A subgroup of light-driven sodium pumps with an additional Schiff base counterion.

Light-driven sodium pumps (NaRs) are unique ion-transporting microbial rhodopsins. The major group of NaRs is characterized by an NDQ motif and has two aspartic acid residues in the central region essential for sodium transport. Here we identify a subgroup of the NDQ rhodopsins bearing an additional glutamic acid residue in the close vicinity to the retinal Schiff base. We thoroughly characterize a member of this subgroup, namely the protein ErNaR from Erythrobacter sp. HL-111 and show that the additional glutamic acid results in almost complete loss of pH sensitivity for sodium-pumping activity, which is in contrast to previously studied NaRs. ErNaR is capable of transporting sodium efficiently even at acidic pH levels. X-ray crystallography and single particle cryo-electron microscopy reveal that the additional glutamic acid residue mediates the connection between the other two Schiff base counterions and strongly interacts with the aspartic acid of the characteristic NDQ motif. Hence, it reduces its pKa. Our findings shed light on a subgroup of NaRs and might serve as a basis for their rational optimization for optogenetics.

Interobserver variation in the classification of tumor deposits in rectal cancer-is the use of histopathological characteristics the way to go?

The focus on lymph node metastases (LNM) as the most important prognostic marker in colorectal cancer (CRC) has been challenged by the finding that other types of locoregional spread, including tumor deposits (TDs), extramural venous invasion (EMVI), and perineural invasion (PNI), also have significant impact. However, there are concerns about interobserver variation when differentiating between these features. Therefore, this study analyzed interobserver agreement between pathologists when assessing routine tumor nodules based on TNM 8. Electronic slides of 50 tumor nodules that were not treated with neoadjuvant therapy were reviewed by 8 gastrointestinal pathologists. They were asked to classify each nodule as TD, LNM, EMVI, or PNI, and to list which histological discriminatory features were present. There was overall agreement of 73.5% (κ 0.38, 95%-CI 0.33-0.43) if a nodal versus non-nodal classification was used, and 52.2% (κ 0.27, 95%-CI 0.23-0.31) if EMVI and PNI were classified separately. The interobserver agreement varied significantly between discriminatory features from κ 0.64 (95%-CI 0.58-0.70) for roundness to κ 0.26 (95%-CI 0.12-0.41) for a lone arteriole sign, and the presence of discriminatory features did not always correlate with the final classification. Since extranodal pathways of spread are prognostically relevant, classification of tumor nodules is important. There is currently no evidence for the prognostic relevance of the origin of TD, and although some histopathological characteristics showed good interobserver agreement, these are often non-specific. To optimize interobserver agreement, we recommend a binary classification of nodal versus extranodal tumor nodules which is based on prognostic evidence and yields good overall agreement.

Current and Emerging Biomarkers and Imaging Modalities for Nonalcoholic Fatty Liver Disease: Clinical and Research Applications.

PURPOSE: Nonalcoholic fatty liver disease (NAFLD) is a metabolic disorder that frequently coexists with obesity, metabolic syndrome, and type 2 diabetes. The NAFLD spectrum, ranging from hepatic steatosis to nonalcoholic steatohepatitis, fibrosis, and cirrhosis, can be associated with long-term hepatic (hepatic decompensation and hepatocellular carcinoma) and extrahepatic complications. Diagnosis of NAFLD requires detection of liver steatosis with exclusion of other causes of chronic liver disease. Screening for NAFLD and identification of individuals at risk of end-stage liver disease represent substantial challenges that have yet to be met. NAFLD affects up to 25% of adults, yet only a small proportion will progress beyond steatosis to develop advanced disease (steatohepatitis and fibrosis) associated with increased morbidity and mortality. Identification of this cohort has required the gold standard liver biopsy, which is both invasive and expensive. The use of serum biomarkers and noninvasive imaging techniques is an area of significant clinical relevance. This narrative review outlines current and emerging technologies for the diagnosis of NAFLD, nonalcoholic steatohepatitis, and hepatic fibrosis. METHODS: We reviewed the literature using PubMed and reviewed national and international guidelines and conference proceedings to provide a comprehensive overview of the evidence. FINDINGS: Significant advances have been made during the past 2 decades that have enhanced noninvasive assessment of NAFLD without the need for liver biopsy. For the detection of steatosis, abdominal ultrasonography remains the first-line investigation, although a controlled attenuation parameter using transient elastography is more sensitive. For detecting fibrosis, noninvasive serum markers of fibrosis and algorithms based on routine biochemistry are available, in addition to transient elastography. These techniques are well validated and have been incorporated into national and international screening guidelines. These approaches have facilitated more judicious use of liver biopsy but are yet to entirely replace it. Although serum biomarkers present a pragmatic and widely available screening approach for NAFLD in large population-based studies, magnetic resonance imaging techniques offer the benefit of achieving high degrees of accuracy in disease grading, tumor staging, and assessing therapeutic response. IMPLICATIONS: This diagnostic clinical and research field is rapidly evolving; increasingly combined applications of biomarkers and transient elastography or imaging of selective (intermediate or high risk) cases are being used for clinical and research purposes. Liver biopsy remains the gold standard investigation, particularly in the context of clinical trials, but noninvasive options are emerging, using multimodality assessment, that are quicker, more tolerable, more widely available and have greater patient acceptability.

Variation in histopathological assessment and association with surgical quality indicators following oesophagectomy.

BACKGROUND: Histopathological outcomes, such as lymph node yield and margin positivity, are used to benchmark and assess surgical centre quality, and are reported annually by the National Oesophago-Gastric Cancer Audit (NOGCA) in England and Wales. The variation in pathological specimen assessment and how this affects these outcomes is not known. METHODS: A survey of practice was circulated to all tertiary oesophagogastric cancer centres across England and Wales. Questions captured demographic data, and information on how specimens were prepared and analysed. National performance data were retrieved from the NOGCA. Survey results were compared for tertiles of lymph node yield, and circumferential and longitudinal margins. RESULTS: Survey responses were received from 32 of 37 units (86 per cent response rate), accounting for 93.1 per cent of the total oesophagectomy volume in England and Wales. Only 5 of 32 units met or exceeded current guidelines on specimen preparation according to the Royal College of Pathologists guidelines. There was wide variation in how centres defined positive (R1) margins, and how margins and lymph nodes were assessed. Centres with the highest nodal yield were more likely to use systematic fat blocking, and to re-examine specimens when the initial load was low. Systematic blocking of lesser curve fat resulted in significantly higher rates of patients with at least 15 lymph nodes examined (91.4 versus 86.5 per cent; P = 0.027). CONCLUSION: Preparation and histopathological assessment of specimens varies significantly across institutions. This challenges the validity of currently used surgical quality metrics for oesophageal and other tumours.

A Phase II Study of Biodegradable Stents Plus Palliative Radiotherapy in Oesophageal Cancer.

AIMS: Self-expanding metal stents provide rapid improvement of dysphagia in oesophageal cancer but are associated with complications. The aim of the present study was to test the effectiveness of an alternative treatment of combining biodegradable stents with radiotherapy. MATERIALS AND METHODS: A Simon two-stage single-arm prospective phase II trial design was used to determine the efficacy of biodegradable stents plus radiotherapy in patients with dysphagia caused by oesophagus cancer who were unsuitable for radical treatment. Fourteen patients were recruited and data from 12 were included in the final analyses. RESULTS: Five of 12 patients met the primary end point: one stent-related patient death; four further interventions for dysphagia within 16 weeks of stenting (41.7%, 95% confidence interval 15.2-72.3%). The median time to a 10-point deterioration of quality of life was 2.7 weeks. Nine patients died within 52 weeks of registration. The median time to death from any cause was 15.0 weeks (95% confidence interval 9.6-not reached). CONCLUSION: The high re-intervention observed, which met the pre-defined early stopping criteria, meant that the suggested alternative treatment was not sufficiently effective to be considered for a larger scale trial design. Further work is needed to define the place of biodegradable stents in the management of malignant oesophageal strictures.

Systemic neoadjuvant chemotherapy in modern pancreatic cancer treatment: a systematic review and meta-analysis.

BACKGROUND: Pancreatic ductal adenocarcinoma remains a disease with a poor prognosis despite advances in surgery and systemic therapies. Neoadjuvant therapy strategies are a promising alternative to adjuvant chemotherapy. However, their role remains controversial. This meta-analysis aims to clarify the benefits of neoadjuvant therapy in resectable pancreatic ductal adenocarcinoma. METHODS: Eligible studies were identified from MEDLINE, Embase, Web of Science and the Cochrane Library. Studies comparing neoadjuvant therapy with a surgery first approach (with or without adjuvant therapy) in resectable pancreatic ductal adenocarcinoma were included. The primary outcome assessed was overall survival. A random-effects meta-analysis was performed, together with pooling of unadjusted Kaplan-Meier curve data. RESULTS: A total of 533 studies were identified that analysed the effect of neoadjuvant therapy in pancreatic ductal adenocarcinoma. Twenty-seven studies were included in the final data synthesis. Meta-analysis suggested beneficial effects of neoadjuvant therapy with prolonged survival compared with a surgery-first approach, (hazard ratio 0.72, 95% confidence interval 0.69-0.76). In addition, R0 resection rates were significantly higher in patients receiving neoadjuvant therapy (relative risk 0.51, 95% confidence interval 0.47-0.55). Individual patient data analysis suggested that overall survival was better for patients receiving neoadjuvant therapy (P = 0.008). CONCLUSIONS: Current evidence suggests that neoadjuvant chemotherapy has a beneficial effect on overall survival in resectable pancreatic ductal adenocarcinoma in comparison with upfront surgery and adjuvant therapy. Further trials are needed to address the need for practice change.

Differences in the Calculated Transvenous Pressure Drop between Chronic Hydrocephalus and Idiopathic Intracranial Hypertension.

BACKGROUND AND PURPOSE: Chronic hydrocephalus is associated with dilated ventricles despite a normal intracranial pressure. In idiopathic intracranial hypertension, the ventricles are normal despite an elevated intracranial pressure. This apparent paradox has largely remained unexplained. It is suggested that a pressure difference between the superficial and deep venous territories of the brain could account for the variation between the 2 diseases. The purpose of this paper is to investigate the cause of this pressure difference. MATERIALS AND METHODS: Using MR phase-contrast imaging, we calculated the hydraulic diameters of the sagittal and straight sinuses in 21 patients with hydrocephalus, 20 patients with idiopathic intracranial hypertension, and 20 age-matched controls. The outflow resistance of each sinus was estimated using the Poiseuille equation. The outflow pressure was estimated using the flow data. A smaller subset of the patients with hydrocephalus had these studies repeated after successful shunt insertion. RESULTS: In hydrocephalus, the sagittal sinuses were 21% smaller than those in controls (P < .001); the straight sinuses were not significantly different. In idiopathic intracranial hypertension, both sinuses were not significantly different from those of controls. The pressure drop from the sagittal sinus to the end of the straight sinus was elevated by 1.2 mm Hg in hydrocephalus (P = .001) but not significantly different from that in controls in idiopathic intracranial hypertension. Shunt insertion dilated the sagittal sinuses in hydrocephalus, leaving them 18% larger than normal and eliminating the transvenous pressure change. CONCLUSIONS: There is a transvenous pressure difference in hydrocephalus that is absent in idiopathic intracranial hypertension. This difference is eliminated by shunt insertion. The findings may have a bearing on ventricular dilation.

British Society of Gastroenterology position statement on serrated polyps in the colon and rectum

Serrated polyps have been recognised in the last decade as important premalignant lesions accounting for between 15% and 30% of colorectal cancers. There is therefore a clinical need for guidance on how to manage these lesions; however, the evidence base is limited. A working group was commission by the British Society of Gastroenterology (BSG) Endoscopy section to review the available evidence and develop a position statement to provide clinical guidance until the evidence becomes available to support a formal guideline. The scope of the position statement was wide-ranging and included: evidence that serrated lesions have premalignant potential; detection and resection of serrated lesions; surveillance strategies after detection of serrated lesions; special situations-serrated polyposis syndrome (including surgery) and serrated lesions in colitis; education, audit and benchmarks and research questions. Statements on these issues were proposed where the evidence was deemed sufficient, and re-evaluated modified via a Delphi process until >80% agreement was reached. The Grading of Recommendations, Assessment, Development and Evaluations (GRADE) tool was used to assess the strength of evidence and strength of recommendation for finalised statements. Key recommendation: we suggest that until further evidence on the efficacy or otherwise of surveillance are published, patients with sessile serrated lesions (SSLs) that appear associated with a higher risk of future neoplasia or colorectal cancer (SSLs ≥10 mm or serrated lesions harbouring dysplasia including traditional serrated adenomas) should be offered a one-off colonoscopic surveillance examination at 3 years (weak recommendation, low quality evidence, 90% agreement).

Conjugal amyotrophic lateral sclerosis: a case report from Scotland.

BACKGROUND: Conjugal amyotrophic lateral sclerosis is rare, with significant effects on psychological and care needs. We report a case of conjugal amyotrophic lateral sclerosis disease from central Scotland. This case is particularly unusual as both patients were diagnosed within an 18-month period and experienced the disease simultaneously, with similar symptomatology and progression. CASE PRESENTATION: Patient A was a 71-year-old man who presented with unilateral arm weakness and wasting. Patient B was a 68-year-old woman who presented with unilateral shoulder and elbow weakness. Diagnosis of amyotrophic lateral sclerosis was made within a few months of presentation in both cases, based on typical clinical symptomatology together with supportive neurophysiological testing. Interventions included enteral feeding and non-invasive ventilation. The time period between symptom onset and death was 5 years for Patient A and 3.5 years for Patient B. CONCLUSION: This case illustrates two main points: the care issues surrounding cases of conjugal neurological disease, and the psychological issues in these patients. There are significant care issues arising when co-habiting couples both develop severe functionally limiting neurological diseases at the same time. The more slowly progressive nature of Patient A's disease may be at least partially explained by the support he was able to receive from Patient B before she developed symptoms. Secondly, there are important psychological effects of living with someone with the same - but more advanced - progressive and incurable neurological disease. Thus, Patient B was reluctant to have certain interventions that she had observed being given to her husband. Lastly, no plausible shared environmental risk factors were identified, implying that the co-occurrence of ALS in this couple was a random association.

Maintenance of polygenic sex determination in a fluctuating environment: an individual-based model.

R. A. Fisher predicted that individuals should invest equally in offspring of both sexes, and that the proportion of males and females produced (the primary sex ratio) should evolve towards 1:1 when unconstrained. For many species, sex determination is dependent on sex chromosomes, creating a strong tendency for balanced sex ratios, but in other cases, multiple autosomal genes interact to determine sex. In such cases, the maintenance of multiple sex-determining alleles at multiple loci and the consequent among-family variability in sex ratios presents a puzzle, as theory predicts that such systems should be unstable. Theory also predicts that environmental influences on sex can complicate outcomes of genetic sex determination, and that population structure may play a role. Tigriopus californicus, a copepod that lives in splash-pool metapopulations and exhibits polygenic and environment-dependent sex determination, presents a test case for relevant theory. We use this species as a model for parameterizing an individual-based simulation to investigate conditions that could maintain polygenic sex determination. We find that metapopulation structure can delay the degradation of polygenic sex determination and that periods of alternating frequency-dependent selection, imposed by seasonal fluctuations in environmental conditions, can maintain polygenic sex determination indefinitely.

Role of chemoradiotherapy in oesophageal cancer -- adjuvant and neoadjuvant therapy.

Despite low postoperative mortality rates, the long-term outcomes from surgical-based treatment for oesophageal cancer remain poor. Chemoradiotherapy (CRT), either given before surgical resection as neoadjuvant therapy or after resection as adjuvant therapy, has been postulated to improve these outcomes. This systematic review examines the evidence for these approaches. The evidence for postoperative radiotherapy is limited and conclusions are difficult, but it may have a role in patients at high risk of local relapse (positive margins). The addition of chemotherapy is recommended when possible. Patient selection is important due to the associated toxicities. The evidence for neoadjuvant treatment is stronger and based on the current evidence neoadjuvant CRT can be recommended as a treatment approach in T2-T4, N1-3 oesophageal cancer for both adenocarcinoma and squamous cell carcinoma, but further work is needed to establish its superiority over neoadjuvant chemotherapy alone, particularly for adenocarcinoma. We recommend that further studies divide the two histologies and they should be treated as two separate diseases.

Additive genetic variance and developmental plasticity in growth trajectories in a wild cooperative mammal.

Individual variation in growth is high in cooperative breeders and may reflect plastic divergence in developmental trajectories leading to breeding vs. helping phenotypes. However, the relative importance of additive genetic variance and developmental plasticity in shaping growth trajectories is largely unknown in cooperative vertebrates. This study exploits weekly sequences of body mass from birth to adulthood to investigate sources of variance in, and covariance between, early and later growth in wild meerkats (Suricata suricatta), a cooperative mongoose. Our results indicate that (i) the correlation between early growth (prior to nutritional independence) and adult mass is positive but weak, and there are frequent changes (compensatory growth) in post-independence growth trajectories; (ii) among parameters describing growth trajectories, those describing growth rate (prior to and at nutritional independence) show undetectable heritability while associated size parameters (mass at nutritional independence and asymptotic mass) are moderately heritable (0.09 ≤ h(2) < 0.3); and (iii) additive genetic effects, rather than early environmental effects, mediate the covariance between early growth and adult mass. These results reveal that meerkat growth trajectories remain plastic throughout development, rather than showing early and irreversible divergence, and that the weak effects of early growth on adult mass, an important determinant of breeding success, are partly genetic. In contrast to most cooperative invertebrates, the acquisition of breeding status is often determined after sexual maturity and strongly impacted by chance in many cooperative vertebrates, who may therefore retain the ability to adjust their morphology to environmental changes and social opportunities arising throughout their development, rather than specializing early.

Is there a need for postoperative follow-up after routine urogynaecological procedures? Patients will self-present if they have problems.

INTRODUCTION AND HYPOTHESIS: The value of outpatient appointments for postoperative review has been questioned for many years, and the surgeon practice around this issue is varied. The aim of this study, as part of a larger study assessing postoperative follow-up, was to assess how many patients self-present to their general practitioner (GP) or the emergency department after surgery for urogynaecology procedures. METHODS: A retrospective observational study of postoperative urogynaecology patients between 2007 and 2012 was performed using the British Society of Urogynaecology (BSUG) database to identify patients. These records were correlated with hospital and GP records to assess whether any patient was seen postoperatively for a procedure-related problem. RESULTS: There were 244 patients with complete data on the BSUG database, of whom 25 (10 %) presented to hospital/secondary care in the year following their surgery; only three of these were admitted for problems related to their surgery. There was a response rate of 70 % from GPs for access to their records. This represented 171 patients, 90 of whom (52.3 %) presented to their GP within a year of surgery mostly for a minor procedure-related event: 11 of these were re-referred to secondary care, and the remainder were treated in the community. CONCLUSIONS: The most important aspect of patient care is safety, and this should not be compromised if, for example, postoperative review were to be moved to primary care. As expected, this study shows that patients will self-present if they have problems postoperatively.

Lower gastrointestinal endoscopy: guidance on indications for biopsy.

Lower gastrointestinal endoscopy is a commonly undertaken procedure and has assumed even greater prominence with the inception of the NHS Bowel Cancer Screening Programme (BCSP). Workloads are also constantly increasing within histopathology departments and this has led to a need for workload management by laboratories. Advanced endoscopic techniques now allow for targeted biopsies within settings such as inflammatory bowel disease surveillance and the BCSP. In this article, we provide guidance to the endoscopist for optimal biopsy protocols that are designed to maximise the chance of a subsequent histopathological examination providing definitive results and to reduce the number of unnecessary biopsies, in which histopathology is unlikely to deliver clinically useful information. The majority of the article focuses on biopsy taking within a defined range of clinical situations that are commonly encountered by endoscopists.

Social structure mediates environmental effects on group size in an obligate cooperative breeder, Suricata suricatta.

Population dynamics in group-living species can be strongly affected both by features of sociality per se and by resultant population structure. To develop a mechanistic understanding of population dynamics in highly social species we need to investigate how processes within groups, processes linking groups, and external drivers act and interact to produce observed patterns. We model social group dynamics in cooperatively breeding meerkats, Suricata suricatta, paying attention to local demographic as well as dispersal processes. We use generalized additive models to describe the influence of group size, population density, and environmental conditions on demographic rates for each sex and stage, and we combine these models into predictive and individual-based simulation models of group dynamics. Short-term predictions of expected group size and simulated group trajectories over the longer term agree well with observations. Group dynamics are characterized by slow increases during the breeding season and relatively sharp declines during the pre-breeding season, particularly after dry years. We examine the demographic mechanisms responsible for environmental dependence. While individuals appear more prone to emigrate after dry years, seasons of low rainfall also cause reductions in reproductive output that produce adult-biased age distributions in the following dispersal season. Adult subordinates are much more likely to disperse or be evicted than immature individuals, and demographic structure thus contributes to crashes in group size. Our results demonstrate the role of social structure in characterizing a population's response to environmental variation. We discuss the implications of our findings for the population dynamics of cooperative breeders and population dynamics generally.

Oesophageal Chemoradiotherapy in the UK--current practice and future directions.

The SCOPE 1 trial closed to recruitment in early 2012 and has demonstrably improved the quality of UK radiotherapy. It has also shown that there is an enthusiastic upper gastrointestinal clinical oncology community that can successfully complete trials and deliver high-quality radiotherapy. Following on from SCOPE 1, this paper, authored by a consensus of leading UK upper gastrointestinal radiotherapy specialists, attempts to define current best practice and the questions to be answered by future clinical studies. The two main roles for chemoradiotherapy (CRT) in the management of potentially curable oesophageal cancer are definitive (dCRT) and neoadjuvant (naCRT). The rates of local failure after dCRT are consistently high, showing the need to evaluate more effective treatments, both in terms of optimal local and systemic therapeutic components. This will be the primary objective of the next planned UK dCRT trial and here we discuss the role of dose escalation and systemic therapeutic options that will form the basis of that trial. The publication of the Dutch 'CROSS' trial of naCRT has shown that this pre-operative approach can both be given safely and offer a significant survival benefit over surgery alone. This has led to the development of the UK NeoSCOPE trial, due to open in 2013. There will be a translational substudy to this trial and currently available data on the role of biomarkers in predicting response to therapy are discussed. Postoperative reporting of the pathology specimen is discussed, with recommendations for the NeoSCOPE trial. Both of these CRT approaches may benefit from recent developments, such as positron emission tomography/computed tomography and four-dimensional computed tomography for target volume delineation, planning techniques such as intensity-modulated radiotherapy and 'type b' algorithms and new treatment verification methods, such as cone-beam computed tomography. These are discussed here and recommendations made for their use.

Comparing virtual with conventional microscopy for the consensus diagnosis of Barrett's neoplasia in the AspECT Barrett's chemoprevention trial pathology audit.

AIMS: To compare the diagnostic accuracy of conventional versus virtual microscopy for the diagnosis of Barrett's neoplasia. METHODS AND RESULTS: Sixty-one biopsies from 35 ASPirin Esomeprazole ChemopreventionTrial (AspECT) trial patients were given a Barrett's neoplasia score (1-5) by a panel of five pathologists using conventional microscopy. Thirty-three biopsies positive for neoplasia were digitized and rescored blindly by virtual microscopy. Diagnostic reliability was compared between conventional and virtual microscopy using Fleiss' kappa. There was substantial reliability of diagnostic agreement (κ = 0.712) scoring the 61 biopsies and moderate agreement scoring the subgroup of 33 'positive' biopsies with both conventional microscopy (κ = 0.598) and virtual microscopy (κ = 0.436). Inter-observer diagnostic agreement between two pathologists by virtual microscopy was substantial (κ = 0.76). Comparison of panel consensus neoplasia scores between conventional and virtual microscopy was almost perfect (κ = 0.8769). However, with virtual microscopy there was lowering of the consensus neoplasia score in nine biopsies. CONCLUSIONS: Diagnostic agreement with virtual microscopy compares favourably with conventional microscopy in what is recognized to be a challenging area of diagnostic practice. However, this study highlights possible limitations for this method in the primary diagnostic setting.

Colorectal cancer staging using TNM 7: is it time to use this new staging system?

The authors audited pathological colorectal cancer staging according to tumour node metastasis (TNM) 7 and using TNM 5 as a gold standard. 144 consecutive colorectal cancer resection specimens were staged prospectively using both TNM 5 and TNM 7 criteria during routine reporting by specialist gastrointestinal pathologists within a single institution. The pN stage remained the same under both systems apart from the required subclassification of pN1 and pN2 under TNM 7. The TNM 7 pN1c category was used in only 3% of cases. All cases staged as pT4 underwent reversal of pT4 subclassification using TNM 7 compared with TNM 5. A previous study revealed stage migration from pN1 to pN2 in 32.6% of cases under TNM 7 compared with TNM 5. The difference in frequency of pN stage migration between this study and our audit suggests that the application of TNM 7 to the assessment of discontinuous/satellite tumour foci is subject to significant inter-observer variability.