Over the past 20 years, 110,000 women across the UK have contributed to a pioneering breast cancer study that could one day predict who is at risk of developing the disease before tumours have the chance to form. The Breast Cancer Now Generations Study, entering its 20th year, has become one of the largest and longest-running studies of its kind, providing critical insights into the causes of breast cancer.

Led by the Institute of Cancer Research, London, and funded by Breast Cancer Now, this extensive study has already uncovered hundreds of genetic factors and lifestyle influences linked to the disease. Each year, 55,000 women in the UK are diagnosed with breast cancer. Researchers are hopeful that findings from this study will lead to predictive tools capable of identifying women at high risk, enabling early interventions that could save millions of lives.

“We know that breast cancer is not caused by a single factor,” says Professor Amy Berrington, co-lead of the study. “It’s a combination of genetics, lifestyle choices, and various life events that influence the likelihood of developing the disease.”

Key risk factors identified in the breast cancer study

Through its vast collection of data—comprising over half a million questionnaires and numerous blood samples—the study has already identified key risk factors. These findings are essential for developing risk-assessment tools that could guide personalised prevention strategies, from more frequent screenings to risk-reducing drugs or preventative surgeries.

Genetic changes

One of the most significant contributions of the Generations Study is its identification of over 300 genetic variations, known as single nucleotide polymorphisms (SNPs), that influence breast cancer risk. While each genetic change has a small effect, the cumulative impact is substantial. This discovery has led to the creation of a genetic risk score, helping to identify women at high risk—even if they have no family history of the disease.

Family history

A woman’s family history is a key predictor of her breast cancer risk. Approximately 10% of cases occur in women with a direct family history. However, the Generations Study has refined how family history is assessed. It’s not just the number of cases that matters, but the size and age of a woman’s family. This nuanced approach helps researchers make more accurate predictions, guiding women to make informed decisions about their health.

Early menstruation

The age at which a woman experiences her first period has been linked to her long-term risk of breast cancer. Women who start menstruating at a younger age are exposed to hormones for a longer period, increasing their lifetime risk. Childhood obesity and lack of physical activity, both contributors to early menstruation, further impact breast cancer risk.

Smoking

While smoking is a known risk factor for various types of cancer, its link to breast cancer has only recently been explored in detail. The Generations Study found that women who smoke—especially those who started before the age of 17—have a significantly higher risk of developing breast cancer. This risk is amplified for women with a family history of the disease.

Physical activity

Exercise has long been associated with a decreased risk of breast cancer, particularly among younger women. According to data from the Generations Study, even moderate physical activity can reduce risk. This reinforces the importance of staying active, whether through structured exercise or everyday activities like gardening and housework.

Childlessness

The decision to have children can also impact breast cancer risk. Women who have children tend to have a lower risk of breast cancer in the long term, although the risk of developing more aggressive forms of the disease (such as triple-negative breast cancer) may be slightly higher in the years following childbirth.

Fertility hormones

High levels of anti-Müllerian hormone (AMH), which indicates a woman’s ovarian reserve, have been linked to an increased risk of breast cancer. AMH levels can predict not only the timing of menopause but also the risk of developing breast cancer before menopause.

Early menopause

Reaching menopause at an early age is a known risk factor for breast cancer. Women who experience menopause later in life are exposed to higher levels of hormones. The Generations Study has identified several genetic changes associated with early menopause, and lifestyle factors such as smoking and alcohol consumption can also influence the timing of menopause.

Looking ahead

The Breast Cancer Now Generations Study is poised to make a lasting impact on how we understand and prevent breast cancer. As research continues, it will lead to even more refined tools for predicting breast cancer risk, allowing for earlier intervention and more personalised treatment options. With ongoing support, this groundbreaking breast cancer study could be a critical step toward reducing the global burden of breast cancer, ensuring better outcomes for women everywhere.

For more information about this study and how you can support future research, visit Breast Cancer Now’s website.

Contact us today to learn how we can support you with tailored health strategies or further insights into this study.

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