Therapeutic trials for long COVID-19: A call to action from the interventions taskforce of the RECOVER initiative

Although most individuals recover from acute SARS-CoV-2 infection, a significant number continue to suffer from Post-Acute Sequelae of SARS-CoV-2 (PASC), including the unexplained symptoms that are frequently referred to as long COVID, which could last for weeks, months, or even years after the acute phase of illness. The National Institutes of Health is currently funding large multi-center research programs as part of its Researching COVID to Enhance Recover (RECOVER) initiative to understand why some individuals do not recover fully from COVID-19. Several ongoing pathobiology studies have provided clues to potential mechanisms contributing to this condition. These include persistence of SARS-CoV-2 antigen and/or genetic material, immune dysregulation, reactivation of other latent viral infections, microvascular dysfunction, and gut dysbiosis, among others. Although our understanding of the causes of long COVID remains incomplete, these early pathophysiologic studies suggest biological pathways that could be targeted in therapeutic trials that aim to ameliorate symptoms. Repurposed medicines and novel therapeutics deserve formal testing in clinical trial settings prior to adoption. While we endorse clinical trials, especially those that prioritize inclusion of the diverse populations most affected by COVID-19 and long COVID, we discourage off-label experimentation in uncontrolled and/or unsupervised settings. Here, we review ongoing, planned, and potential future therapeutic interventions for long COVID based on the current understanding of the pathobiological processes underlying this condition. We focus on clinical, pharmacological, and feasibility data, with the goal of informing future interventional research studies.

CureSCi Metadata Catalog-Making sickle cell studies findable

OBJECTIVES

To adopt the FAIR principles (Findable, Accessible, Interoperable, Reusable) to enhance data sharing, the Cure Sickle Cell Initiative (CureSCi) MetaData Catalog (MDC) was developed to make Sickle Cell Disease (SCD) study datasets more Findable by curating study metadata and making them available through an open-access web portal.

METHODS

Study metadata, including study protocol, data collection forms, and data dictionaries, describe information about study patient-level data. We curated key metadata of 16 SCD studies in a three-tiered conceptual framework of category, subcategory, and data element using ontologies and controlled vocabularies to organize the study variables. We developed the CureSCi MDC by indexing study metadata to enable effective browse and search capabilities at three levels: study, Patient-Reported Outcome (PRO) Measures, and data element levels.

RESULTS

The CureSCi MDC offers several browse and search tools to discover studies by study level, PRO Measures, and data elements. The "Browse Studies," "Browse Studies by PRO Measures," and "Browse Studies by Data Elements" tools allow users to identify studies through pre-defined conceptual categories. "Search by Keyword" and "Search Data Element by Concept Category" can be used separately or in combination to provide more granularity to refine the search results. This resource helps investigators find information about specific data elements across studies using public browsing/search tools, before going through data request procedures to access controlled datasets. The MDC makes SCD studies more Findable through browsing/searching study information, PRO Measures, and data elements, aiding in the reuse of existing SCD data.

Prognosis and oncogenomic profiling of patients with tropomyosin receptor kinase fusion cancer in the 100,000 genomes project

INTRODUCTION

Neurotrophic tyrosine receptor kinase (NTRK) gene fusions are oncogenic drivers in various tumor types. Limited data exist on the overall survival (OS) of patients with tumors with NTRK gene fusions and on the co-occurrence of NTRK fusions with other oncogenic drivers.

MATERIALS AND METHODS

This retrospective study included patients enrolled in the Genomics England 100,000 Genomes Project who had linked clinical data from UK databases. Patients who had undergone tumor whole genome sequencing between March 2016 and July 2019 were included. Patients with and without NTRK fusions were matched. OS was analyzed along with oncogenic alterations in ALK, BRAF, EGFR, ERBB2, KRAS, and ROS1, and tumor mutation burden (TMB) and microsatellite instability (MSI).

RESULTS

Of 15,223 patients analyzed, 38 (0.25%) had NTRK gene fusions in 11 tumor types, the most common were breast cancer, colorectal cancer (CRC), and sarcoma. Median OS was not reached in both the NTRK gene fusion-positive and -negative groups (hazard ratio 1.47, 95% CI 0.39-5.57, P = 0.572). A KRAS mutation was identified in two (5%) patients with NTRK gene fusions, and both had hepatobiliary cancer. High TMB and MSI were both more common in patients with NTRK gene fusions, due to the CRC subset. While there was a higher risk of death in patients with NTRK gene fusions compared to those without, the difference was not statistically significant.

CONCLUSION

This study supports the hypothesis that NTRK gene fusions are primary oncogenic drivers and the co-occurrence of NTRK gene fusions with other oncogenic alterations is rare.

Abstract 394: Prognosis and molecular characteristics of patients with TRK fusion cancer in the 100,000 Genomes Project

Background: NTRK gene fusions are oncogenic drivers in various tumor types. Overall survival (OS) of patients (pts) with tumors harboring NTRK fusions compared to pts without is unknown, and data on co-occurrence of NTRK fusions with other oncogenic drivers are limited.1

Methods: This retrospective study used genomic data generated by the 100,000 Genomes Project with linked clinical data from UK cancer databases. Pts with cancer who had undergone tumor whole genome sequencing between Mar 2016 and Jul 2019 were included. OS of pts with and without NTRK fusions, matched by exact and distance matching with a 1:4 NTRK+:NTRK− ratio, was analyzed by Kaplan-Meier method and Cox regression. Key alterations in ALK, BRAF, EGFR, HER2, KRAS and ROS1, and tumor mutation burden (TMB) and microsatellite instability (MSI), were evaluated along with NTRK gene fusions.

Results: Of 15,223 pts analyzed, 38 (0.2%) had NTRK fusions, identified in 11 cancers (Genomics England classification), the most common being breast cancer (n=9), colorectal cancer (CRC; n=9), and sarcoma (n=7). While there was no significant OS difference in pts with and without NTRK fusions, the HR was 1.47 (95% CI 0.39-5.57; Table). Of the tested oncogenic drivers, only KRAS mutation was identified in 2 (5%) pts with an NTRK fusion (both hepatobiliary cancer), while oncogenic driver frequency in pts without NTRK fusions ranged from 0.1-11.6%. High TMB was more common in pts with NTRK fusions than in those without (21% vs 6%), as was high MSI (18% vs 6%); all pts with NTRK fusions and high TMB and/or MSI had CRC.

Conclusions: While no statistical difference in OS was observed, there was a trend to higher risk of death in pts with NTRK fusions compared to those without, consistent with a recent US study.1 Co-occurrence of NTRK fusions and other biomarkers was rare, except for high TMB and high MSI in CRC. These results highlight NTRK fusions as actionable biomarkers and emphasize the need for NTRK gene fusion testing.

NTRK− (n=72†)NTRK+ (n=18†)Median follow-up (IQR), years2.28 (1.57-2.98)2.01 (1.40-2.97)Median OS (IQR), yearsNE (NE-NE)NE (NE-NE)Landmark OS, % (95% CI)1 year96 (91-100)94 (84-100)2 years94 (89-100)87 (71-100)3 years88 (78-99)87 (71-100)HR (95% CI)1.47 (0.39-5.57)†Only patients with linked clinical data and who were matched were included in the OS analysis.1CI, confidence interval; HR, hazard ratio; IQR, interquartile range; NE, not estimable; NTRK; neurotrophic tyrosine receptor kinase; OS, overall survival.1. Bazhenova L, et al. Clin Cancer Res. 2020;26(12 Suppl 1):09-09.

Citation Format: John Bridgewater, Xiaolong Jiao, Mounika Parimi, Clare Flach, Jeran Stratford, Atanas Kamburov, Arndt Schmitz, Jihong Zong, John A. Reeves, Karen Keating, Amanda Bruno, Marc Fellous, Lyudmila Bazhenova. Prognosis and molecular characteristics of patients with TRK fusion cancer in the 100,000 Genomes Project [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 394.

Health resource utilization of labor induction versus expectant management

BACKGROUND

Although induction of labor of low-risk nulliparous women at 39 weeks reduces the risk of cesarean delivery compared with expectant management, concern regarding more frequent use of labor induction remains, given that this intervention historically has been thought to incur greater resource utilization.

OBJECTIVE

The objective of the study was to determine whether planned elective labor induction at 39 weeks among low-risk nulliparous women, compared with expectant management, was associated with differences in health care resource utilization from the time of randomization through 8 weeks postpartum.

STUDY DESIGN

This is a planned secondary analysis of a multicenter randomized trial in which low-risk nulliparous women were assigned to induction of labor at 39 weeks or expectant management. We assessed resource utilization after randomization in 3 time periods: antepartum, delivery admission, and discharge through 8 weeks postpartum.

RESULTS

Of 6096 women with data available, those in the induction of labor group (n = 3059) were significantly less likely in the antepartum period after randomization to have at least 1 ambulatory visit for routine prenatal care (32.4% vs 68.4%), unanticipated care (0.5% vs 2.6%), or urgent care (16.2% vs 44.3%), or at least 1 antepartum hospitalization (0.8% vs 2.2%, P < .001 for all). They also had fewer tests (eg, sonograms, blood tests) and treatments (eg, antibiotics, intravenous hydration) prior to delivery. During the delivery admission, women in the induction of labor group spent a longer time in labor and delivery (median, 0.83 vs 0.57 days), but both women (P = .002) and their neonates (P < .001) had shorter postpartum stays. Women and neonates in both groups had similar frequencies of postpartum urgent care and hospital readmissions (P > .05 for all).

CONCLUSION

Women randomized to induction of labor had longer durations in labor and delivery but significantly fewer antepartum visits, tests, and treatments and shorter maternal and neonatal hospital durations after delivery. These results demonstrate that the health outcome advantages associated with induction of labor are gained without incurring uniformly greater health care resource use.

Abstract 5276: Impact of duplicate removal on low frequency NGS somatic variant calling

Cancer genomic profiles created by analysis of targeted Next Generation Sequencing (NGS) panels is emerging as a powerful tool for making informed clinical decisions. Of the critical informatics challenges to address, accurate mutation calls and allele frequency estimations after accounting for PCR-mediated artifacts are debated. The process of sample preparation for NGS sequencing involves amplification by PCR. While PCR is relatively error-free, mistakes early in DNA synthesis can be compounded, driving detection of spurious mutations and having an adverse impact on clinical reporting. Previous reports have addressed the utility of detecting and removing PCR duplicate reads in Mendelian applications but have rarely examined its use with targeted NGS panels.

We performed deduplication with 3 widely used tools (Samtools, Samblaster, and Picard) to understand sensitivity to call low frequency alleles and any impact on false positive/negative rates. Furthermore, we evaluated effects of duplicate removal on targeted panels of varying sizes and effects of sample matrices using replicates of 7 verified reference samples with several digitally confirmed alleles with frequencies ranging from 1-5%.

It is not practical to perform deduplication on PCR-enriched panels, therefore, we assessed 3 different hybrid enrichment panels of varying size (387kb, 1.3Mb, and 54Mb). Deduplication by Picard resulted in a greater decrease in the mean depth for the smaller panels (32-59%) compared to Exome (15%), showing that higher molecular diversity lowers duplication rates. Uniformity (percent of ROI with depth within 20% of the mean depth) improved 6-18% after deduplication for the smaller panels, but only 1% for the Exome.

Independent of panel size, about 32% of the total reads were marked as duplicates, reducing the power to call low frequency variants by 18%. Importantly, after added sequencing 95-96% of onco-specific variants were detected post-deduplication with a lower limit of detection of 3% compared to 2.5% pre-removal. For low-quality DNA samples we find no benefit in added sequencing for any panel. We also generally observed higher sensitivity (0% to 10% for SNV and -3% to 3% for indels) post deduplication.

Molecular diversity also varies by sample type. Intact DNA show higher molecular diversity and lower duplication rates than degraded FFPE samples. We profiled mixed-quality FFPE samples (n = 85), good-quality fresh frozen samples (n = 3), and NA12878 (n = 1) on our smallest panel and noted duplication rates of 64±14%, 40±5% and 30% respectively. On average, deduplication cut the number of SNV calls by 17.4%, with the FFPE samples affected the most (2-88%).

From our analysis we recommend performing deduplication during analysis of targeted panels. While we observed the most benefit for smaller panels with low uniformity, improved variant sensitivity was seen regardless of panel size. During experimental design, we advise a worksheet to guide deduplication decisions.

Citation Format: Jeran Stratford, Gunjan Hariani, Jeff Jasper, Chad Brown, Wendell Jones, Victor J. Weigman. Impact of duplicate removal on low frequency NGS somatic variant calling. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5276.

Abstract B71: Multiplexed kinase inhibitor beads identify multiple pathways of resistance to PI3K inhibition facilitating the rational selection of novel combination therapies in pancreatic cancer

KRAS mutational activation plays a critical role in tumorigenesis, but exactly which downstream KRAS effector pathway is critical for this role remains less clear. One of the most studied downstream pathways is the phosphatidylinositol-3-kinase (PI3K) pathway which mediates cellular metabolism, growth, and survival. We have previously shown using validated pancreatic ductal adenocarcinoma (PDAC) patient derived xenograft (PDX) mouse models that treatment with BKM120 (a pan-class 1 PI3K inhibitor, currently in Phase I/II clinical trials) resulted in tumor growth inhibition (p = 0.017) but not regression. In this study, we evaluated possible mechanisms of resistance to BKM120 therapy. We developed a novel multiplex inhibitor bead/mass spectrometry (MIB/MS) assay to measure the activation state of the kinome. We have recently shown that kinome response to kinase inhibitor therapy (i.e. kinome reprogramming) is a potential mechanism of resistance in triple negative breast cancer in response to MEK inhibition and in drug-resistant leukemia in response to imatinib. We hypothesized that kinome reprogramming may play a role in resistance to PI3K inhibition in PDAC and used MIB/MS to identify second targets that may be used in combination with PI3K inhibitors.

We found kinome reprogramming in response to PI3K inhibition through both previously known as well as less studied pathways. For instance, we found MEK1 and MEK2 activation in response to BKM120 treatment. MEK activation has previously been implicated in resistance to PI3K inhibition and combined MEK and PI3K inhibition has been shown to be synergistic in PDAC. However, our results suggest that resistance to PI3K may be mediated through many more pathways than MEK alone. We found ErbB1, ErbB2 and ErbB3 activation in response to BKM120 treatment in both cell lines and PDX tumors. ErbB2 and ErbB3 activation has previously been noted in response to PI3K inhibition in breast cancer. However, no studies have evaluated this combination in PDAC. Thus we evaluated the effect of combined PI3K and pan-ErbB inhibition in a panel of 10 PDAC cell lines using BKM120 and dacomitinib (a pan-ErbB inhibitor currently in Phase III clinical trials). Combined treatment with BKM120 and dacomitinib inhibited proliferation in 10 of 10 PDAC cell lines evaluated. This combination showed impressive synergy across all cell lines with a mean combination index of 0.24 (0.00245 – 0.49).

MIB/MS is a powerful unbiased approach to identify second targets for combination therapy. We identified both known and novel kinase pathways that may mediate resistance to PI3K inhibition in PDAC. Our results suggest that pan-ErbB inhibition may be a promising second target in combination with PI3K inhibition in PDAC. Combination studies in PDX models are ongoing. Pan-ErbB and PI3K inhibition in PDAC may be more effective than either single agent alone and should be considered in clinical trials.

Citation Format: Christopher J. Tignanelli, Jeran Stratford, Richard Moffitt, Rachel Reuther, Gary L. Johnson, Jen Jen Yeh. Multiplexed kinase inhibitor beads identify multiple pathways of resistance to PI3K inhibition facilitating the rational selection of novel combination therapies in pancreatic cancer. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr B71.

Comparison of adaptive radiotherapy techniques for the treatment of bladder cancer

OBJECTIVE

Day-to-day anatomical variations complicate bladder cancer radiotherapy treatment. This work quantifies the impact on target coverage and irradiated normal tissue volume for different adaptive strategies.

METHODS

20 patients were retrospectively planned using different three-dimensional conformal radiotherapy treatment strategies for whole-bladder carcinoma: (i) "conventional" treatment used isotropic expansion of the clinical target volume (CTV) by 15 mm to the planning target volume (PTV) for daily treatment; (ii) "plan of the day" used daily volumetric on-treatment imaging [cone beam CT (CBCT)] to select from four available plans with varying superior PTV margins; (iii) "composite" strategies used on-treatment CBCTs from Fractions 1-3 to inform a composite CTV and adapted PTV (5- and 10-mm margins for composite 1 and composite 2, respectively) for subsequent treatment. Target coverage was evaluated from available CBCTs (the first three fractions then the minimum weekly thereafter), and the reduction in the irradiated volume (i.e. within the 95% isodose) was quantified.

RESULTS

Plan of the day improved target coverage (i.e. all of the bladder within the 95% isodose throughout the treatment) relative to conventional treatment (p=0.10), while no such benefit was observed with composite 2. Target coverage was reduced with composite 1 relative to conventional treatment. The mean irradiated volume was reduced by 17.2%, 35.0% and 14.6% relative to conventional treatment, for plan of the day, composite 1 and composite 2, respectively (p<0.01 in all cases). No parameters predictive of large changes in bladder volume later in the treatment were identified.

CONCLUSIONS

Adaptive techniques can maintain or improve target coverage while allowing for reduced irradiated volume and possibly reduced toxicity. The plan-of-the-day technique appeared to provide the optimal balance between target coverage and normal tissue sparing.

ADVANCES IN KNOWLEDGE

This study suggests that plan-of-the-day techniques will provide optimal outcomes for adaptive bladder radiotherapy.

A megavoltage scatter correction technique for cone-beam CT images acquired during VMAT delivery

Kilovoltage cone-beam CT (kV CBCT) can be acquired during the delivery of volumetric modulated arc therapy (VMAT), in order to obtain an image of the patient during treatment. However, the quality of such CBCTs is degraded by megavoltage (MV) scatter from the treatment beam onto the imaging panel. The objective of this paper is to introduce a novel MV scatter correction method for simultaneous CBCT during VMAT, and to investigate its effectiveness when compared to other techniques. The correction requires the acquisition of a separate set of images taken during VMAT delivery, while the kV beam is off. These images--which contain only the MV scatter contribution on the imaging panel--are then used to correct the corresponding kV/MV projections. To test this method, CBCTs were taken of an image quality phantom during VMAT delivery and measurements of contrast to noise ratio were made. Additionally, the correction was applied to the datasets of three VMAT prostate patients, who also received simultaneous CBCTs. The clinical image quality was assessed using a validated scoring system, comparing standard CBCTs to the uncorrected simultaneous CBCTs and a variety of correction methods. Results show that the correction is able to recover some of the low and high-contrast signal to noise ratio lost due to MV scatter. From the patient study, the corrected CBCT scored significantly higher than the uncorrected images in terms of the ability to identify the boundary between the prostate and surrounding soft tissue. In summary, a simple MV scatter correction method has been developed and, using both phantom and patient data, is shown to improve the image quality of simultaneous CBCTs taken during VMAT delivery.

Anatomical failure following laparoscopic antireflux surgery (LARS): does it really matter?

INTRODUCTION

Failure rates of laparoscopic antireflux surgery (LARS) vary from 2-30%. A degree of anatomical failure is common, and the most common failure is intrathoracic wrap herniation. We have assessed anatomical integrity of the crural repair and wrap using marking Liga clips placed at the time of surgery and compared this with symptomatic outcome.

PATIENTS AND METHODS

A prospective study was undertaken on 50 patients who underwent LARS in a single centre over a 3-year period. Each had an X-ray on the first postoperative day and a barium swallow at 6 months at which the distance was measured between the marking Liga clips. An increase in interclip distance of > 25-49% was deemed 'mild separation', and an increase of > 50% 'moderate separation'. Patients completed a standardised symptom questionnaire at 6 months.

RESULTS

At 6 months' postoperatively, 22% had mild separation of the crural repair with a mean Visick score of 1.18, and 54% had moderate separation with a mean Visick score of 1.26. Mild separation of the wrap occurred in 28% with a mean Visick score of 1.21 and 22% moderate separation with a mean Visick score of 1.18. Three percent had mild separation of both the crural repair and wrap with a mean Visick score of 1.0, and 16% moderate separation with a mean Visick score of 1.13. Of patients, 14% had evidence of some degree of failure on barium swallow but only one of these was significant intrathoracic migration of the wrap which was symptomatic and required re-do surgery.

CONCLUSIONS

The prevalence of some form of anatomical failure, as determined by an increase in the interclip distance, is high at 6 months' postoperatively following LARS. However, this does not seem to correlate with a subjective recurrence of symptoms.

Randomized clinical trial of laparoscopic total (Nissen) versus posterior partial (Toupet) fundoplication for gastro-oesophageal reflux disease based on preoperative oesophageal manometry

Background

Laparoscopic fundoplication is an accepted treatment for symptomatic gastro-oesophageal reflux disease. The aim of this study was to clarify whether total (Nissen) or partial (Toupet) fundoplication is preferable, and whether preoperative oesophageal manometry should be used to determine the degree of fundoplication performed.

Methods

Preoperative oesophageal manometry was used to stratify 127 patients with established gastro-oesophageal reflux disease into effective (75) and ineffective (52) oesophageal motility groups. Patients in each group were randomized to Nissen (64) or Toupet (63) fundoplication.

Results

No significant differences between the operative groups were seen in heartburn, regurgitation or other reflux-related symptoms up to 1 year after surgery. Dysphagia of any degree (27 versus 9 per cent; P = 0·018) and chest pain on eating (22 versus 5 per cent; P = 0·018) were more prevalent at 1 year in the Nissen group. There were no differences in postoperative symptoms between the effective and ineffective motility groups. Surgery failed in eight patients on postoperative pH criteria, three in the Nissen group and five in the Toupet group.

Conclusion

Any differences in the symptomatic outcome of laparoscopic Nissen and Toupet fundoplication appear minimal. There is no reason to tailor the degree of fundoplication to preoperative oesophageal manometry.

The extended learning curve for laparoscopic fundoplication: a cohort analysis of 400 consecutive cases

Many studies have looked at the learning curve associated with laparoscopic Nissen fundoplication (LNF) in a given institution. This study looks at the learning curve of a single surgeon with a large cohort of patients over a 10-year period. Prospective data were collected on 400 patients undergoing laparoscopic fundoplication for over 10 years. The patients were grouped consecutively into cohorts of 50 patients. The operating time, the length of postoperative hospital stay, the conversion rate to open operation, the postoperative dilatation rate, and the reoperation rate were analyzed. Results showed that the mean length of operative time decreased from 143 min in the first 50 patients to 86 min in the last 50 patients. The mean postoperative length of hospital stay decreased from 3.7 days initially to 1.2 days latterly. There was a 14% conversion to open operation rate in the first cohort compared with a 2% rate in the last cohort. Fourteen percent of patients required reoperation in the first cohort and 6% in the last cohort. Sixteen percent required postoperative dilatation in the first cohort. None of the last 150 patients required dilatation. In conclusion, laparoscopic fundoplication is a safe and effective operation for patients with gastroesophageal reflux disease. New techniques and better instrumentation were introduced in the early era of LNF. The learning curve, however, continues well beyond the first 20 patients.

Developments in and experience of kilovoltage X-ray cone beam image-guided radiotherapy

This paper offers a realistic review of kilovoltage X-ray cone beam tomography integrated with the treatment machine for image-guided radiotherapy in the light of experience taking a commercial system from prototype development into clinical use. It shows that key practicalities cannot be ignored, in particular the regular characterization of mechanical flex during gantry rotation, the mapping of defects in flat panel image transducers and their response to X-ray exposure. The number of X-ray projections and the doses required for clinically useful cone beam reconstruction at different therapy sites are considered in the context of imaging that is fit for purpose. Three roles for cone beam tomography in radiotherapy are identified: patient setup in three dimensions (3D), where even low dose cone beam tissue detail is superior to megavoltage imaging; disease targeting where, despite wide field scatter and slow scanning, it is possible to generate images that are suitable for tumour delineation even at challenging sites; adaptive treatment planning, where calibrated cone beam images have been shown to provide sufficient target detail to support "plan of the day" selection and have the potential for planning with bulk corrections. With frequent use in mind, the need to limit patient dose during setup, yet maximize much needed image quality in the target zone, is considered. Finally, it is noted that the development of cone beam tomography for radiotherapy is far from complete, with X-ray source, image transducer, reconstruction algorithms and techniques for image profile collection still being researched.

Radiotherapy Treatment Verification in the UK: An Audit of Practice in 2004

AIMS

To audit current practice related to treatment verification undertaken in radiotherapy departments throughout the UK.

MATERIALS AND METHODS

A questionnaire was circulated to the radiotherapy service managers of 62 radiotherapy centres in the UK. This looked in detail at the department demographics, imaging equipment, site-specific verification protocols, and training and competency assessment of staff responsible for verification.

RESULTS

The response rate was 48% (30/62). All departments were using megavoltage imaging equipment in routine clinical practice. Twenty-four out of 29 (83%) departments that had electronic portal imaging capability were using image analysis software for verification. Twenty-nine out of 30 (97%) departments had site-specific written verification protocols. Twenty out of 30 (67%) treatment centres audited set-up errors within their department. Forty-three per cent of centres were using simulator image as the reference image of choice across all sites. Electronic portal imaging, alone or in combination with portal film, was being used for verification in 75% of the centres. Fifty-three per cent of centres used off-line correction strategies for measuring set-up errors across all sites. Radiographer-led interventions were primarily in the pelvis.

CONCLUSION

Presently in the UK, verification strategies vary widely at individual treatment sites and between departments. Dedicated departmental verification teams, with input from radiographers, physicists and clinicians, may assist in the effective implementation of evidence-based verification. The inclusion of comprehensive verification protocols within multicentre radiotherapy trials encourages standardisation across treatment centres.

An assessment of clinically optimal gold marker length and diameter for pelvic radiotherapy verification using an amorphous silicon flat panel electronic portal imaging device

Verification of target organ position is essential for the accurate delivery of conformal radiotherapy. Megavoltage electronic portal imaging with flat panel amorphous silicon detectors delivers high quality images that can be used for verification of bony landmark position. Gold markers implanted into the target organ can be visualized and used as a surrogate of actual organ position. On-line compensation for marker displacement, by adjusting patient position, can reduce geometric errors associated with radiation delivery. This study assesses the optimal marker length and diameter to be used with an amorphous silicon (a-Si) flat panel detector and electronic portal images (EPIs), prior to implementation of a clinical programme of gold marker insertion in prostate cancer patients. Seven marker sizes varying from 3 mm to 8 mm in length and 0.8 mm to 1.1 mm in diameter were investigated in a group of patients undergoing pelvic radiotherapy using an 8 MV Elekta SL20 linear accelerator. Markers were placed on the skin entry and exit sites of the treatment beam and EPIs in both lateral and anterior pelvic views were acquired. Three observers independently assessed visibility success and failure using a subjective scoring system. Markers less than 5 mm in length or 0.9 mm in diameter were poorly visualized (<70% visualization success in lateral EPIs). The marker measuring 0.9 mm x 5 mm appears to be clinically optimal in pelvic radiotherapy patients (80% visualization success in lateral EPIs) and will be used for actual organ implantation.

A poor response to proton pump inhibition is not a contraindication for laparoscopic antireflux surgery for gastro esophageal reflux disease

BACKGROUND

We aimed to determine if a poor response to proton pump inhibitors (PPIs) can predict a poor outcome following laparoscopic antireflux surgery (LARS) in our surgically treated population.

METHODS

A total of 324 patients undergoing LARS were included in this study. Following standardized assessment, patients recorded the efficacy of their medication on visual analogue scales. Pre- and postoperative symptom scores were recorded, with outcomes measured by modified Visick scores.

RESULTS

There were 233 good responders (>50% relief) and 91 poor responders (<49% relief). Both groups demonstrated a significant decline in postoperative symptom scores. Ninety-four percent of good responders had an excellent or good outcome, compared to 87% of poor responders. Twenty-seven patients reported a fair or poor outcome, despite improved postoperative symptom scores. Fifteen of these patients reported continuing heartburn; five had positive pH tests.

CONCLUSION

Our results do not support the assumption that a poor response to PPIs equates to a poor outcome after LARS.

Laparoscopic fundoplication in mentally normal children with gastroesophageal reflux disease

Laparoscopic antireflux surgery has been performed in neurologically impaired and scoliotic children. We aimed to assess the effectiveness of laparoscopic fundoplication in mentally normal children with gastroesophageal reflux disease that failed to respond to medical therapy. Data were prospectively collected (symptoms, medical therapy, endoscopies' findings) on 12 children (nine boys, three girls) aged 9-15 years with gastroesophageal reflux disease. Pre- and postoperative ambulatory 24-h pH and DeMeester and Johnson scores were also recorded. Effectiveness of surgery was assessed by comparison of pre- and postoperative total acid exposure time, Visick grade, need for antireflux medication and symptom scores. In total, 11 children underwent a laparoscopic Nissen fundoplication and one underwent a Toupet procedure. Median length of stay was 2 (2-3) nights. The median preoperative pH acid exposure time (AET) was 4.7 (0.8-16.4) percent compared with postoperative AET of 0.4 (0-3) percent. Early postoperative dysphagia occurred in four out of 12 patients, requiring a total of six dilatations. Postoperative Visick scores were: grade I=7 and grade II=5. Laparoscopic fundoplication can be safely performed and is effective in children with GERD who have failed to respond to medical therapy.

Preoperative esophageal body motility does not influence the outcome of laparoscopic Nissen fundoplication for gastroesophageal reflux disease

We evaluated a policy of performing laparoscopic antireflux surgery without tailoring the procedure to the results of preoperative esophageal motility tests. A total of 117 patients (82 with normal esophageal motility; 35 with ineffective motility, IEM) underwent laparoscopic Nissen fundoplication for symptomatic gastroesophageal reflux. There were no significant differences in preoperative symptom length, dysphagia, DeMeester symptom scores, acid exposure times or lower esophageal sphincter pressures between the two groups. Both groups showed postoperative improvements in DeMeester symptom scores, dysphagia and acid exposure, with no differences between groups. At 1 year after surgery, 95% of the normal motility group and 91% of the IEM group had a good/excellent outcome from surgery. None of the IEM group required postoperative dilatation or reoperation. Patients with IEM fare equally well from laparoscopic Nissen fundoplication as those with normal esophageal motility. There is no merit in tailoring antireflux surgery to the results of preoperative motility tests.

Changes to the TEF schemes can have significant impacts on regulation and management of PCDD/F and PCB

The changes recommended by the World Health Organisation (WHO) to the toxic equivalency factors (TEFs) for polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) and the recommendation to extend both the TEF scheme and the tolerable daily intake (TDI) to include "dioxin-like" PCB congeners have significant implications for regulators who have relied heavily on the International TEF (I-TEF) scheme in setting and monitoring limits and exposure to these compounds. This paper examines example data sets of sources, environmental concentrations, food and exposure to indicate likely changes in calculated toxic equivalent (TEQ) due to the recommended changes to TEFs. Many published data sets available do not provide congener specific data for PCDD/F which limits the ability to recalculate TEQs. There are even fewer congener specific data published to enable calculation of TEQs for the dioxin-like PCBs. In general TEQs calculated using the WHO scheme for emissions to air were found to show small increases (in the order of 1-10%) in comparison to the I-TEQ (for PCDD/F), some sludge samples showed substantial decreases (up to 70%). Levels in food and calculations of exposure showed that the change to TEFs for PCDD/F increased calculated exposure by 10-20% while the change to PCB TEFs decreased calculated TEQ attributable to PCB by 0-10%. The effects of including PCB in the overall TEQ and the changes to TEFs for PCDD/F substantially increase calculated TEQ exposure. Congener specific data should be presented to allow calculation of desired TEQ and the impact of the changes on emission limits, regulations on sludge use and environmental quality standards should all be carefully considered. The absence of data on emissions of dioxin-like PCB means that it is not possible to estimate with any certainty the impact on overall TEQ emissions of including the nominated PCB. Given the potential for confusion with the proliferation of TEFs and the extension to include both PCDD/F and PCB in the calculation of TEQs it is important that great care is taken to clearly express which compounds are included and which TEF scheme has been applied in each case.