Behind the headlines: Understanding weight and breast cancer risk

Every day, researchers are uncovering more about the complex relationship between our bodies, our environments and our risk of developing cancer.  

Recent headlines exploring the link between excess weight and breast cancer – as well as new research into whether weight loss medicines could support treatment – highlight just how fast this science is moving.

At Yorkshire Cancer Research, we welcome research in any area that may help people survive cancer and live longer, healthier lives.  

But it’s important that these conversations are grounded in clear, evidence-based information. As our understanding of cancer evolves, so too must the ways we support people across Yorkshire to prevent, prepare for and recover from cancer.

What we know about weight and breast cancer

Scientists have identified several biological reasons why carrying extra body weight can increase the risk of breast cancer, particularly in women who have been through the menopause.

After menopause, most oestrogen is produced in fat tissue. Higher levels of body fat can lead to higher levels of this hormone. Because oestrogen encourages breast cells to grow and divide, this can increase the chance of DNA mistakes that may lead to cancer. As fat cells grow larger, they can also become stressed and inflamed, releasing chemicals that help cancer cells grow and survive.

Higher insulin levels, which are more common among people with higher body weight, may also play a role by sending “growth signals’’ around the body. While this part of the science is less certain, experts agree that the connection between excess weight and postmenopausal breast cancer risk is well established.

In Yorkshire, 4,771 women are diagnosed with breast cancer each year.  

As the proportion of women with excess weight continues to rise across the UK, the number of cancers linked to this risk factor is also expected to increase.

In fact, it’s estimated that excess weight will overtake smoking as the leading preventable cause of cancer in women by 2043 – so more must be done to raise awareness and support people to maintain a healthy weight throughout their lives. 

Supporting people to live well after cancer

Helping women lose weight after cancer is important because treatments such as chemotherapy, hormonal therapy and targeted therapy can lead to weight gain.  

Weight gain can negatively impact the likelihood of survival in women with breast cancer. Those living with excess weight after treatment have an increased risk of cancer coming back.

Weight loss medicines may help people with breast cancer lose weight, which may improve their prognosis.  

However, there is currently limited safety data on their use in people with breast cancer, and researchers have called for more long-term trials.

While research into weight loss medicines may offer new avenues for supporting people after treatment, there are already proven, accessible ways we can help people recover better after cancer.  

One of the most effective is exercise.

That’s why Yorkshire Cancer Research funds Active Together, a research-backed cancer exercise treatment service funded by Yorkshire Cancer Research and designed by Sheffield Hallam University’s Advanced Wellbeing Research Centre.

Active Together helps people prepare for and recover from cancer treatment through personalised fitness, nutrition and wellbeing support. Research shows that exercise before, during and after cancer treatment can:

• improve recovery
• increase survival
• reduce the risk of cancer coming back
• reduce side effects such as fatigue, nausea and anxiety
• support better mental wellbeing
• shorten time spent in hospital and reduce complications from surgery.

More than 3,000 people across Yorkshire have already benefitted from Active Together.  

An evaluation of service in Sheffield found that among those who took part, many experienced reduced fatigue and increased strength. The benefits also go beyond the physical, with 97% of people reporting that their wellbeing improved during the time they spent taking part. 

Helping Yorkshire stay healthy for the future

Keeping to a healthy weight throughout life is one of the best ways women can reduce their risk of postmenopausal breast cancer and at least 12 other cancers.  

Services like Active Together show what’s possible when personalised support is made available to everyone with cancer, no matter who they are or where they live.  

We will continue to work with policymakers to make sure exercise both before and after cancer treatment becomes a reality.

By investing in research and delivering lifechanging services across the region, Yorkshire Cancer Research is helping to create a Yorkshire free from cancer.