Asked if giving free screening to some groups and not others could be politically controversial, Woodhouse said "it would be wrong to let politics get in the way of the evidence".
"The alternative to that is to place Māori at greater risk than they already are, and that would be wrong."
Woodhouse said another focus should be on lifting participation in existing free screening. That should be done through changes such as promoting self-testing for cervical cancer screening.
This morning, Health Minister David Clark wouldn't say if he opposed dropping the screening age for Māori and Pacific New Zealanders, but said the priority was rolling out the existing screening programme to all DHBs - something expected to be done by June 2021.
Clark said it was important that clinical advice drove the decision and "to date, the advice that I've had is that the biggest improvements in equity are around making sure that we get people out to get the screening."
"The DHBs that have come on latterly have much improved, as a whole, rates of Maori screenings...I think we do, in the first instance, the things we know will make a difference and then when we've done those things, we see what the next steps are."
Bowel cancer (also called colon, rectal or colorectal) kills more than 1200 New Zealanders every year - more than breast and prostate cancer combined.
Early detection is critical to chances of survival, but the disease can be symptomless and others can be reluctant to act when they appear.
For this reason, health authorities piloted a free screening programme in Waitematā DHB from 2012. West and North Aucklanders aged 50 to 74 years were invited to send in faecal testing kits that detect tiny traces of blood that may signal pre- or bowel cancer. If positive, a colonoscopy is done.
Lives were saved and the previous National-led Government pledged almost $200 million to extend it nationally by June 2021. The roll-out is at the halfway point, with 10 of 20 DHBs offering screening.
However, screening is less likely to help Māori and Pacific New Zealanders. That's because the starting age was moved up a decade when the screening pilot went national, to 60.
More than a quarter of bowel cancers strike Pacific New Zealanders between 50 and 59, the latest annual data shows, with one-in-five Māori bowel cancers taking hold in that time.
That compares to about 11 per cent in non-Maori and non-Pacific.
Modelling has indicated that if the age was lowered to 50, then 60 extra bowel cancers a year could be found in Māori, and 25 extra in Pacific New Zealanders. For context, in 2016 there were 232 bowel cancers in Māori registered, with 81 deaths.
The ministry says it is "exploring implementation options" to drop the age for Māori and Pacific people, but no decision had been made. A previous report raised concerns about pressure on DHB colonoscopy services, and the risk of harm from earlier screening such as infection and the possibility of false positives.
Health workers, academics, and organisations including the Cancer Society, Bowel Cancer NZ and the Māori Medical Practitioners Association have lobbied for screening to be immediately dropped to age 50 for Māori and Pacific New Zealanders, saying it is unacceptable for a major health initiative to widen inequities. DHBs have also raised concerns about the current screening age and how this is unfair to Māori.
Peeni Henare, Associate Health Minister with responsibility for Māori health, has previously said achieving equity of health outcomes in crucial, but for the moment the ministry was focused on the national rollout.
"It's important to get the foundation right - to establish the programme within available resources first before any changes to parameters are considered that may increase demand, particularly on colonoscopy services," he said in a previous statement to the Herald.
