Cross Talk Between Diet, Microbiome, and Cancer

The close association between diet and cancer initiation and progression is well established. Over the past decade, multiple studies have shown the beneficial impact of select diets, such as ketogenic diet, calorie restriction, and omega-3 enriched diets, on tumor burden and progression in preclinical and epidemiological studies. It is now appreciated that diet influences both host metabolism as well as the endocrine gut microbiome. The microbiome comprises more than a trillion microorganisms known to impact human health and disease, ranging from bacteria (gram-positive and negative) to fungi and protozoa. The gut microbiota can contribute to different outcomes in pathologies by modulating host immunity. Besides the gut, changes in the oral microbiome (such as periodontal infection) also correlate with the increased incidences and pathologies in multiple cancers (oral, breast, and pancreatic cancer). Recent studies have unmasked how dietary-based interventions can impact microbial communities, which modulates tumor expansion and response to standard chemo and immunotherapies. Given that certain solid tumors are refractory to immunotherapies, there is a clinical need to review the expanding literature on the trilateral interaction between diet, microbiome, and cancer.

Dietary management of tumor-bearing hosts can impact pathological outcomes with many studies focusing on host and gut microbial metabolism impact on the immune system. Diets are shown to impact metabolism of the target organ, e.g., the tumor (focus of this Research Topic) or distant sites (systemic organs) via the supply of micro and macronutrients. Diets' direct influence on the microbial communities (gut and oral microbiome) can also modulate tumor progression and patients’ response to cancer treatments. Significantly, microbiota can influence the anti-cancer compounds' stability, toxicity, and efficacy in cancer patients. Also, the role of gut microbiome as a clinical predictor in immune-related adverse events is appreciated. Thus, dietary-based microbial modulation has a diverse impact on tumor progression, which needs to be carefully assessed to develop effective cancer therapeutics. This Research Topic aims to review the evidence for dietary-based interventions on tumor progression and therapeutic outcomes via direct (immune or metabolic) or indirect (modulation of the microbiome and in turn the immune system) mechanisms. This review will advance the field and help identify critical mechanisms/players for future investigations as well as develop better nutritional-based therapeutic tools for cancer patients.

This Research Topic welcomes Review/Mini Review articles in the field of dietary (specific diets or dietary patterns) or microbiome-based studies in tumor models, including but not limited to the following areas:

• Dietary-based interventions in tumor models
• Impact of diet on local and systemic immunity in tumor studies
• Dietary-based metabolic perturbation in the tumor microenvironment
• Diet and gut microbiome interaction in tumor metabolism
• Role of the oral microbiome in tumor immunity and metabolism
• Impact of diet and microbiome on therapeutic response to cancer