About eight lives have already been saved in Hutt Valley and Wairarapa by bowel screening, according to experts.
Bowel screening has been available to people in Waitematā since 2011 under a pilot screening programme.
But in a long-awaited move, Hutt Valley and Wairarapa became the first two areas to offer screening permanently under a national programme, for those aged 60 to 74. Waitematā District Health Board transitioned into this programme in January.
Details released to RNZ yesterday by the clinical director of the programme, Susan Parry, reveal that since July when screening went live in Hutt Valley and Wairarapa, nine cancers have been detected in the former and five in the latter.
Since the programme began in Waitematā, 444 cancers have been detected, according to the latest "snapshot" from the national programme.
Dr Parry stressed that the figures represent people with a cancer diagnosis.
"To date, 14 bowel cancers have been detected but I think we should actually talk about 14 people who've had the opportunity to have their lives changed as a result of the bowel screening programme."
She said the numbers involved in Hutt Valley and Wairarapa were too small to say what the results could be for those people.
However, data from the pilot could help with that:
"We would expect that at least 60 percent [of the cancers detected] would be at stage one and two and ... certainly 40 percent stage one, and those people will definitely have [their] lives saved."
Dr Parry said screening is going to plan in Hutt Valley and Wairarapa.
"At this point in time we're seeing exactly what we anticipated. We're seeing that about five percent of people who return the test have a positive test, and we anticipate that about seven in 100 of those people that go on to have a colonoscopy will have cancer.
"But what we also need to mention is that of those people who go to colonoscopy at least a third will have an advanced polyp that if removed can prevent cancer developing in the future. And that's an important number of people as well."
Dr Parry said those eligible in the Southern DHB, covering Otago and Southland, would be next in line for the free screening, by the end of April.
After that, Counties Manukau DHB is expected to be next, by the end of June, followed by Nelson Marlborough in August, Lakes DHB in Rotorua in September, and Hawke's Bay in October. The remaining DHBs will follow by mid 2021.