An inquiry into the Southern District Health Board's (DHB) admission to the national bowel screening programme will be a distraction, the Ministry of Health says.
Doctors, researchers and cancer-care campaigners are calling for an investigation similar to the Cartwright Inquiry in the late 1980s.
They say lives have been lost because the Southern DHB was ill-equipped to deliver colonoscopies to those showing symptoms of cancer, let alone the added workload of screening, when it joined in 2018.
Critics of the process, Dr Phil Bagshaw and Professor Brian Cox, earlier this week called on the government to launch the inquiry.
They were supported by Dunedin GP Dr Dave McKay, recently retired Southland surgeon Dr Murray Pfeifer, and cancer care campaigner Melissa Vining.
The primary concern was Southern DHB did not have the capacity to provide colonoscopies to all those showing symptoms of colorectal cancer before its admission to the screening programme.
So when the programme went live, those with symptoms went to the bottom of the heap and in some cases had referrals declined.
In a statement, the ministry's chief medical officer, Dr Andrew Connolly, said an inquiry would be a distraction to a well-performing service.
"The ministry's assessment is that the DHB's involvement in the screening programme has been very successful in the region and the DHB should focus on building on these gains," Connolly said.
"The ministry accepts that the success of the programme, combined with a higher than expected positivity rate, did initially mean that a greater number of colonoscopies and surveillance procedures were required than initially anticipated."
But additional resources were allocated once this was realised, Connolly said.
The risks and benefits to participants and the wider community have to be balanced when introducing a screening programme, he said.
Connolly said the ministry assessed the readiness of each DHB.
"Introducing the programme is the result of years of planning and preparation, involving multiple stakeholders and individuals, all of whom collectively apply their skills and experience. As a result of bowel screening 243 bowel cancers have been detected and 2,333 colonoscopies performed (April 2018 to 17 May 2021)."
Most of the 243 people whose bowel cancers were detected in the screening programme were asymptomatic - and none were on the symptomatic wait lists, Connolly said.
"Of the 243 bowel cancers detected 32.7 percent were stage one cancers. This has resulted in 90 people having a 90 percent chance of a five-year survival rate. Only 11 percent of patients diagnosed with bowel cancer on the symptomatic lists had stage one cancer diagnosed.
"Additionally, around 60 to 65 percent of the screening colonoscopies, polyps were removed, and these people were put on surveillance screening colonoscopy list. This materially reduces the chances of these patients developing bowel cancer in the future.
"Southern DHB's bowel cancer detection rate through the screening programme is higher than the national rate."
Southern DHB detects 10 cancers for every 100 colonoscopies performed, compared to the national average of seven cancers diagnosed for every 100 colonoscopies performed, he said.
As chair of the Southern Endoscopy Oversight Group, Andrew Connolly said if he were asked to sum up, he would describe the DHB screening programme as adding significantly to the health and well-being of the public of the region.
At the same time the delivery of colonoscopy to symptomatic patients has been very good, he said.
"I am confident the SDHB is doing well and work continues to do fully implement all the recommendations accepted by the Board."
Health Minister Andrew Little also showed little appetite for an inquiry as he did not directly address the calls in response to RNZ questions.
In a statement he said he was satisfied with the process leading to Southern DHB's admission into the bowel screening programme and he was not unduly concerned about the longer wait times for colonoscopies in the district.