How antibiotics ‘can increase the speed of breast cancer growth’

A POSSIBLE link between antibiotic use and an increased rate of breast cancer growth has been identified by scientists.

Researchers discovered that treating mice with broad-spectrum antibiotics made their breast cancer tumours grow more quickly.

They also noticed an increase in the size of secondary tumours that grew in other organs when the cancer spread. Despite the apparently alarming findings, the team said their results provide ‘crucial insight’ and could lead to a refinement in antibiotic use in people suffering from breast cancer.

In the study researchers from the Quadram Institute in Norwich and the University of East Anglia used a cocktail of five antibiotics, and also the commonly used antibiotic cefalexin, to investigate how disrupting a healthy balance of bacteria in the gut affected breast cancer growth in mice.

They found the use of antibiotics led to the loss of a beneficial gut bacteria, which in turn sped up tumour growth.

Further investigation revealed a type of immune cell, known as mast cells, was found in larger numbers in the animals treated with antibiotics. Blocking the function of these cells reversed the effects of the antibiotics and reduced the aggressive growth of tumours. It is hoped the results could also lead to new ways to counteract the negative effects certain antibiotics could have on breast cancer.

This is important because while chemotherapy is a cornerstone of treatment it reduces the number of white blood cells, making people more susceptible to infection. Antibiotics are therefore often prescribed to control infections during chemotherapy.

Dr Simon Vincent, of Breast Cancer Now – the charity which funded the study – said: ‘While the link between antibiotics and breast cancer growth may sound alarming, we want to remind everyone affected that this is early stage research that has currently only been tested in mice.’ And he added: ‘Excitingly, this has already highlighted that by targeting mast cells we could potentially halt antibiotic-induced breast cancer growth.’

Around 55,000 women are diagnosed with breast cancer each year.