High-Fiber Diet Linked to Better Treatment Responses in Skin Cancer

Patients with skin cancer who were fed a high-fiber diet showed better response rates to treatment and longer event-free survival, according to data from the DIET trial which were published in the Journal of Clinical Oncology.

This small, controlled trial evaluated whether a high-fiber diet could improve outcomes for patients with melanoma who were being treated with immunotherapy. Eligible patients were given either a high-fiber diet or a standard healthy diet while undergoing treatment. The study also showed that fewer patients in the high-fiber group experienced serious immune-related side effects. Overall, these results suggest that diet may help boost the effectiveness of immunotherapy, but additional research is needed to confirm these findings.

“Having a study like the DIET study will hopefully shed some light on patient-modifiable factors that we can incorporate into real practice,” Ma explained in an interview with CURE.

He is a faculty member in the Division of Hematology, Medical Oncology and Palliative Care, is an assistant professor within the Department of Medicine, and is a faculty affiliate of the Department of Dermatology, all at the University of Wisconsin, School of Medicine and Public Health.

During the interview, Ma broke down the background and findings from the DIET study, as well as highlighted the importance of incorporating trials like the DIET study into clinical practice. Moreover, in two additional articles published on CURE, he broke down key findings from the ASCO Annual Meeting, as well as recent notable updates across the landscape of skin cancer.

CURE: To begin, can you discuss any recent research exploring how diet or the gut microbiome may influence treatment outcomes for patients with melanoma?

Ma: What was interesting was the DIET study, a phase 2 study examining outcomes for patients who received high-fiber diets versus those with standard dietary fiber intake.

To provide a little background on why this study was conducted: as we know, over the years, the gut microbiome may play a very important role in our immune system. We're beginning to learn that the immune system of your gut, the bacteria in your gut, may actually impact how you respond to treatments like immunotherapy. This particular study investigates the role of dietary fiber and how it might potentially help optimize or improve the gut microbiome, so that patients with, for example, advanced stage melanoma could potentially benefit more from immunotherapy.

What was the design of the study evaluating the impact of dietary fiber intake on immunotherapy response in patients with melanoma?

This was a double-blind, randomized controlled study where half of the patients had a higher intake of fiber, 30 to 50 grams of fiber per day, versus the standard arm, which was about 20 grams of fiber per day. The investigators from the study found, first of all, that increasing fiber intake was safe and tolerable, which is one of the most important things we want to ensure with any clinical trial.

They also looked at its efficacy, and interestingly enough, they actually found that patients who had an increased fiber intake had a numerically higher response to immunotherapy than those patients who had standard amounts of dietary fiber intake. So that is a very interesting preliminary finding so far.

What findings were derived from this research?

What was also very notable and interesting was that those patients who had an increase in fiber intake actually experienced fewer dermatologic side effects. This means they had less itchiness and less rash when they had an increased intake of dietary fiber. Rash and itchiness are very common side effects from immunotherapy, so it's actually very great and reassuring as a medical oncologist to see something like that—that there's something we can impact in our diet that might actually reduce that type of side effect.

As you can imagine, the results of this phase 2 study are quite promising. It's very interesting and hopefully promising to hear that we might be seeing a phase 3 study on this in the future to see if dietary intake, something that patients can actually alter, might be able to help them benefit more from immunotherapy. This is very exciting, and we're very much looking forward to seeing the future outcome of a study like this. I think what patients oftentimes ask us is what they can do at home that can get them better outcomes.

In many ways, there aren't a lot of great studies out there that say things like supplements, the food we eat, or exercise regimens are really going to improve outcomes. Having a study like the DIET study will hopefully shed some light on patient-modifiable factors that we can incorporate into real practice.

As we close, what message would you like to share with patients and families navigating a skin cancer diagnosis today?

As an oncologist who treats melanoma and skin cancer, we really didn't have many options in terms of treatment 10 to 20 years ago. There's been so much breakthrough in terms of treatment options for our patients. For the foreseeable future, I can only imagine that treatment is only going to get better.

We now have patients living longer than ever before, and many patients are surviving with even advanced stage 4 cancer, including melanoma and skin cancer. It's been an unprecedented time where patients are living longer than ever before, and so this particular month, to me, really means hope for the future, the hope that many patients with cancer diagnoses are going to be able to live longer than ever before, especially as we work towards finding a cure for this really bad disease.

Reference

“Clinical outcomes of the DIET study: A randomized controlled phase 2 trial of a high fiber diet intervention (HFDI) in patients with melanoma receiving immune checkpoint blockade (ICB),” by Dr. Yufan Qiu, et al. Journal of Clinical Oncology.

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