Faecal transplants could help our microbiome fight cancer

Our bodies are not quite ours. Among our own cells sit a few trillion bacteria and fungi inhabiting our skin, nose and guts. This ensemble of organisms is our microbiome.

A new study reviewing over 200 publications has looked at the microbiome’s role in response to cancer, finding that these friendly bugs lead to better health outcomes.

“This [paper] has been a compiling of all the other research that’s been done over the last five years,” SAHMRI cancer immunologist Dr Stephen Blake told Cosmos.

“[It’s] focusing on how specific gut bacteria, fungi and viruses can change how our body responds to immunotherapy and conventional treatments such as radiotherapy and chemotherapy.”

The research has been published in Nature Reviews Immunology.

Cancer treatment is designed to kill cancer cells, but it also affects both normal cells, and our microbiome. Ensuring that the microbiome can get back up to speed as soon as the treatment is done might change the success rate of the treatment.

“The human gut is home to trillions of microbes that influence how our bodies respond to cancer treatments, especially immunotherapy,” says Professor David Lynn, a Flinders University immunologist.

“This study highlights the potential of the gut microbiota to enhance cancer therapies. We’ve long suspected these microbes are crucial and now we have growing evidence to support that.”

An example in the paper of this working particularly well is in ‘immune checkpoint blockade’ treatment. This is a kind of treatment where your own immune cells are tweaked to better respond to a type of immune checkpoint overexpressed in cancer cells.

While this treatment works particularly well in about half of the cases, it wasn’t effective for the rest.

But the paper highlights a study that found that a faecal transplant – and therefore switching over the microbiome – would give patients a second chance at success.

“If you take a faecal transplant from a person who has completely responded to treatment, and put it into someone who’s failed checkpoint inhibitors, in around 30% of the people […] they would start responding to treatment,” says Blake.

“So, quite a dramatic improvement in that study.”

The researchers also looked at how microbiomes could protect and enhance cancer therapies, particularly using faecal transplants, but other methods as well.  

“The use of microbiota transplant in cancer and during treatment is quite experimental at this stage. Nothing has been approved, but there are a number of phase 1-3 clinical trials currently testing it,” says Blake.

To confirm this, more studies will need to be done looking into whether this is better than standard treatment. In the meantime, to look after our microbiome, there are also some less invasive options.  

“Preclinically there’s very clear evidence that some prebiotics and probiotics will be beneficial, but the clinical studies backing these up are underway and haven’t been published yet,” Blake adds. 

But “there’s now fairly clear evidence that a healthy diet and having lots of fibre will improve your gut microbiome, which is likely in turn to mean that you will respond better to treatment.”

So, pass the sauerkraut.