal cancer, which is to extend ’watch-and-wait’ to earlier-stage tumors, not normally treated with chemoradiotherapy, to define the up-side and down-side regarding quality of life (QOL) and anorectal/sexual/urinary function from this approach. We reviewed the literature regarding a ‘watch-and-wait’ strategy after neoadjuvant chemoradiotherapy. The primary outcome measure was complete clinical response. Secondary measures included colostomy rate, functional outcomes and QOL. There is a trend to use chemoradiotherapy in earlier tumors using dose-escalation of radiation and/or additional chemotherapy, resulting in high rates of complete clinical response, which may impact adversely on QOL if radical surgery is subsequently required. Focusing on organ-preservation as the primary goal of treatment rather than overall functional outcomes and QOL for the whole population, may not provide patients with sufficient information for optimal decision-making.

How to measure tumour response in rectal cancer? An explanation of discrepancies and suggestions for improvement

Various methods categorize tumour response after neoadjuvant therapy, including down-staging and tumour regression grading. Response categories allow comparison of different treatments within clinical trials and predict outcome. A reproducible response categorization could identify subgroups with high or low risk for the most appropriate subsequent treatments, like watch and wait. Lack of standardization and interpretation difficulties currently limit the usability of these approaches. In this review we describe these difficulties for the evaluation of chemoradiation in rectal cancer. An alternative approach of tumour response is based on patterns of residual disease, including fragmentation. We summarise the evidence behind this alternative method of response categorisation, which explains a number of very relevant clinical discrepancies. These issues include differences between downstaging and tumour regression, high local regrowth in advanced tumours during watchful waiting procedures, the importance of resection margins, the limited value of post-treatment biopsies and the relatively poor outcome of patients with a near complete pathological response. Recognition of these patterns of response can allow meaningful development of novel biomarkers in the future.

Controversies around epithelial-mesenchymal plasticity in cancer metastasis

Experimental evidence accumulated over decades has implicated epithelial-mesenchymal plasticity (EMP), which collectively encompasses epithelial-mesenchymal transition and the reverse process of mesenchymal-epithelial transition, in tumour metastasis, cancer stem cell generation and maintenance, and therapeutic resistance. However, the dynamic nature of EMP processes, the apparent need to reverse mesenchymal changes for the development of macrometastases and the likelihood that only minor cancer cell subpopulations exhibit EMP at any one time have made such evidence difficult to accrue in the clinical setting. In this Perspectives article, we outline the existing preclinical and clinical evidence for EMP and reflect on recent controversies, including the failure of initial lineage-tracing experiments to confirm a major role for EMP in dissemination, and discuss accumulating data suggesting that epithelial features and/or a hybrid epithelial-mesenchymal phenotype are important in metastasis. We also highlight strategies to address the complexities of therapeutically targeting the EMP process that give consideration to its spatially and temporally divergent roles in metastasis, with the view that this will yield a potent and broad class of therapeutic agents.

Pretreatment TACC3 expression in locally advanced rectal cancer decreases the response to neoadjuvant chemoradiotherapy

Chemoradiotherapy combined with surgical resection is the standard treatment for locally advanced rectal cancer, but not all the patients respond to neoadjuvant treatment. Transforming acidic coiled-coil protein-3 (TACC3) is frequently aberrantly expressed in rectal cancer tissue. In this study, we investigated whether TACC3 could serve as a biomarker predictive of the efficacy of chemoradiotherapy. In all, 152 rectal cancer patients with tumor tissue collected at biopsy and set aside before treatment were enrolled in this study. All patients received chemoradiotherapy and surgical resection. Immunohistochemically detected tumoral TACC3 expression significantly decreased sensitivity to chemoradiotherapy [risk ratio (RR) = 2.236, 95% confidence interval (CI): 1.447-3.456; P = 0.001] and thus the pathological complete response rate (P = 0.001). TACC3 knockdown using specific siRNA enhanced radiotherapy-induced decreases in proliferation and colony formation by HCT116 and SW480 cells and increased the incidence of radiotherapy-induced apoptosis. Cox multivariate analysis showed that TACC3 was a significant prognostic factor for overall survival (P = 0.017) and disease-free survival (P = 0.020). These findings suggest TACC3 expression may be predictive of chemoradiotherapy sensitivity and prognosis in locally advanced rectal cancer.

Tumor budding outperforms ypT and ypN classification in predicting outcome of rectal cancer after neoadjuvant chemoradiotherapy

Background

Budding is a complementary prognostic factor for colorectal cancer. In this study, we aimed to clarify the role of tumor budding in rectal cancer patients after preoperative chemoradiotherapy.

Methods

A total of 124 patients with rectal cancer treated with neoadjuvant chemoradiotherapy and consecutive surgery were included. Surgical specimens were evaluated for budding and routine clinicopathological features. Budding was evaluated on hematoxylin and eosin (H&E)-stained slides and by cytokeratin immunohistochemical (IHC) staining.

Results

A budding rate of 36.9% (n = 38) by H&E and 55.6% (n = 55) by IHC was observed. Budding was significantly associated with a high ypT and ypN status, poor differentiation, and low degrees of tumor regression. Moreover, budding was strongly predictive of a worse patient outcome, as measured by tumor recurrence or death. In multivariate analyses, budding remained the only significant parameter for overall survival and was even superior to the ypT and ypN status (budding in H&E: hazard ratio (HR) 2.72, 95% confidence interval (95% CI) 1.15–6.44, p = 0.023; budding in IHC: HR 5.19, 95% CI 1.62–16.61, p = 0.006).

Conclusion

Budding is a strong prognostic predictor of survival in rectal cancer patients after neoadjuvant therapy. A standardized evaluation of tumor budding after neoadjuvant therapy may thus aid in risk stratification and guide the clinical management of patients with rectal cancer. Immunostaining can help to enhance the diagnostic accuracy and prognostic significance.

The microRNA-200 family acts as an oncogene in colorectal cancer by inhibiting the tumor suppressor RASSF2

This study aimed to determine whether manipulation of the microRNA-200 (miR-200) family could influence colon adenocarcinoma cell behavior. The miR-200 family has a significant role in tumor suppression and functions as an oncogene. In vitro studies on gain and loss of function with small interfering RNA demonstrated that the miR-200 family could regulate RASSF2 expression. Knockdown of the miR-200 family in the HT-29 colon cancer cell line increased KRAS expression but decreased signaling in the MAPK/ERK signaling pathway through reduced ERK phosphorylation. Increased expression of the miR-200 family in the CCD-841 colon epithelium cell line increased KRAS expression and led to increased signaling in the MAPK/ERK signaling pathway but increased ERK phosphorylation. Functionally, knockdown of the miR-200 family led to decreased cell proliferation in the HT-29 cells; therefore, increased miR-200 family expression could increase cell proliferation in the CCD-841 cell line. The present study included a large paired miR array dataset (n=632), in which the miR-200 family was significantly found to be increased in colon cancer when compared with normal adjacent colon epithelium. In a miR-seq dataset (n=199), the study found that miR-200 family expression was increased in localized colon cancer compared with metastatic disease. Decreased expression was associated with poorer overall survival. The miR-200 family directly targeted RASSF2 and was inversely correlated with RASSF2 expression (n=199, all P<0.001). Despite the well-defined role of the miR-200 family in tumor suppression, the present findings demonstrated a novel function of the miR-200 family in tumor proliferation.

Local environment in biopsy better predict the pathological response to neoadjuvant chemoradiotherapy in rectal cancer

Neoadjuvant chemoradiotherapy (nCRT) followed by surgery is the standard treatment for locally advanced rectal cancer. Here, we analyzed the impact of local and systemic environments on the tumor response to preoperative chemoradiotherapy in rectal cancer. We recruited 141 patients with rectal cancer treated with nCRT. We evaluated the local tumor environment, including tumor-infiltrating lymphocytes (TILs), intratumor budding (ITB), and the systemic inflammatory environment, including the neutrophil-to-lymphocyte ratio (NLR) and C-reactive protein (CRP) level. Our finding revealed that tumor regression was significantly associated with the density of CD8+ TILs in the intraepithelial, the presence of ITB, the combination of NLR and CRP (NLR-CRP) value, and the combination of CD8+ intraepithelial TIL (iTIL) density and ITB presence. Moreover, multivariate analysis showed that only the combination of CD8+ iTILs and ITB was an independent predictive factor for the pathological response to nCRT in rectal cancer. Our finding demonstrate that the local tumor environment was a better predictor of the tumor response than the systemic environment and thus provided new insight into screening for patients who are more likely to benefit from cancer treatment.

A novel tumor-based epithelial-to-mesenchymal transition score that associates with prognosis and metastasis in patients with Stage II/III colorectal cancer

It is increasingly appreciated that host factors within the tumor center and microenvironment play a key role in dictating colorectal cancer (CRC) outcomes. As a result, the metastatic process has now been defined as a result of epithelial-mesenchymal transition (EMT). Establishment of the role of EMT within the tumor center and its effect on the tumor microenvironment would be beneficial for prognosis and therapeutic intervention in CRC. The present study assessed five immunohistochemical EMT markers within the tumor center on a 185 Stage II/III CRC patient tissue microarray. In 185 patients with CRC, cytoplasmic snail (HR 1.94 95% confidence interval [CI] 1.15-3.29, p = 0.012) and a novel combined EMT score (HR 3.86 95% CI 2.17-6.86, p < 0.001) were associated with decreased cancer-specific survival. The combined EMT score was also associated with increased tumor budding (p = 0.046), and systemic inflammation (p = 0.007), as well as decreased memory T-cells within the stroma (p = 0.030) and at the invasive margin (p = 0.035). Furthermore, the combined EMT score was associated with cancer-specific survival independent of TNM-stage (HR 4.12 95% CI 2.30-7.39, p < 0.001). In conclusion, a novel combined EMT score stratifies patient's survival in Stage II/III CRC and associates with key factors of tumor metastasis. Therefore, the combined EMT score could be used to identify patients at risk of micrometastases and who may benefit from standard adjuvant therapy, potentially in combination with EMT blockade.

The potential predictive value of tumor budding for neoadjuvant chemoradiotherapy response in locally advanced rectal cancer

Purpose

This study was conducted to investigate the potential predictive value of tumor budding for neoadjuvant chemoradiotherapy response in locally advanced rectal cancer.

Patients and methods

Surgical specimens of 128 ypUICC (Union for International Cancer Control) stage 0–III mid-to-low rectal cancer patients were identified from a prospectively maintained colorectal cancer database and classified into two groups using the 10 high-power field average method: none/mild tumor budding (BD-0) and moderate/severe tumor budding (BD-1). Overall survival, relapse-free survival (RFS), and recurrence estimates were calculated using the Kaplan–Meier method and compared with the log-rank test. For RFS, a multivariable Cox’s proportional hazards regression analysis was performed.

Results

No (n = 20) or mild (n = 27) tumor budding (BD-0) was identified in 47 (37%) and moderate (n = 52) or severe (n = 29) tumor budding (BD-1) in 81 (63%) surgical specimens. Positive tumor budding (BD-1) was associated with significantly reduced T‑level downstaging (P < 0.001) and tumor regression (P < 0.001). After a median follow-up time of 7 years (range 2.9–146.7 months), BD-0 patients had more favorable 5‑year RFS (90 vs. 71%, P = 0.02) and distant recurrence (2 vs. 12%, P = 0.03) estimates. Multivariable analyses confirmed BD-1 as a negative predictive parameter for RFS (hazard ratio = 3.44, 95% confidence interval 1.23–9.63, P = 0.018).

Conclusions

Our data confirm tumor budding as a strong prognostic factor and its potential predictive value for neoadjuvant chemoradiotherapy response in locally advanced rectal cancer patients. This provides the opportunity to modify and individualize neoadjuvant therapy regimens for non-responders.

Novel biomarkers for patient stratification in colorectal cancer: A review of definitions, emerging concepts, and data

Colorectal cancer (CRC) treatment has become more personalised, incorporating a combination of the individual patient risk assessment, gene testing, and chemotherapy with surgery for optimal care. The improvement of staging with high-resolution imaging has allowed more selective treatments, optimising survival outcomes. The next step is to identify biomarkers that can inform clinicians of expected prognosis and offer the most beneficial treatment, while reducing unnecessary morbidity for the patient. The search for biomarkers in CRC has been of significant interest, with questions remaining on their impact and applicability. The study of biomarkers can be broadly divided into metabolic, molecular, microRNA, epithelial-to-mesenchymal-transition (EMT), and imaging classes. Although numerous molecules have claimed to impact prognosis and treatment, their clinical application has been limited. Furthermore, routine testing of prognostic markers with no demonstrable influence on response to treatment is a questionable practice, as it increases cost and can adversely affect expectations of treatment. In this review we focus on recent developments and emerging biomarkers with potential utility for clinical translation in CRC. We examine and critically appraise novel imaging and molecular-based approaches; evaluate the promising array of microRNAs, analyze metabolic profiles, and highlight key findings for biomarker potential in the EMT pathway.

Tumour budding in rectal cancer. A comprehensive review

A unique and fundamental characteristic of malignant neoplastic cells is their ability to invade other tissues and metastasise. The first step in this process is the dissociation of some of these cells from the tumour invasion front, named tumour budding (TB). This phenomenon has become increasingly relevant in recent years due to its association with adverse clinicopathological characteristics and with the epithelial-mesenchymal transition. TB has been studied by mixing colon with rectal tumours, but it is clinically important to differentiate these types of tumours. A review in two databases without language restriction was performed from 1950 to 2017 about TB with an emphasis on rectal cancer. We present various aspects of TB, from its terminology and evaluation to its molecular aspects, through its clinical associations. TB is associated with adverse clinicopathological features, like lymphovascular invasion, lymph node metastasis, and decreased survival. More studies of the clinicopathological, molecular, and epidemiological characteristics of TB in rectal cancer are needed.

Adjuvant Chemotherapy Seemed Not to Have Survival Benefit in Rectal Cancer Patients with ypTis-2N0 After Preoperative Radiotherapy and Surgery from a Population-Based Propensity Score Analysis

BACKGROUND

Adjuvant chemotherapy is currently offered routinely, as standard, after radical resection for patients with rectal cancer receiving neo-adjuvant chemoradiation. However, the efficacy of adjuvant chemotherapy in patients with ypTis-2N0M0 has not been documented to the same extent, and the survival benefit remained controversial. The purpose of this work was to determine the role of chemotherapy in patients with ypTis-2N0M0 classification.

MATERIALS AND METHODS

Data were obtained from the Surveillance, Epidemiology, and End Results database (n = 4,217). A propensity score model was utilized to balance baseline covariates.

RESULTS

Of the 4,217 included patients, 335 with ypTis-2N0M0 did not receive adjuvant chemotherapy. There were comparable cancer-specific survivals (CSS) between those undergoing adjuvant chemotherapy or not (log-rank test = 0.136, p = .712) in the overall sample. After propensity score matching, the cancer-specific survival did not differ between the chemotherapy and observation groups (log-rank test = 0.089, p = .765). Additionally, the Cox model did not demonstrate adjuvant chemotherapy as the prognostic factor, with hazard ratio = 0.95 (95% confidence interval 0.69-1.32) for CSS. Furthermore, the 10-year cumulative CSS was 78.7% and 79.4% between the chemotherapy and observation groups, indicating no significance, and no impact of adjuvant chemotherapy on survival was observed in different subgroups stratified by T stage, histological grade, histology, lymph nodes, and tumor size.

CONCLUSION

Patients with ypTis-2N0 rectal cancer did not benefit from adjuvant chemotherapy after preoperative radiology and radical surgery in this cohort study. These results provided new insight into the routine use of adjuvant chemotherapy for patients with rectal cancer with completed neo-adjuvant radiotherapy and curative surgery.

IMPLICATIONS FOR PRACTICE

Inconsistent recommendations for patients with rectal cancer receiving neo-adjuvant chemoradiation are offered by clinical guidelines. Adjuvant chemotherapy had no cancer-specific survival benefit, not only in the whole cohort, but also in the propensity score-matched cohort. A Cox model also confirmed adjuvant chemotherapy was not a significant prognostic factor in ypTis-2N0 rectal cancer. No survival benefit conferred by adjuvant chemotherapy was observed, regardless of whether T stage, histological type, grade, lymph nodes and tumor size varied.

Identification of biomarker microRNAs for predicting the response of colorectal cancer to neoadjuvant chemoradiotherapy based on microRNA regulatory network

Preoperative radiotherapy or chemoradiotherapy has become a standard procedure for treatment of patients with locally advanced colorectal cancer (CRC). However, patients’ responses to treatment are different and personalized. MicroRNAs (miRNAs) are promising biomarkers for predicting personalized responses. In this study, we collected 30 publicly reported miRNAs associated with chemoradiotherapy of CRC. We extracted 46 differentially expressed miRNAs from samples of responders and non-responders to preoperative radiotherapy from the Gene Expression Omnibus dataset (Student's t test, p-value < 0.05 and |fold-change| > 2). We performed a systematic and integrative bioinformatics analysis to identify biomarker miRNAs for prediction of CRC responses to chemoradiotherapy. Using the bioinformatics model, miR-198, miR-765, miR-671-5p, miR-630, miR-371-5p, miR-575, miR-202, miR-483-5p and miR-513a-5p were screened as putative biomarkers for treatment response. Literature validation and functional enrichment analysis were exploited to confirm the reliability of the predicted miRNAs. Quantitative polymerase chain reaction showed that seven of the candidates were significantly differentially expressed between radiosensitive and insensitive CRC cell lines. The unique target genes of miR-198 and miR-765 were altered significantly upon transfection of specific miRNA mimics in the radiosensitive cell line. These results demonstrated the predictive power of our model and suggested that miR-198, miR-765, miR-630, miR-371-5p, miR-575, miR-202 and miR-513a-5p could be used for predicting the response of CRC to preoperative chemoradiotherapy.

Circulating Tumor Cells and Implications of the Epithelial-to-Mesenchymal Transition

The majority of cancer-related deaths result from metastasis, the process by which cancer cells escape the primary tumor site and enter into the blood circulation in order to disseminate to secondary locations throughout the body. Tumor cells found within the circulation are referred to as circulating tumor cells (CTCs), and their detection and enumeration correlate with poor prognosis. The epithelial-to-mesenchymal transition (EMT) is a dynamic process that imparts epithelial cells with mesenchymal-like properties, thus facilitating tumor cell dissemination and contributing to metastasis. However, EMT also results in the downregulation of various epithelial proteins typically utilized by CTC technologies for enrichment and detection of these rare cells, resulting in reduced detection of some CTCs, potentially those with a more metastatic phenotype. In addition to the current clinical role of CTCs as a prognostic biomarker, they also have potential as a predictive biomarker via CTC characterization. However, CTC characterization is complicated by the unknown biological significance of CTCs possessing an EMT-like phenotype, and the ability to capture and understand this CTC subpopulation is an essential step in the utilization of CTCs for patient management. This chapter will review the process of EMT and its contribution to metastasis; discusses current and future clinical applications of CTCs; and describes both traditional and novel methods for CTC enrichment, detection, and characterization with a specific focus on CTCs with an EMT phenotype.

Lymphocyte-to-monocyte ratio before chemoradiotherapy represents a prognostic predictor for locally advanced rectal cancer

Research indicates that cancer-triggered inflammation plays a pivotal role in carcinogenesis. Here, we aimed to evaluate the correlation of lymphocyte-to-monocyte ratio (LMR) before neoadjuvant chemoradiotherapy (CRT) with clinical outcomes in patients with locally advanced rectal cancer (LARC). We retrospectively enrolled 317 consecutive patients with LARC between 2004 and 2013. The optimal cutoff values of LMR were determined using receiver operating curve analysis. Overall survival (OS) and disease-free survival related to the LMR were analyzed using the log-rank test and multivariate Cox regression methods. We found that a low LMR (≤4.91) was prominently correlated with worse prognostic features and a shorter 3-year survival rate of LARC. Moreover, multivariate Cox analysis revealed that elevated LMR was an independent factor for better OS (hazard ratio 0.538, 95% confidence interval 0.292–0.991, P=0.047). In addition, univariate logistic regression analysis showed that the LMR was not associated with tumor pathologic regression. In conclusion, LMR is identified as a valuable prognostic marker for predicting the OS of LARC patients receiving CRT.

MicroRNAs as Biomarkers in Colorectal Cancer

MicroRNAs (miRs) are small RNAs that repress mRNA translation, resulting in the degradation of mRNAs and regulation of the expression levels of various genes. Recent studies have shown that aberrant miR expression has a functional role in the initiation and progression of various malignancies, including colorectal cancer (CRC), which is one of the leading causes of cancer-related death worldwide. miRs have also been shown to have applications as diagnostic, prognostic, and predictive biomarkers because of their high tissue specificity, stability, and altered expression in tumor development. In this report, we examined the role of miRs as biomarkers in CRC through a review of meta-analyses and large-scale analyses having strong statistical confidence in the study outcomes. We also discuss current issues in the clinical application of these miRs.

Diffusion kurtosis imaging evaluating epithelial-mesenchymal transition in colorectal carcinoma xenografts model: a preliminary study

Epithelial-mesenchymal transition (EMT) plays an important role in aggravating invasiveness and metastatic behavior of colorectal cancer (CRC). Identification of EMT is important for structuring treatment strategy, but has not yet been studied by using noninvasive imaging modality. Diffusion kurtosis imaging (DKI) is an advanced diffusion weighted model that could reflect tissue microstructural changes in vivo. In this study, EMT was induced in CRC cells (HCT116) by overexpressing Snail1 gene. We aimed to investigate the value of DKI in identifying EMT in CRC and decipher the correlations between DKI-derived parameters and EMT biomarker E-cadherin and cell proliferative index Ki-67 expression. Our results revealed that HCT116/Snail1 cells presented changes consistent with EMT resulting in significant increase in migration and invasion capacities. DKI could identify CRC with EMT, in which the DKI-derived parameter diffusivity was significantly lower, and kurtosis was significantly higher than those in the CRC/Control. Diffusivity was negatively and kurtosis was positively correlated with Ki-67 expression, whereas diffusivity was positively and kurtosis was negatively correlated with E-cadherin expression. Therefore, our study concluded that DKI can identify EMT in CRC xenograft tumors. EMT-contained CRC tumors with high Ki-67 and low E-cadherin expression were vulnerable to have lower diffusivity and higher kurtosis coefficients.

Preoperative chemoradiotherapy for rectal cancer: the sensitizer role of the association between miR-375 and c-Myc

Administration of chemoradiation before tumor resection has revolutionized the management of locally advanced rectal cancer, but many patients have proven resistant to this preoperative therapy. Our group recently reported a negative correlation between c-Myc gene expression and this resistance. In the present study, integrated analysis of miRNA and mRNA expression profiles was conducted in 45 pre-treatment rectal tumors in order to analyze the expressions of miRNAs and c-Myc and their relationship with clinicopathological factors and patient survival. Twelve miRNAs were found to be differentially expressed by responders and non-responders to the chemoradiation. Functional classification revealed an association between the differentially expressed miRNAs and c-Myc. Quantitative real-time PCR results showed that miRNA-148 and miRNA-375 levels were both significantly lower in responders than in non-responders. Notably, a significant negative correlation was found between miRNA-375 expression and c-Myc expression. According to these findings, miRNA-375 and its targeted c-Myc may be useful as a predictive biomarker of the response to neoadjuvant treatment in patients with locally advanced rectal cancer.

Significance of E-cadherin and CD44 expression in patients with unresectable metastatic colorectal cancer

The loss of adhesion molecules is reported to be associated with tumor invasion and metastasis in numerous types of cancer. Epithelial (E)-cadherin is an important molecule for cell-to-cell adhesion, while cluster of differentiation (CD)44 is an important molecule for cell-to-extracellular matrix adhesion. The focus of the present study was to evaluate the significance of the expression of E-cadherin and CD44 in patients with the unresectable metastatic colorectal cancer (CRC) who are undergoing palliative chemotherapy. Formalin-fixed, paraffin-embedded samples were obtained from 49 patients who underwent primary tumor resection and who were receiving palliative chemotherapy for unresectable metastatic CRC. The expression of E-cadherin and CD44 was evaluated using immunohistochemistry. The expression of E-cadherin was not significantly associated with progression-free survival (PFS; P=0.2825) or overall survival (OS; P=0.6617). The expression of CD44 was not associated with PFS (P=0.4365), but it did exhibit a certain level of association with OS (P=0.0699). However, the combined low expression of E-cadherin and CD44 demonstrated a significant association with decreased PFS (P=0.0101) and OS (P=0.0009). The combined loss of E-cadherin and CD44 expression also led to a reduction in the objective response rate and disease control rate (P=0.0076 and P=0.0294, respectively). A univariate analysis indicated that the combined low expression of E-cadherin and CD44 (P=0.0474) and sex (P=0.0330) were significantly associated with decreased PFS, and multivariate analysis confirmed combined low expression of E-cadherin and CD44 as an independent risk factor for decreased PFS [hazard ratio (HR), 8.276; 95% confidence interval (CI), 1.383-43.311; P=0.0227]. Univariate and multivariate analyses also indicated that the combined low expression of E-cadherin and CD44 expression was a significant prognostic factor for poor OS (HR, 15.118; 95% CI, 2.645-77.490; P=0.0039). Therefore the current study suggests that the combined low expression of E-cadherin and CD44 is an effective independent predictor of decreased chemotherapeutic outcome and survival in patients with unresectable metastatic CRC.

Extramural vascular invasion and response to neoadjuvant chemoradiotherapy in rectal cancer: Influence of the CpG island methylator phenotype

AIM

To identify whether CpG island methylator phenotype (CIMP) is predictive of response to neoadjuvant chemoradiotherapy (NACRT) and outcomes in rectal cancer.

METHODS

Patients undergoing NACRT and surgical resection for rectal cancer in a tertiary referral centre between 2002-2011 were identified. Pre-treatment tumour biopsies were analysed for CIMP status (high, intermediate or low) using methylation specific PCR. KRAS and BRAF status were also determined using pyrosequencing analysis. Clinical information was extracted from case records and cancer services databases. Response to radiotherapy was measured by tumour regression scores determined upon histological examination of the resected specimen. The relationship between these molecular features, response to NACRT and oncological outcomes were analysed.

RESULTS

There were 160 patients analysed with a median follow-up time of 46.4 mo. Twenty-one (13%) patients demonstrated high levels of CIMP methylation (CIMP-H) and this was significantly associated with increased risk of extramural vascular invasion (EMVI) compared with CIMP-L [8/21 (38%) vs 15/99 (15%), P = 0.028]. CIMP status was not related to tumour regression after radiotherapy or survival, however EMVI was significantly associated with adverse survival (P < 0.001). Intermediate CIMP status was significantly associated with KRAS mutation (P = 0.01). There were 14 (9%) patients with a pathological complete response (pCR) compared to 116 (73%) patients having no or minimal regression after neoadjuvant chemoradiotherapy. Those patients with pCR had median survival of 106 mo compared to 65.8 mo with minimal regression, although this was not statistically significant (P = 0.26). Binary logistic regression analysis of the relationship between EMVI and other prognostic features revealed, EMVI positivity was associated with poor overall survival, advanced “T” stage and CIMP-H but not nodal status, age, sex, KRAS mutation status and presence of local or systemic recurrence.

CONCLUSION

We report a novel association of pre-treatment characterisation of CIMP-H with EMVI status which has prognostic implications and is not readily detectable on pre-treatment histological examination.

Simultaneous integrated protection : A new concept for high-precision radiation therapy

OBJECTIVE

Stereotactic radiotherapy near serial organs at risk (OAR) requires special caution. A novel intensity-modulated radiotherapy (IMRT) prescription concept termed simultaneous integrated protection (SIP) for quantifiable and comparable dose prescription to targets very close to OAR is described.

MATERIALS AND METHODS

An intersection volume of a planning risk volume (PRV) with the total planning target volume (PTV) defined the protection volume (PTV_SIP). The remainder of the PTV represented the dominant PTV (PTV_dom). Planning was performed using IMRT. Dose was prescribed to PTV_dom according to ICRU in 3, 5, 8, or 12 fractions. Constraints to OARs were expressed as absolute and as equieffective doses at 2 Gy (EQD2). Dose to the gross risk volume of an OAR was to respect constraints. Violation of constraints to OAR triggered a planning iteration at increased fractionation. Dose to PTV_SIP was required to be as high as possible within the constraints to avoid local relapse.

RESULTS

SIP was applied in 6 patients with OAR being large airways (n = 2) or bowel (n = 4) in 3, 5, 8, and 12 fractions in 1, 3, 1, and 1 patients, respectively. PTVs were 14.5-84.9 ml and PTV_SIP 1.8-3.9 ml (2.9-13.4 % of PTV). Safety of the plans was analyzed from the absolute dose-volume histogram (dose to ml). The steepness of dose fall-off could be determined by comparing the dose constraints to the PRVs with those to the OARs (Wilcoxon test p = 0.001). Constraints were respected for the corresponding OARs. All patients had local control at a median 9 month follow-up and toxicity was low.

CONCLUSION

SIP results in a median dose of ≥100 % to PTV, to achieve high local control and low toxicity. Longer follow-up is required to verify results and a prospective clinical trial is currently testing this new approach in chest and abdomen stereotactic body radiotherapy.

Systematic review and meta-analysis of the impact of tumour budding in colorectal cancer

Background:

Tumour budding is a histological finding in epithelial cancers indicating an unfavourable phenotype. Previous studies have demonstrated that it is a negative prognostic indicator in colorectal cancer (CRC), and has been proposed as an additional factor to incorporate into staging protocols.

Methods:

A systematic review of papers until March 2016 published on Embase, Medline, PubMed, PubMed Central and Cochrane databases pertaining to tumour budding in CRC was performed. Study end points were the presence of lymph node metastases, recurrence (local and distal) and 5-year cancer-related death.

Results:

A total of 7821 patients from 34 papers were included, with a mean rate of tumour budding of 36.8±16.5%. Pooled analysis suggested that specimens exhibiting tumour budding were significantly associated with lymph node positivity (OR 4.94, 95% CI 3.96–6.17, P<0.00001), more likely to develop disease recurrence over the time period (OR 5.50, 95% CI 3.64–8.29, P<0.00001) and more likely to lead to cancer-related death at 5 years (OR 4.51, 95% CI 2.55–7.99, P<0.00001).

Conclusions:

Tumour budding in CRC is strongly predictive of lymph node metastases, recurrence and cancer-related death at 5 years, and its incorporation into the CRC staging algorithm will contribute to more effective risk stratification.

MicroRNA in rectal cancer

In rectal cancer, one of the most common cancers worldwide, the proper staging of the disease determines the subsequent therapy. For those with locally advanced rectal cancer, a neoadjuvant chemoradiotherapy (CRT) is recommended before any surgery. However, response to CRT ranges from complete response (responders) to complete resistance (non-responders). To date we are not able to separate in advance the first group from the second, due to the absence of a valid biomarker. Therefore all patients receive the same therapy regardless of whether they reap benefits. On the other hand almost all patients receive a surgical resection after the CRT, although a watch-and-wait procedure or an endoscopic resection might be sufficient for those who responded well to the CRT. Being highly conserved regulators of gene expression, microRNAs (miRNAs) seem to be promising candidates for biomarkers. Many studies have been analyzing the miRNAs expressed in rectal cancer tissue to determine a specific miRNA profile for the ailment. Unfortunately, there is only a small overlap of identified miRNAs between different studies, posing the question as to whether different methods or differences in tissue storage may contribute to that fact or if the results simply are not reproducible, due to unknown factors with undetected influences on miRNA expression. Other studies sought to find miRNAs which correlate to clinical parameters (tumor grade, nodal stage, metastasis, survival) and therapy response. Although several miRNAs seem to have an impact on the response to CRT or might predict nodal stage, there is still only little overlap between different studies. We here aimed to summarize the current literature on rectal cancer and miRNA expression with respect to the different relevant clinical parameters.

Targeting Notch to overcome radiation resistance

Radiotherapy represents an important therapeutic strategy in the treatment of cancer cells. However, it often fails to eliminate all tumor cells because of the intrinsic or acquired treatment resistance, which is the most common cause of tumor recurrence. Emerging evidences suggest that the Notch signaling pathway is an important pathway mediating radiation resistance in tumor cells. Successful targeting of Notch signaling requires a thorough understanding of Notch regulation and the context-dependent interactions between Notch and other therapeutically relevant pathways. Understanding these interactions will increase our ability to design rational combination regimens that are more likely to be safe and effective. Here we summarize the role of Notch in mediating resistance to radiotherapy, the different strategies to block Notch in cancer cells and how treatment scheduling can improve tumor response. Finally, we discuss a need for reliable Notch related biomarkers in specific tumors to measure pathway activity and to allow identification of a subset of patients who are likely to benefit from Notch targeted therapies.

MicroRNAs as growth regulators, their function and biomarker status in colorectal cancer

Gene expression is in part regulated by microRNAs (miRNAs). This review summarizes the current knowledge of miRNAs in colorectal cancer (CRC); their role as growth regulators, the mechanisms that regulate the miRNAs themselves and the potential of miRNAs as biomarkers. Although thousands of tissue samples and bodily fluids from CRC patients have been investigated for biomarker potential of miRNAs (>160 papers presented in a comprehensive tables), none single miRNA nor miRNA expression signatures are in clinical use for this disease. More than 500 miRNA-target pairs have been identified in CRC and we discuss how these regulatory nodes interconnect and affect signaling pathways in CRC progression.

Can tumor regression grade influence survival outcome in ypT3 rectal cancer?

PURPOSE

Locally advanced rectal cancer (LARC) patients achieving ypT3 status following neoadjuvant chemoradiation are considered to have poor response with minimal downstaging. However, residual cancer cell amounts vary in the subserosa/perirectal fat. Tumor regression grading (TRG) is an evaluation method based on the proportion of fibrosis and residual cancer cells. The aim of this study is to assess the influence of TRG in ypT3 rectal cancer patients who received neoadjuvant chemoradiation.

METHODS

We retrospectively reviewed 325 LARC patients who received neoadjuvant chemoradiation and surgery. TRG scores were recorded by two independent pathologists. Among these patients, 143 were staged as ypT3. We analyzed TRG and other clinicopathological factors and their relationship with survival outcome including overall survival (OS) and disease-free survival (DFS).

RESULTS

Among 143 ypT3 patients, 44 (30.8 %) were TRG1, 84 (58.7 %) were TRG2 and 15 (10.5 %) were TRG3. Seventy-nine (55.3 %) of these patients had metastatic lymph nodes. In univariate analysis, TRG was not associated with DFS (TRG2 vs TRG1, P = 0.852; TRG3 vs TRG1, P = 0.593) or OS (TRG2 vs TRG1, P = 0.977; TRG3 vs TRG1, P = 0.665). Palliative surgery (HR 3.845; 95 % CI 1.670-8.857; P = 0.002) and metastatic lymph nodes after surgery (HR 5.894; 95 % CI 1.142-3.48; P = 0.015) were significantly associated with decreased DFS, while palliative surgery was the only factor associated with worse OS (HR 6.011; 95 % CI 2.150-16.810; P = 0.001). Palliative surgery (HR 3.923; 95 % CI 1.696-9.073; P = 0.001) and metastatic lymph nodes (HR 2.011; 95 % CI 1.152-3.512; P = 0.014) also showed prognostic significance for DFS in multivariate analysis.

CONCLUSIONS

Residual cancer cells evaluated by TRG score after neoadjuvant chemoradiation do not influence survival outcome in ypT3 rectal cancer patients. However, lymph node status is a significant prognostic factor in ypT3 patients.

Biomarkers and Molecular Imaging as Predictors of Response to Neoadjuvant Chemoradiotherapy in Patients With Locally Advanced Rectal Cancer

Standard treatment of patients with locally advanced rectal cancer (LARC) includes neoadjuvant chemoradiotherapy (NCRT) followed by surgery. Tumor regression after NCRT varies substantially among individuals and pathological complete response is a known prognostic factor for LARC. The identification of a predictive model for response to chemoradiotherapy would help clinicians to identify patients who would probably benefit from multimodal treatment and to perform an early assessment of individual prognosis. Carcinoembryonic antigen has proven to be a good predictor of response in several clinical trials. Other widely studied predictive models in LARC include molecular biomarkers, analyzed at various levels and by different techniques, and molecular imaging, in particular magnetic resonance imaging and positron emission tomography/computed tomography. Although none of the studied markers have been approved in clinical practice, their evaluation in larger, prospective trials and in combined predictive models could be of use to define tailored therapeutic strategies.

Predictive and prognostic biomarkers for neoadjuvant chemoradiotherapy in locally advanced rectal cancer

Locally advanced rectal cancer is regularly treated with trimodality therapy consisting of neoadjuvant chemoradiation, surgery and adjuvant chemotherapy. There is a need for biomarkers to assess treatment response, and aid in stratification of patient risk to adapt and personalise components of the therapy. Currently, pathological stage and tumour regression grade are used to assess response. Experimental markers include proteins involved in cell proliferation, apoptosis, angiogenesis, the epithelial to mesenchymal transition and microsatellite instability. As yet, no single marker is sufficiently robust to have clinical utility. Microarrays that screen a tumour for multiple promising candidate markers, gene expression and microRNA profiling will likely have higher yield and it is expected that a combination or panel of markers would prove most useful. Moving forward, utilising serial samples of circulating tumour cells or circulating nucleic acids can potentially allow us to demonstrate tumour heterogeneity, document mutational changes and subsequently measure treatment response.

Circulating tumour cells and the epithelial mesenchymal transition in colorectal cancer

Circulating tumour cells (CTCs) hold great potential as liquid biopsies to prognosticate disease and guide treatment in colorectal cancer. However, their emerging role in determining the molecular phenotype of tumour metastasis carries even more promising clinical use in the provision of comprehensive biomarker detection for targeted therapies and determination of drug resistance. The isolation of CTCs is technology dependent, and in the case of epithelial cell adhesion molecule-based platforms, the ability to detect cells that have undergone the epithelial to mesenchymal transition (EMT) is ineffective. CTCs displaying a mesenchymal phenotype are believed to have an increased metastatic potential. The rarity of CTCs provides another challenge in the enumeration of these cells. The future will likely involve the analysis of individual CTCs at any stage of the EMT in order to provide real-time phenotypic and molecular snapshots capable of tracking the dynamic evolution of tumour progression over time.