Hypertension as a predictor of advanced colorectal cancer outcome and cetuximab treatment response

Background

Adrenergic receptor stimulation is involved in the development of hypertension (htn) and has been implicated in cancer progression and dissemination of metastases in various tumours, including colon cancer. Adrenergic antagonists such as beta-blockers (bbs) demonstrate inhibition of invasion and migration in colon cancer cell lines and have been associated with decreased mortality in colorectal cancer (crc). We examined the association of baseline htn and bb use with overall (os) and progression-free survival (pfs) in patients with pretreated, chemotherapy refractory, metastatic crc (mcrc). We also examined baseline htn as a predictor of cetuximab efficacy.

Methods

Using data from the Canadian Cancer Trials Group co.17 study [cetuximab vs. best supportive care (bsc)], we coded baseline htn and use of anti-htn medications, including bbs, for 572 patients. The chi-square test was used to assess the associations between those variables and baseline characteristics. Cox regression models were used for univariate and multivariate analyses of os and pfs by htn diagnosis and bb use.

Results

Baseline htn, bb use, and anti-htn medication use were not found to be prognostic for improved os. Baseline htn and bb use were not significant predictors of cetuximab benefit.

Conclusions

In chemorefractory mcrc, neither baseline htn nor bb use is a significant prognostic factor. Baseline htn and bb use are not predictive of cetuximab benefit. Further investigation to determine whether baseline htn or bb use have a similarly insignificant impact on prognosis in patients receiving earlier lines of treatment remains warranted.

Remediating doctors' performance to restore patient safety: a realist review protocol

INTRODUCTION

Underperformance by doctors poses a risk to patient safety. Remediation is an intervention designed to remedy underperformance and return a doctor to safe practice. Remediation is widely used across healthcare systems globally, and has clear implications for both patient safety and doctor retention. Yet, there is a poor evidence base to inform remediation programmes. In particular, there is a lack of understanding as to why and how a remedial intervention may work to change a doctor's practice. The aim of this research is to identify why, how, in what contexts, for whom and to what extent remediation programmes for practising doctors work to support patient safety.

METHODS AND ANALYSIS

Realist review is an approach to evidence synthesis that seeks to develop programme theories about how an intervention works to produce its effects. The initial search strategy will involve: database and grey literature searching, citation searching and contacting authors. The evidence search will be extended as the review progresses and becomes more focused on the development of specific aspects of the programme theory. The development of the programme theory will involve input from a stakeholder group consisting of professional experts in the remediation process and patient representatives. Evidence synthesis will use a realist logic of analysis to interrogate data in order to develop and refine the initial programme theory into a more definitive realist programme theory of how remediation works. The study will follow and be reported according to Realist And Meta-narrative Evidence Syntheses-Evolving Standards (RAMESES).

ETHICS AND DISSEMINATION

Ethical approval is not required. Our dissemination strategy will include input from our stakeholder group. Customised outputs will be developed using the knowledge-to-action cycle framework, and will be targeted to: policy-makers; education providers and regulators, the National Health Service, doctors and academics.

PROSPERO REGISTRATION NUMBER

CRD42018088779.

The International Landscape of Medical Licensing Examinations: A Typology Derived From a Systematic Review

BACKGROUND

National licensing examinations (NLEs) are large-scale examinations usually taken by medical doctors close to the point of graduation from medical school. Where NLEs are used, success is usually required to obtain a license for full practice. Approaches to national licensing, and the evidence that supports their use, varies significantly across the globe. This paper aims to develop a typology of NLEs, based on candidacy, to explore the implications of different examination types for workforce planning.

METHODS

A systematic review of the published literature and medical licensing body websites, an electronic survey of all medical licensing bodies in highly developed nations, and a survey of medical regulators.

RESULTS

The evidence gleaned through this systematic review highlights four approaches to NLEs: where graduating medical students wishing to practice in their national jurisdiction must pass a national licensing exam before they are granted a license to practice; where all prospective doctors, whether from the national jurisdiction or international medical graduates, are required to pass a national licensing exam in order to practice within that jurisdiction; where international medical graduates are required to pass a licensing exam if their qualifications are not acknowledged to be comparable with those students from the national jurisdiction; and where there are no NLEs in operation. This typology facilitates comparison across systems and highlights the implications of different licensing systems for workforce planning.

CONCLUSION

The issue of national licensing cannot be viewed in isolation from workforce planning; future research on the efficacy of national licensing systems to drive up standards should be integrated with research on the implications of such systems for the mobility of doctors to cross borders.

Multiple breath washout in pediatric patients after lung transplantation

Forced expiratory volume in 1 second (FEV₁ ) from spirometry is the most commonly used parameter to detect early allograft dysfunction after lung transplantation (LTx). There are concerns regarding its sensitivity. Nitrogen-multiple breath washout (N₂ -MBW) is sensitive at detecting early global (lung clearance index [LCI]) and acinar (S_acin ) airway inhomogeneity. We investigated whether N₂ -MBW indices indicate small airways pathology after LTx in children with stable spirometry. Thirty-seven children without bronchiolitis obliterans syndrome [BOS] at a median of 1.6 (0.6-3.0) years after LTx underwent N₂ -MBW and spirometry, 28 of those on 2 occasions (≤6 months apart) during clinically stable periods. Additional longitudinal data (11 and 8 measurements, respectively) are provided from 2 patients with BOS. In patients without BOS, LCI and S_acin were significantly elevated compared with healthy controls. LCI was abnormal at the 2 test occasions in 81% and 71% of patients, respectively, compared with 30% and 39% of patients with abnormal FEV₁ /forced vital capacity (FVC). Correlations of LCI with FEV₁ /FVC (r = 0.1, P = .4) and FEV₁ (r = -0.1, P = .6) were poor. N₂ -MBW represents a sensitive and reproducible tool for the early detection of airways pathology in stable transplant recipients. Moreover, indices were highly elevated in both patients with BOS. Spirometry and LCI showed poor correlation, indicating distinct and complementary physiologic measures.

Prospective randomized trial of neoadjuvant chemotherapy during the 'wait period' following preoperative chemoradiotherapy for rectal cancer: results of the WAIT trial

AIM

The aim was to determine whether the addition of additional cycles of chemotherapy during the 'wait period' following neoadjuvant chemoradiotherapy for rectal cancer improves the pathological complete response (pCR) rate.

METHOD

Rectal cancer patients were randomly allocated either to a standard 10 week wait period before surgery (standard chemoradiotherapy, SCRT) or to receive three cycles of fluorouracil based chemotherapy following chemoradiotherapy during a similar 10 week wait (extended chemoradiotherapy, XCRT). The primary end-point was pCR as determined by blinded pathological assessment.

RESULTS

Forty-nine patients were randomized (SCRTn = 24, XCRTn = 25). pCR occurred in 10 patients overall but there was no significant difference in pCR between the groups (SCRTn = 6, XCRTn = 4, P = 0.49).

CONCLUSION

The addition of three cycles of 5-fluorouracil/leucovorin in a 10 week wait period after conventional chemoradiotherapy seems to result in similar pCR rates in patients with locally advanced rectal cancer based on this small randomized trial.

An experimental demonstration of a new type of proton computed tomography using a novel silicon tracking detector

PURPOSE

Radiography and tomography using proton beams promise benefit to image guidance and treatment planning for proton therapy. A novel proton tracking detector is described and experimental demonstrations at a therapy facility are reported. A new type of proton CT reconstructing relative "scattering power" rather than "stopping power" is also demonstrated. Notably, this new type of imaging does not require the measurement of the residual energies of the protons.

METHODS

A large area, silicon microstrip tracker with high spatial and temporal resolution has been developed by the Proton Radiotherapy Verification and Dosimetry Applications consortium and commissioned using beams of protons at iThemba LABS, Medical Radiation Department, South Africa. The tracker comprises twelve planes of silicon developed using technology from high energy physics with each plane having an active area of ∼10 × 10 cm segmented into 2048 microstrips. The tracker is organized into four separate units each containing three detectors at 60° to one another creating an x-u-v coordinate system. Pairs of tracking units are used to reconstruct vertices for protons entering and exiting a phantom containing tissue equivalent inserts. By measuring the position and direction of each proton before and after the phantom, the nonlinear path for each proton through an object can be reconstructed.

RESULTS

Experimental results are reported for tracking the path of protons with initial energies of 125 and 191 MeV. A spherical phantom of 75 mm diameter was imaged by positioning it between the entrance and exit detectors of the tracker. Positions and directions of individual protons were used to create angular distributions and 2D fluence maps of the beam. These results were acquired for 36 equally spaced projections spanning 180°, allowing, for the first time, an experimental CT image based upon the relative scattering power of protons to be reconstructed.

CONCLUSIONS

Successful tracking of protons through a thick target (phantom) has demonstrated that the tracker discussed in this paper can provide the precise directional information needed to perform proton radiography and tomography. When synchronized with a range telescope, this could enable the reconstruction of proton CT images of stopping power. Furthermore, by measuring the deflection of many protons through a phantom, it was demonstrated that it is possible to reconstruct a new kind of CT image (scattering power) based upon this tracking information alone.

Venous thromboembolism in patients with esophageal or gastric cancer undergoing neoadjuvant chemotherapy

There is a well-established link between cancer and venous thromboembolism (VTE), and patients receiving chemotherapy for esophageal or gastric cancer appear at high risk of developing VTE. The incidence of VTE in the neoadjuvant setting in these patients is poorly understood, as is the role for thromboprophylaxis during neoadjuvant chemotherapy. A PubMed search was conducted using a combination of terms including; esophageal & gastric cancer, deep venous thrombosis (DVT), VTE, neoadjuvant, chemotherapy and chemoradiotherapy. One hundred and fifty-four articles were retrieved and a narrative review was conducted. For patients with esophageal and gastric cancer the incidence of VTE ranged from 4 to 19%. Gastric cancer (Odds Ratio [OR] 6.38, [95% CI: 1.96-20.80]) and Stage III/IV disease, (OR 5.16 [95% CI: 1.29-20.73]) were identified as risk factors for developing VTE. Neoadjuvant chemotherapy was identified as an independent risk factor for developing VTE. Symptomatic and asymptomatic VTE have a similar effect on mortality. Median overall survival for asymptomatic VTE was 13.9 months (95% CI: 5.0-∞) versus 12.8 months (95% CI: 4.7-30.3) if the VTE was symptomatic. Neoadjuvant chemotherapy is a significant risk factor for VTE in patients with esophageal and gastric cancer. Intervention to minimize the risk using pharmacological and mechanical thromboprophylaxis should be considered, and this should start in the neoadjuvant period.

UK Policy on Doctor Remediation: Trajectories and Challenges

Around the world, policy-makers, academics, and health service professionals have become increasingly aware of the importance of remediation, the process by which poor performance is "remedied," as part of the changing landscape of medical regulation. It is, therefore, an opportune time to critique the UK experience with remediation policy. This article frames, for the first time, the UK remediation policy as developing from a central policy aim that was articulated in the 1990s: to accelerate the identification of underperformance and, subsequently, remedy any problems identified as soon as possible. In pursuit of this aim, three policy trajectories have emerged: professionalizing and standardizing remediation provision; linking remediation with other forms of regulation, namely relicensure (known in the UK as medical revalidation); and fostering obligations for doctors to report themselves and others for remediation needs. The operationalization of policy along these trajectories, and the challenges that have arisen, has relevance for anyone seeking to understand or indeed improve remediation practices within any health care system. It is argued here that the UK serves as an example of the more general challenges posed by seeking to integrate remediation policy within broader frameworks of medical governance, in particular systems of relicensure, and the need to develop a solid evidence base for remediation practices.

A new silicon tracker for proton imaging and dosimetry

For many years, silicon micro-strip detectors have been successfully used as tracking detectors for particle and nuclear physics experiments. A new application of this technology is to the field of particle therapy where radiotherapy is carried out by use of charged particles such as protons or carbon ions. Such a treatment has been shown to have advantages over standard x-ray radiotherapy and as a result of this, many new centres offering particle therapy are currently under construction around the world today. The Proton Radiotherapy, Verification and Dosimetry Applications (PRaVDA) consortium are developing instrumentation for particle therapy based upon technology from high-energy physics. The characteristics of a new silicon micro-strip tracker for particle therapy will be presented. The array uses specifically designed, large area sensors with technology choices that follow closely those taken for the ATLAS experiment at the HL-LHC. These detectors will be arranged into four units each with three layers in an x-u-v configuration to be suitable for fast proton tracking with minimal ambiguities. The sensors will form a tracker capable of tracing the path of ~200 MeV protons entering and exiting a patient allowing a new mode of imaging known as proton computed tomography (pCT). This will aid the accurate delivery of treatment doses and in addition, the tracker will also be used to monitor the beam profile and total dose delivered during the high fluences used for treatment. We present here details of the design, construction and assembly of one of the four units that will make up the complete tracker along with its characterisation using radiation tests carried out using a 90Sr source in the laboratory and a 60 MeV proton beam at the Clatterbridge Cancer Centre.

The impact of large scale licensing examinations in highly developed countries: a systematic review

BACKGROUND

To investigate the existing evidence base for the validity of large-scale licensing examinations including their impact.

METHODS

Systematic review against a validity framework exploring: Embase (Ovid Medline); Medline (EBSCO); PubMed; Wiley Online; ScienceDirect; and PsychINFO from 2005 to April 2015. All papers were included when they discussed national or large regional (State level) examinations for clinical professionals, linked to examinations in early careers or near the point of graduation, and where success was required to subsequently be able to practice. Using a standardized data extraction form, two independent reviewers extracted study characteristics, with the rest of the team resolving any disagreement. A validity framework was used as developed by the American Educational Research Association, American Psychological Association, and National Council on Measurement in Education to evaluate each paper's evidence to support or refute the validity of national licensing examinations.

RESULTS

24 published articles provided evidence of validity across the five domains of the validity framework. Most papers (n = 22) provided evidence of national licensing examinations relationships to other variables and their consequential validity. Overall there was evidence that those who do well on earlier or on subsequent examinations also do well on national testing. There is a correlation between NLE performance and some patient outcomes and rates of complaints, but no causal evidence has been established.

CONCLUSIONS

The debate around licensure examinations is strong on opinion but weak on validity evidence. This is especially true of the wider claims that licensure examinations improve patient safety and practitioner competence.

'Shrink' losses in commercially sized corn silage piles: Quantifying total losses and where they occur

Silage 'shrink' (i.e., loss of fresh chopped crop between ensiling and feedout) represents a nutrient loss which can degrade air quality as volatile carbon compounds, degrade surface waterways due to seepage, or degrade aquifers due to seepage. Virtually no research has documented shrink in large silage piles. The term 'shrink' is often ill defined, but can be expressed as losses of wet weight (WW), oven dry matter (oDM), and oDM corrected for volatiles lost in the drying oven (vcoDM). Corn silage piles (4 wedge, 2 rollover/wedge, 1 bunker) from 950 to 12,204 tonnes as built, on concrete (4), soil (2) and a combination (1) in California's San Joaquin Valley, using a bacterial inoculant, covered within 24 h with an oxygen barrier inner film and black/white outer plastic, fed out using large front end loaders through an electronic feed tracking system, and from the 2013 crop year, were used. Shrink as WW, oDM and vcoDM were 90±17, 68±18 and 28±21 g/kg, suggesting that much WW shrink is water and much oDM shrink is volatiles lost during analytical oven drying. Most shrink occurred in the silage mass with losses from exposed silage faces, as well as between exposed face silage removal and the total mixed ration mixer, being low. Silage bulk density, exposed silage face management and face use rate did not have obvious impacts on any shrink measure, but age of the silage pile during silage feedout impacted shrink losses ('older' silage piles being higher), but most strongly for WW shrink. Real shrink losses (i.e., vcoDM) of large well managed corn silage piles are low, the exposed silage face is a small portion of losses, and many proposed shrink mitigations appeared ineffective, possibly because shrink was low overall and they are largely directed at the exposed silage face.