In vivo- and in vitro research accumulate mounting evidence, that the interaction between the colorectal microbiota and the immune system plays an important role in the development and progression of colorectal cancer and for the treatment outcomes. In future, modulation of the microbiota and immune system will, by all accounts, become important targets for prevention and treatment of colorectal cancer. In this review, we summarise current knowledge on bacterial drivers, biofilm formation, colon cancer sidedness and oncological treatment of colorectal cancer including the use of checkpoint inhibitors.