The Breast Cancer Now Generations Study

The Breast Cancer Now Generations Study was set up in 2004 to help understand the causes of breast cancer. At the moment, we don’t know why one woman will develop the disease while another won’t. This is an enormous project following more than 113,000 UK women for 40 years. The study will help us understand who may be more likely to develop the disease and what we could do to prevent it.

What is the study about?

There is never one single cause of breast cancer. A combination of our genes, lifestyle choices and events throughout life all contribute to the likelihood of developing the disease. The Breast Cancer Now Generations Study is investigating all these different factors that may change a woman’s risk of developing breast cancer.

Knowing all these factors and understanding how they may combine to cause breast cancer will help us identify women who have a high chance of developing the disease. And knowing what factors contribute to this increased risk, women could receive more accurate advice about the best risk-reducing steps they can take.

How will the study answer these questions?

There are more than 113,000 UK women of different ages and from different backgrounds taking part in this study. Some of them will develop breast cancer, but others won’t. And researchers will try to understand the differences between them.

All women taking part in the study completed a detailed questionnaire about their lifestyle, including diet, alcohol intake and even the kind of jobs they do. They also provided blood samples to give researchers information about their genetics and to track their hormone levels.

Women will be asked to send in follow up questionnaires and blood samples every few years for 40 years in total. This will allow researchers to gather enough data to uncover as many factors linked to breast cancer as possible.

Much of the analysis of the study is carried out by Professor Olivia Fletcher at the Breast Cancer Now Toby Robins Research Centre and Professor Richard Houlston at the Institute of Cancer Research.

Breast Cancer Now is also funding the Male Breast Cancer Study, which is investigating the risk factors linked to breast cancer in men.

What has the Generations Study discovered so far?

Running for over 16 years now, the Generations Study has already expanded our understanding of breast cancer.

• Helping to identify more than 160 common genetic changes linked to the disease, it has significantly contributed to our knowledge of how genetics can influence breast cancer. Only around 5% of women with breast cancer have inherited an altered gene, like BRCA1 or BRCA2. But now we know that there are small genetic changes that individually change the risk a tiny bit, but combined, can change it considerably. The total number of small genetic changes linked to the disease has now reached 350. It will help to more accurately estimate a woman’s personal likelihood of getting breast cancer.
• We now know that smoking can increase the chance of developing breast cancer, especially if started at a young age or if a woman has family history of breast cancer. It means we can urge women to quit smoking to keep their risk of breast cancer as low as possible and have evidence as to why.
• Light exposure at night was previously considered a potential risk factor. Thanks to the study, we now know that women who have the lightest bedrooms are no more likely to develop breast cancer than those in the darkest bedrooms.
• We now know that stress is unlikely to cause breast cancer and can reassure women who think stress may have been responsible for their disease.
• The study has also contributed to our understanding of how the use of hormone replacement therapy (HRT) increases the risk of breast cancer.
• We now know that working night shifts doesn’t increase a woman’s likelihood of developing the disease, reassuring many women who need to work at night.
• The study has uncovered that high levels of a particular fertility hormone are linked to breast cancer. Testing for this hormone in the future could help more accurately find younger women who may be at higher risk of developing breast cancer before the menopause.
• We better understand the complex relationship between pregnancy and breast cancer. It includes factors such as firstborn’s birth weight, length of pregnancy and pregnancy complications and how they may impact on breast cancer risk. Uncovering the biological reasons behind this could help us find new ways to prevent the disease.
• The study has also suggested an improved way to assess a woman’s chance of getting breast cancer based on her family history of the disease.

Currently, I’m analysing data form wristband activity trackers. Over 12,000 women have worn them for 8 days to continuously measure their physical activity 24 hours a day. I’m particularly interested in answering questions on how the amount of physical activity changes with age, who exercises more and who doesn’t, and what the main barriers are.

 Dr Michael Jones, Senior Staff Researcher at The Institute of Cancer Research, London, working on the Generations Study

With over 20 more years to go, we expect the Generations Study to bring many more breakthroughs, helping us better understand breast cancer and finding better ways to prevent the disease.

Get in touch

If you're a member of the Generations Study and want to contact the study team, please phone 020 8722 4469 or email generationscohort@icr.ac.uk.