Back in December we wrote about Jeremy Hunt’s announcement that six centres in England would start using Bowel Scope Screening (BSS, also known as flexi-scope or flexible sigmoidoscopy) as part of their bowel screening programme in 2013.
This week, 55 year olds in the South of Tyne region (which includes Gateshead, Sunderland and South Tyneside) received the first wave of letters inviting them to be screened.
This is great news. Cancer Research UK has been involved in Bowel Scope Screening from the beginning – we co-funded a 16 year study which showed that it cuts deaths by over 40 per cent, and – unlike the current test – can actually prevent a third of bowel cancers among those screened.
As a result, it has the potential to save thousands of lives from bowel cancer each year.
As soon as the trial results were published in 2010, we said we wanted the Government to add BSS to the existing bowel screening programme, and later that year, they agreed, setting aside £60m to fund it.
Since then we’ve been calling for Bowel Scope Screening to start as soon as possible, so it’s fantastic to see it finally happen.
The test used in Bowel Scope Screening, flexible sigmoidoscopy , uses a flexible tube with a camera and a light on the end to look into your lower bowel. It can spot both early-stage cancers and pre-cancerous growths known as ‘polyps,’ which can be immediately removed to prevent them developing into cancer.
Recent studies have shown that people find it ‘acceptable’ and ‘reassuring’.
It’s not a new test – it’s been used to diagnose bowel cancer in patients with symptoms for many years. But what is new is using it in this way to screen the population before they even have symptoms. And this could have a huge impact on bowel cancer in this country.
This is the first of six ‘pilot’ centres which will iron out any potential problems in the system before rolling out BSS to the rest of the country. Over the next few months, another five centres will then start to offer Bowel Scope Screening.
By 2016, everyone in England should be invited to have a test at the age of 55.
Bowel Scope Screening adds to the existing bowel screening programme, which uses the Faecal Occult Blood Test (FOBT) – which looks for blood in your stools. People are invited from age 60 to participate (or age 50 in Scotland).
Under the new plans, if you live in England, you’ll be invited to be screened using BSS when you turn 55. If you decide not to go (and it is your decision), you can change your mind up until you turn 60. At that point you’ll be invited to take part in the existing bowel screening programme.
Whether or not you decide to have BSS, you will still be invited to take part in the existing screening programme at 60, to help spot any cancer that might develop later on. Although it hasn’t been shown to prevent cancer in the same way as BSS, FOBT is still an important way of helping to diagnose bowel cancer at an early stage, when treatment is more likely to be successful. The evidence so far suggests it’s made a big impact already and BSS takes this a step further.
This is an important first step. Now we need to make sure that everyone can benefit from Bowel Scope Screening. At the moment BSS is only being rolled out in England. We want to see Scotland, Wales and Northern Ireland develop their own plans for BSS, including making sure they have the right facilities available.
If this test is made available across the UK, thousands of deaths will be prevented, and – even better – potentially thousands of people will be spared from ever having to experience this terrible disease.
Yarnall, Crouch & Lewis (Division of Genetics and Molecular Medicine, King’s College London, United Kingdom.). Cancer Epidemiology 2013 Jan 29
Background: Epidemiological studies have identified potentially modifiable risks for colorectal cancer, including alcohol intake, diet and a sedentary lifestyle. Modelling these environmental factors alongside genetic risk is critical in obtaining accurate estimates of disease risk and improving our understanding of behavioural modifications. Methods: 14 independent single nucleotide polymorphisms identified though GWAS studies and reported on by the international consortium COGENT were used to model genetic disease risk at a population level. Six well validated environmental risks were selected for modelling together with the genetic risk factors (alcohol intake; smoking; exercise levels; BMI; fibre intake and consumption of red and processed meat). Through a simulation study using risk modelling software, we assessed the potential impact of behavioural modifications on disease risk. Results: Modelling the genetic data alone leads to 24% of the population being classified as reduced risk; 60% average risk; 10% elevated risk and 6% high risk for colorectal cancer. Adding alcohol consumption to the model reduced the elevated and high risk categories to 9% and 5% respectively. The simulation study suggests that a substantial proportion of individuals could reduce their disease risk profile by altering their behaviour, including reclassification of over 62% of heavy drinkers. Conclusion: Modelling lifestyle factors alongside genetic risk can provide useful strategies to select individuals for screening for colorectal cancer risk. Impact: Quantifying the impact of moderating behaviour, particularly related to alcohol intake and obesity levels, is beneficial for informing health campaigns and tailoring prevention strategies.
Over the last 30 years the lifetime risk of colorectal cancer (CRC) for men has almost doubled, from 3.5% to 6.9% in the UK in 2008. For women the increase is more than a quarter, rising from 3.9% to 5.4%. Since both genetic and environmental factors contribute to the susceptibility to colorectal cancer, this trend may be due to a change in the dietary and lifestyle factors of the general population leading to higher levels of obesity and more sedentary pastimes.
The major risk factor for colorectal cancer is age and over 85% of colorectal cancer occurs in people over the age of 60. Other risk factors include the presence of polyps and people having an Ashkenazi Jewish genetic heritage. The use of non-steroidal anti-inflammatory drugs (NSAIDs), hormone replacement therapy and aspirin use have also been associated with disease risk. However, it is estimated that between 52 and 57% of colorectal cancers are associated with lifestyle and environmental factors. Many risk factors for colorectal cancer may be modified by intervention, ranging from known risks, such as increased risk from a sedentary lifestyle and dietary changes. The evidence for dietary factors indicates possible increased risk from diets low in fibre, garlic, calcium, fruit, vegetables and fish and high in red and processed meat. In addition to alcohol, BMI, smoking and exercise, we chose to model the most consistent and well validated dietary findings, which suggest that low levels of fibre and high levels of red and processed meat are both significant risk factors.
The international consortium COGENT (COlorectal cancer GENeTics) have identified many of the known genetic variants that predispose to CRC with the 14 single nucleotide polymorphisms (SNPs) found to be convincingly associated with CRC risk from GWA studies summarized in Houlston et al.’s recent update. Of these 14 SNPs, the mean odds ratio per allele is 1.14, with the highest odds ratio reported for SNP rs16892766 near the EIF3H gene (OR 1.28).
The identification of SNPs that contribute to susceptibility for CRC has raised the prospect of genetic screening. Companies such as DeCODEme and 24andme include panels of SNPs for CRC in their genetic testing panels, yet research suggests that the genetic risk prediction alone is of questionable utility. In this research study, we combined the known genetic risk with data on the environmental risks for CRC, enabling more complete risk prediction. We applied a statistical risk model and to determine the impact of modelling environmental factors alongside the 14 genetic susceptibility loci identified by the COGENT consortium.
Early screening for colorectal cancer can be extremely helpful in identifying individuals with polyps and nonpolypoid lesions and preventing the development of cancer. Regular faecal occult blood tests (FOBT) in the over 50 s for example have been found to reduce the number of deaths due to CRC by 15–33%. In the UK, screening is offered to all men and women aged between 60 and 69 at a cost of £77.3 million and this will be extended to 74 year olds. However, it has been suggested that if individuals are provided with a personalized disease risk assessment from their combined genetic and environmental profile, they are likely to be more motivated to alter their lifestyle as a preventative measure, which would increase the effectiveness of health campaigns. In this study we develop predictions of CRC risk in different sub populations and assess the impact of modifying lifestyle factors on risk levels. By providing predictions of disease risk both before and after a lifestyle change for a given genetic profile, the study illustrates the potential benefits for both selection of candidates for screening programmes and the tailored promotion of healthier lifestyle choices, in high risk groups.
There are several modifiable risk factors for colorectal cancer and building predictive models encompassing both genetic and environmental factors enables us to move in the direction of a complete assessment of disease risk. This paper describes a predictive model which takes account of the known genetic contribution as well as the modifiable risks. There is considerable evidence to suggest that detecting polyps in the early stages can reduce mortality rates for colorectal cancer and whilst the interactions between the genetic and environmental elements are undeniably complex, separating out the inherited risk from the lifestyle factors using this model helps to illustrate the potential gains from modifying lifestyle behaviour and could usefully inform healthy lifestyle campaigns.
Our findings indicate that that cessation of alcohol consumption and reducing obesity levels lead to the most significant changes to the proportion of the population reducing their disease risk category. Whilst this could have been predicted to some extent by the higher odds ratios for these factors, it is the combination of relative risk, together with the prevalence of the factor within the population that determines the overall impact. In addition, being able to create personalized risk predictions in this way, has the potential to motivate greater behavioural change, showing for example, that it is possible to significantly reduce disease risk by moving from a high risk category to an average risk category though increasing fibre levels; cessation of alcohol consumption or weight management, given a particular genetic profile. Further research is required to increase understanding of how individuals respond to risk assessment based on genetic information. This may increases their motivation since the results are personal, or decrease their motivation because they consider that their genetic risk cannot be modified.
Our focus has been on risk categorization, and not on the absolute level of risk estimated from the combination of genetic and environmental risk factors, which is modest for most categories. There are two advantages to this strategy. Firstly it moves away from the strategy used, for example, by direct-to-consumer genetic testing companies such as 23andme and deCODEme (who provide a single figure of risk with no confidence intervals) towards the strategy deployed in genetic counselling of using a qualitative risk level, which can be more easily interpreted for the purpose of risk prediction. Secondly, it puts a stronger statistical framework on the risk model: an assignment to elevated risk implies that the risk is statistically distinct from the risk of the average, baseline, individual, given the uncertainty of the parameters used in the model.
There are several limitations of the model. Firstly, the model is built from estimates in the literature extracted from different studies. This enables researchers to select the best study to capture information on each risk factor, but assumes that information is directly comparable between studies. This limits the precision with which risk estimates can be calculated. A further limitation is that the model assumes all risk factors entered are independent. For known gene and environment interactions, this can be overcome by either modelling the interaction explicitly as an environmental risk factor, or by omitting known genetic loci to prevent over-representation of a risk factor (such as SNPs on the FTO gene which are associated with BMI). Within the genetic component, linkage disequilibrium between SNPs can be tested to confirm no correlation at a population level; few interactions of risk between genetic loci have been identified, so the assumption of independence should not be a major problem. For the environmental component, assumptions of independence are more difficult to assess. Lack of independence may lead to inaccuracies in the population frequencies estimated, but the contribution of environmental factors to the model is based on relative risks that are estimated in the presence of relevant covariates, so levels of risk should not be inflated. Increasing our understanding of the association between lifestyle factors, as well as between genes and the environment, will be important in obtaining more accurate assessments of risk. In addition, the accuracy could be further improved by more specific modelling of the population being targeted. Applying data with relative risks by sex, by population group, or for individuals with a first degree relative with CRC for example, would provide more accurate estimations of disease risk specific to those populations.
Colorectal cancer screening programmes are widespread, but are age-targeted and look for signs of cancer in early development. In contrast, the methods described here can be used to target lifestyle factors, and are relevant for younger age-groups. The approach could encourage behavioural changes and help to reduce CRC rates. Although the model indicates that certain individuals can reduce their CRC risk by changing their behaviour, the time taken for changes in environmental risk factors to have an effect on risk is unknown, and will differ by factor. Additional research is needed to further elucidate the genetic and environmental contributions to disease risk and to measure the longer term impact of behavioural change on disease outcomes.
From March, Norwich, South of Tyne, St Mark’s London, Surrey, West Kent and Wolverhampton NHS trusts will offer screening to everyone aged over 55.
The screening involves a thin, bendy tube with a camera attached being placed into the rectum and lower bowel.
Currently, those aged 60-69 in England are offered faecal occult blood tests.
“Over 90% of cases of bowel cancer can be treated successfully if caught in the initial stages”
Mark Flannagan Chief Executive of Beating Bowel Cancer
If any blood is found in the faeces, the person will be invited for further tests – usually a colonoscopy, where a thin, flexible tube with a camera is guided along the entire length of the large bowel.
The new screening will invite younger, symptomless patients to have a similar camera check, a flexible sigmoidoscopy, of the lower part of their large bowel to look for any abnormal growths.
Screening in this way allows doctors to remove growths that might otherwise turn in to cancer and treat any cancers already present.
Mark Flannagan, chief executive of Beating Bowel Cancer, said: “We welcome the government’s commitment to the introduction of flexible sigmoidoscopy as part of the prime minister’s previous pledge which will give patients greater access to diagnostic tests. This is vital if we are to save lives.
“Over 90% of cases of bowel cancer can be treated successfully if caught in the initial stages, so screening is essential to ensure we give patients the best chance of recovery. Bringing in this test has the potential to save thousands of lives through early detection.
“We look forward to playing our part in ensuring a full programme is rolled out across England as quickly as possible so that many more people across the country can benefit.”
About one in 20 people in the UK will develop bowel cancer during their lifetime.
It is the third most common cancer in the UK, and the second leading cause of cancer deaths, with more than 16,000 people dying from it each year.
The plans will be unveiled on Tuesday at the Britain Against Cancer conference, where Mr Hunt is expected to say England has lagged behind other comparable countries in cancer survival league tables for too long.
For some cancer types, survival rates are 10-15% lower in England than in comparable countries such as Australia, Canada and Sweden.
Outcomes of the Bowel Cancer Screening Programme (BCSP) in England after the first 1 million tests
Introduction The Bowel Cancer Screening Programme in England began operating in 2006 with the aim of full roll out across England by December 2009. Subjects aged 60–69 are being invited to complete three guaiac faecal occult blood tests (6 windows) every 2 years. The programme aims to reduce mortality from colorectal cancer by 16% in those invited for screening.
Methods All subjects eligible for screening in the National Health Service in England are included on one database, which is populated from National Health Service registration data covering about 98% of the population of England. This analysis is only of subjects invited to participate in the first (prevalent) round of screening.
Results By October 2008 almost 2.1 million had been invited to participate, with tests being returned by 49.6% of men and 54.4% of women invited. Uptake ranged between 55–60% across the four provincial hubs which administer the programme but was lower in the London hub (40%). Of the 1.08 million returning tests 2.5% of men and 1.5% of women had an abnormal test. 17 518 (10 608 M, 6910 F) underwent investigation, with 98% having a colonoscopy as their first investigation. Cancer (n=1772) and higher risk adenomas (n=6543) were found in 11.6% and 43% of men and 7.8% and 29% of women investigated, respectively. 71% of cancers were ‘early’ (10% polyp cancer, 32% Dukes A, 30% Dukes B) and 77% were left-sided (29% rectal, 45% sigmoid) with only 14% being right-sided compared with expected figures of 67% and 24% for left and right side from UK cancer registration.
Conclusion In this first round of screening in England uptake and fecal occult blood test positivity was in line with that from the pilot and the original European trials. Although there was the expected improvement in cancer stage at diagnosis, the proportion with left-sided cancers was higher than expected.
Significance of this study
What is already known about this subject?
Randomised trials of colorectal (bowel) cancer screening have indicated that a biennial guaiac-based faecal occult blood test has the potential to reduce colorectal cancer mortality by about 25% in those accepting screening and by 16% in those offered screening.
In the UK trials and pilot studies uptake was between 50% and 60%.
Factors such as age, ethnic background, deprivation and gender are known to influence uptake.
What are the new findings?
Overall uptake in this first round of screening was 55–60% in the provinces in keeping with previous studies but was much lower in the London area at only 40%.
Uptake of the offer of colonoscopy in those with an abnormal test was high but only 83% of those with abnormal tests underwent colonoscopy.
Early cancer (Dukes A or B) was found in 70% of those with cancer.
The proportion of screen-detected cancers that were found in the right colon was lower than expected.
How might these impact on clinical practice in the foreseeable future?
If these early results are maintained the Bowel Cancer Screening Programme will achieve the intended 16% reduction in overall bowel cancer mortality.
Different screening strategies may be required to effectively screen for right-sided bowel cancer.