Dr. Manoj Sharma-
Dr. Sharma is a Professor and Chair of the Social and Behavioral Health Department and an Adjunct Professor in Internal Medicine at the University of Nevada, Las Vegas (UNLV). He is a global expert in health promotion.
Colorectal cancer (CRC) is among the most common cancers worldwide and is associated with a significant number of deaths. Recent global estimates show that an estimated 1.9 million cases are diagnosed each year leading to 900,000 deaths. Deaths can be reduced with early diagnosis and treatment of CRC. The American Cancer Society recommends a variety of screening tests for colorectal cancer screening in people in the age group 45 to 75 years that are chosen by the person and their healthcare provider. The stool-based tests that are non-invasive and are preferred by people who do not want invasive tests are:
- Highly sensitive fecal immunochemical test (FIT) which needs to be conducted every year.
- Highly sensitive guaiac-based fecal occult blood test (gFOBT) which also needs to be conducted every year.
- Cologuard or multi-targeted stool DNA test (mt-sDNA) which needs to be conducted every 3 years has become very popular.
The visual (structural) exams of the colon and rectum-based tests that are invasive are:
- Colonoscopy which is recommended every 10 years.
- CT colonography (virtual colonoscopy) which is recommended every 5 years.
- Flexible sigmoidoscopy (FSIG) which is recommended every 5 years.
However, there are pros and cons to each of these tests. The stool-based tests are not very accurate while visual exams can have adverse effects due to being invasive. According to the United States Preventive Services Task Force, only one-third of people undergo screening in the ages 45 to 75 when it is recommended. In such a situation, a blood test for colorectal cancer would be quite welcome.
A recent study published in the New England Journal of Medicine has tested such a blood test with the ability to detect 83% of people with CRC. This test is yet to be approved by the Food and Drug Administration (FDA) but seems promising. The test has been developed by a company called Guardant Health. The mechanism by which this test works is to identify circulating tumor DNA.
The downside with this blood test will be that if a person tests positive then they will still have to undergo colonoscopy which many people fear. Yet, if this blood test gets approved it will provide more alternatives to people getting screened.
