Dr. Chyke Doubeni - Presidential Term Professor

Chyke Doubeni: Colorectal cancer is one of the most important cancers we face in this country. It was responsible for about 50,000…Actually, over 50,000 deaths last year in 2012. The interesting thing about this cancer is that we can prevent the cancer through a screen and other modalities of treatment and prevention. Our interest in this study was to understand the extent to which colonoscopy, which is now the most commonly used screening test, could prevent the risk of diagnosis of advanced colorectal cancers.

Why we're interested in this topic, specifically advanced colorectal cancers, because these are the cancers that results in death primarily. Screen tests should be able to prevent cancers or detect them at an earlier, more treatable phase. So, we were interested in finding out if colonoscopy does prevent the risk of diagnosis of advanced colorectal cancers in average risk populations.

Now, the average risk populations was studied on people who have not had any of the traditional risk factors of colorectal cancer such a polyp or a very strong family history of having colorectal cancers. We received funding from the government under the [inaudible 00:01:16] to conduct a study, and those funding streams were only provided for about two years. So, the timeline was very short to conduct this very extensive study.

But, that was not the main challenge. For a study like this, an observational study of colorectal cancer screening, we needed to be sure that we knew the reason why the tests were done. Colonoscopy was used for many years for diagnosis of colorectal cancer. That is for symptoms or conditions that the doctor felt could be associated with colorectal cancer or the illnesses in gastrointestinal tract. The use of a screening colonoscopy is a relative [inaudible 00:01:58] use of the test. As a result, we needed to be sure that when we say a test was for screening, that indeed it was for screening.

So, in our study we went to the medical records, which are imperfect, but does provide information about the intent of the referral. We provided as much information as we got to an expert group, who would then review information and determine if the test was for screening. The findings from our study should be important to a wide spectrum of people from clinicians who provide advice about screening to patients that in the eligible age to patients who are trying to make decisions about colorectal cancer screening.

It's also important for people who are making decisions about providing services for screening, those that lead programs for colorectal cancer screen, Policy leaders, and other people who are involved in researching the area of colorectal cancer screening.

We found in this study that the use of colonoscopy for screening in average risk persons reduce the risk of diagnosis with advanced colorectal cancers by 70% overall. And, on the right side, which is really where the questions have lingered, we found that this seems to be effective by about 60%, which is quite interesting. We're quite surprised by that level of efficacy. This is also important, because [inaudible 00:03:24] of the colon is where the colonoscopy has an advantage over a sigmoidoscopy. Sigmoidoscopy only reaches to the left side of the colon. Colonoscopy can reach to the right. So, that advantage has now been proven to be the case. This study does suggest that is the case.

This is a very important study, but the more important question that we need to answer is whether the colonoscopy reduces the risk of dying from colorectal cancer when it's used for screening in general population. And, that's a much more important question for us to answer in the future. And, the other important question that we also need to answer is the extent to which colonoscopy, is it equivalent or better as the other screening tests that I use. These include sigmoidoscopy and the test for blood in the stool that are also available in this country.