A noninvasive colon cancer DNA stool test has been developed which requires no medical intervention or special diet, no time lost from work, and can even be done at home, researchers from the Mayo Clinic reported at the American Association for Cancer Research special conference on Colorectal Cancer. This DNA methylation test is likely to transform colorectal cancer screening procedures, the scientists believe. Over 100,000 people in the USA are diagnosed with colon cancer every year and 39,000 with rectal cancer, according to the American Cancer Society. The National Health Service (NHS), UK, says that there are 38,600 new colorectal cancer diagnoses each year, and 16,250 deaths. Colorectal cancer includes any type of cancerous lump, growth or tumor of the colon or rectum.
The conference presenters said colorectal cancer is the second highest cause of cancer deaths in the USA, and the third most common adult cancer. In many cases, people only know they have the disease when it has already advanced – no more than 60% of adults aged 50+ ever undergo any type of screening, according to the CDC (Centers for Disease Control and Prevention).
Colorectal cancer is also known as bowel cancer.
David Ahlquist, M.D., a Mayo Clinic gastroenterologist believes screening rates are low because current procedures involve a great deal of inconvenience for the patient.
Dr. Ahlquist said:
There is definitely an incentive and legitimate justification to be designing a screening approach that is user friendly, affordable and has the ability to detect pre-cancers. The noninvasive stool DNA test we have developed is simple for patients, involves no diet or medication restriction, no unpleasant bowel preparation, and no lost work time, as it can be done from home. Positive tests results would be followed up with colonoscopy.
Ahlquist and team are assessing an experimental DNA stool test being developed by Wisconsin molecular diagnostics company, Exact Sciences. It uses a stool sample and can identify DNA alterations in cells linked to the presence of tumors – the genetic alterations come from pre-cancerous or cancerous lesions which are shed into the stool.
The assessment of this test involved 1,100 participants. The investigators identified 65% of precancerous adenomas larger than 1 cm as well as 85% of cancers. A polyps over 1 cm in size is much more likely to develop into cancer. Precancerous adenomas and cancers were spotted on both sides of the colon with equal accuracy, the researchers informed.
Adenomas are benign tumors. They either resemble or occur in glandular tissue. When an adenoma becomes cancerous, it is then called an adenocarcinoma.
87% of stage 1 to 3 colorectal cancers were detected by the test, and 69% of stage 4 cases. Colorectal cancer is much easier to cure during stages 1 to 3.
The DNA test creators, Exact Sciences, say additional human trials will probably take place in 2011.
Source: AACR (American Association for Cancer Research)
Written by Christian Nordqvist