Bowel Screening – from Pilot to National Programme

News article

08 June 2017

New Zealand’s National Bowel Screening Programme (NBSP) is being rolled out from July and, once operating nationwide, is expected to reduce the toll of disease and death from one of our most preventable and treatable cancers.

Clinical Director Dr Susan Parry says it’s exciting to see the bowel screening programme, New Zealand’s first ever cancer screening programme for both men and women, about to get underway.

She says, “This is a hugely significant step for New Zealand which, with just over 3000 cases a year, has one of the highest rates of bowel cancer in the world.”

The NBSP will ultimately be available throughout the country to everyone aged 60 to 74 who is eligible for publicly funded healthcare.

“When the programme is fully operating more than 700,000 people will be invited for free screening every two years, and initially between 500-700 cancers are expected to be found annually.”

Dr Parry says information gathered by the Waitemata Bowel Screening Pilot has been used to plan the national programme.

The starting age for the NBSP has been set at 60 years, which is older than the starting age used in the Pilot. The positivity threshold (the threshold which triggers a ‘positive’ or abnormal test result that requires further investigation) will be higher than that used in the Pilot.

It was important to use wide parameters for the Pilot, to collect as much information as possible.  Pilot studies overseas have taken a similar approach.

Dr Parry says the parameters for the national programme have been set so that the benefits of screening outweigh harms, by targeting those most of risk of having bowel cancer.

“Screening is being offered to those most likely to have a bowel cancer or a polyp detected if they’re referred to colonoscopy.  This is important as colonoscopy is an invasive procedure which carries a degree of risk, as is the case for most medical procedures. The potential harms of screening people who are less likely to have bowel cancer include increased anxiety and high numbers of colonoscopies in which no problems are found.  

“Having sufficient colonoscopy capacity is also a factor. We need to be able to refer people for colonoscopy who’ve had a positive test through screening but not create such demand that we delay access for other people who may have symptoms.

“There are limited numbers of specialists or health professionals trained to perform colonoscopy, and whilst resources have and are being increased in New Zealand we need to work within our projected available capacity. This has also been the case for other countries starting bowel screening programmes,” Dr Parry says.

Further information

Further information on the age-range and positivity thresholds chosen for the national programme and why they are different to the Pilot can be found below.

  • The Waitemata Pilot used an age range of 50-74 and a of faecal immunochemical test (FIT) threshold of 75ng Hb/ml buffer
  • Bowel screening through the NBSP is being offered to eligible people aged 60-74, with a FIT threshold of 200ng Hb/ml buffer.

The FIT can detect tiny traces of blood in bowel motions that may be an early sign of pre-cancerous polyps (growths) or bowel cancer.

Key information from the Pilot that influenced the parameters chosen for the national programme include findings that:

  • Approximately 80 percent of cancers detected were in people aged 60–74 years.
  • Approximately 80 percent of cancers were found following a FIT result of greater than 200ng Hb/ml buffer

The combined effect of the age range and positivity threshold set for the NBSP is that approximately 62% of the cancers detected in the Pilot would have been detected using the national programme parameters.

The chosen age range and positivity threshold for the NBSP will mean:

  • Screening is offered to those most likely to have a bowel cancer or an advanced polyp (pre-cancerous growth) detected by a follow-on colonoscopy.This is important because colonoscopy is an invasive procedure that carries some risk. It is critical to ensure the benefits of screening outweigh potential harms.
  • Fewer than half the number of colonoscopies will be required for the national programme compared to if the Pilot parameters had been used. This means bowel screening can start in 2017, rather than being delayed until capacity is increased.(Most Western countries offering population screening for bowel cancer start with limited age ranges because of available colonoscopy capacity).

The national roll-out

The NBSP is initially being offered from July 2017 to eligible people in the Hutt Valley and Wairarapa DHB areas. The remaining DHBs will join in stages, with the roll-out expected to be completed in 2020.

Waitemata will continue screening through the Pilot until the end of this year and transition to the national programme in January 2018.

Dr Parry says she hopes New Zealanders will take the opportunity to participate fully in the programme, which is free and uses a simple test that can be done at home.

“Bowel cancer often has no symptoms but regular screening can help detect it at an early stage, when it can be more successfully treated. In those proceeding to colonoscopy after a positive test result, the removal of polyps may also prevent cancers from developing in the future.

“As the programme is phased in throughout the country, it will also help raise awareness of bowel cancer amongst both the general public and health professionals, and of the need for people to seek medical advice if they have any symptoms that concern them.”

For information on the screening programme, including who is eligible and how to do the test, visit the National Screening Unit website.

For further background on the National Bowel Screening Programme.


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