Pre-trial inter-laboratory analytical validation of the FOCUS4 personalised therapy trial

INTRODUCTION

Molecular characterisation of tumours is increasing personalisation of cancer therapy, tailored to an individual and their cancer. FOCUS4 is a molecularly stratified clinical trial for patients with advanced colorectal cancer. During an initial 16-week period of standard first-line chemotherapy, tumour tissue will undergo several molecular assays, with the results used for cohort allocation, then randomisation. Laboratories in Leeds and Cardiff will perform the molecular testing. The results of a rigorous pre-trial inter-laboratory analytical validation are presented and discussed.

METHODS

Wales Cancer Bank supplied FFPE tumour blocks from 97 mCRC patients with consent for use in further research. Both laboratories processed each sample according to an agreed definitive FOCUS4 laboratory protocol, reporting results directly to the MRC Trial Management Group for independent cross-referencing.

RESULTS

Pyrosequencing analysis of mutation status at KRAS codons12/13/61/146, NRAS codons12/13/61, BRAF codon600 and PIK3CA codons542/545/546/1047, generated highly concordant results. Two samples gave discrepant results; in one a PIK3CA mutation was detected only in Leeds, and in the other, a PIK3CA mutation was only detected in Cardiff. pTEN and mismatch repair (MMR) protein expression was assessed by immunohistochemistry (IHC) resulting in 6/97 discordant results for pTEN and 5/388 for MMR, resolved upon joint review. Tumour heterogeneity was likely responsible for pyrosequencing discrepancies. The presence of signet-ring cells, necrosis, mucin, edge-effects and over-counterstaining influenced IHC discrepancies.

CONCLUSIONS

Pre-trial assay analytical validation is essential to ensure appropriate selection of patients for targeted therapies. This is feasible for both mutation testing and immunohistochemical assays and must be built into the workup of such trials.

TRIAL REGISTRATION NUMBER

ISRCTN90061564.

A comparison of formalin and GEWF in fixation of colorectal carcinoma specimens: rates of lymph node retrieval and effect on TNM staging

AIMS

The Royal College of Pathologists recommend that a median of at least 12 lymph nodes should be harvested during pathological staging of colorectal cancer. It is not always easy to harvest the required number, especially in patients with rectal cancer receiving neoadjuvant therapy. Lymph node revealing solutions, for example, GEWF, may improve nodal yield. GEWF is safe, cheap and easy to use.

METHODS

In a controlled trial, lymph node yields were compared after secondary specimen dissection following either 24 h of further fixation in formalin (n=101) or GEWF immersion (n=99). The number, size and tumour status of additional lymph nodes identified were compared between groups. Twenty-seven cases that received long-course neoadjuvant therapy were also assessed.

RESULTS

Median lymph node yield at primary dissection met national standards overall (19) but also in the long-course neoadjuvant therapy group (13). Lymph nodes were smaller in neoadjuvant cases compared with non-neoadjuvant cases (mean size range 1.3-5.6 mm vs 1.5-8.9 mm). The use of further fixation and GEWF detected more nodes at secondary dissection. The mean number of additional nodes harvested was greater with formalin (8.3) than GEWF (7.3). There was no significant difference in the mean size of the additional lymph nodes detected between groups (point estimate 1.02; 95% CI -0.58 to 2.63; p=0.211). Upstaging triggering adjunct chemotherapy occurred in 1% (2/200) of cases.

CONCLUSIONS

The routine use of adjunct techniques to identify additional lymph nodes is unnecessary with underlying high-quality dissection practice. Emphasis should be placed upon education and training, spending appropriate time dissecting and ensuring specimens are sufficiently fixed beforehand.

Automated PCR detection of BRAF mutations in colorectal adenocarcinoma: a diagnostic test accuracy study

BACKGROUND

Testing for BRAF mutations in colorectal carcinoma (CRC) is important in the screening pathway for Lynch syndrome and is of prognostic value to guide management. This is a diagnostic accuracy study of the Idylla system, a novel and automated alternative PCR system.

METHODS

100 consecutive formalin-fixed, paraffin-embedded CRC resection cases were tested for BRAF mutations using the Idylla automated platform and compared with standard (Cobas) PCR.

RESULTS

The sensitivity of the Idylla BRAF test was 100% and the specificity was 96%. Only one discordant Idylla positive/standard PCR negative result occurred and on Droplet Digital PCR demonstrated a mutation not identified by traditional PCR in this case.

CONCLUSION

This study has validated the Idylla system for BRAF testing in CRC and demonstrated a possibly greater sensitivity, in addition to cost effectiveness and shorter turnaround time, when compared with standard PCR.

Expression of survivin and p53 modulates honokiol-induced apoptosis in colorectal cancer cells

Honokiol is a small biphenolic compound, which exerts antitumor activities; however, the precise mechanism of honokiol-induced apoptosis in the human colorectal cancer cells remains unclear. Here, we show that survivin and p53 display the opposite role on the regulation of honokiol-induced apoptosis in the human colorectal cancer cells. Honokiol induced the cell death and apoptosis in various colorectal cancer cell lines. Moreover, honokiol elicited the extrinsic death receptor pathway of DR5 and caspase 8 and the intrinsic pathway of caspase 9. The common intrinsic and extrinsic downstream targets of activated caspase 3 and PARP protein cleavage were induced by honokiol. Interestingly, honokiol reduced anti-apoptotic survivin protein and gene expression. Transfection with a green fluorescent protein (GFP)-survivin-expressed vector increased the colorectal cancer cell viability and resisted the honokiol-induced apoptosis. Meantime, honokiol increased total p53 and the phosphorylated p53 proteins at Ser15 and Ser46. The p53-wild type colorectal cancer cells were exhibited greater cytotoxicity, apoptosis and survivin reduction than the p53-null cancer cells after treatment with honokiol. Together, these findings demonstrate that the existence of survivin and p53 can modulate the honokiol-induced apoptosis in the human colorectal cancer cells.

MiR-29b downregulates canonical Wnt signaling by suppressing coactivators of β-catenin in human colorectal cancer cells

The β-catenin/Wnt signaling pathway is activated in many cancers and its constitutive activation has a central role in colorectal cancer pathogenesis. Recent studies have highlighted the role of microRNAs as novel regulators of gene expression including that of signaling intermediates from the Wnt signaling pathway. The purpose of our study was to determine the role of miR-29b in the regulation of Wnt signaling in human colorectal cancer cells. TOPFlash/FOPFlash reporter assays, gene expression studies by quantitative RT-PCR and western blot analysis were used to study the effect of ectopic expression of miR-29b on canonical Wnt signaling. miR-29b antagonized transactivation of β-catenin target genes by downregulating coactivators of β-catenin (TCF7L2, Snail, and BCL9L) in SW480 cells. miR-29b targeted the 3'UTR of BCL9L and decreased its expression with a consequent decrease in nuclear translocation of β-catenin. Ectopic expression of miR-29b inhibited anchorage independent cell growth, promoted reversal of epithelial to mesenchymal transition and reduced the ability of conditioned medium from SW480 cells to induce in vitro tube formation in endothelial cells. These results have unraveled a novel role of miR-29b in Wnt signaling in human colorectal cancer cells with implications in the treatment of colorectal cancer.

Frequent BRAF mutation in early-onset colorectal cancer in Taiwan: association with distinct clinicopathological and molecular features and poor clinical outcome

BACKGROUND

Occurrence of early-onset colorectal cancer (EOCRC) under the age of 30 is very rare and the molecular characteristics are poorly understood. A low BRAF mutation rate has been noted in several studies of EOCRC from Western countries.

AIMS

To determine the clinicopathological and molecular features of EOCRCs in Taiwan.

METHODS

KRAS/BRAF gene mutation, mismatch repair protein immunohistochemistry, microsatellite instability and CpG island methylation phenotype analyses were examined to determine the molecular characteristics of EOCRC.

RESULTS

Sixty-six patients with EOCRC at our hospital between 2000 and 2012 were studied. BRAF mutation was detected in 11 of the 59 tumours analysed (19%) and the rate was significantly higher than the overall BRAF mutation rate of colorectal cancer in patients older than 30 years (p<0.001). Clinically, 9 of 11 patients with BRAF-mutated tumours presented with advanced-stage diseases and they presented significantly more frequently with stage IV disease than those with BRAF wild-type tumours (p=0.042). Histologically, BRAF mutation was associated with a poorly differentiated histology, a serrated precursor polyp and focal signet ring cell differentiation (p=0.042, 0.008 and 0.008, respectively). None of the BRAF-mutated tumours was mismatch repair protein-deficient and/or microsatellite instability-high. Overall survival of patients with BRAF-mutated tumours was significantly worse than that of patients with BRAF wild-type tumours, despite adjustment for the disease stages and tumour differentiation.

CONCLUSIONS

BRAF mutation was frequent in EOCRCs in Taiwan and was associated with distinct clinicopathological and molecular features.

Genetic architecture of colorectal cancer

Colorectal cancer (CRC) is a complex disease that develops as a consequence of both genetic and environmental risk factors. A small proportion (3-5%) of cases arise from hereditary syndromes predisposing to early onset CRC as a result of mutations in over a dozen well defined genes. In contrast, CRC is predominantly a late onset 'sporadic' disease, developing in individuals with no obvious hereditary syndrome. In recent years, genome wide association studies have discovered that over 40 genetic regions are associated with weak effects on sporadic CRC, and it has been estimated that increasingly large genome wide scans will identify many additional novel genetic regions. Subsequent experimental validations have identified the causally related variant(s) in a limited number of these genetic regions. Further biological insight could be obtained through ethnically diverse study populations, larger genetic sequencing studies and development of higher throughput functional experiments. Along with inherited variation, integration of the tumour genome may shed light on the carcinogenic processes in CRC. In addition to summarising the genetic architecture of CRC, this review discusses genetic factors that modify environmental predictors of CRC, as well as examples of how genetic insight has improved clinical surveillance, prevention and treatment strategies. In summary, substantial progress has been made in uncovering the genetic architecture of CRC, and continued research efforts are expected to identify additional genetic risk factors that further our biological understanding of this disease. Subsequently these new insights will lead to improved treatment and prevention of colorectal cancer.

Systematic analysis of missed colorectal cancer cases and common pitfalls in diagnosis

BACKGROUND

Missed colorectal cancer on endoscopic or radiological investigations may delay diagnosis and impact outcome. This study audits incidence of previous investigations in patients with colorectal cancer, considers outcome in 'missed' cancer cases and examines the diagnostic pathway in the derived case series to identify common pitfalls in diagnosis.

METHODS

Patients diagnosed with colorectal cancer in 2011 at a single National Health Service (NHS) Trust were reviewed. Incidence of endoscopic and radiological investigations in the 3 years preceding diagnosis and outcome data were collected. Cases of prior investigation not leading to diagnosis were considered 'missed' cancers and survival compared with 'detected' cases. The diagnostic pathway in each 'missed' case was reviewed.

RESULTS

395 colorectal cancer cases were studied. Eighteen (4.6%) patients underwent previous investigation including colonoscopy (n=4), flexible sigmoidoscopy (n=5), barium enema (n=5) and diagnostic abdominal CT scan (n=12), median 708 days prior to diagnosis. Previous investigation predicted reduced overall and disease-free survival (HR 2.07, p=0.04 and HR 2.66, p<0.0001), after age and gender adjustment. Ten different categories termed 'pitfalls' were derived from analysis of the diagnostic pathway. These included CT scanning for abdominal pain without further investigation (n=7), rectosigmoid cancer following a previous diagnosis of diverticular disease (n=4) and incomplete diagnostic investigations without adequate follow-up (n=3).

CONCLUSIONS

A proportion of patients diagnosed with colorectal cancer have previously been investigated for gastrointestinal symptoms and survival appears reduced in these patients. Regular audit and analysis of previous investigations can identify common pitfalls in diagnosis, which should be used to inform training and improve practice.

Colorectal cancer screening: a global overview of existing programmes

Colorectal cancer (CRC) ranks third among the most commonly diagnosed cancers worldwide, with wide geographical variation in incidence and mortality across the world. Despite proof that screening can decrease CRC incidence and mortality, CRC screening is only offered to a small proportion of the target population worldwide. Throughout the world there are widespread differences in CRC screening implementation status and strategy. Differences can be attributed to geographical variation in CRC incidence, economic resources, healthcare structure and infrastructure to support screening such as the ability to identify the target population at risk and cancer registry availability. This review highlights issues to consider when implementing a CRC screening programme and gives a worldwide overview of CRC burden and the current status of screening programmes, with focus on international differences.

Aspirin use after diagnosis but not prediagnosis improves established colorectal cancer survival: a meta-analysis

OBJECTIVE

The objective of this meta-analysis was to systematically assess the survival benefit of aspirin use before or after diagnosis for patients with colorectal cancer (CRC).

DESIGN

Relevant studies were identified through searching PubMed, Embase and Cochrane databases before May 2014. Two investigators extracted data independently for baseline characteristics and outcomes from the included studies. Either a fixed-effects or a random-effects model was derived to composite the pooled HR for overall mortality and CRC-specific mortality of CRC.

RESULTS

Seven studies on postdiagnosis aspirin therapy and seven studies on prediagnosis aspirin use were finally included in this meta-analysis. The overall survival benefit associated with postdiagnosis aspirin use represented an HR of 0.84 (95% CI 0.75 to 0.94). This effect was observed both in colon cancer (HR=0.78, 95% CI 0.64 to 0.96) and in rectal cancer (HR=0.90, 95% CI 0.83 to 0.98). Besides, the survival benefit of postdiagnosis aspirin use appeared to be confined to those patients with positive prostaglandin endoperoxide synthase 2 (PTGS2, also known as cyclooxygenase-2, COX-2) expression (HR=0.65, 95% CI 0.50 to 0.85) and with mutated PIK3CA tumours (HR=0.58, 95% CI 0.37 to 0.90). Aspirin use postdiagnosis was not associated with CRC-specific mortality (HR=0.77, 95% CI 0.52 to 1.14). We observed no evidence of an association between prediagnosis aspirin use and CRC overall mortality (HR=1.01, 95% CI 0.96 to 1.06) or CRC-specific mortality (HR=0.93, 95% CI 0.82 to 1.05).

CONCLUSIONS

These findings provide further indication that postdiagnosis aspirin therapy improved CRC overall survival, especially for patients with positive PTGS2 (COX-2) expression and mutated PIK3CA tumours.

Molecular markers for colorectal cancer screening

Colorectal cancer (CRC), although a significant cause of morbidity and mortality worldwide, has seen a declining incidence and mortality in countries with programmatic screening. Faecal occult blood testing and endoscopic approaches are the predominant screening methods currently. The discovery of the adenoma-carcinoma sequence and a greater understanding of the genetic and epigenetic changes that drive the formation of CRC have contributed to innovative research to identify molecular markers for highly accurate, non-invasive screening tests for CRC. DNA, proteins, messenger RNA and micro-RNA have all been evaluated. The observation of tumour cell exfoliation into the mucocellular layer of the colonic epithelium and proven stability of DNA in a harsh stool environment make stool DNA a particularly promising marker. The development of a clinically useful stool DNA test has required numerous technical advances, including optimisation in DNA stabilisation, the development of assays with high analytical sensitivity, and the identification of specific and broadly informative molecular markers. A multitarget stool DNA test, which combines mutant and methylated DNA markers and a faecal immunochemical test, recently performed favourably in a large cross-sectional validation study and has been approved by the US Food and Drug Administration for the screening of asymptomatic, average-risk individuals. The ultimate way in which molecular marker screening assays will be used in clinical practice will require additional studies to determine optimal screening intervals, factors affecting compliance, management of false-positive results, and the use of these assays in high-risk populations, as well as other considerations.

Decreased expression of heat shock protein 20 in colorectal cancer and its implication in tumorigenesis

Heat shock protein 20 (HSP20), which is a member of the small heat shock protein family, is known to participate in many pathological processes, such as asthma, intimal hyperplasia, and insulin resistance. However, the function of HSP20 in cancer development is not yet fully understood. In this study, we identified HSP20 as a down-regulated protein in 20 resected colorectal cancer (CRC) specimens compared with their paired normal tissues. Because HSP20 proteins were barely detectable in HCT-116 cells (a human colorectal cancer cell line), recombinant adenovirus encoding HSP20 (Ad-HSP20) was used to induce HSP20 overexpression in HCT-116 cells. Infection of Ad-HSP20, but not control adenovirus (Ad-GFP), reduced viability, and induced massive apoptosis in a time-dependent manner. The forced expression of HSP20 enhanced caspase-3/7 activity and down-regulated the anti-apoptotic Bcl-xL and Bcl-2 mRNA and protein levels. In addition, immunohistochemical analysis of 94 CRC specimens for HSP20 protein showed that reduced HSP20 expression was related to advanced TNM stage, lymph node metastasis, and tumor recurrence. Our study shows, for the first time, that expression of the HSP20 protein has a pro-death role in colorectal cancer cells. Therefore, HSP20 may have value as a prognostic tumor marker and its overexpression might be a novel strategy for CRC therapy.

High Ki67 expression is an independent good prognostic marker in colorectal cancer

AIMS

To correlate Ki67 expression with outcome in colorectal cancer (CRC).

METHODS

Ki67 labelling index (Ki67LI) was analysed by immunohistochemistry on a tissue microarray containing 1800 CRCs. The results were compared with clinicopathological and molecular parameters.

RESULTS

Ki67LI was considered low in 26.3%, moderate in 56.7% and high in 17.0% of 1653 interpretable CRCs. High Ki67 expression was associated with low tumour stage (p<0.0001) and nodal status (p=0.0315), but not with tumour grade (p=0.8639), histological tumour type (p=0.1542) or tumour localisation, and was an independent prognosticator of favourable survival (p=0.0121). High Ki67 expression was also significantly associated with high-level nuclear β-catenin and p53 expression (p<0.0001 and p=0.0095, respectively).

CONCLUSIONS

In summary, our data show that high Ki67 expression in CRCs is associated with good clinical outcome. Ki67, p53 and β-catenin overexpression seem to be linked to CRC, and indicate a cellular state of high proliferative activity. Finally, our findings strongly argue for a clinical utility of Ki67 immunostaining as an independent prognostic biomarker in CRC.

Impact of preoperative serum albumin on 30-day mortality following surgery for colorectal cancer: a population-based cohort study

Objective

Surgery is the only potentially curable treatment for colorectal cancer (CRC), but it is hampered by high mortality. Human serum albumin (HSA) below 35 g/L is associated with poor overall prognosis in patients with CRC, but evidence regarding the impact on postoperative mortality is sparse.

Methods

We performed a population-based cohort study including patients undergoing CRC surgery in North and Central Denmark (1997–2011). We categorised patients according to HSA concentration measured 1–30 days prior to surgery date. We used the Kaplan-Meier method to compute 30-day mortality and Cox regression model to compute HRs as measures of the relative risk of death, controlling for potential confounders. We further stratified patients by preoperative conditions, including cancer stage, comorbidity level, and C reactive protein concentration.

Results

Of the 9339 patients undergoing first-time CRC surgery with preoperative HSA measurement, 26.4% (n=2464) had HSA below 35 g/L. 30-day mortality increased from 4.9% among patients with HSA 36–40 g/L to 26.9% among patients with HSA equal to or below 25 g/L, compared with 2.0% among patients with HSA above 40 g/L. The corresponding adjusted HRs increased from 1.75 (95% CI 1.25 to 2.45) among patients with HSA 36–40 g/L to 7.59 (95% CI 4.95 to 11.64) among patients with HSA equal to or below 25 g/L, compared with patients with HSA above 40 g/L. The negative impact associated with a decrement of HSA was found in all subgroups.

Conclusions

A decrement in preoperative HSA concentration was associated with substantial concentration-dependent increased 30-day mortality following CRC surgery.

Definition and taxonomy of interval colorectal cancers: a proposal for standardising nomenclature

OBJECTIVE

Interval colorectal cancers (interval CRCs), that is, cancers occurring after a negative screening test or examination, are an important indicator of the quality and effectiveness of CRC screening and surveillance. In order to compare incidence rates of interval CRCs across screening programmes, a standardised definition is required. Our goal was to develop an internationally applicable definition and taxonomy for reporting on interval CRCs.

DESIGN

Using a modified Delphi process to achieve consensus, the Expert Working Group on interval CRC of the Colorectal Cancer Screening Committee of the World Endoscopy Organization developed a nomenclature for defining and characterising interval CRCs.

RESULTS

We define an interval CRC as a "colorectal cancer diagnosed after a screening or surveillance exam in which no cancer is detected, and before the date of the next recommended exam". Guidelines and principles for describing and reporting on interval CRCs are provided, and clinical scenarios to demonstrate the practical application of the nomenclature are presented.

CONCLUSIONS

The Working Group on interval CRC of the World Endoscopy Organization endorses adoption of this standardised nomenclature. A standardised nomenclature will facilitate benchmarking and comparison of interval CRC rates across programmes and regions.

Post-colonoscopy colorectal cancer (PCCRC) rates vary considerably depending on the method used to calculate them: a retrospective observational population-based study of PCCRC in the English National Health Service

OBJECTIVE

Post-colonoscopy colorectal cancer (PCCRC) is a key quality indicator of colonoscopy. This study compares methods for defining PCCRC rates, proposes a new method of calculating them and quantifies them across the English National Health Service (NHS).

DESIGN

This retrospective observational population-based study involved all individuals with a first primary diagnosis of colorectal cancer made between 2001 and 2010 and treated in the English NHS. Previously published methods for deriving PCCRC rates were applied to the linked routine health data for this population to investigate the effect on the rate. A new method, based on the year of the colonoscopy rather than colorectal cancer diagnosis, was then used to calculate PCCRC rates.

RESULTS

Of 297,956 individuals diagnosed with colorectal cancer, a total of 94,648 underwent a colonoscopy in the 3 years prior to their diagnosis. The application of the published methods and exclusion criteria to the dataset produced significantly different PCCRC rates from 2.5% to 7.7%. The new method demonstrates that PCCRC rates within 3 years of colonoscopy (without exclusions) decreased in the English NHS over 8 years, falling from 10.6% to 7.3% for colonoscopies performed in 2001 and 2007 respectively.

CONCLUSIONS

The method used to determine PCCRC rates significantly affects findings with potential to substantially underestimate rates. To enable international benchmarking there needs to be a standardised method for defining PCCRC. This study proposes a new methodology using colonoscopy as a denominator and between 2001 and 2007 this method indicated an 8.6% PCCRC rate across the English NHS. It also demonstrated PCCRC rates have fallen over time.

Progeny from irradiated colorectal cancer cells acquire an EMT-like phenotype and activate Wnt/β-catenin pathway

Radiotherapy remains a major approach to adjuvant therapy for patients with advanced colorectal cancer, however, the fractionation schedules frequently allow for the repopulation of surviving tumors cells, neoplastic progression, and subsequent metastasis. The aim of the present study was to analyze the transgenerational effects induced by radiation and evaluate whether it could increase the malignant features on the progeny derived from irradiated parental colorectal cancer cells, Caco-2, HT-29, and HCT-116. The progeny of these cells displayed a differential radioresistance as seen by clonogenic and caspase activation assay and had a direct correlation with survivin expression as observed by immunoblotting. Immunofluorescence showed that the most radioresistant progenies had an aberrant morphology, disturbance of the cell-cell adhesion contacts, disorganization of the actin cytoskeleton, and vimentin filaments. Only the progeny derived from intermediary radioresistant cells, HT-29, reduced the E-cadherin expression and overexpressed β-catenin and vimentin with increased cell migration, invasion, and metalloprotease activation as seen by immunoblotting, wound healing, invasion, and metalloprotease activity assay. We also observed that this most aggressive progeny increased the Wnt/β-catenin-dependent TCF/LEF activity and underwent an upregulation of mesenchymal markers and downregulation of E-cadherin, as determined by qRT-PCR. Our results showed that the intermediate radioresistant cells can generate more aggressive cellular progeny with the EMT-like phenotype. The Wnt/β-catenin pathway may constitute an important target for new adjuvant treatment schedules with radiotherapy, with the goal of reducing the migratory and invasive potential of the remaining cells after treatment.

Grading lymph node metastasis: a feasible approach for prognostication of patients with stage III colorectal cancer

This study aimed to assess the clinicopathological significance of tumour differentiation of metastatic lymph node tissue in patients with American Joint Committee on Cancer (AJCC)/Union for International Cancer Control (UICC) stage III colorectal cancer. In a cohort of 145 patients, lymph node grades were G1 in 77 (53.1%), G2 in 41 (28.3%) and G3 in 27 (18.6%) cases, respectively. Despite differences in 77 (53.1%) cases, primary tumour and lymph node grade correlated significantly (Somer's D=0.639; p<0.001). Lymph node grade was significantly associated with N classification (p=0.009), tumour size (p=0.024) and lymphovascular invasion (p=0.004). Patients with lymph node grade G1 had better progression-free survival (p=0.031) and cancer-specific survival (p=0.008). Multivariable analysis identified lymph node grade as independent predictor of cancer-specific survival in this cohort. In conclusion, lymph node grade emerged as a promising novel prognostic variable for patients with AJCC/UICC stage III disease. Additional studies are warranted to validate this new finding.

Effectiveness, training and quality assurance of colonoscopy screening for colorectal cancer

Screening for colorectal cancer has been proven to be effective in reducing colorectal cancer incidence and mortality. While the precise benefit of screening exclusively by colonoscopy is not yet known, unarguably, the exam is central to the success of any screening programme. The test affords the opportunity to detect and resect neoplasia across the entire large bowel and is the definitive examination when other screening tests are positive. However, colonoscopy is invasive and often requires sedation as well as extensive bowel preparation, all of which puts the patient at risk. Furthermore, the test can technically be demanding and, unarguably, there is variation in how it is performed. This variation in performance has now been definitively linked to important outcome measures. For example, interval cancers are more common in low adenoma detectors as compared with high adenoma detectors. This review outlines the most current thinking regarding the effectiveness of colonoscopy as a screening tool. It also outlines key concepts to optimise its performance through robust quality assurance programmes and high-quality training.