Scientists have found increased immune response to antigens produced by a particular intestinal bacteria in patients with polyps and early stage I or II colorectal cancer.
Antibodies against the Streptococcus bovis antigen RpL7/L12 were higher in the blood of polyp and early cancer patients than healthy individuals. However, the increased immune response had disappeared in patients with more advanced stage III or IV cancer.
No similar antibody increase was found to endotoxin, a key component of cell walls in most intestinal bacteria, leading the scientists to believe that Streptococcus bovis and RpL7/L12 is unique in its ability to cause early polyps to become cancerous.
Annemarie Boleij,MSc and her team in the Netherlands concluded,
These findings are indicative of an increased exposure to antigen RpL7/L12 during early stages of colon carcinogenesis and suggest that intestinal bacteria such as S. bovis constitute a risk factor for the progression of premalignant lesions into early stage carcinomas. Clearly, the current findings emphasize the necessity for further studies on the possible etiologic relationship between intestinal bacteria and human colorectal cancer.