Probiotics and cancer: How the gut microbiome can affect cancer risk

Speaking at our very first Probiota Asia summit, Vitetta said there was 'mechanistic evidence' that the intestinal microbiota plays a large role in defining both the efficacy and toxicity of chemotherapeutic agents.

He further stated that some members of the human intestinal microbiome are 'intimately involved' in the development and progression of cancer through adverse interactions with the immune system.

Other intestinal microbiome members, however, can protect against cancer via beneficial interactions with the immune system, such as the Bacteroides ​species which helps protect against cancer by boosting T-cell infiltration.

The most logical link

Vitetta hypothesised that the immune system is the "most logical link"​ between cancer and the microbiome, since resident microbes can modulate inflammation and therefore, influence immune cells' reaction to tumour cells.

Citing a study involving mice that had been implanted with melanoma tumours, he said the oral administration of Bifidobacteria​ on its own improved tumour control in the mice, while oral administration of Bifidobacterium breve ​in combination with immunotherapy stopped tumour growth completely.

Bifidobacteria​ was said to help eradicate cancer cells or pathogens by activating macrophages, which introduce antigens from cancer cells or bacteria to T cells.

Furthermore, the immune system's anti-cancer therapeutic potential is buoyed by the fact that specific tumour cells can be targeted, while regular cells remain mostly unharmed.

Probiotics' anti-cancer potential

Vitetta also spoke about the possibility of using probiotics as adjunctive medicines, saying they could reduce toxicity arising from cancer treatments like radiation therapy by enhancing intestinal barrier function and facilitating the maintenance of intestinal membrane integrity.

Through their ability to modulate immune response and intestinal microbiota, they can be "used as an adjuvant for cancer prevention and / or treatment"​, and may even suppress not just intestinal but extra-intestinal cancers as well.

In addition, more evidence is emerging that the gut microbiota can modulate the body's response to chemotherapeutic drugs, resulting in three main clinical outcomes: the facilitation of drug efficacy, reversal and compromise of anti-cancer effects, and mediation of toxicity.