Each year we frequently hear that a word, color, or child’s name is chosen as the leading example and most frequently used in each of these categories. It is certainly true that when it comes to “cancer theories” over the last two or three years, the term “microbiome” is the winner.

The concept is that the bacteria in our gastrointestinal (GI) tract play a major role in the development of a variety of malignancies. The microbiome has also been shown to modulate anticancer drug efficacy. Altered gut microbiota are associated with resistance to chemotherapy drugs and immune checkpoint inhibitors while supplementation of distinct bacterial species restores responses to anticancer drugs.

Accumulating evidence has revealed the potential of modulating the gut microbiota to enhance the efficacy of anticancer drugs. Regardless of the valuable findings by preclinical models and clinical data of patients with cancer, a more thorough understanding of the interactions of the microbiota with cancer therapy helps researchers identify novel strategies for cancer prevention, stratify patients for more effective treatment and reduce treatment complications.

Gut microbiota are also linked to cancer through increasing inflammation in the GI tract. The key is to unlock the mechanisms used by distinct bacterial species to modulate cancer growth, alter immune responses and modify the efficacy of chemotherapeutic drugs. The ultimate challenge is to regulate the gut microbiota to achieve both prevention and treatment strategies for a number of cancers such as colon, gastric and pancreatic malignancy.

While the makeup of the “microbiome” of patients with cancer is not currently captured in our cancer registries, the acquisition of these data may be a future key to unraveling the role of gut bacteria as a precursor of clinical cancer diagnoses. Stay tuned!