Our Changing World: Solving a genetic cancer puzzle

6:46 am on 19 September 2024
A portrait of Maybelle as she stands on some grass in front of a cream and red trimmed Marae flanked by trees, with a bright blue sky int he background.

Maybelle McLeod has worked at Kimihauora Clinic for 30 years and is set to retire from the day to day operations to take up a trustee role. Photo: Justine Murray

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A whānau-centred research project to find the genetic cause behind a deadly form of stomach cancer is still going strong after almost 30 years.

Kimi Hauora Health and University of Otago geneticists teamed up in 1995 to find the genetic change responsible for the early deaths of members of the McLeod whānau.

Project founder Maybelle McLeod's cousin died of stomach cancer at the age of just 28. A trained nurse, she moved from Nelson to Tauranga to work alongside her cousin George McLeod to help whānau get tested.

George McLeod died in 1993 from stomach cancer, and that's when Maybelle started her work at Kimi Hauora alongside the late Rangi McLeod, Hira McLeod, and Pauline Harawira. While the clinic staff focussed on finding answers as to why this disease had cause the early deaths of loved ones, stories of a makutu (curse) had circulated.

"Half of them (family) had moved away, changed their names, been sent to other places, adopted, to dodge the bullet...the illness and probably the makutu" Maybelle says.

A tentative start

In 1995 Kimi Hauora staff attended a genetics research conference in Wellington which led to a contact number given to her for the Cancer Genetics Laboratory at the University of Otago. A meeting was organised at Mangatawa marae with Professor Tony Reeves and Professor Parry Guilford.

"We went up and spent a morning with them talking through the project and from there had numerous more meetings…I'd go back quite a few times with more hui with the whānau to talk about what could be done and how long it could take" remembers Parry.

An agreement was formalised and tissue and blood samples of the whānau members were collected by Maybelle and the team for use by the geneticists. Because the stomach cancer seemed to be inherited across generations, a detailed whakapapa of the McLeod whānau was vital to the research, but Maybelle says in those first few years there was a level of suspicion when handing over this important information.

"We didn't really trust them for a long time, we were always wandering if we were doing the right thing"

Professor Parry Guilford remembers those formative years.

"I think for Maybelle it was harder…she didn't know whether we were really maybe driven by other ideas…I think there was certainly a suspicion from Māori in general that they were distrustful of genetic researchers…for me I knew what I wanted which was to sort out the high death of cancer in that family"

Finding the culprit

Maybelle thought it would take quite some time, but in fact it was just 18 months into this formal partnership that Parry and his team discovered the cancer-causing genetic change that underpins this form of inherited stomach cancer, called Hereditary Diffuse Gastric Cancer (HDGC).

Maybelle remembers the news given by Parry in person.

"They came into the building and said…we've found it, and I couldn't believe it" she says.

After the discovery and confirmation of the cancer-causing change in the CDH1 gene, there was a sense of urgency, and testing of the whānau ramped up.

People with this genetic change, or mutation, have a vastly increased likelihood (56-70 percent lifetime risk) of developing stomach cancer, so many who test positive make the difficult choice of having surgery to have their stomach removed.

Erin Gardiner, Dr Jeremy Rossaak;Pauline Harawira, Professor Parry Guilford;Maybelle Mcloed and Associate Professor Karyn Paringatai at the front roro at Tamapahore wharenui.

Erin Gardiner, Dr Jeremy Rossaak;Pauline Harawira, Professor Parry Guilford;Maybelle Mcloed and Associate Professor Karyn Paringatai at the front roro at Tamapahore wharenui. Photo: Royal Society Te Apārangi

A worldwide impact

In the almost three decades since, this research has saved many lives.

"We've estimated that there are over 35-40,000 people with the mutation in Europe and the U.S…we think that 28,000 would have developed cancer if they'd been left alone, so potentially the research has led to about 28,000 people in Europe and the U.S having their lives saved…I do have to stress that they'll be saved by people in their own countries…but we can say that our research started off that push" says Parry.

The research between Kimi Hauora Health Clinic and the Cancer Research Centre at the University of Otago has won many awards and grants over the years, including the 2023 Prime Ministers Science Prize, Te Pūiaki Putaiao Matua a Te Pirimia along with a grant of $500,000. The money will be used to build an online hub for affected families, and to do further research into care for patients post-stomach-removal surgery.

The team at Kimi Hauora remain busy, but after 30 years Maybelle McLeod is set to retire from the office.

"I'll be glad to lie-in everyday I'm over this…. thirty years in July I have been at this that's a long time for someone to be in a job"

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