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Advancing BowelScreen

By Mindo - 18th Jun 2021

The doctor listens in on the icon of the intestine on blurred background.

After a challenging 16 months, BowelScreen is progressing plans to extend age eligibility, but colonoscopy capacity remains a key limiting factor. Clinical Director Prof Pádraic MacMathuna spoke to Catherine Reilly about the impact of the Covid-19 pandemic and upcoming developments

BowelScreen is planning to extend screening to 59-year-olds in 2022, Clinical Director Prof Pádraic MacMathuna has informed the Medical Independent (MI). While a welcome development, it falls far short of a recommendation in the National Cancer Strategy 2017-2026, which said the HSE should ensure “appropriate” capacity to expand colorectal cancer screening to “all” 55-to-74-year-olds by the end of 2021.

First offered in October 2012, BowelScreen was established to provide screening initially to all eligible men and women aged 60-to-69 and ultimately to the full 55-to-74 age group. No expansion of screening in the identified age range has been implemented to date.

A home faecal immunochemical test (FIT) kit is sent by post every two years to the eligible population who consent to participate and the vast majority receive a negative result. Those who receive a positive FIT result are referred for screening colonoscopy.

Currently, 14 endoscopy units are participating in BowelScreen with University Hospital Waterford the most recent addition in late 2020. A further three units are set to join BowelScreen in the coming months.

Prof Pádraic MacMathuna

Prof MacMathuna said that “there is an enthusiasm in several units to come on board”. The units’ infrastructure – principally the colonoscopy capacity – is the key consideration. BowelScreen can provide support for equipment and manpower in these units. Initially, the screening programme plans to extend age eligibility downwards, which will be implemented gradually. Given the parallel demand for urgent and routine colonoscopies in the symptomatic service, screening expansion is a delicate act.

“We’d like to do it right down to 55 [sooner], but the colonoscopy capacity is the core issue,” said Prof MacMathuna.
The national capacity for endoscopy needs to be increased to meet the requirements of both symptomatic and screened populations, he stated.

The programme decided to first expand age eligibility downwards, because colon polyp formation generally begins in the 50s. Furthermore, many individuals reaching 70-plus will already have been invited to participate (and a proportion have participated) in BowelScreen.


Colorectal cancer is one of the most common cancers diagnosed in Ireland and the second most common cause of cancer death overall (third most common in females). Annually, an average of 1,633 men and 1,186 women are diagnosed with colorectal cancer, according to National Cancer Registry Ireland (NCRI) figures. In Ireland it is often detected at an advanced stage.

A Lancet Oncology study published in 2019 found that, of seven high-income countries, survival figures for Irish patients were second lowest for colon and rectal cancer, although survival rates were improving (five-year survival for colon cancer diagnosed from 2010-2014 was 61.8 per cent; and 62.4 per cent for rectal cancer).

BowelScreen aims to detect colorectal cancer as early as possible and identify and remove polyps in the colon before they may develop into cancers. In the programme’s second screening round from 2016 to 2017, it invited 546,767 eligible people, screened 226,374 clients, performed 6,523 colonoscopies and detected 410 cancers.

This represented a screening uptake rate of 41.4 per cent and a cancer detection rate of 1.81 per 1,000 people screened. Some 12,367 adenomas or polyps were removed and these individuals are offered further surveillance colonoscopies to detect and treat any adenoma recurrence at a later date (over 1,700 surveillance colonoscopies were performed in round two).

In addition, 879 sessile serrated lesions (SSLs) were detected. SSLs are flat, pre-cancerous polyps that can develop into bowel cancer and may be difficult to visualise at colonoscopy. BowelScreen is one of the first international bowel screening services to report on these lesions, according to the programme’s report on the second screening round.

Population-based bowel cancer screening aims to reduce deaths from colorectal cancer by 36 per cent after 10 years of offering FIT screening to people aged 55-to-74.

In order to make a significant indent on mortality at population level, the extension of age eligibility and higher participation levels are required.

Prof MacMathuna said that ‘there is an enthusiasm in several units to come on board’

“If you send 100 FIT tests, to make the maximum impact on mortality you should have really a 65-70 per cent uptake,” outlined Prof MacMathuna. “Our uptake is just under 45 per cent, which is not too bad. It started at 38-to-39 [per cent]; it is going in the right direction. This is common in all European experiences where it takes a while to make an impact and get a profile.”

The communications unit at the HSE National Screening Service has sought to raise public awareness, including during bowel cancer awareness month (April). The messaging has emphasised that colorectal cancer is an ‘equal opportunity cancer’, affecting both men and women. BowelScreen is the first cancer prevention screening programme involving men, while women are generally more familiar with cancer screening through BreastCheck and CervicalCheck.

“The participation of men is increasing and there are broader cultural issues about men, particularly middle-aged men, going to their doctors and that is a generic challenge in the healthcare system. But we are trying to emphasise more and more that this is a cancer that affects men and women pretty equally and that men need to be more aware of it,” stated Prof MacMathuna.

BowelScreen has engaged with GP and pharmacist organisations as part of heightening the profile of bowel cancer and the screening initiative.


The pandemic and cyberattack have significantly impacted the programme and work is ongoing to restore activity levels. In this regard, Prof MacMathuna paid tribute to BowelScreen Programme Manager Ms Hilary Coffey Farrell; Deputy Programme Manager Ms Mary Sheedy, and all the programme team, as well as endoscopy staff, for their enormous efforts. The challenge presented by the pandemic “remains significant” and BowelScreen has adjusted the FIT invitations to accommodate reduced capacity. “We anticipate that the BowelScreen programme will gradually regain lost ground by late 2021 into early 2022.”

Documents obtained by MI under Freedom of Information law show BowelScreen has been highly constrained in its ability to deliver colonoscopies during 2020 and early 2021. The pandemic led to a pause in screening invitation activity from March to August 2020.

“One of the major problems that the pandemic had, in terms of colonoscopy and GI [gastrointestinal] services, was that the nursing personnel were transferred into high intensity Covid wards,” commented Prof MacMathuna, adding that physical distancing and extra infection control requirements affected patient throughput.

By late 2020, colonoscopy capacity was operating at 40-to-70 per cent in BowelScreen units. In early 2021, the programme was impacted by the ‘third wave’ of Covid-19 cases. As of early March 2021, five units were operating at reduced capacity; six units advised that they continued doing BowelScreen cases at reduced capacity, but would give clinical prioritisation to index clients; and three units were not doing BowelScreen colonoscopies. Last year 132,597 screening invitations were issued, representing just 46 per cent of total invitations in 2019.

Asked about the issue of delayed diagnoses of colorectal cancer due to the pandemic, Prof MacMathuna said the main concern related to people with symptoms.

“The major impact I think would be in symptomatic patients – in other words, the patients who are going to their doctor with symptoms and that is for all cancers and all diseases, where we are seeing patients presenting later.”

The IMO recently highlighted to the Oireachtas Health Committee that in the first quarter of 2021, some 450 people per month were not seen within the recommended four weeks for an urgent colonoscopy (in the symptomatic service) compared to 15 per month pre-Covid.

In September 2020, 36.2 per cent of people were waiting less than 13 weeks for routine colonoscopy, against a target 65 per cent, states HSE performance data.

In the screening cohort, some international data has indicated that a six-month delay in accessing a colonoscopy after a positive FIT test does not affect outcomes – a matter noted at a meeting of BowelScreen’s colorectal clinical advisory group (CAG) in January.

A study in the journal Endoscopy in 2020 (Zorzi et al), involving an Italian regional screening programme using biennial FIT, found that an increased colorectal cancer prevalence at colonoscopy was observed for a time to colonoscopy of ≥ 270 days (approximately nine months), whereas it was stable for waiting times of < 180 days (approximately six months). The colorectal cancer stage was stable in relation to a waiting time of < 270 days.

Potential changes

BowelScreen is continuing with the current two-yearly FIT invite cycle, but this will be monitored and potentially extended pending the international experience. According to Prof MacMathuna, international experience has documented that a repeat colonoscopy prompted by a repeat FIT-positive test, two years after normal index colonoscopy, is associated with “minimal polyp detection and hence cancer prevention potential”.

Additionally, an increase in the time interval for surveillance colonoscopy following polypectomy is being considered, such that it would align with international guidelines for the symptomatic cohort. In turn, this would release some colonoscopy capacity. All aspects of BowelScreen are monitored and quality assured in line with the programme’s Guidelines for Quality Assurance in Colorectal Screening.

The ‘holy grail’ of a screening programme ideally would be a blood test that would identify an individual who has polyps…

Performance data on endoscopy services is also collected by the HSE/RCPI/RCSI National GI Endoscopy Quality Improvement Programme through the national quality assurance and improvement system (NQAIS) for endoscopy.

Under BowelScreen’s key performance indicators (KPIs), at least 90 per cent of clients should be offered a colonoscopy appointment date that occurs within 20 working days from being deemed clinically suitable following pre-assessment.
As reported by MI in 2019, this KPI has come under strong scrutiny at the programme’s CAG. In April of that year, the CAG noted that this standard was set when BowelScreen was established.

“However, setting this standard for screening clients at the level [of] urgent symptomatic cases is likely [to be] inappropriate and may be putting unwarranted pressure on screening unit resources without any significant clinical gain,” outlined minutes of the CAG meeting in April 2019. The minutes further noted Prof MacMathuna as confirming there were “no international standards requiring a screening client to have a colonoscopy within 20 days”. The CAG agreed to propose that this KPI be changed to 30 working days.

Prof MacMathuna told MI such a change has not yet been finalised. He said there was no clinical significance in moving the period by 10 working days, and as previously indicated, international data suggests that a screening colonoscopy could be offered at a longer interval, without adverse patient impact.

Critical metric

A critical metric in the quality assurance system is the adenoma detection rate (ADR). This is measured in terms of both the individual colonoscopist and screening unit. The minimum ADR standard is 45 per cent of colonoscopies and the achievable standard is greater than or equal to 50 per cent. The majority of units and colonoscopists are meeting the minimum target and many have more than 50 per cent yields, stated Prof MacMathuna. An overall ADR of 56.7 per cent was recorded in BowelScreen data for the second screening round.

Does the programme often identify outliers from the ADR standard? “Not often, but we do,” answered Prof MacMathuna.

“If there is an outlier, we assess the performance of the individual… we look at the total numbers, the clinical lead looks at the total numbers of that individual and their past record. So it is noted centrally and it is the clinical lead’s responsibility to highlight that with the individual.

“We are kept informed of KPIs of all the clinicians, and this includes the surgeons who operate on the patients found to have cancer, the radiologists who examine the CT colons for us and the pathologists likewise….”

On occasions where a private company has been used by some BowelScreen units, Prof MacMathuna maintained that “we have visibility and confirmation of their KPIs in terms of caecal intubation, ADRs, etc”.

“There haven’t been any quality issues of concern. We are keeping an open mind about using any of that type of outsourcing in future. We are trying to increase the capacity by bringing more units on board and perhaps doing some weekend work in different units.”

At present, BowelScreen has no plans to request publication of quality assurance screening data per identifiable unit.
Hospital identifiable data has now been included in the national data reports of the National GI Endoscopy Quality Improvement Programme.

Future screening practice

Like most areas of medical practice, the delivery of bowel screening is likely to evolve over the coming years in line with evidence. Within a decade, it is possible the FIT test may be replaced by a blood test that would more accurately select people requiring colonoscopy.

“The ‘holy grail’ of a screening programme ideally would be a blood test that would identify an individual who has polyps and then we would only target the individuals with a positive blood test for colonoscopy and it would significantly reduce the need for doing a large number of colonoscopies in individuals who turn out don’t need it,” commented Prof MacMathuna.

“There is a lot of work going on and we are potentially getting involved in a large study with collaborators in the States and Europe about this type of study, which I think, hopefully, in five-to-10 years, would replace the FIT test and be much more selective and accurate.”

For now, the FIT test remains an important primary screening tool for colorectal cancer. Indeed, it could be increasingly used for some symptomatic patients (who are not describing blood among their symptoms) to help identify those likely to benefit from colonoscopy. Some centres in Ireland and other countries are investigating use of the FIT and the calprotectin stool test in certain (lower risk) symptomatic cohorts to select for colonoscopy. The idea would be to prioritise for colonoscopy those individuals likely to have polyps, cancer, or inflammatory bowel disease.

FIT testing in symptomatic patients is being coordinated through the hospitals rather than primary care. “But I think there will be more and more discussion of non-invasive tests in the community, both within the bowel screen programme as it stands and in the symptomatic clinical load.” Internationally, research is also examining use of artificial intelligence (AI) as a means of enhancing detection of adenomas during colonoscopy.

Prof MacMathuna noted that the need for enhanced detection is particularly relevant in regard to flat lesions on the right side of the colon. These flat lesions can be subtle and missed “even by the most experienced colonoscopists”.

“There have been some other techniques where you put in a dye in the colon as you are coming back from the caecum. And that shows changes that you would have missed by ordinary white light,” he explained. “The idea behind AI is to be able to pick these things up and flag it for you at the time. Because you want a system whereby you can detect something that was otherwise undetectable and take it out, as opposed to do a study and have to put the patient through another colonoscopy.”

AI is controversial as it can lead to picking up “incidental tiny hyperplastic polyps that have no consequence” resulting in over-treatment. Prof MacMathuna added that Dr Conor Lahiff, Consultant Gastroenterologist at the Mater Misericordiae University Hospital in Dublin, is doing a study using dye-based colonoscopy with BowelScreen support.
It is important to find ways to enhance detection of flat lesions as they are shown to have cancer potential and may develop more rapidly than other precancerous growths – potentially developing into cancer within five years, whereas bowel cancer generally develops over a period of 10 years.

These lesions could account for a significant proportion of post-colonoscopy interval cancers (ie, diagnosed within three years of normal colonoscopy), which are described as uncommon in the screening programme.

Post-CervicalCheck crisis

On foot of the Scally report into CervicalCheck, the HSE commissioned expert reviews of all interval cancer management processes for the three national cancer screening programmes. The report on BowelScreen noted that, in keeping with most international screening programmes, it had not considered interval cancers as unintended or unanticipated incidents as they were “an accepted, unavoidable occurrence in population screening programmes”.
As such, a universal disclosure policy had not been implemented for interval cancers by BowelScreen except where harm had been attributed to programme failings.

“This was most notable following a patient safety incident in one of the programme’s endoscopy units in 2014. The management of that incident and the quality assurance measures in place within the BowelScreen programme were reviewed by an external expert following the incident. The BowelScreen programme was found to have implemented open disclosure in an appropriate manner…,” stated the report.

The expert report, published in October 2020, made a number of recommendations for BowelScreen including strengthening informational materials on the benefits and limitations of screening and including explicit information on the occurrence of interval cancers and on the opportunity to discuss their case should a patient develop a post-colonoscopy colorectal cancer (PCCRC).

It also recommended improving communications with NCRI to enable timelier validation of interval cancers and the calculation of the interval cancers rate in the BowelScreen programme. In accordance with the BowelScreen memorandum of understanding with local screening units, the unit “will continue to openly discuss the diagnosis, treatment plan and review of the screening colonoscopy with the patient following diagnosis of a PCCRC”, advised the report.

Anyone diagnosed with bowel cancer can request a review of their screening history and BowelScreen is putting in place a new review process currently. Prof MacMathuna said the programme has been working with the NCRI to
develop an IT link to enhance BowelScreen’s capture of information on all interval cancers. In due course, “it will give us a much more accurate reflection of our post-colonoscopy cancer rate, which is the international benchmark”.

No legal cases have been issued against BowelScreen in regard to interval cancers.

“BowelScreen to date hasn’t gotten into that space. The presumption with my colleagues, however, is that it
is only a matter of time.” By its nature, the material available for review in bowel screening differs from that in breast and cervical screening programmes.

“The colonoscopy situation is that the colonoscopy report is a narrative in writing, with specific photographs of areas of the caecum and rectum and whatever lesions are detected. There is never a cancer that you are seeing on a photograph that the colonoscopist somehow says wasn’t there, it doesn’t work like that.”

Medico-legal concerns have not yet been a deterrent to recruitment. “Most of the units are happy to engage with BowelScreen as they see it as a positive initiative in terms of their specialty. As well, there is a financial incentive because they get additional nursing expertise, they get help towards equipment and resources and some places will get additional medical staff. So it is positive.”

But if the situation becomes “more medico-legally contentious”, as with BreastCheck and CervicalCheck, GI doctors may decide to stick to the symptomatic clinical service.

“It will compromise, if not discontinue, the screening programmes if the medico-legal situation remains the same unfortunately.…”

“Hopefully it won’t come to that.”

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