New research using data from the Breast Cancer Now Generations Study* has mapped how lifestyle factors linked to breast cancer risk, like smoking and alcohol consumption, change throughout women's lives.
The findings identify key life stages for behaviour transitions, which could guide targeted approaches to support women to have a healthy lifestyle and reduce their risk of breast cancer.
The study published in Scientific Reports and led by researchers at Imperial College London and The Institute of Cancer Research, London, analysed data from more than 110,000 women taking part in the Breast Cancer Now Generations Study.
They investigated how major breast cancer risk factors related to lifestyle, such as alcohol consumption, smoking, physical activity and body mass index change through the course of someone’s life.
Many things influence a person's chance of developing breast cancer, including genetics, lifestyle and environment. Some risk factors can’t be changed, but others can be influenced by making lifestyle changes.
Professor Marc Gunter and PhD Student, Isobel Jackson, analysed data from questionnaires completed by women taking part in the Breast Cancer Now Generations Study from when they joined the study between 2003 - 2009, providing information on their alcohol consumption, smoking habits, physical activity and BMI. Researchers also analysed follow-up questionnaires completed on average six and 14 years later, allowing them to track how these behaviours changed for each woman over time.
Their analysis revealed distinct patterns across the course of women’s lives. Alcohol consumption, smoking and physical activity peaked in late adolescence, while BMI steadily increased throughout adulthood peaking in the late 60s.
They found that these lifestyle factors shifted more rapidly at certain stages of life, particularly mid-adulthood.
These patterns also differed substantially between generations. Women born between 1960 and 2003 generally had higher BMI trajectories throughout life and their level of smoking and alcohol consumption peaked at younger ages than women born between 1908 and 1959.
Understanding when these lifestyle behaviours are most likely to change could help public health experts develop more targeted, age-specific approaches to reducing breast cancer risk.
Professor Marc Gunter, Chair in Cancer Epidemiology and Prevention in the Department of Epidemiology and Biostatistics at the School of Public Health at Imperial College London said:
“Our study has shown that adolescence and early adulthood may be a particularly important time to encourage physical activity and help prevent rapid weight gain. Meanwhile, early to mid-adulthood, from around the 30s to 50s, could be a key period for tackling rising BMI and renewed increases in alcohol consumption.
“By identifying when these behaviour transitions are most likely to occur, the findings could help inform more tailored public health strategies aimed at reducing breast cancer risk across the population.”
Professor Amy Berrington, Professor of Clinical Cancer Epidemiology and Lead of the Generations Study at The Institute of Cancer Research, London said:
"These lifestyle factors also cause a wide range of other chronic diseases including diabetes, cardiovascular disease and other cancers so these public health strategies would have a much broader impact on women's health."
Dr Simon Vincent, chief scientific officer at Breast Cancer Now, which funded the research, said:
"We know that at least 23% of breast cancers could be prevented through healthy lifestyle changes, including being physically active, maintaining a healthy weight and drinking less alcohol.
"This study gives us valuable insight into when these behaviours are most likely to change. Understanding these key life stages could help us better support women to make lasting changes that reduce their risk of breast cancer. This is exactly the kind of research the Breast Cancer Now Generations Study was designed to enable.
“Even when we understand all the benefits, we know healthy lifestyle changes aren’t always easy to make and sustain, so it’s important that women are properly supported to do so.
“Anyone looking for support and information on breast cancer can speak to our expert nurses by calling our free, confidential helpline on 0808 800 6000 or visit breastcancernow.org.”
ENDS
Notes to Editors
The research is published in Scientific Reports and is available at the following link: s41598-026-60923-x.pdf
*About the Breast Cancer Now Generations Study
Launched in 2004, the Breast Cancer Now Generations Study is one of the most ambitious and comprehensive studies of its kind anywhere in the world.
This landmark project, based at the Institute of Cancer Research London, and funded by Breast Cancer Now, is following over 110,000 women for 40 years to understand the causes of breast cancer. Some will develop breast cancer, while others won’t. Through regular questionnaires, DNA analysis and collection of blood samples, our researchers are trying to understand what the differences between these two groups are.
Over the last two decades, scientists have published more than 90 papers using data from the Generations Study uncovering the complex web of genetics, lifestyle choices and environmental factors that influence breast cancer risk. Knowing all these factors will help us identify women who have a high chance of developing breast cancer. And it could help us give women more accurate advice about how they can reduce their risk.
Breast Cancer Now thanks M&S for their continuous support of the Breast Cancer Now Generations Study.
For more information visit: The Generations Study | Breast Cancer Now