Expertscape is pleased to speak with Dr. Douglas Rex, an Expertscape World Expert in numerous topics, and specifically in colon cancer. Dr. Rex is Distinguished Professor Emeritus of Medicine at Indiana University School of Medicine, Chancellor’s Professor at Indiana University Purdue University Indianapolis, and Director of Endoscopy at Indiana University Hospital in Indianapolis. We discussed his extensive background, mentors, his thoughts about procedures, and the latest advancements in the area of colon cancer and gastroenterology.

Expertscape: - How did you get involved in the study of gastroenterology and colon cancer?

Dr. Douglas Rex: I attended medical school, internal medicine residency, and GI fellowship at Indiana University. GI fellowship then was two years as opposed to the current three, and I spent 18 months of fellowship in the laboratory working on alcohol metabolism, with the intent of becoming a physician-scientist as a faculty member. However, I quickly realized that maintaining my own laboratory would make me a second rank clinician and endoscopist, and I really liked endoscopy and clinical medicine. So as a young faculty member I dropped the scientist tract and became a full-time clinician. However, I learned a lot about controlled studies from my time in the laboratory, where my mentor was the great Ting-Kai Li.

As a clinician, my first mentor was Glen Lehman. Glen is still practicing and was a fabulous endoscopy teacher. At that time, he was moving toward doing ERCP full time. Because my clinical fellowship was so short, Glen steered me toward colonoscopy, studying colon polyps, and colon cancer prevention. He had some data sitting around that he gave to me to write up and which became my first clinical publications.

I also had two important role models, both in New York City, neither of whom I met until I had been on the faculty for several years. One was Jerry Waye, who just retired from GI at Mt. Sinai at the age of 85, and who was the premier colonoscopy teacher of his generation. As a fellow and young faculty member, I heard him speak at many national meetings on colonoscopy and wanted to be just like him. My other mentor from afar was Sid Winawer, who was at Memorial Sloan Kettering. I consider Sid the first great endoscopy researcher, primarily because he organized the large randomized controlled trial called the National Polyp Study. Sid and Jerry combined the features I wanted to emulate, namely to be a great clinical investigator, and also a first-class technical colonoscopist.

Expertscape: What are the most important questions to be asking physicians about colon cancer prevention?

Dr. Rex: Colon cancer is the second leading cause of cancer death in the US, which is tragic because the disease is largely preventable. The biggest obstacle to success that we have is that screening rates in the US have plateaued at a little over 60%. If you are over 50, and some would now say over 45, and you haven’t been screened for colon cancer, you should ask yourself and your primary care provider: why not? Colonoscopy is still the best and most effective way to screen, but not everyone is willing to undergo colonoscopy, and there are good non-invasive options. Right now, probably the best-studied and most cost effective is an annual or biennial fecal immunochemical test (FIT). FIT is very inexpensive, and very effective if performed every year or two.

Colonoscopy can be used as a primary screening modality, which was a major focus of my early clinical investigation. If any screening test other than colonoscopy is positive, then a colonoscopy is required to identify any cancer or precancerous growths (polyps) that are present. Colonoscopy is very powerful, but as a medical procedure it is quite operator dependent. This means that some doctors are very good at finding polyps during colonoscopy, removing them effectively, and using colonoscopy at cost-effective intervals. Some doctors that do colonoscopy are quite poor at it.

Probably my most significant achievement as a clinical investigator to date has been developing the adenoma detection rate (ADR) concept, which measures how effectively individual colonoscopists detect precancerous polyps. If it is time to have a colonoscopy, and you want to understand whether your doctor is going to perform the examination effectively, you want to know their ADR. If they don’t measure their ADR, that’s a signal of a problem.

Expertscape: Our users may wonder: “There are plenty of colonoscopists near me. Are there particular considerations that warrant traveling a distance to see a world expert?”

Dr. Rex: For a routine colonoscopy, there is usually no reason to travel a great distance. Rather you should identify a colonoscopist in your area who is really serious about polyp detection and who has demonstrated a high ADR, and has a good safety record. If there isn’t such a doctor, then traveling is worthwhile.

There are several reasons why traveling a considerable distance to see someone like myself or another regional expert would be worthwhile. One is when a precancerous lesion (“polyp”) has been identified, and the doctor believes it can’t be taken out by colonoscopy or has tried one or more times to remove the lesion and has not been successful. In this instance many patients are referred for surgical resection. As a general rule, surgery is unnecessary and should not be used for the treatment of benign colorectal polyps (lesions that don’t have cancer in them). Surgery has greater risk of mortality, morbidity, and cost compared to endoscopic resection. Most of these difficult polyps can be removed using colonoscopy by an expert interventional colonoscopist.

A second reason to travel is if surgery is recommended just because of a substantial polyp burden; that is, there are just many polyps, perhaps including some large polyps. Colonoscopists don’t get adequately reimbursed for all the work involved in “clearing” a colon with a lot of polyps. Clearing such a colon of polyps by colonoscopy is sometimes viewed as just too much trouble or too risky. As in all things, the details are important. Thus, a patient with extensive familial adenomatous polyposis should generally have all or most of the colon removed surgically. On the other hand, the overwhelming majority of patients with serrated polyposis syndrome, which is by far the most common polyp syndrome, can have their polyp burden cleared by colonoscopy and without surgery.

Finally, some patients have very challenging colonic anatomy which prevents colonoscopy from being completed. Visiting an expert is appropriate in this instance, as a variety of special colonoscopes and techniques allow colonoscopic examination of the entire colon in almost all patients.

Expertscape: What are you working on now, and what to you hope to discover?

Dr. Rex: I continue to focus on colonoscopy quality and making colonoscopy less operator dependent. I am engaged in clinical trials on products designed to make the bowel cleansing prior to colonoscopy more tolerable. People who have had a colonoscopy usually say the worst part of it was ingesting the bowel preparation. Much of my practice is in complex colonoscopy, i.e. large polyp resection, completing colonoscopy in patients with previous incomplete examinations, and patients with heavy polyp burdens.

Expertscape: Tell us about what do you like about working at IU Health?

Dr. Rex: Other than college I’m a life-long Hoosier, so practicing at Indiana University has kept me connected to my roots and family, which I like. IU has a tradition of being good to clinical people like myself. I hold the highest academic rank IU offers, something that would be hard for a clinician to achieve at many universities. My division chiefs have wisely left me alone to do my work, for which I’m grateful. University Hospital has been very generous over the years with facilitating my clinical research operations.

Expertscape: Should the public be encouraged by the progress being made in the field of colorectal cancer prevention?

Dr. Rex: The biggest issue in colorectal cancer from a public health perspective is the large number of people that don’t get screened. COVID-19 is an additional setback because a substantial population segment is worried that it’s not safe to go the hospital or an endoscopy center. Actually, endoscopy centers are very safe places.

We need a simpler effective and cost-effective screening test for colon cancer. We have a blood test now, but it doesn’t perform adequately. There are blood tests on the horizon and in clinical trials that appear promising. As for colonoscopy, if you find the right doctor, it’s never been safer and it’s astonishingly effective.

Expertscape: Thank you for your time, Dr. Rex. It has been a genuine pleasure, and we wish you continued success in your efforts!

Visit Expertscape to find experts like Dr. Rex, in thousands of medical topics — experts who can potentially help you.