Scientists and physicians have long thought that cancers were sterile environments. However, it has recently been shown that, like almost everywhere in the human body, tumors were in fact profitable for microorganisms. More than that, studies revealed that each tumor located in different parts of the body have specific microbiomes with bacteria adapted to it. For example, we find bacteria assimilating smokes in lung cancer of smokers or even bacteria digesting gerbamicine, a chemotherapy molecule administered during cancer treatment . As different phages infect different bacterial strains, it is important to identify the microbiome from cancer we want to target with our therapy in order to choose a compatible phage. Not all cancer microbiomes have been characterized. However, some information can be found on some cancers.
It is known that a healthy prostate has a lot of bacteria. So it is not surprising that tumors in this organ present a microbiome. The most abundant bacteria genus is Propionibacterium  which could be a valid target for our engineered phage.
Like for the prostate, this organ is known to have an enriched microbiome. Microbiomes differ with cancer types, in this cancer it also differs with the location in the colon. If it is more distal the principal genus are Alistipes, Akkermansia, Halomonas and Shewanella. In the case of a proximal tumor, more Faecalibacterium, Blautia and Clostridium are found .
Another cancer associated with the digestive tract is pancreas cancer. It has been shown that Escherichia coli can migrate from the gut to the pancreas cancer  during its development however few articles mentioned its presence in tumoral microbiomes . The major genus are Pseudomonas, Citrobacter and Klebsiella  .
Next cancer is pulmonary cancer. Nowadays, the lungs microbiome is more and more studied, tumors included. Yet no particular phyla has been clearly identified but it has been shown that genus Veillonella and Megasphaera are characterizing lungs with cancer. 
Pediococcus, Burkholderia, Sphingomonas, Chryseobacterium, Enterococcus, Staphylococcus, Treponema and Francisella with the first one being slightly more abundant .
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