One in four breast cancers are potentially preventable, an exhaustive evidence review the Breast Cancer Risk Factors website has shown.

A 563-page review of evidence which was launched on Monday, goes over evidence-based information about 68 personal, family, genetic, lifestyle and environmental risk factors that can raise or lower the chances of developing breast cancer.

The report has in fact been uploaded in the form of a website by Cancer Australia that provides the most up-to-date information, explaining the magnitude of risk for each factor, and the strength of the research supporting them. With breast cancer being the most commonly diagnosed cancer in Australia, accounting for over 13 per cent of all new cancers in 2018, this website is bound to be a powerful tool..

Other than the factors that cannot be changed -such us sex, ageing, family history and genetic mutations – the website lists how, according to the data, one in four breast cancers can potentially be prevented, as Cancer Australia CEO Dr Helen Zorbas declared.

Smoking may increase the risk of breast cancer, and the case for recommending a diet rich in vegetables, dairy and calcium is also beneficial.

Alcohol, for example, significantly raises the risk of developing breast cancer with one standard alcoholic drink a day raising the risk of breast cancer by 7 per cent.

Factors like stress, living in major cities, higher socio-economic status, higher breast density, younger age of menarche, older age at menopause, being overweight, having a first child at an older age and not having children can also have an impact and are therefore listed under the “convincing” category.

Another category, labelled “probable” – lists risk factors likely to be linked to breast cancer, without as much strong evidence to support the information.

For pre-menopausal women, those who exercise vigorously probably have around 17 per cent lower risk of breast cancer than women who do low levels of vigorous physical activity. At the same time, nearly 8 per cent of post-menopausal breast cancers in Australia each year are linked to a lack of physical activity.

“That’s really powerful information to act on,” Dr Zorbas said. “The more active you are, the greater the benefits.”

Meanwhile, the “suggestive” risk factor category – defined as having some evidence of a link but not strong enough to be more certain – includes eating processed meats, shift work, and having a previous cancer other than breast cancer. On the bottom tier of evidence are abortion and miscarriage, which have no association with breast cancer, according to information on the Breast Cancer Risk Factors website.

“We sometimes tend to focus on rare or unproven risks instead of what the evidence is really telling us,” Dr Zorbas said.

“Women can now readily access the most accurate information, based on the highest quality evidence, on which they can act. Having one or more risk factors doesn’t mean an individual will develop breast cancer. Most people with a number of risk factors won’t.”

“In practice I see women who develop breast cancer and there is no obvious or no risk factors,” Dr Zorbas stressed.

“But we should not resile the importance and power of knowledge on which women can act to reduce their risk.”