Groundbreaking weight loss shots relied on by millions of dieters and diabetics could make breast cancer treatments stop working, experts warn.
The drugs, including Ozempic and Wegovy, have ushered in a new era in the fight against obesity, helping dieters lose up to a fifth of their body weight.
But US doctors monitoring women being treated for an aggressive form of breast cancer have found that the injections have an ‘adverse impact’ on the way the body responds to chemotherapy and immunotherapy.
It meant that patients given the jab – known collectively as glucagon-like peptide-1 receptor agonists or GLP-1s – were less likely to be completely free of cancer after treatment and were at greater risk of the tumors returning.
Consultant clinical oncologist Dr John Glees said the findings were ‘concerning’, adding: ‘These weight loss drugs are relatively new, so it is very concerning that patients taking them are less likely to be cancer-free after treatment.’
The study followed hundreds of women with early-stage triple-negative breast cancer during and after treatment.
Several dozen were already taking GLP-1s and continued to do so while undergoing cancer treatment.
Tests two years later showed that only 28 percent of women given GLP-1s responded completely to the cancer therapies and were free of cancer.
Groundbreaking weight loss shots relied on by millions of dieters and diabetics around the world could cause breast cancer treatments to stop working, experts warn
US doctors monitoring women being treated for breast cancer have found that the injections – collectively known as glucagon-like peptide-1 receptor agonists or GLP-1s – ‘adversely impact’ the way the body responds to chemotherapy and immunotherapy .
More than twice as many – 63 percent – of those who did not receive GLP-1 treatment were cancer-free.
Dr. Bethania Santos, an oncologist and researcher at UT Southwestern Medical Center in Dallas who presented the study today at the San Antonio Breast Cancer Symposium, said, “The use of GLP-1 may need to be carefully considered during breast cancer treatment.”
The researchers also discovered GLP-1s had infiltrated tumor cells and immune cells in patient samples.
Although it was not yet fully understood what this meant, Dr. Santon suggested that it could somehow make tumor cells more resistant to standard treatments.
Dr. Glees added: ‘We know that obesity increases the risk of cancer, and so drugs like Ozempic, which help people lose weight, can also reduce that risk.
‘The injections also appear to protect the heart and possibly the brain.
‘But we need to think very carefully about this new data and do more research.
‘It’s important that patients don’t panic, but it’s also critical that women tell their cancer specialist if they are taking any of these GLP-1 drugs while they are undergoing cancer treatment.’
Checking your breasts should be part of your monthly routine so that you notice any unusual changes. Simply rub and feel from top to bottom, in semi-circles and in a circular motion around your breast tissue to identify any abnormalities
Symptoms of breast cancer to look out for include lumps and swellings, dimpling of the skin, color changes, discharge and rash or crusting around the nipple
Ozempic, Wegovy and the similar drug Mounjaro are self-administered weekly.
Limited studies have suggested that weight loss shots may be helpful in reducing the risk of breast and other cancers.
One in seven women in Britain will be diagnosed with breast cancer in their lifetime – around 56,000 per year – making it the most common form of cancer in Britain.
In the US the figure is about 300,000 per year. About 85 percent of women diagnosed with breast cancer survive more than five years.
However, triple-negative breast cancer – which accounts for around 15 percent of all breast cancers in Britain and the US – is much more difficult.
Typically, it grows and spreads faster than other types of breast cancer and there are fewer treatment options.
On average, about 77 percent of women with triple negative breast cancer survive their cancer five years or more after they are diagnosed, but depending on the stage, this can be as high as 12 percent.
Breast cancer specialist and author Dr Liz O’Riordan said: ‘This is an important study and more research is needed.
‘It appears that GLP-1s can make cancer cells less responsive to chemotherapy and immunotherapy.
‘This means their cancer is much more likely to return.
‘On the other hand, we think that giving women GLP-1s after they complete cancer treatment to keep their weight down may reduce the chance of cancer returning.
‘We need more thought about the way these patients are treated, and more research to understand what’s going on.’