Human embryoids: A new strategy of recreating the first steps of embryonic development in vitro

Molecular mechanisms surrounding early human embryonic events such as blastocyst formation, implantation, and the specification of the body axes are some of the most attractive research questions of developmental biology today. A knowledge on the detailed signaling landscape underlying these critical events in the human could impact the way we treat early pregnancy disorders and infertility, and considerably advance our abilities to make precise human tissues in a lab. However, owing to ethical, technical, and policy restrictions, research on early human embryo development historically stalled behind animal models. The rapid progress in 3D culture of human embryonic stem cells over the past years created an opportunity to overcome this critical challenge. We review recently developed strategies of making 3D models of the human embryo built from embryonic stem cells, which we refer to as embryoids. We focus on models aimed at reconstituting the 3D epithelial characteristics of the early human embryo, namely the intra/extraembryonic signaling crosstalk, tissue polarity, and embryonic cavities. We identify distinct classes of embryoids based on whether they explicitly include extraembryonic tissues and we argue for the merit of compromising on certain aspects of embryo mimicry in balancing the experimental feasibility with ethical considerations. Human embryoids open gates toward a new field of synthetic human embryology, allowing to study the long inaccessible stages of early human development at unprecedented detail.

Comparing physical mechanisms for membrane curvature-driven sorting of BAR-domain proteins

Protein enrichment at specific membrane locations in cells is crucial for many cellular functions. It is well-recognized that the ability of some proteins to sense membrane curvature contributes partly to their enrichment in highly curved cellular membranes. In the past, different theoretical models have been developed to reveal the physical mechanisms underlying curvature-driven protein sorting. This review aims to provide a detailed discussion of the two continuous models that are based on the Helfrich elasticity energy, (1) the spontaneous curvature model and (2) the curvature mismatch model. These two models are commonly applied to describe experimental observations of protein sorting. We discuss how they can be used to explain the curvature-induced sorting data of two BAR proteins, amphiphysin and centaurin. We further discuss how membrane rigidity, and consequently the membrane curvature generated by BAR proteins, could influence protein organization on the curved membranes. Finally, we address future directions in extending these models to describe some cellular phenomena involving protein sorting.

In vitro modeling of early mammalian embryogenesis

Synthetic embryology endeavors to use stem cells to recapitulate the first steps of mammalian development that define the body axes and first stages of fate assignment. Well-engineered synthetic systems provide an unparalleled assay to disentangle and quantify the contributions of individual tissues as well as the molecular components driving embryogenesis. Experiments using a mixture of mouse embryonic and extra-embryonic stem cell lines show a surprising degree of self-organization akin to certain milestones in the development of intact mouse embryos. To further advance the field and extend the mouse results to human, it is crucial to develop a better control of the assembly process as well as to establish a deeper understanding of the developmental state and potency of cells used in experiments at each step of the process. We review recent advances in the derivation of embryonic and extraembryonic stem cells, and we highlight recent efforts in reconstructing the structural and signaling aspects of embryogenesis in three-dimensional tissue cultures.

Curving Cells Inside and Out: Roles of BAR Domain Proteins in Membrane Shaping and Its Cellular Implications

Many cellular processes rely on precise and timely deformation of the cell membrane. While many proteins participate in membrane reshaping and scission, usually in highly specialized ways, Bin/amphiphysin/Rvs (BAR) domain proteins play a pervasive role, as they not only participate in many aspects of cell trafficking but also are highly versatile membrane remodelers. Subtle changes in the shape and size of the BAR domain can greatly impact the way in which BAR domain proteins interact with the membrane. Furthermore, the activity of BAR domain proteins can be tuned by external physical parameters, and so they behave differently depending on protein surface density, membrane tension, or membrane shape. These proteins can form 3D structures that mold the membrane and alter its liquid properties, even promoting scission under various circumstances.As such, BAR domain proteins have numerous roles within the cell. Endocytosis is among the most highly studied processes in which BAR domain proteins take on important roles. Over the years, a more complete picture has emerged in which BAR domain proteins are tied to almost all intracellular compartments; examples include endosomal sorting and tubular networks in the endoplasmic reticulum and T-tubules. These proteins also have a role in autophagy, and their activity has been linked with cancer. Here, we briefly review the history of BAR domain protein discovery, discuss the mechanisms by which BAR domain proteins induce curvature, and attempt to settle important controversies in the field. Finally, we review BAR domain proteins in the context of a cell, highlighting their emerging roles in cell signaling and organelle shaping.

Evaluating the reliability of a tool to measure the quality of gastrointestinal multidisciplinary cancer conferences: A generalizability study

Background

Lamb et al. developed the metric for the observation of decision-making tool (MTB-MODe) to evaluate the quality of urologic multidisciplinary cancer conferences (MCCs) in the United Kingdom. We used generalizability theory to assess the reliability of a modified version of MTB-MODe in a North American context. Specifically, we wished to determine if the tool could distinguish between high- and low-quality MCC decision-making.

Methods

Two assessors independently evaluated two MCCs (MCC1, MCC2) using the modified MTB-MODe. Generalizability theory was used to assess overall tool reliability and to identify sources most likely to contribute to variance in reliability scores. A total of 60 cases were evaluated.

Results

The overall reliability scores of MCC1 and MCC2 were 0.72 and 0.74, respectively. Inter-rater reliability scores were reasonable (>0.55) and raters did not contribute significantly to variance in reliability scores. Internal consistency of the individual MTB-MODe items was low, demonstrating that items were not highly correlated.

Conclusions

The MTB-MODe reliably assessed the quality of individual MCC cases. Raters did not contribute significantly to reliability scores, suggesting that the tool can be successfully implemented using a single rater. Low internal consistency of the MTB-MODe items demonstrates that the tool can be used to provide feedback on individual tool items. Such data can be used by stakeholders to help improve MCC quality.

Organizing membrane-curving proteins: the emerging dynamical picture

Lipid membranes play key roles in cells, such as in trafficking, division, infection, remodeling of organelles, among others. The key step in all these processes is creating membrane curvature, typically under the control of many anchored, adhered or included proteins. However, it has become clear that the membrane itself can mediate the interactions among proteins to produce highly ordered assemblies. Computer simulations are ideally suited to investigate protein organization and the dynamics of membrane remodeling at near-micron scales, something that is extremely challenging to tackle experimentally. We review recent computational efforts in modeling protein-caused membrane deformation mechanisms, specifically focusing on coarse-grained simulations. We highlight work that exposed the membrane-mediated ordering of proteins into lines, meshwork, spirals and other assemblies, in what seems to be a very generic mechanism driven by a combination of short and long-ranged forces. Modulating the mechanical properties of membranes is an underexplored signaling mechanism in various processes deserving of more attention in the near future.

Synthetic embryology: controlling geometry to model early mammalian development

Differentiation of embryonic stem cells in vitro is an important tool in dissecting and understanding the mechanisms that govern early embryologic development. In recent years, there has been considerable progress in creating organoids that model gastrulation, neurulation or organogenesis. However, one of the key challenges is reproducibility. Geometrically confining stem cell colonies considerably improves reproducibility and provides quantitative control over differentiation and tissue shape. Here, we review recent advances in controlling the two-dimensional or three-dimensional organization of cells and the effect on differentiation phenotypes. Improved methods of geometrical control will allow for an even more detailed understanding of the mechanisms underlying embryologic development and will eventually pave the way for the highly reproducible generation of specific tissue types.

Long-Range Organization of Membrane-Curving Proteins

Biological membranes have a central role in mediating the organization of membrane-curving proteins, a dynamic process that has proven to be challenging to probe experimentally. Using atomic force microscopy, we capture the hierarchically organized assemblies of Bin/amphiphysin/Rvs (BAR) proteins on supported lipid membranes. Their structure reveals distinct long linear aggregates of proteins, regularly spaced by up to 300 nm. Employing accurate free-energy calculations from large-scale coarse-grained computer simulations, we found that the membrane mediates the interaction among protein filaments as a combination of short- and long-ranged interactions. The long-ranged component acts at strikingly long distances, giving rise to a variety of micron-sized ordered patterns. This mechanism may contribute to the long-ranged spatiotemporal control of membrane remodeling by proteins in the cell.

Pulling Membrane Nanotubes from Giant Unilamellar Vesicles

The reshaping of the cell membrane is an integral part of many cellular phenomena, such as endocytosis, trafficking, the formation of filopodia, etc. Many different proteins associate with curved membranes because of their ability to sense or induce membrane curvature. Typically, these processes involve a multitude of proteins making them too complex to study quantitatively in the cell. We describe a protocol to reconstitute a curved membrane in vitro, mimicking a curved cellular structure, such as the endocytic neck. A giant unilamellar vesicle (GUV) is used as a model of a cell membrane, whose internal pressure and surface tension are controlled with micropipette aspiration. Applying a point pulling force on the GUV using optical tweezers creates a nanotube of high curvature connected to a flat membrane. This method has traditionally been used to measure the fundamental mechanical properties of lipid membranes, such as bending rigidity. In recent years, it has been expanded to study how proteins interact with membrane curvature and the way they affect the shape and the mechanics of membranes. A system combining micromanipulation, microinjection, optical tweezers, and confocal microscopy allows measurement of membrane curvature, membrane tension, and the surface density of proteins, concurrently. From these measurements, many important mechanical and morphological properties of the protein-membrane system can be inferred. In addition, we lay out a protocol of creating GUVs in the presence of physiological salt concentration, and a method of quantifying the surface density of proteins on the membrane from fluorescence intensities of labeled proteins and lipids.

The mesoscopic membrane with proteins (MesM-P) model

We present the Mesoscopic Membrane with Proteins (MesM-P) model, an extension of a previously developed elastic membrane model for mesoscale simulations of lipid membranes. MesM-P employs a discrete mesoscopic quasi-particle approach to model protein-facilitated shape and topology changes of the lipid membrane on length and time scales inaccessible to all-atom and quasimolecular coarse-grained molecular dynamics simulations. We investigate the ability of MesM-P to model the behavior of large lipid vesicles as a function of bound protein density. We find four distinct mechanisms for protein aggregation on the surface of the membrane, depending on membrane stiffness and protein spontaneous curvature. We also establish a connection between MesM-P and the results of higher resolution coarse-grained molecular dynamics simulations.

Friction Mediates Scission of Tubular Membranes Scaffolded by BAR Proteins

Membrane scission is essential for intracellular trafficking. While BAR domain proteins such as endophilin have been reported in dynamin-independent scission of tubular membrane necks, the cutting mechanism has yet to be deciphered. Here, we combine a theoretical model, in vitro, and in vivo experiments revealing how protein scaffolds may cut tubular membranes. We demonstrate that the protein scaffold bound to the underlying tube creates a frictional barrier for lipid diffusion; tube elongation thus builds local membrane tension until the membrane undergoes scission through lysis. We call this mechanism friction-driven scission (FDS). In cells, motors pull tubes, particularly during endocytosis. Through reconstitution, we show that motors not only can pull out and extend protein-scaffolded tubes but also can cut them by FDS. FDS is generic, operating even in the absence of amphipathic helices in the BAR domain, and could in principle apply to any high-friction protein and membrane assembly.

Embryoids, organoids and gastruloids: new approaches to understanding embryogenesis

Cells have an intrinsic ability to self-assemble and self-organize into complex and functional tissues and organs. By taking advantage of this ability, embryoids, organoids and gastruloids have recently been generated in vitro, providing a unique opportunity to explore complex embryological events in a detailed and highly quantitative manner. Here, we examine how such approaches are being used to answer fundamental questions in embryology, such as how cells self-organize and assemble, how the embryo breaks symmetry, and what controls timing and size in development. We also highlight how further improvements to these exciting technologies, based on the development of quantitative platforms to precisely follow and measure subcellular and molecular events, are paving the way for a more complete understanding of the complex events that help build the human embryo.

Physical basis of some membrane shaping mechanisms

In vesicular transport pathways, membrane proteins and lipids are internalized, externalized or transported within cells, not by bulk diffusion of single molecules, but embedded in the membrane of small vesicles or thin tubules. The formation of these 'transport carriers' follows sequential events: membrane bending, fission from the donor compartment, transport and eventually fusion with the acceptor membrane. A similar sequence is involved during the internalization of drug or gene carriers inside cells. These membrane-shaping events are generally mediated by proteins binding to membranes. The mechanisms behind these biological processes are actively studied both in the context of cell biology and biophysics. Bin/amphiphysin/Rvs (BAR) domain proteins are ideally suited for illustrating how simple soft matter principles can account for membrane deformation by proteins. We review here some experimental methods and corresponding theoretical models to measure how these proteins affect the mechanics and the shape of membranes. In more detail, we show how an experimental method employing optical tweezers to pull a tube from a giant vesicle may give important quantitative insights into the mechanism by which proteins sense and generate membrane curvature and the mechanism of membrane scission.This article is part of the themed issue 'Soft interfacial materials: from fundamentals to formulation'.

Collaborative case conferences in rectal cancer: case series in a tertiary care centre

BACKGROUND

In many hospitals, resource barriers preclude the use of preoperative multidisciplinary cancer conferences (mccs) for consecutive patients with cancer. Collaborative cancer conferences (cccs) are modified mccs that might overcome such barriers.

METHODS

We established a ccc at an academic tertiary care centre to review preoperative plans for patients with rectal cancer. Attendees included only surgeons who perform colorectal cancer procedures and a radiologist with expertise in cross-sectional imaging. Individual reviews began with the primary surgeon presenting the case information and initial treatment recommendations. Cross-sectional images were then reviewed, the case was discussed, and consensus on ccc-treatment recommendations was achieved. Outcomes for the present study were changes in treatment recommendations defined as "major" (that is, redirection of patient to preoperative radiation from straight-to-surgery or uncertain plan, or redirection of the patient to straight-to-surgery from preoperative radiation or plan uncertain) or as "minor" (that is, referral to a multidisciplinary cancer clinic, request additional tests, change type of neoadjuvant therapy, change type of surgery). Chart reviews provided relevant patient, tumour, and treatment information.

RESULTS

Between September 2011 and September 2012, 101 rectal cancer patients were discussed at a ccc. Of the 35 management plans (34.7%) that were changed as a result, 8 had major changes, and 27 had minor changes. Available patient and tumour factors did not predict for a change in treatment recommendation.

CONCLUSIONS

Preoperative cccs at a tertiary-care centre changed treatment recommendations for one third of patients with rectal cancer. Given that no specific factor predicted for a treatment plan change, it is likely prudent that all rectal cancer patients undergo some form of collaborative review.

Eastern Canadian Colorectal Cancer Consensus Conference 2013: Emerging Therapies in the Treatment of Pancreatic, Rectal, and Colorectal Cancers

The annual Eastern Canadian Colorectal Cancer Consensus Conference held in Montreal, Quebec, 17–19 October 2013, marked the 10-year anniversary of this meeting that is attended by leaders in medical, radiation, and surgical oncology. The goal of the attendees is to improve the care of patients affected by gastrointestinal malignancies. Topics discussed during the conference included pancreatic cancer, rectal cancer, and metastatic colorectal cancer.

When Physics Takes Over: BAR Proteins and Membrane Curvature

Cell membranes become highly curved during membrane trafficking, cytokinesis, infection, immune response, or cell motion. Bin/amphiphysin/Rvs (BAR) domain proteins with their intrinsically curved and anisotropic shape are involved in many of these processes, but with a large spectrum of modes of action. In vitro experiments and multiscale computer simulations have contributed in identifying a minimal set of physical parameters, namely protein density on the membrane, membrane tension, and membrane shape, that control how bound BAR domain proteins behave on the membrane. In this review, we summarize the multifaceted coupling of BAR proteins to membrane mechanics and propose a simple phase diagram that recapitulates the effects of these parameters.

Celebrating Soft Matter's 10th anniversary: screening of the calcium-induced spontaneous curvature of lipid membranes

Lipid membranes are key regulators of cellular function. An important step in membrane-related phenomena is the reshaping of the lipid bilayer, often induced by binding of macromolecules. Numerous experimental and simulation efforts have revealed that calcium, a ubiquitous cellular messenger, has a strong impact on the phase behavior, structural properties, and the stability of membranes. Yet, it is still unknown the way calcium and lipid interactions affect their macroscopic mechanical properties. In this work, we studied the interaction of calcium ions with membrane tethers pulled from giant unilamellar vesicles, to quantify the mechanical effect on the membrane. We found that calcium imposes a positive spontaneous curvature on negatively charged membranes, contrary to predictions we made based on the proposed atomic structure. Surprisingly, this effect vanishes in the presence of physiologically relevant concentrations of sodium chloride. Our work implies that calcium may be a trigger for membrane reshaping only at high concentrations, in a process that is robustly screened by sodium ions.

Endophilin-A2 functions in membrane scission in clathrin-independent endocytosis

During endocytosis, energy is invested to narrow the necks of cargo-containing plasma membrane invaginations to radii at which the opposing segments spontaneously coalesce, thereby leading to the detachment by scission of endocytic uptake carriers. In the clathrin pathway, dynamin uses mechanical energy from GTP hydrolysis to this effect, assisted by the BIN/amphiphysin/Rvs (BAR) domain-containing protein endophilin. Clathrin-independent endocytic events are often less reliant on dynamin, and whether in these cases BAR domain proteins such as endophilin contribute to scission has remained unexplored. Here we show, in human and other mammalian cell lines, that endophilin-A2 (endoA2) specifically and functionally associates with very early uptake structures that are induced by the bacterial Shiga and cholera toxins, which are both clathrin-independent endocytic cargoes. In controlled in vitro systems, endoA2 reshapes membranes before scission. Furthermore, we demonstrate that endoA2, dynamin and actin contribute in parallel to the scission of Shiga-toxin-induced tubules. Our results establish a novel function of endoA2 in clathrin-independent endocytosis. They document that distinct scission factors operate in an additive manner, and predict that specificity within a given uptake process arises from defined combinations of universal modules. Our findings highlight a previously unnoticed link between membrane scaffolding by endoA2 and pulling-force-driven dynamic scission.

Reshaping biological membranes in endocytosis: crossing the configurational space of membrane-protein interactions

Lipid membranes are highly dynamic. Over several decades, physicists and biologists have uncovered a number of ways they can change the shape of membranes or alter their phase behavior. In cells, the intricate action of membrane proteins drives these processes. Considering the highly complex ways proteins interact with biological membranes, molecular mechanisms of membrane remodeling still remain unclear. When studying membrane remodeling phenomena, researchers often observe different results, leading them to disparate conclusions on the physiological course of such processes. Here we discuss how combining research methodologies and various experimental conditions contributes to the understanding of the entire phase space of membrane-protein interactions. Using the example of clathrin-mediated endocytosis we try to distinguish the question 'how can proteins remodel the membrane?' from 'how do proteins remodel the membrane in the cell?' In particular, we consider how altering physical parameters may affect the way membrane is remodeled. Uncovering the full range of physical conditions under which membrane phenomena take place is key in understanding the way cells take advantage of membrane properties in carrying out their vital tasks.

Molecular and thermodynamic insights into the conformational transitions of Hsp90

Hsp90, the most abundant cellular protein, has been implicated in numerous physiological and pathological processes. It controls protein folding and prevents aggregation, but it also plays a role in cancer and neurological disorders, making it an attractive drug target. Experimental efforts have demonstrated its remarkable structural flexibility and conformational complexity, which enable it to accommodate a variety of clients, but have not been able to provide a detailed molecular description of the conformational transitions. In our molecular dynamics simulations, Hsp90 underwent dramatic structural rearrangements into energetically favorable stretched and compact states. The transitions were guided by key electrostatic interactions between specific residues of opposite subunits. Nucleotide-bound structures showed the same conformational flexibility, although ADP and ATP seemed to potentiate these interactions by stabilizing two different closed conformations. Our observations may explain the difference in dynamic behavior observed among Hsp90 homologs, and the atomic resolution of the conformational transitions helps elucidate the complex chaperone machinery.

Clustering and stability of functional lower gastrointestinal symptom after enteric infection

BACKGROUND

Current diagnostic criteria for functional gut disorder are based on symptom clusters observed after sporadic onset. It remains unclear whether symptoms group similarly in functional disorders of postinfectious etiology. We utilized observational data from the Walkerton Health Study (WHS) to: (i) determine groupings of functional gastrointestinal symptoms among patients exposed to acute gastroenteritis (GE), and (ii) assess the stability of these symptoms grouping over time.

METHODS

WHS participants 16 years of age and older at the time of the outbreak were included, if they had completed a modified Talley's Bowel Disease Questionnaire (BDQ) and responded 'yes' to a screening question as to whether they had experienced abdominal pain in the last 2 weeks. Exploratory factor analysis (EFA) using tetrachoric correlations was undertaken to identify symptom constructs. Hierarchical cluster analysis using the k-means method was used to create cluster groupings of patients based on these factors. Confirmatory factors analysis using responses to BDQ questionnaire administered at 4, 6, and 8 years after the outbreak was performed to assess stability of symptom domains over time.

KEY RESULTS

A total of 773 participants were eligible for inclusion [62.2% female, mean age 43.1 years (SD = 16.9)]. Eighty-four percent were exposed to acute GE during the outbreak. Two symptom groupings of abdominal pain with either diarrhea or constipation together explained 85.7% of the total variance. Cluster analysis identified four patients groupings based on these factors. These clusters could be qualitatively described as diarrhea- and constipation-predominant, mixed bowel pattern, and no predominance of bowel movements abnormalities. Results of the confirmatory factor analysis validating symptom domains identified in Year 1 showed that the baseline model was acceptable at 4 and 6 years after the outbreak and approached acceptability at 8 years. Values of root mean square error of approximation were 0.071 (90% CI: 0.053, 0.089) at 4 and 0.071 (90% CI: 0.049, 0.092) at 6 years and 0.089 (90% CI: 0.065, 0.114) at 8 years.

CONCLUSIONS & INFERENCES

The majority of subjects with postinfectious functional bowel disorders belong to groups with symptoms of abdominal pain and either diarrhea or constipation. These symptom groupings were stable across time.

Mechanism and thermodynamics of ligand binding to auxin amidohydrolase

BrILL2 is catalytically the most efficient auxin amidohydrolase from Brassica rapa, playing a key role in auxin metabolism by catalyzing its release from amino acid conjugates. Auxins, with the most abundant representative indole-acetic acid ([1H-indol-3-yl]-acetic acid, IAA), are a group of plant hormones that in very small concentrations regulate ubiquitin-mediated degradation of transcription regulators. Kinetic studies on BrILL2 showed that it hydrolyzes alanine conjugates of IAA and of its larger analogues, indole-propionic acid (3-[1H-indol-3-yl]-propionic acid, IPA) and indole-butyric acid (4-[1H-indol-3-yl]-butyric acid, IBA). Structurally, BrILL2 belongs to the largest known family of metallopeptidases (M20) that share a recognizable 3D structure, characterized by two perpendicular domains. Its members have been implicated in numerous biochemical processes and have been found across all species sequenced to date. Here, molecular dynamics simulations were carried out to study structural and thermodynamic properties of ligand binding to BrILL2. A conformational change was captured in multiple copies of 10 ns long simulations, described by a rigid body movement of the two domains, and its associated key interactions between residues were examined. For the three substrates, complexes in two possible binding modes were recreated, along with a single binding mode for the putative substrate tryptophanyl-alanine (Trp-Ala), which were subsequently simulated in multiple copies of 10 ns long simulations. Thermodynamic calculations were used to assess their binding affinities and explain the selectivity toward the longer ligands. Based on the results, a possible route for the reaction is proposed.

Outcomes following a limited approach to radiotherapy in rectal cancer

BACKGROUND

Variation in the use of neoadjuvant and adjuvant radiotherapy for rectal cancer suggests an opportunity to avoid it in all but patients at highest risk of local recurrence.

METHODS

Between 1 July 1999 and 1 February 2006, patients with primary rectal cancer were treated by a single surgeon operating at McMaster University, Hamilton, Ontario, Canada. Digital rectal examination and pelvic computed tomography were used to determine whether the mesorectal margin was threatened by tumour and thus whether preoperative radiotherapy would be needed. The study outcome was local tumour recurrence.

RESULTS

Forty-six (48 per cent) of 96 patients received preoperative radiation therapy. The median follow-up was 4·2 years. Tumours were fixed or tethered in 31 (67 per cent) of the 46 irradiated patients. In contrast, no tumour was fixed in unirradiated patients and only ten (20 per cent) of the 50 tumours were tethered. The proportion of patients with stage I or II tumours based on final pathology was similar: 61 per cent (28 of 46) and 56 per cent (28 of 50) in irradiated and unirradiated groups respectively (P = 0·287). There were four (9 per cent) and two (4 per cent) local recurrences among irradiated and unirradiated patients respectively (P = 0·422).

CONCLUSION

Limiting preoperative radiotherapy in rectal cancer to patients with a threatened circumferential margin does not compromise patient outcome.

Rectal cancer surgery and regional lymph nodes

In patients with rectal cancer, the status of regional or mesorectal lymph nodes is central to both tumor staging and predicting local and distant recurrence. The importance of mesorectal lymph nodes in rectal cancer should inform treatment decisions around pre-operative diagnostic imaging, surgical techniques, pathologic assessment, and the use of radiation therapy.

Patterns of surgical care for uterine cancers in Ontario

OBJECTIVES

To facilitate the planning of future resources for cancer services in Ontario, Cancer Care Ontario commissioned an evaluation of operative services delivered for uterine cancer.

METHODS

Women with an incident diagnosis of a uterine malignancy were identified from 1 April 2003 to 31 March 2004 using the Ontario Cancer Registry. Record linkages were created to other provincial health databases such as the Ontario Health Insurance Plan.

RESULTS

Uterine cancer affected 1,436 women. Disease specific rates of cancer were higher in rural areas and those from the highest income quintiles. Surgery occurred in 94.7% of women. Use of surgery did not appear to vary by SEC, urban/rural residence or LHIN. Gynecologists conducted 76.1% of the operations. Lymphadenectomy took place in 18.7% of women. Lymphadenectomy rates were highest in gynecologic oncologists (43.3%). All women were assessed by CXR. Radiation therapy consults were preformed in half of the women with uterine cancer but treatment was only delivered in half of those seen. Medical oncologists saw about 6.3% of women with uterine cancers.

CONCLUSIONS

There appear to be variations in incidence rates of uterine cancer with disease being more frequent in those of the highest SES. In two-thirds of the population, surgery is delivered in the region where the patient lives. Subspecialty care from gynecologic oncologists was provided to one-third of women. Rates of lymphadenectomy as part of a surgical attempt to assess disease spread appear low. These pilot data would be enhanced with further information such as comorbidity, treatment intent (palliative/curative), histology, grade and stage.

Patterns of care for the initial management of cervical cancer in Ontario

OBJECTIVE

To facilitate the planning of resources for cancer services in Ontario, Cancer Care Ontario commissioned an evaluation of operative services delivered for cervical cancer.

METHODS

Women with an incident diagnosis of cervical cancer were identified from 1 April, 2003 to 31 March, 2004 using the Ontario Cancer Registry. Record linkages were created to other provincial health databases such as the Ontario Health Insurance Plan.

RESULTS

There were 513 incident cases. Disease-specific rates of cancer were higher in rural areas and those from lower income quintiles. Forty-three percent of women had no surgery. Use of surgery did not appear to vary by SEC, urban/rural residence or LHIN. Women of younger age were more like to receive surgery for cervical cancer. Gynecologists conducted 63% of the operations. Gynecologics were most likely to complete a lymphadenectomy (70.3%). All women were assessed by CXR. Only 22% of women had a CT scan of the abdomen and pelvis. Radiation consults were performed in half of the women with cervix cancer but treatment was only delivered to half of those seen. Medical oncologists saw about 10% of women with cervical cancers.

CONCLUSIONS

There appear to be variations in incidence rates of cervical cancer, with cancers being more frequent in rural areas. In two-thirds of the population, surgery is performed in the region where the patient lives. Subspecialty care from gynecologic oncologists was provided to one-third of women. These preliminary data would be enhanced with further information such as comorbidity, treatment intent (palliative/curative), histology, grade and stage.

Patterns of care in the initial management of women with vulvar cancers in Ontario

BACKGROUND

To facilitate the planning of future resources for cancer services in Ontario, Cancer Care Ontario commissioned an evaluation of operative services delivered for vulvar cancer.

METHODS

Women with an incident diagnosis of vulvar malignancy were identified from 1, April 2003 to 31 March, 2004 using the Ontario Cancer Registry. Record linkages were created to other provincial health databases such as the Ontario Health Insurance Plan.

RESULTS

Vulvar cancers affected 148 women. Disease specific rates of cancer were higher in rural areas and in women in the lower income quintiles. No surgery occurred in 17.6% of women. Use of surgery did not appear to vary by urban/rural residence or LHIN. Ontario's 17 gynecologic oncologists performed 75% of the surgeries. Groin lymphadenectomy rate was 52.8%. Surgery was performed in the LHIN of residence for 41% of women. All women were assessed by CXR. CT scan of the abdomen and pelvis occurred in 77%. MRIs were done infrequently. Radiation consults were preformed in half of the women with vulvar cancer but treatment was only delivered in half of those seen. Medical oncologists saw about 10% of women with gynecologic cancers.

CONCLUSIONS

There appear to be variations in incidence rates of vulvar cancer with disease being more frequent in rural areas. Subspecialty care from gynecologic oncologists was provided to 75% of women. Rates of lymphadenectomy as part of a surgical attempt occurred in 52.8% of women. These data would be enhanced with further information such as comorbidity, treatment intent (palliative/curative), histology, grade and stage.

Patterns of care in the initial management of women with ovarian cancer in Ontario

BACKGROUND

To facilitate the planning of future resources for cancer services in Ontario, Cancer Care Ontario commissioned an evaluation of operative services delivered for ovarian cancers. The affected population was characterized in terms of age, location of residence, and SES. Operative care delivery was described in terms of inpatient verses outpatient access, LHIN of treatment, surgical specialist providing treatment, and specific operative procedures. The investigations and consults around the time of diagnosis are described.

METHODS

Women with an incident diagnosis of an ovarian malignancy were identified from 1 April 2003 to 31 March 2004 using the Ontario Cancer Registry. Record linkages were created to other provincial health databases such as the Ontario Health Insurance Plan.

RESULTS

We report on 963 women with ovarian cancer. The incidence of disease was related to increasing age. Access to surgery correlated with the highest income quintile, urban residence and LHIN. Twenty-seven percent of women did not have surgery for their ovarian cancer. Women of younger age were more like to receive surgery for ovarian cancer. Use of a laparotomy for biopsy was most common in community hospital (40%). Lymphadenectomy rates were low overall; rates for gynecologic oncologists were 13.2%. All women were assessed by CXR. CT scan of abdomen and pelvis occurred in 77% of women. MRIs were done infrequently. Medical oncology were involved in 26.6% of the patients.

CONCLUSIONS

These pilot data would be enhanced with further information such as comorbidity, treatment intent (palliative/curative), histology, grade and stage. However, there are clear referral patterns to academic centres which means a need for manpower and hospital resources to deal with this population.

Screening cancer patients for clinical trial eligibility: A randomized study

6529

Background: The overall proportion of cancer patients enrolled into clinical trials is undesirably low. Research suggests many aspects of the recruitment process can be improved. The present study was undertaken to evaluate the benefit of identifying potentially eligible (PE) clinical trial patients for physicians. Methods: Consenting physicians were randomized to 26 weeks of screening support or not, and were then crossed-over to the other strategy for a second 26-week time period. A computer program reviewed new patient consultations to identify PE clinical trial patients. Physicians receiving support were provided with written individualized details of patient eligibility for trials prior to their medical consultation. The primary outcome of interest was the difference, by physician, in the number of patients who were approached for consent to enter a clinical trial. Results: Thirty-six physicians participated in the 52-week study. 5051 consultations were screened in a blinded fashion, 2,376 when physicians had support and 2,675 when they did not. 939 of 2,376 (39.5%) consultations were identified as involving PE patients when physicians were receiving support, and 1,061 of 2,675 (39.7%) when without. The primary outcome of the study, by physician, did not demonstrate a statistically significant improvement, with 4.1 patients per physician without vs. 4.7 patients with screening support (p>0.05). Secondary analysis demonstrated that the overall proportion of patients approached with the clinical trial option increased from 149/2,675 (5.6%) to 169/2,376 (7.1%) with screening support (Chi-square, p=0.024) and that the number of patients that entered a clinical trial also increased from 60/2,675 (2.2%) to 83/2,376 (3.5%) (Chi-square, p=0.007). Conclusions: This study suggests that individualized patient screening for clinical trial eligibility may be useful to improve the numbers of patients approached to consider clinical trials. The number of new patients that entered clinical trials remained low, and ongoing research to facilitate improvements is required.

No significant financial relationships to disclose.

Invasive vulvar cancer in a woman with human immunodeficiency virus: case report and review of the literature

BACKGROUND

: HIV is associated with a decrease in cellular immunity which allows for persistence of high-risk HPV types and this can predispose the woman to dysplasia or cancer of the gynecologic tract.

CASE

: We present a case of Stage 3 vulvar cancer in a 33-year-old HIV positive woman. The patient was treated with primary radiation; unfortunately there was persistent disease. Exenterative surgery was planned but abandoned due to a positive presacral node.

CONCLUSION

: The optimal treatment of advanced vulvar cancer in HIV positive patients remains unclear given the small number of cases reported in the literature. Lessons from the anal cancer literature may help inform the care of vulvar cancer patients given the comparable high prevalence of this disease in the patients infected with HIV.

Cone dystrophy phenotype associated with a frameshift mutation (M280fsX291) in the alpha-subunit of cone specific transducin (GNAT2)

AIM

To describe the phenotype of a three generation consanguineous Pakistani family containing six individuals with autosomal recessive cone dystrophy caused by mutation in GNAT2.

METHODS

Five of the six affected individuals underwent an ophthalmological examination, electrodiagnostic testing, fundus photography, autofluorescence imaging, and detailed psychophysical testing.

RESULTS

All five examined patients had a history of nystagmus from infancy, photophobia, defective colour vision, and poor visual acuity. The nystagmus in three of the individuals had lessened with time. Fundus examination revealed an abnormal foveal appearance, without frank atrophy or pigmentation. Electroretinography (ERG) revealed absent ISCEV cone flicker ERGs with some preservation of responses to short wavelength stimulation. Rod ERGs showed no definite abnormality, but maximal (mixed rod-cone) response a-wave amplitudes were mildly subnormal. Rudimentary residual colour vision was detected in three individuals. There is clinical evidence of progressive visual acuity reduction in two older individuals.

CONCLUSION

Mutation in the alpha-subunit of cone specific transducin (GNAT2) is characterised by an infantile onset cone dystrophy. Some affected individuals may show deterioration of visual acuity with time.

Optimal preoperative assessment and surgery for rectal cancer may greatly limit the need for radiotherapy

BACKGROUND

Radiation is being used increasingly in the management of patients with rectal cancer. Over the past decade the Basingstoke Colorectal Research Unit has combined precision total mesorectal excision with the highly selective use of preoperative radiotherapy.

METHODS

One hundred and fifty consecutive patients who underwent major surgical excision for cancers of all stages comprised the study group. Preoperative clinical assessment was based largely on tumour size, fixation and distance from the anal verge. Only preoperative radiotherapy was considered and this only for tumours judged to be at high risk of mesorectal fascia involvement.

RESULTS

During a 5-year period 35 of 150 patients were selected for preoperative irradiation. In the non-irradiated patients the local recurrence rate after a median follow-up period of 870 (range 51-1903) days was 2.6 per cent (three of 115 patients), compared with 17.1 per cent (six of 35 patients) in those chosen for irradiation. Sixty patients (52.2 per cent) who were not irradiated were node positive. The local recurrence rate for the whole group was 6.0 per cent.

CONCLUSION

The great majority of patients undergoing major excision for rectal cancer can be managed without radiation therapy if the preoperative assessment of the mesorectal fascia and surgery are performed optimally.

A snapshot of waiting times for cancer surgery provided by surgeons affiliated with regional cancer centres in Ontario

BACKGROUND

There is evidence that delays in treatment result in increased psychosocial morbidity for patients diagnosed with cancer. We evaluated waiting times for care among cancer patients treated by surgeons affiliated with regional cancer centres in Ontario.

METHODS

Dates for 5 key events related to the surgical management of a patient with cancer were collected by a convenience sample of surgeons who treat breast, gynecologic, colorectal, head and neck, thoracic and urologic cancers. The key events were initial referral, first surgical visit, main treatment decision, major surgery and receipt of postoperative pathology report. The surgeons were also asked to judge the appropriateness of the waiting times for the intervals studied and to identify factors associated with inappropriate delays.

RESULTS

A total of 62 surgeons affiliated with 8 regional cancer centres participated; data were collected for 1456 patients who underwent assessment and whose surgical visit occurred between Jan. 31 and May 31, 2000. The median waiting time from referral to first visit was 11.0 days, from first visit to treatment decision 0.0 days, from treatment decision to surgery 20.0 days and from surgery to receipt of the pathology report 8.0 days. The median waiting times for the 2 summary intervals (referral to surgery and referral to receipt of the pathology report) were 37.0 and 48.0 days respectively. The waiting times varied by cancer type; for example, the median time from referral to surgery varied from 29.0 days for colorectal cancers to 64.0 days for urologic cancers. The same interval varied from 19.0 to 43.0 days by treatment centre. The waiting times did not vary substantially by patient age. The surgeons judged that 344 (37.2%) of the 925 patients with dates for the referral-to-surgery interval had inappropriately long waiting times. They indicated that contributing factors to these inappropriate waits were shortage of operating room time (in 181 cases), lack of other resources such as diagnostic tests or allied health personnel (in 156) and patient preference or circumstance (in 28) (factors were not mutually exclusive).

INTERPRETATION

Many of the patients with cancer seen by surgeons affiliated with regional cancer centres in Ontario may be experiencing significant delays in the assessment and treatment of their cancer.

Hospital procedure volume and teaching status do not influence treatment and outcome measures of rectal cancer surgery in a large general population

A clear benefit of increased hospital procedure volume or teaching hospital status on outcomes of rectal cancer surgery has yet to be shown. Few have examined treatment differences that may lead to varying outcomes. This study assessed the impact of hospital procedure volume and teaching status on both treatment and outcome measures of rectal cancer surgery in a large general population. Data were obtained for 1072 incident cases of rectal adenocarcinoma diagnosed in 1990 from Ontario, Canada, and treated with a major resection. Hospitals were classified by teaching status and procedure volume. Pathology reports were examined for 418 procedures. Abdominoperineal resections accounted for 31.0% of all procedures. There were no clinically significant differences in treatment measures, operative mortality, and long-term survival among the hospital groups according to both univariate and multivariate analyses. In conclusion, the absence of a hospital volume or teaching status effect on treatment and outcome measures suggests that for rectal cancer surgery in Ontario, centralization of procedures into high-volume or teaching centers is unlikely to improve surgical quality.