A recent study from King’s College London, in the United Kingdom, investigates whether dietary patterns might influence how well certain cancer drugs work.
The study, co-led by ZOE’s Scientific Co-Founder Prof. Tim Spector, focused on advanced melanoma, a type of skin cancer.
They found that patients who followed a Mediterranean diet more closely benefited the most from the cancer treatment. And gut bacteria seemed to be key.
The results of the study appear in JAMA Oncology.
Melanoma and current treatments
Melanoma is the third most common form of skin cancer in the United States. And because it commonly spreads to other parts of the body, it causes more deaths than other types of skin cancer.
A range of treatments is available for melanoma, but immunotherapies are some of the newest and most promising options.
In brief, immunotherapies help your immune system identify and fight cancer cells more effectively.
Over the last decade or so, a form of immunotherapy called immune checkpoint blockade (ICB) has significantly improved survival times for people with this type of cancer.
According to Dr. Veronique Bataille, who organized the recent study, “Immunotherapy has revolutionized the treatment of different types of advanced cancer.”
However, not all patients respond to these lifesaving drugs. Understandably, scientists want to know why. And there’s growing interest in the role of gut bacteria.
Are gut bacteria involved?
Recent evidence suggests that gut bacteria might influence how effective ICB is.
Studies have shown that patients with a “favorable gut microbiome” are more likely to respond well after treatment with ICB.
There’s also some early evidence that stool transplants might one day help improve patients’ responses to these drugs.
In previous research, the authors of the current study identified certain gut bacteria associated with an improved response to ICB. These included “good” bugs like Bifidobacterium pseudocatenulatum, Roseburia spp., and Akkermansia muciniphila.
And because your diet influences your gut microbiome, the scientists explored whether dietary patterns might affect people’s responses to ICB, in the most recent study.
What did they do?
To investigate, the authors recruited 91 people with melanoma who underwent ICB in the U.K. or the Netherlands.
The researchers used questionnaires to gather information about the participants' diets and assessed how closely they followed the Mediterranean diet.
The team also collated data on how often the participants ate plant-based foods and their quality.
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Cancer progression was measured using scanning technology.
From this data, the researchers calculated the “overall response rate” to treatment, which is the proportion of participants whose tumors were destroyed or significantly reduced by ICB.
They also measured the progression-free survival at 12 months — how many participants lived for 12 months without their cancer getting worse.
What did they find?
Following their analysis, the authors concluded that:
“A Mediterranean-style diet that is enriched in whole grains, fish, nuts, fruit, legumes, and vegetables is associated with a higher probability of response in ICB-treated patients with advanced melanoma.”
And they believe that the improved response to immunotherapy is likely linked to the gut microbiome.
As the authors explain in their paper, earlier research has shown that fiber, polyphenols, and antioxidants — all of which the Mediterranean diet contains in abundance — influence the immune system and have antitumor activities.
Short-chain fatty acids (SCFAs) might play a part, too. “Good” gut bacteria produce SCFAs as they feast on fiber. And these acids have a range of important roles throughout your body.
Scientists have shown that the Mediterranean diet is associated with SCFA-producing gut bugs.
And previous studies have spotted an association between higher levels of SCFAs and better responses to immunotherapy.
Although the authors note that this is a relatively small study, the findings align with earlier work.
For instance, a study from 2022 showed that people with melanoma who consumed lower levels of fiber and omega-3 fatty acids were more likely to respond poorly to ICB treatment.
And because the Mediterranean diet is rich in fiber and omega-3-containing fish, nuts, and seeds, this lines up with the new findings.
As the body of evidence grows, it’s looking increasingly likely that variation in the gut microbiome plays a part in the success of immunotherapy at an individual level.
“The connection between the diet, gut microbes, and helping the immune system fight cancer is one of the most exciting areas of medical research,” says Tim.
“Our two publications clearly show the importance of a gut-friendly diet for improving your chances of surviving cancer.”
Tim believes that “All cancer patients should now be given potentially lifesaving dietary advice, such as increasing plant diversity, reducing ultra-processed foods, and adding fermented foods, before starting therapies.”
Scientists need to carry out more research to confirm these findings.
But while we wait, the dietary advice laid out by Tim above is likely to bring health benefits. So, whether you’re starting a course of cancer treatment or not, it's sensible dietary advice.
Association of a Mediterranean diet with outcomes for patients treated with immune checkpoint blockade for advanced melanoma. JAMA Oncology. (2023). https://jamanetwork.com/journals/jamaoncology/fullarticle/2801594
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Diet-driven microbial ecology underpins associations between cancer immunotherapy outcomes and the gut microbiome. Nature Medicine. (2022). https://www.nature.com/articles/s41591-022-01965-2
Fecal microbiota transplant promotes response in immunotherapy-refractory melanoma patients. Science. (2020). https://www.science.org/doi/abs/10.1126/science.abb5920
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