An overview of cancer and the human microbiome

Mutual beneficial associations with the microbial consortia are an essential requisite of human life. Microbial communities have both a symbiotic and a pathogenic standpoint, which portrays a context-dependent scenario of the human microbiome. The symbiotic assemblage works to develop indispensable functions of the human body such as immune system, digestive system, defense against colonization by pathobionts and their toxins, etc. Furthermore, any deviation in the resource utilization by the symbionts due to host factors comprising lifestyle changes, diet, drugs, immunocompromised states, and co-morbidities could perturb beneficial microbes communities and promote the invasion by opportunistic pathogens thus, disrupting the homeostatic state. Microbial infestations have proved to be carcinogenic but this does not spontaneously establish a cancer hallmark, rather they initiate a cascade of events that disturbs the normal cellular activities finally these defective machineries invade distant sites of the body, submitting to a devastative transformed internal milieu. Significant technological and system biology advances have been made in elucidating a lucid but complex basis of such microbe-associated malignancies. This chapter discusses the recent advances, without compromising the concepts of the inception studies, including a brief version of the microbial status in cancer generation, mechanistic approaches adapted, therapeutic interventions, system biology approaches with special mention on the study design gaps, challenges in addressing the drawbacks and finally with a perspective of the future targeted studies, has been a focus of this piece of work.