Professor Ann Richardson, who did the research with James Hayes, said: "Age is the most important risk factor for breast cancer for women so the risk goes up as women get older ... but these other factors, which overall are less important than age, are things women can potentially do something about."
The study found obese post-menopausal women - those over the age of 50 - had the highest risk of getting breast cancer and this was particularly concerning for Maori and Pacific Island women who had greater obesity rates.
Other preventive factors were limiting alcohol intake, doing physical exercise and reducing the use of hormone replacement treatment.
The study also considered diet, oral contraceptive use, tobacco, breast feeding and the age of women when they first give birth, and combined international evidence on risk factors with the prevalence of them among European, Maori and Pacific Island women in New Zealand.
Breast Cancer Foundation chief executive Evangelia Henderson said the findings reinforced that reducing obesity in older women was the best way to stop breast cancer.
"I think obesity and lack of physical activity are two lifestyle factors that are getting worse and worse over time ... Both of those two factors can have a significant impact on reducing our breast cancer risk."
Growing alcohol consumption among younger women was also of concern.
Michelle Perry, with Max, believes her healthy lifestyle has helped her cope with her cancer treatment. Photo / Greg Bowker
Hard to take the second time around
Michelle Perry questions why anybody wouldn't maintain a healthy weight, limit alcohol and exercise regularly if it gave them a better chance of avoiding breast cancer.
The 40-year-old Kaukapakapa woman was diagnosed with breast cancer in 2011 and thought chemotherapy, herceptin - a drug for breast cancer - and a mastectomy had helped her beat it until a check-up in March revealed the aggressive cancer had spread to her liver.
The mother-of-two is now having chemotherapy for 18 weeks, has gone back on herceptin and has put herself on a no-sugar diet.
While Mrs Perry is a healthy weight and has never smoked or drunk alcohol, her advice to other women is to give themselves the best chance.
"It's common sense, really. Eat healthy, try and have a healthy lifestyle and don't work yourself crazy because you never know what is going to happen tomorrow."
Mrs Perry said she and her husband Scott were trying to remain positive. "The first time round you think you are really lucky if you have got rid of it and the second time round your chances are a bit less. It is a bit harder to take the second time around because it is not very fair."
Mrs Perry thought her healthy lifestyle had helped her cope with the treatment and said the only side effects had been losing her hair and some tiredness.
Limit drink, keep active
Lifestyle factors that could help prevent breast cancer:
1. Reduce obesity
2. Limit alcohol consumption
3. Regular physical activity
4. Reduce hormone replacement therapy use
Source: University of Canterbury
The deadly facts:
*Only 27 per cent of breast cancers occur in women under 50
*Breast cancer is the most common cause of cancer in Kiwi women
*2700 women a year are diagnosed with breast cancer
*More than 600 women a year die from breast cancer
*New Zealand has one of the highest rates of breast cancer
