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The study that spans generations

The last post looked at the achievements of Breast Cancer Campaign’s Scientific Fellows.  This blog takes us on a journey that began 10 years ago – to find the root causes of breast cancer.

Talkin’ ‘bout my Generation

Can you remember what you were doing on 2 September 2004? At Breakthrough Breast Cancer this day marked the public launch of the Generations Study – a landmark study designed to identify and understand the complex mix of genetic, lifestyle and hormonal factors involved in the development of breast cancer. The response to the media campaign was phenomenal, with 15,000 women signing up to the study on the first day.  Just over ten years later and more than 113,000 have signed up, making it the world’s largest epidemiological study to find out the causes of breast cancer.

But what does it mean to be part of the study and what exciting new findings have been made as a result?

Epidemiology, Cohorts and Doll

Around 50,000 women are diagnosed with breast cancer each year in the UK. Half of these cases could be prevented if we knew more about the causes of the disease – a science known as epidemiology. Epidemiologists use cohort studies, where participants are followed up and observed over a long period of time in order to determine whether exposure to certain factors may be linked to the development of a particular disease. It was through a cohort study, called the British Doctors Study, that the renowned epidemiologist Sir Richard Doll provided compelling evidence for the link between cigarette smoking and lung cancer in the 1950s.

Who are you?

In 2002, epidemiologist Professor Tony Swerdlow and Professor Alan Ashworth approached Breakthrough Breast Cancer and the Institute of Cancer Research with an idea for a new cohort study to find out more about the genetic, lifestyle and hormonal causes of breast cancer.  They knew that knowing more about these causes could help to identify women at higher risk of developing breast cancer and ultimately, try to prevent the disease.  After careful evaluation by a group of scientific experts the project was given the green light and the Generations Study was born.

Women who have signed up to the study provide a blood sample so that scientists can understand inherited (genetic), hormonal and other factors which may influence breast cancer risk. They must also complete a confidential questionnaire to identify lifestyle and reproductive factors which may play a role in breast cancer risk.  This is no flimsy questionnaire either – it’s 50 plus pages covering in detail everything that does or is thought to impact breast cancer risk.  Women taking part in the Study are then followed for up to 40 years with blood samples and questionnaires taken periodically since lifestyle, genetic and hormonal risk factors may differ throughout life.  

Women aged from 16 to over 100 years old, and from all over the UK, have been inspired to become part of the Generations study. In some cases entire families have registered.  Caroline Holmes, who signed up for the study along with her mother Judith and daughter Sarah said:

There are three generations of my family taking part in the study, and that says it all really. It’s about following women at all stages of their lives.

The magic bus of results

So what advances in knowledge has the Generations Study given us? Genetic data obtained has so far led to the identification of more than 60 single nucleotide polymorphisms, or single letter changes in the genetic code, associated with the development of breast cancer. This more than doubles what we previously knew about the inherited risks of breast cancer. These genetic markers could be useful in generating genetic tests to assess an individual woman’s breast cancer risk.

In fact in April 2015 a large international group, including the Generations Study, showed that by combining 77 of the known genetic markers for breast cancer into a single test they could more confidently predict an individual's lifetime risk of breast cancer.  This prediction was even stronger when they combined the test with results from testing for faulty BRCA genes or taking into account a woman’s family history.  This shows that combining genetic markers can not only improve prediction of risk but can also strengthen predictions made based on other known risk factors.

The Generations Study has also shown that  increased density of breast tissue and an imbalance in sex hormones when combined is a much better predictor of breast cancer risk than using either alone.  In the future this information could be captured at routine breast screening appointments and could help identify women who would benefit from extra screening.

And last but not least, the study has uncovered the role of life events such as the importance of earlier breast development and the onset of regular periods, how lifestyle factors such as drinking more alcohol and weighing more as an adult, and how age at menopause all impact on breast cancer risk.

Join together

The merger of Breast Cancer Campaign and Breakthrough Breast Cancer offers an exciting chance for even more researchers to get involved with the Study. Scientists funded by both charities have already worked together using blood and questionnaire data from the Generations Study.  Dr James Flanagan, a Campaign funded scientist, in collaboration with Professor Garcia-Closas, a Breakthrough funded scientist, showed that women who have a certain modification in the DNA of their white blood cells have an increased risk of breast cancer.

Over the remaining 30 years, the Generations Study can only be expected to yield more exciting information which can be used to better understand breast cancer risk and empower women to make lifestyle choices to reduce their risk.  The words of Generations Study participant, Caroline Holmes, sum it up perfectly:

Cancer brings chaos to families and we have the potential not only to change the way that breast cancer is treated in the future, but also to ultimately one day remove the worry altogether, and that’s really exciting.

Dr Emma Blamont – Senior Research Insight and Innovation Officer

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