Streptococcus bovis: Causal or incidental involvement in cancer of the colon?

Though one of these articles is from 2006, it does again raise the question: how many chronic bacterial infections — pathogenic biofilms — contribute to cancer? So far, three are proven. How many more will be?
Strep bovis in Bood and Cancer of GI tract Review.pdf
Strep Bovis Strep gallolyticus biofilms and GI Cancer.pdf
Flow chart Strep (bovis).jpg