Editing Malignant transformation (section)

===Bacteria===

==== ''Helicobacter pylori'' and gastric cancer====

In 1995 epidemiologic evidence indicated that ''Helicobacter pylori'' infection increases the risk for gastric carcinoma.<ref name="pmid7762738">{{cite journal |vauthors=Correa P |title=Helicobacter pylori and gastric carcinogenesis |journal=Am. J. Surg. Pathol. |volume=19 |pages=S37–43 |year=1995 |issue=Suppl 1 |pmid=7762738 }}</ref>  More recently, experimental evidence showed that infection with ''[[Helicobacter pylori]]'' cagA-positive bacterial strains results in severe degrees of inflammation and oxidative DNA damage, leading to progression to gastric cancer.<ref name="pmid24664859">{{cite journal |vauthors=Raza Y, Khan A, Farooqui A, Mubarak M, Facista A, Akhtar SS, Khan S, Kazi JI, Bernstein C, Kazmi SU |title=Oxidative DNA damage as a potential early biomarker of Helicobacter pylori associated carcinogenesis |journal=Pathol. Oncol. Res. |volume=20 |issue=4 |pages=839–46 |year=2014 |pmid=24664859 |doi=10.1007/s12253-014-9762-1 |s2cid=18727504 }}</ref>

====Other bacterial roles in carcinogenesis====

Perera et al.<ref name="pmid27677454">{{cite journal |vauthors=Perera M, Al-Hebshi NN, Speicher DJ, Perera I, Johnson NW |title=Emerging role of bacteria in oral carcinogenesis: a review with special reference to perio-pathogenic bacteria |journal=J Oral Microbiol |volume=8 |pages=32762 |year=2016 |pmid=27677454 |pmc=5039235 |doi= 10.3402/jom.v8.32762}}</ref> referred to a number of articles pointing to roles of bacteria in other cancers.  They pointed to single studies on the role of ''Chlamydia trachomatis'' in cervical cancer, ''Salmonella typhi'' in gallbladder cancer, and both ''Bacteroides fragilis'' and ''Fusobacterium nucleatum'' in colon cancer.  Meurman has recently summarized evidence connecting oral microbiota with carcinogenesis.<ref name="pmid21523227">{{cite journal |vauthors=Meurman JH |title=Oral microbiota and cancer |journal=J Oral Microbiol |volume=2 |pages= 5195|year=2010 |pmid=21523227 |pmc=3084564 |doi=10.3402/jom.v2i0.5195 }}</ref>  Although suggestive, these studies need further confirmation.