Publications by authors named "Jon Shelton"

4 Publications

  • Page 1 of 1

Impact of the COVID-19 pandemic on the detection and management of colorectal cancer in England: a population-based study.

Lancet Gastroenterol Hepatol 2021 03 15;6(3):199-208. Epub 2021 Jan 15.

Clinical Trial Service Unit and Epidemiological Studies Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK; Medical Research Council Population Health Research Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK; Big Data Institute, University of Oxford, Oxford, UK.

Background: There are concerns that the COVID-19 pandemic has had a negative effect on cancer care but there is little direct evidence to quantify any effect. This study aims to investigate the impact of the COVID-19 pandemic on the detection and management of colorectal cancer in England.

Methods: Data were extracted from four population-based datasets spanning NHS England (the National Cancer Cancer Waiting Time Monitoring, Monthly Diagnostic, Secondary Uses Service Admitted Patient Care and the National Radiotherapy datasets) for all referrals, colonoscopies, surgical procedures, and courses of rectal radiotherapy from Jan 1, 2019, to Oct 31, 2020, related to colorectal cancer in England. Differences in patterns of care were investigated between 2019 and 2020. Percentage reductions in monthly numbers and proportions were calculated.

Findings: As compared to the monthly average in 2019, in April, 2020, there was a 63% (95% CI 53-71) reduction (from 36 274 to 13 440) in the monthly number of 2-week referrals for suspected cancer and a 92% (95% CI 89-95) reduction in the number of colonoscopies (from 46 441 to 3484). Numbers had just recovered by October, 2020. This resulted in a 22% (95% CI 8-34) relative reduction in the number of cases referred for treatment (from a monthly average of 2781 in 2019 to 2158 referrals in April, 2020). By October, 2020, the monthly rate had returned to 2019 levels but did not exceed it, suggesting that, from April to October, 2020, over 3500 fewer people had been diagnosed and treated for colorectal cancer in England than would have been expected. There was also a 31% (95% CI 19-42) relative reduction in the numbers receiving surgery in April, 2020, and a lower proportion of laparoscopic and a greater proportion of stoma-forming procedures, relative to the monthly average in 2019. By October, 2020, laparoscopic surgery and stoma rates were similar to 2019 levels. For rectal cancer, there was a 44% (95% CI 17-76) relative increase in the use of neoadjuvant radiotherapy in April, 2020, relative to the monthly average in 2019, due to greater use of short-course regimens. Although in June, 2020, there was a drop in the use of short-course regimens, rates remained above 2019 levels until October, 2020.

Interpretation: The COVID-19 pandemic has led to a sustained reduction in the number of people referred, diagnosed, and treated for colorectal cancer. By October, 2020, achievement of care pathway targets had returned to 2019 levels, albeit with smaller volumes of patients and with modifications to usual practice. As pressure grows in the NHS due to the second wave of COVID-19, urgent action is needed to address the growing burden of undetected and untreated colorectal cancer in England.

Funding: Cancer Research UK, the Medical Research Council, Public Health England, Health Data Research UK, NHS Digital, and the National Institute for Health Research Oxford Biomedical Research Centre.
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March 2021

Establishing population-based surveillance of diagnostic timeliness using linked cancer registry and administrative data for patients with colorectal and lung cancer.

Cancer Epidemiol 2019 08 15;61:111-118. Epub 2019 Jun 15.

Cancer Research UK, Angel Building, 407 St John Street, London, EC1V 4AD, UK. Electronic address:

Background: Diagnostic timeliness in cancer patients is important for clinical outcomes and patient satisfaction but, to-date, continuous monitoring of diagnostic intervals in nationwide incident cohorts has been impossible in England.

Methods: We developed a new methodology for measuring the secondary care diagnostic interval (SCDI - first relevant secondary care contact to diagnosis) using linked cancer registration and healthcare utilisation data. Using this method, we subsequently examined diagnostic timeliness in colorectal and lung cancer patients (2014-15) by socio-demographic characteristics, diagnostic route and stage at diagnosis.

Results: The approach assigned SCDIs to 94.4% of all incident colorectal cancer cases [median length (90th centile) of 25 (104) days] and 95.3% of lung cancer cases [36 (144) days]. Advanced stage patients had shorter intervals (median, colorectal: stage 1 vs 4 - 34 vs 19 days; lung stage 1&2 vs 3B&4 - 70 vs 27 days). Routinely referred patients had the longest (colorectal: 61, lung: 69 days) and emergency presenters the shortest intervals (colorectal: 3, lung: 14 days). Comorbidities and additional diagnostic tests were also associated with longer intervals.

Conclusion: This new method can enable repeatable nationwide measurement of cancer diagnostic timeliness in England and identifies actionable variation to inform early diagnosis interventions and target future research.
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August 2019

The fraction of cancer attributable to modifiable risk factors in England, Wales, Scotland, Northern Ireland, and the United Kingdom in 2015.

Br J Cancer 2018 04 23;118(8):1130-1141. Epub 2018 Mar 23.

Centre for Cancer Prevention, Wolfson Institute of Preventive Medicine, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK.

Background: Changing population-level exposure to modifiable risk factors is a key driver of changing cancer incidence. Understanding these changes is therefore vital when prioritising risk-reduction policies, in order to have the biggest impact on reducing cancer incidence. UK figures on the number of risk factor-attributable cancers are updated here to reflect changing behaviour as assessed in representative national surveys, and new epidemiological evidence. Figures are also presented by UK constituent country because prevalence of risk factor exposure varies between them.

Methods: Population attributable fractions (PAFs) were calculated for combinations of risk factor and cancer type with sufficient/convincing evidence of a causal association. Relative risks (RRs) were drawn from meta-analyses of cohort studies where possible. Prevalence of exposure to risk factors was obtained from nationally representative population surveys. Cancer incidence data for 2015 were sourced from national data releases and, where needed, personal communications. PAF calculations were stratified by age, sex and risk factor exposure level and then combined to create summary PAFs by cancer type, sex and country.

Results: Nearly four in ten (37.7%) cancer cases in 2015 in the UK were attributable to known risk factors. The proportion was around two percentage points higher in UK males (38.6%) than in UK females (36.8%). Comparing UK countries, the attributable proportion was highest in Scotland (41.5% for persons) and lowest in England (37.3% for persons). Tobacco smoking contributed by far the largest proportion of attributable cancer cases, followed by overweight/obesity, accounting for 15.1% and 6.3%, respectively, of all cases in the UK in 2015. For 10 cancer types, including two of the five most common cancer types in the UK (lung cancer and melanoma skin cancer), more than 70% of UK cancer cases were attributable to known risk factors.

Conclusion: Tobacco and overweight/obesity remain the top contributors of attributable cancer cases. Tobacco smoking has the highest PAF because it greatly increases cancer risk and has a large number of cancer types associated with it. Overweight/obesity has the second-highest PAF because it affects a high proportion of the UK population and is also linked with many cancer types. Public health policy may seek to mitigate the level of harm associated with exposure or reduce exposure levels-both approaches may effectively impact cancer incidence. Differences in PAFs between countries and sexes are primarily due to varying prevalence of exposure to risk factors and varying proportions of specific cancer types. This variation in turn is affected by socio-demographic differences which drive differences in exposure to theoretically avoidable 'lifestyle' factors. PAFs at UK country level have not been available previously and they should be used by policymakers in devolved nations. PAFs are estimates based on the best available data, limitations in those data would generally bias toward underestimation of PAFs. Regular collection of risk factor exposure prevalence data which corresponds with epidemiological evidence is vital for analyses like this and should remain a priority for the UK Government and devolved Administrations.
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April 2018

Variations in parthenolide content and daily dose of feverfew products.

Am J Health Syst Pharm 2002 Aug;59(16):1527-31

School of Pharmacy, Southwestern Oklahoma State University, 100 Campus Drive, Weatherford, OK 73096, USA.

Variations in the parthenolide content of feverfew products available to consumers were studied. Feverfew products were analyzed for the content of parthenolide, the purported active component. The actual weight of feverfew was determined only in those products containing dried feverfew leaf. The total daily doses of feverfew leaf and parthenolide were calculated by using the instructions on each product label. Parthenolide content was determined by high-performance liquid chromatography. The quantity of feverfew leaf in each capsule was similar to that stated on the label and ranged from 25 to 500 mg. Parthenolide content per dosage form varied 150-fold (from 0.02 to 3.0 mg), while percent parthenolide varied 5.3-fold (from 0.14% to 0.74%). If a person consumed the daily dose recommended on the label, intake of dried feverfew leaf would range from 225 to 2246 mg/day, a 10-fold variation, while intake of parthenolide would range from 0.06 to 9.7 mg/day, a 160-fold variation. Large variations were observed in the parthenolide contents and daily intake as recommended by the labeling in commercial feverfew products.
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August 2002