Bowel Cancer

The Problems With the Bowel Screening Pilot

April 2014
What is it about general elections and screening programmes?

The promise to establish a national cervical screening programme was announced during the lead up to the 1990 election, following the release of the report of the Cartwright Inquiry into the treatment of cervical cancer at National Women’s Hospital in August 1988. The breast cancer screening programme was launched in a hell of hurry in December 1998 in the lead up to the 1999 election.

This year being another election year, pressure is mounting on the government to prematurely roll out a national bowel screening programme.1, 2, 3

This would be a big mistake because the 4-year bowel cancer screening pilot currently underway in the Waitemata DHB is having problems, and any attempt to launch a national bowel screening programme without rectifying the issues causing major concerns would result in utter chaos and simply confirm that those in charge of our health system are unwilling to learn from the lessons of the past.

Currently all people aged between 50 and 74 years of age who live in the Waitemata DHB area and are eligible for publicly funded health care are being offered a free bowel screen. The pilot began in October 2011 and is due to be completed in 2015, by which time most of those who have taken part will have been screened twice.

It would be incredibly foolish and unethical to rush in to establishing yet another screening programme before we know precisely what resources are needed to screen, examine, diagnose and treat the healthy people that are being encouraged to undertake the screening test. The pilot bowel screening programme in Waitemata DHB has revealed some unexpected problems that must be thoroughly assessed and rectified before any other DHB inflicts bowel screening on its population. More about these later.


The Faecal Occult Blood Test (FOBT) involves sending in a faecal sample that is tested for any traces of blood.

While a positive result means that blood is detected in the faecal sample, it does not mean the person has bowel cancer. It simply means that a further test is needed to find what is causing the blood to be there.

It is important that those who choose to be screened understand that the FOBT is not 100% accurate. In fact it is not known what the false positive rate and the false negative rate of this screening test is. This is not good news as it means a lot of people are going to become very anxious and may remain anxious even when a further test, a colonoscopy, does not find anything wrong.


If the first test result is positive for the presence of blood an appointment will be made for a colonoscopy which is an examination that looks at the lining of the bowel to check for the presence of polyps. A polyp is a benign growth on a stalk. Around 80% of bowel cancers begin life as an adenomatous or benign polyp. Polyps develop very slowly and usually take many years to turn into a cancer.

It is considered best practice to remove all polyps found during the colonoscopy which are then sent to the laboratory for testing. The Waitemata DHB pilot has revealed that those being referred for a colonoscopy have large numbers of polyps and it is taking a lot more time than was anticipated to remove them.

As Waitemata DHB is struggling to meet the unexpected demand on its colonoscopy services due to the time each colonoscopy takes, people are waiting many weeks for their colonoscopy after learning that the result of the FOBT indicates they need one. For many it is a nerve-wracking wait.

The Emotional Impact

However, the anxiety experienced while waiting for the colonoscopy appointment is just the start. There is no relief in sight even after the lab results arrive. Even if the polyps are found to be benign people are being advised to come back in six months and have another examination.

This is completely unnecessary and does nothing to reduce anxiety levels. It can result in people remaining in a constant state of stress and fear, which in itself can be harmful for their physical and emotional health and wellbeing.

Of course, the media has been silent about the downsides of the bowel cancer screening pilot, preferring instead to run stories about those who had their polyps removed and found evidence of cancer or of pre-cancer – the success stories don’t differentiate between the two.

Ministry of Health

The Ministry of Health isn’t exactly being honest about the bowel screening pilot either. Their website says the pilot is looking at the safety and effectiveness of bowel screening.3 But it isn’t. The pilot is actually a cohort study which will not provide evidence of safety and effectiveness the way a randomised controlled trial (RCT) would do. The pilot is simply an implementation feasibility study which seems to be ignoring the very real potential for harm including the risks of overdiagnosis and overtreatment.

It is also not clear whether it is measuring the effect on the wait time to investigation on people presenting with symptomatic bowel cancer. This is surprising and of concern in a feasibility/implementation study, as it is an important population safety aspect.

The MOH website also features a statement that says “international evidence shows that bowel cancer screening programmes can save lives through early diagnosis and treatment.”4 There is no reference to what international evidence they are referring to. As no effect has been demonstrated on all-cause mortality this is simply not true.5, 6

It is totally unacceptable that the Ministry of Health is not providing balanced information about both the bowel cancer screening pilot and screening programmes in general. Part of the problem is the composition of the working groups that the MOH/NSU chooses to establish and oversee screening programmes.

Accurate Data

Before any decision is made to establish a national bowel screening programme it is vitally important that such a decision is based on accurate data. Waitemata DHB is working on this and is very aware of the need to make sure that both the Ministry and the Minister of Health do not make a decision based on data that subsequently proves to be incorrect.

The Auckland DHB is very clear that it does not have the capacity to provide the services required. At its Hospital Advisory Committee meeting on 19 February a discussion revealed that the increased colonoscopy requirements will “place an additional strain on the anatomical pathology service and highlights the need for trained nurses to assist.” All three Auckland DHBs have the same issues in regard to these wait lists. The minutes of the meeting record that while the government has no national or regional programme it does have a 4-year pilot in place at Waitemata DHB. “At the end of the pilot the government will consider the results and costs with a view to determining how to proceed nationally.” Note it is “how” not “whether.”

Evaluating the Pilot

An evaluation of sorts has been built into the bowel screening pilot, but as already noted it is not measuring the potential for harm in terms of over-diagnosis and overtreatment

There is also the very real possibility that a national bowel screening programme would not be cost effective. Even if the Waitemata DHB pilot does indicate that the resources required indicate it should not go ahead, all the DHBs know that the government is going to roll it out nationwide regardless of the cost to the health system or the harm it can cause to healthy people.

  1. Dying of embarrassment: NZ tops bowel cancer rates, 22 January 2014, New Zealand Herald
  2. John Maslin, Group urges screening for bowel cancer, 10 March 2014, New Zealand Herald.
  3. National Radio “Morning Report” 9 April 2014
  4. MoH, Bowel Screening Pilot Monitoring Indicators
  5. MoH, About Bowel Screening
  6. Hewitson P et al: Cochrane systematic review of colorectal cancer screening using the fecal occult blood test (hemoccult): an update. Am J Gastroenterol. 2008 Jun;103(6):1541-9.
  7. NCI, Colorectal Cancer Screening (PDQ®)–Health Professional Version