Greater than 75–95% of colorectal cancer occurs in people with little or no genetic risk. Risk factors include older age, male gender, high intake of fat, alcohol, red meat, processed meats, obesity, smoking, and a lack of physical exercise. Approximately 10% of cases are linked to insufficient activity. The risk from alcohol appears to increase at greater than one drink per day. Drinking 5 glasses of water a day is linked to a decrease in the risk of colorectal cancer and adenomatous polyps. Streptococcus gallolyticus is associated with colorectal cancer. Some strains of Streptococcus bovis/Streptococcus equinus complex are consumed by millions of people daily and thus may be safe. 25 to 80% of people with Streptococcus bovis/gallolyticus bacteremia have concomitant colorectal tumors. Seroprevalence of Streptococcus bovis/gallolyticus is considered as a candidate practical marker for the early prediction of an underlying bowel lesion at high risk population. It has been suggested that the presence of antibodies to Streptococcus bovis/gallolyticus antigens or the antigens themselves in the bloodstream may act as markers for the carcinogenesis in the colon.
Colorectal cancer ( CRC ), also known as bowel cancer and colon cancer , is the development of cancer from the colon or rectum (parts of the large intestine ).  A cancer is the abnormal growth of cells that have the ability to invade or spread to other parts of the body.  Signs and symptoms may include blood in the stool , a change in bowel movements, weight loss and feeling tired all the time.