New research suggests environmental, rather than genetic, factors are behind New Zealand's high rates of breast cancer.

Doctors from the University of Auckland undertook gene expression profiles, which measure tumour biology, and found there is no clear difference between breast tumours found in Kiwi patients and those from patients overseas.

The study, "Gene expression profiling of breast tumours from New Zealand patients", was led by the university's Medical and Health sciences facility.

Leading researcher Professor Andrew Shelling said while the study suggested more research was needed, on another level the findings were "reassuring".


"If there was something really obvious that stood out as being different in our genes, then that could suggest something in our environment was driving up rates," he said.

On the flipside, the results suggested the factors behind our high rates were something that could be understood and eventually fixed.

The study used breast tumour samples from 106 female breast cancer patients located in Auckland and Christchurch.

Around 30,000 genes in tumours from the patients were analysed on a gene expression microarray chip and then compared to results from women recruited in similar studies from Sweden, Singapore, France and the United Kingdom.

Shelling said overall analysis showed there was no significant biological differences between breast tumours from Kiwi patients and those overseas.

He said the results rang true with numerous studies directed at health system inequalities and the identification of lifestyle factors and their link with breast cancer risk in New Zealand women.

Breast cancer survivor Fay Sowerby said the results were essentially a good thing. However, she said it showed we needed increased knowledge around causes and better tools for detection.

"We do have higher occurrences compared to other countries," she said.

"Therefore we need to look at why this is and how we can both prevent it and detect cases earlier to cut down the number of women needing treatment like chemo."

Sowerby, who is also a trustee for New Zealand research company Breast Cancer Cure, said her own cancer was not detected despite having a mammogram several months before she found the cancer herself.

"I was at Lululemon in the changing rooms trying on a top when I brushed my hand across my breast and felt a lump," she said.

The Remuera resident went through chemotherapy and radiology treatment before undergoing lumpectomy to remove the cancerous tissue from her breast.

She said there was a raft of factors women should be aware of. Lifestyle factors like alcohol consumption and smoking came into play, she said, as did other health factors like breast cancer running in the family.

A spokeswoman for the New Zealand Breast Cancer Foundation said the findings provide a valuable heads-up that a focus needed to be put on early detection.

"We still have a long way to go to understand the full range of factors causing breast cancer, and it's great to have Kiwi researchers digging into this," she said.