The microbiome is extremely important for human health; more recently its role in the context of cancer became clear. Microbial effects range from enhancing cancer immunity and cancer therapy efficacy, to promoting cancer progression and inhibiting treatment efficacy. These broad implications led researchers to investigate these specific interactions, as well as how modification of the microbiome can improve cancer survival and treatment efficacy. While these interactions are better established for cancers such as gastric cancer, they are far less understood in others. As nonsmall cell lung cancer (NSCLC) makes up the majority of lung cancer cases, and is among the top causes of cancer deaths worldwide, understanding the mechanisms by which the microbiome may impact progression and treatment is crucial to improve patient survival and treatment response. A literature review was conducted to reveal the crosslink between human microbiome and lung cancer. This includes immune priming, induction of pro-or anti-tumor response, and the local effects of intra-tumoral microbiota. Overall, this is a complex multifactorial relationship, and there are broad implications as to how this knowledge can improve cancer treatment. Solutions include manipulation of the microbiome using probiotics, bacterial vaccines and antibiotics. Bacteria biomarkers may also be used as a diagnostic tool. The microbiome, defined as the collection of genomes from all the microorganisms found in a particular environment, is an emerging and widely studied factor in human health. Its implications in cancer are manifold (1). Specific microorganisms that are found within a specific environment (i.e., the microbiota) induce anti-tumor immunity through immune priming (1, 2). Dysbiosis, genotoxins, and inflammatory responses to microbiota are associated with cancer development (1). Additionally, cancer treatment efficacy can be enhanced or inhibited by intra-tumoral and gut microbiota (3-5). This knowledge leads to many questions regarding the interactions between the microbiome, cancer and cancer therapies. Most importantly, how can a better understanding of these interactions lead to improvement of current treatment efficacy? Compared to the gastrointestinal (GI) tract, the microbiota of the lung and other organs are far less understood (4, 6). Lung cancer is the first cause of death among oncologic patients and the second most common cancer worldwide (7). Investigating microbial-cancer relationships will aid in a better understanding of the role of microbes in mechanisms underlying tumorigenesis behind this as well as other cancers and hopefully improve treatment efficacy (4). These factors are poorly understood in lung cancer (3, 8, 9). Therefore, this review aims 4807 This article is freely accessible online.