Obesity and alcohol are key drivers of breast cancer risk in women as they age

Embargoed until: Publicly released: 2026-03-30 00:01

Australia; NSW

Photo by Kateryna Hliznitsova on Unsplash

Women in middle to older age who are overweight/obese or who drink alcohol are more likely to be diagnosed with breast cancer, according to Australian research. The team used data from a long-term health study to investigate various lifestyle factors and how they may be linked to breast cancer risk in 12,782 women aged 45-50 at the beginning of the study. Over 25 years, 941 of the women were diagnosed with breast cancer. The researchers say those who were obese/overweight were more likely to develop breast cancer compared to those who were underweight or at an ideal weight. Any amount of alcohol consumption was also linked to a higher breast cancer risk, they say, and they say women who did not have a partner also had a higher risk. Other lifestyle factors studied, including smoking and the use of hormone replacement therapy, were not linked to a higher risk of breast cancer among these women, the researchers add.

Journal/
conference: BMJ Open

Organisation/s: The University of Sydney, The University of Newcastle, Hunter Medical Research Institute (HMRI)

Funder: This study used data from the Australian Longitudinal Study on Women’s Health (ALSWH), University of Newcastle and University of Queensland. The authors would like to thank Australian Government Department of Health for funding ALSWH and to the women who participated in the ALSWH surveys. The authors acknowledge the Australian Capital Territory, New South Wales, Northern Territory, Queensland, South Australian, Tasmanian, Victorian, and Western Australian Cancer Registries for providing data, and the Australian Institute of Health and Welfare (AIHW) as the integrating authority.

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