A Path Divergent

Five Questions for Robert Sandler, a world-renowned gastroenterologist who has challenged a major theory about the cause of diverticulosis.

A Path Divergent
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Robert Sandler, MD, MPH/Photo courtesy of Brian Strickland

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Robert Sandler, MD, MPH, has spent much of his career researching colon cancer, the best ways to prevent the disease, and what might contribute to its prevalence. He’s a leader in what has become a crowded field. Now Dr. Sandler is pioneering a new research frontier in diverticulosis, a condition where muscle layers in the colon weaken and cause outpouches. Diverticulosis affects 60 percent of people over 60 years of age. It can lead to painful symptoms. Yet, the causes of diverticulosis are not fully understood.

In a sense, he’s taken his own advice – the kind he’s given many young doctors he has mentored over the years. Dr. Sandler is pursuing research in a field ripe for further inquiry. For this and his years of dedication to mentees, Dr. Sandler was honored this spring with the Distinguished Mentor Award from the American Gastroenterology Association.

We meet with Dr. Sandler to ask him five questions about his research, how to prevent colon cancer, and his recent game-changing findings in the diverticulosis field.

medsymbol redWhy did you choose biology as a major and then medicine as a career?

I knew from a very early age that I wanted to be a doctor, probably because there was a pediatrician that I admired. Those were the days when doctors did house calls; this stuck in my mind. Also, my parents really wanted me to become a doctor. My dad co-owned a hardware store, and during the summers – rather than letting me work in the air-conditioned store – he had me working on a truck, delivering very heavy things like washing machines and cast iron pipes. That eliminated any interest in the hardware business as a career.

Not many kids from my high school went to college. Frankly, I chose Union College in Schenectady, NY, because I knew someone who went there. But they did have a good science department. Biology seemed like a sensible major for somebody who wanted to know how the human body worked. And I really enjoyed biology more than other sciences.

5q-giWhy did you choose gastroenterology as your specialty and why pursue a master’s degree in public health?

People often ask me why I chose gastroenterology, usually when they are about to undergo a colonoscopy. While colonoscopy is perhaps the activity most closely associated with gastroenterology, the reason I chose the field is its breadth. We see patients with diseases of the esophagus, stomach, liver, gallbladder, pancreas, and the large and small bowel. We take care of infectious, metabolic, premalignant, and malignant conditions. Gastroenterology includes the cognitive aspects of making a diagnosis and developing a plan, but also includes procedures like colonoscopy. It’s a great combination of thinking and doing.

I was encouraged to get a degree in public health by my first division chief and mentor Don Powell. Don knew that I wanted to remain in academic medicine; he sensed in me an affinity for epidemiology. (My wife is an epidemiologist). And he sensed that advanced training in epidemiology would make me unique. At that time, in 1980, you could count the number of GI epidemiologists in the country on one hand. Now, we have 12 in our division at UNC. The idea of finding areas that are not crowded has guided my research and helped me guide the people that I have mentored.

5q-newmicroscopeOne of your new research interests is diverticulosis. What is diverticulosis and why study it?

Diverticulosis – not to be confused with diverticulitis – is a condition where the lining of the large bowel protrudes though weak areas in the muscle. These small pouches are almost always asymptomatic, but sometimes can cause problems like bleeding and inflammation, and that condition is called diverticulitis. And it can be very painful.

Uncomplicated diverticulosis is incredibly common – about 60 percent of people 60 and older have the condition. However, although complications are rare, the economic impact is considerable because the condition is so frequent. We’ve reported that an estimated at $2.5 billion is spent each year in the United States to diagnose and treat diverticulosis.

As I read about diverticular disease, I found that most of what we understood was based on older studies that were very limited. I also found that despite the considerable burden, there was only one research study funded by the NIH. So this seemed like an opportunity.

It was difficult to study diverticulosis in the past because the condition is generally asymptomatic and therefore goes undetected. Now that a large majority of people over age 50 undergo colonoscopy screening for colon cancer, for the first time we can learn who has diverticulosis. It’s an unprecedented opportunity to study a disease that has been unstudied. Based on that realization, we used data that we had collected on 2,000 colonoscopy patients to examine risk factors for asymptomatic diverticulosis. The results were a game changer.

It was previously believed that diverticulosis was due to a deficiency of fiber in the diet. But we found that people with diverticulosis actually ate more fiber than did people without the disease. While diverticulosis had previously been thought to be related in constipation, we found the opposite. This research has been confirmed in another dataset and has led to us receiving funding from the NIH. There are now two NIH-funded studies of diverticular disease. So I like to think that I have managed to single-handedly double the NIH-funded research in this field.

5q-bacteriaYou have been the PI on several studies related to the causes of colon cancer and prevention of the disease. How did you get involved in this work and what are the best things people can do to prevent colon cancer?

Despite considerable progress, colon cancer remains the second leading cause of cancer death in the United States. As a gastroenterologist my focus has always been on prevention. For more than 25 years we have been involved in a series of studies funded by the NIH that were designed to learn about risk factors for colon polyps called adenomas that are the precursors of most colon cancers. If we could prevent people from developing adenomas we could prevent them from getting cancers. These studies have included patient interviews as well as the analysis of biological specimens.

About 10 years ago we got interested in learning more about the bacteria that live in the colon as possible mediators of risk, and we were one of the first groups to publish on the topic of the gut microbiome.

We found that people with polyps had different sorts of bacterial communities, in terms of their richness and diversity of bacteria. Now we need to understand what these bacteria are responsible for. Presumably, these bacteria produce chemicals; they metabolize things. So, understanding the “metabalome” is sort of the next adventure beyond identifying the bacteria that compose the microbiome.

For people who would like to lower their risk of colon cancer the recommendations are straightforward: exercise, don’t smoke, drink alcohol in moderation, limit red meat, and avoid obesity. These are sensible recommendations that would also lower risk for cardiovascular disease and other cancers. And of course, get a colonoscopy starting at age 50.

There are two other things I’d recommend. One is to avoid fad diets because they’re usually based on unsubstantiated reports. For instance, there was hope that folic acid would prevent colon cancer, but we studied it and it doesn’t seem to. There’s that “eat like a caveman diet” because cavemen didn’t get cancer. Well, that’s because cavemen only lived 20 or 30 years. Another popular notion is that colonics help prevent colon cancer. It makes intuitive sense that our colon is like a pipe that can get clogged. And we need to make sure it’s clear. But, in fact, the colon is not like a pipe. Stuff doesn’t stick to your colon. Colonics might actually do more harm than good.

The other thing is aspirin. We found that aspirin clearly reduces risk of colon cancer. The concern is that even in low doses aspirin isn’t completely safe; there’s a risk of bleeding. For that reason, doctors – including me – have been reluctant to suggest that people take it. But if people are taking an acid reducer then that might tip the balance; those people might safely take aspirin, though even then it’s still not totally risk free. People should talk to their doctors about this.

5q-trophyThis spring, you received the American Gastroenterology Association’s Distinguished Mentor Award. What has been your approach to mentoring?

One of the most satisfying parts of my job is the opportunity to mentor students, fellows, and faculty. My approach has been to be easily available to mentees and to create opportunities that might not otherwise be available. With the faculty, in particular, my advice has been to find an area that is not already crowded, so that they can quickly become thought leaders. A good example of that is UNC’s Evan Dellon who recognized that a condition called eosinophilic esophagitis was poorly understood, understudied, and increasingly common. Although only recently promoted to associate professor, he is currently recognized as one of the leaders in the field.

Robert Sandler, MD, MPH, is the Nina and John Sessions Distinguished Professor of Medicine and chief emeritus of the GI division at UNC Hospitals.

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