How is cancer associated with host pathogen interaction?
No not necessarily. Cancer can also be caused by bacteria and viruses in your body

The regulation of cancerous tumor development is converged upon by multiple pathways and factors. Besides environmental factors, gastrointestinal (GI) tract cancer can be caused by chronic inflammation, which is generally induced by bacteria, viruses, and parasites. The role of these inducers in cancer development, cell differentiation and transformation, cell cycle deregulation, and in the expression of tumor-associated genes cannot be ignored.
Although Helicobacter pylori activates many oncogenic pathways, particularly those in gastric and colorectal cancers, the role of viruses in tumor development is also significant. Viruses possess significant oncogenic potential to interfere with normal cell cycle control and genome stability, stimulating the growth of deregulated cells. An increasing amount of recent data also implies the association of GI cancers with bacterial colonization and viruses.

You can read more here: Aituov, Bauyrzhan, et al. &quot;Pathogen-driven gastrointestinal cancers: Time for a change in treatment paradigm.&quot; Infectious agents and cancer 7.1 (2012): 18.