Another example of using DNA test to screen for cancer is the stool DNA test for colon cancer. It is a non-invasive test that identifies DNA changes in the cells of a stool sample. The test looks for abnormal DNA associated with colon cancer or precancerous colon polyps. It also detects hidden blood in the stool which can indicate the presence of cancer. It has a great appeal in the US for people who do not want to go through the rather troublesome preparation required for a colonoscopy. Colorectal cancer, which includes bowel, colon or rectal cancer, is the fourth most common type of cancer diagnosis in the UK, with most people over the age of 60. Familial adenomatous polyposis (FAP) is one example of inherited colorectal cancer. It is characterized by cancer of the large intestines (colon) and rectum. Also, it is a rare autosomal-dominant syndrome caused by mutation in the adenomatous polyposis coli (APC) gene. People with this condition will develop benign polyps in the colon. If left untreated, these polyps can turn malignant. The polyps can increase with age, leading to early-onset colorectal cancer at an average age of 39 years.
Gene therapy has been explored as a possible treatment for cancer, including genetically-engineered viruses, gene transfer and immunotherapy. In gene transfer, a foreign gene will be inserted into the cancer cells or into surrounding tissues. By doing so, the gene can kill cancer cells, removing nutrients they need to survive. Using genetically- engineered viruses, it can directly target and destroy cancer cells without affecting the healthy ones. The viruses are engineered so it can infect cancer cells, and create proteins which cause the cells to die.