We know that the gut microbiome plays a huge role in our overall health. New research has linked this complex ecosystem to cancer treatment efficacy. 

Immunotherapy has improved outcomes for various cancer types, but for one type, it appears to be less effective: ovarian cancer. A recent study published in Cancer Immunology Research found that in the case of ovarian cancer, bacterial flagellin disrupted immune checkpoint therapy.

McGinty MT, Putelo AM, Kolli SH, et al. TLR5 signaling causes dendritic-cell dysfunction and orchestrates failure of immune checkpoint therapy against ovarian cancer. Cancer Immunol Res. February 11, 2025.

And experts say this discovery could help us better understand the role of the microbiome when it comes to cancer treatment.

The microbiome link, explained

The microbiome is recognised as a key player in our general health, with increasing attention to its role in cancer progression and prognosis. According to the authors of an article published in Signal Transduction and Targeted Therapy, “Microbes can facilitate the initiation and progression of various types of cancer including gastric cancer, colorectal cancer, hepatocellular carcinoma, breast cancer, and pancreatic ductal adenocarcinoma.”

Zhao LY, Mei JX, Yu G, et al. Role of the gut microbiota in anticancer therapy: from molecular mechanisms to clinical applications. Signal Transduct Target Ther. 2023;8:201.

Researcher Semir Beyaz, PhD, assistant professor at Cold Spring Harbor Laboratory, explained the microbiome-cancer connection and the role of the immune system in a webinar with the National Ovarian Cancer Coalition: “When it comes to cancer, we know that there is an intimate relationship between the microbiome and cancer, both directly and also indirectly through modulating the immune system.”

National Ovarian Cancer Coalition (@nocc_official). Gut Health, Microbiome and Ovarian Cancer. YouTube. June 23, 2023.

Cancer treatment efficacy

In some cases, the microbiome may at least partially explain poor treatment results. The authors of the Signal Transduction and Targeted Therapy article noted that poor response to cancer treatment, including “chemotherapy, radiotherapy, surgery and immunotherapy can be partially ascribed to some microbes.”

Zhao LY, Mei JX, Yu G, et al. Role of the gut microbiota in anticancer therapy: from molecular mechanisms to clinical applications. Signal Transduct Target Ther. 2023;8:201.

Can we use this information about the microbiome to support better treatment outcomes? Experts agree there could be hope.

Available evidence seems to indicate that modulating the composition of the gut microbiota to improve the efficacy of anti-cancer drugs may be feasible.

However, further research is needed in order to see results with future treatments, as“intricate complexities exist, and a deep and comprehensive understanding of how the human microbiota interacts with cancer is critical to realise its full potential in cancer treatment,” the authors wrote.

Supporting patients for a healthy gut

It’s important to educate patients on the gut microbiome and encourage a gut-friendly diet. This can include focusing on plant-predominant meals and reducing consumption of processed foods and sweets.

Dr. Beyaz emphasises the importance of gut health and its benefits when it comes to cancer development and progression. “If you have a balanced diet that has some fiber in it, that has all major micro- and macronutrients represented in a balanced manner, I think that would be sufficient to have a good microbial ecosystem that would sustain your health,” he explained.

National Ovarian Cancer Coalition (@nocc_official). Gut Health, Microbiome and Ovarian Cancer. YouTube. June 23, 2023.