"However, applications for funding to rectify these IT issues were often unsuccessful, as plans for a national IT platform were being made at that stage," the review found.
A root cause analysis of why certain people weren't invited for free screening - some of whom were later diagnosed with cancer - "highlights the impact of the lack of investment" in the IT system for the Waitemata pilot.
"It has been contended that the Ministry of Health decision-makers did not fully understand the clinical implications of these issues."
Free screening is currently in five DHBs, with the other 15 to progressively join, with the entire country covered by 2021.
Overall, today's review found the national roll-out of the bowel screening programme across DHBs was progressing well.
However, current governance "appears to be overly complicated", with clinical governance and Māori leadership areas to be strengthened. When responsibility for the programme was given to the ministry's national screening unit there was a loss of institutional knowledge "exacerbated by an apparent breakdown in relations between the national screening unit and Waitemata DHB".
Other recommendations, which have been accepted by the ministry, include reviewing IT governance, building stronger relationships with DHBs and organisations like Bowel Cancer NZ and the Māori cancer leadership group.
The review panel highlighted an "urgent need" to address workforce issues, partly by increasing the number of colonoscopists being trained. Many DHBs were struggling to meet current colonoscopy wait times, even before the roll-out of screening.
Because of increased bowel cancer awareness, demand for colonoscopies carried out because of possible symptoms has increased about 20 per cent among the five DHBs that have already introduced screening.
"The panel considers that urgent action is required to ensure that DHBs have the capacity to provide screening colonoscopies without causing harm to the delivery of symptomatic and surveillance colonoscopies.
"It is necessary to conduct a complete review of colonoscopy prioritisation processes."
Speaking in Wellington, Clark said the review should give the public confidence in the safety and value of the programme.
"Screening programmes save lives. This review confirms that despite some issues with the pilot programme, overall it performed well...the national roll-out of bowel screening is progressing well."
Each year more than 3000 New Zealanders are diagnosed with bowel cancer and more than 1200 die from it. There can be no warning signs cancer is developing, and early detection is critical.
Under the national programme, screening will be offered every two years to men and women aged 60 to 74. Once fully implemented it's expected to detect 500-700 cancers a year.
A bowel cancer screening programme started in Waitemata DHB in 2011 and detected cancer in 375 people, leading the previous National-led Government to commit to national screening.
Another four DHBs have since joined the programme and Labour pledged $67.1 million of operating funding in this year's Budget to keep extending screening across New Zealand.
However, the programme has been hit by a number of serious problems.
In February, Clark revealed the ministry last year wrote to 2500 eligible Waitemata residents who didn't get screening invitations because their addresses weren't updated on a register.
Three people went on to develop bowel cancer, one of whom died. The ministry said it wasn't possible to say what difference being included in screening would have made.
Clark ordered an independent review of the national programme and apologised unreservedly.
In April the ministry said it had discovered another problem that meant many more people may missed out - bringing the total to about 15,000.
More than 30 people had developed bowel cancer, and work has been ongoing to determine what, if any, difference being missed from screening made.
The bowel screening programme is being run by the Ministry of Health's national screening unit, which has had trouble with other screening programmes. Cervical cancer screening was to this year change to screen for the HPV virus, but in June it was announced that would be delayed until 2021 because IT systems weren't ready.
The Herald has recently reported on tensions between some DHBs and the ministry over low cervical cancer screening coverage rates, particularly for Māori.
• National Bowel Screening Programme
Free bowel screening is currently offered by Hutt Valley, Wairarapa, Waitemata, Southern and Counties Manukau DHBs.
Nelson Marlborough, Lakes and Hawke's Bay DHBs were due to start by November 30, with Whanganui and MidCentral DHBs joining by June 30 2019.
The remaining 10 health boards would then progressively join the programme, with all DHBs on board by June 30, 2021.
