A study using data from over 37,000 'mostly white' women, with and without breast cancer, showed that those who (based on family history and genetics) were considered to be at high risk, but who had maintained a healthy BMI (body mass index), did not consume alcohol or smoke, and did not use menopausal hormone therapy, were able to reduce this risk to that comparable to an 'average white woman in the USA'.
The findings, published in JAMA Oncology, showed that 30 percent of breast cancer cases could be prevented by altering lifestyle factors known to influence cancer risk. The study did not include women with the well-studied BRCA gene mutations, but did include those with other gene variations that have previously been linked to an increased risk of breast cancer.
'While you can't change your genes, this study tells us even people who are at high genetic risk can change their health outlook by making better lifestyle choices such as eating right, exercising and quitting smoking,' said senior author Professor Nilanjan Chatterjee, from the Johns Hopkins Bloomberg School of Public Health.
An international team of researchers analysed data held by the US National Institutes of Health's Breast and Prostate Cancer Cohort Consortium, including 17,171 women with breast cancer and almost 20,000 without the disease. The findings were then compared with data from an additional 6000 women who had participated in a 2010 national survey in the USA.
The researchers looked for 24 known genetic variations that have possible breast cancer links, and matched this with previous research to investigate the strength of their influence on breast cancer. They compared these variations with non-modifiable risk factors, such as age, height and time of first menstruation, and also modifiable risk factors including BMI, smoking and alcohol consumption.
Overall, the model predicts that the effect of healthy lifestyle choices is greater among women who are at a higher risk owing to genetic susceptibility and other non-modifiable risk factors. The findings only relate to a population of white women in the USA, so the research needs to be replicated in women from different ethnicities across the world to be validated.
Breast cancer is the most common form of cancer in women across the world, with age being the greatest risk factor. Women in the USA are called in for routine mammograms at the age of 50, but some experts argue that the age of screening should be lowered to 40 for earlier detection of breast cancer. The model used in this research may help identify women at high risk of breast cancer and allow screening at an earlier and more frequent rate. 'We aren't saying there will be less screening, just smarter screening,' said Professor Chatterjee.
He believes that the results will help women understand that lifestyle changes have the potential to reduce the chances of developing breast cancer, even if they carry high-risk genes. 'These findings may be able to help people better understand the benefits of a healthy lifestyle at an individualised level,' he said.