A virus that is found up more than 85% of the population has turned up in colon cancer samples. The JC virus is expansive, affecting nearly the entire human population from childhood onwards. It's imparted in the air, and maybe also through contaminated food and water. Normally the JC virus is completely harmless, but in people with weak immune systems it has been known to increase the risk of brain cancer and other diseases of the nervous system.
Now researchers at Temple University in the US have found DNA from the JC virus in 20 out of 26 colon cancer samples tested. They also find proteins that the virus produces which seem to play a role in making the tissue malignant. It's not clear, yet, whether the JC virus can cause colon cancer on its own, or whether it is a contributing factor. Further research should reveal if treating the infection might be a useful approach in combatting colon cancer.