Colorectal cancer (CRC) is the second leading cause of death from cancer in the U.S., even though it is highly preventable. Earlier this year, the Wellness Letter took a deep dive into the topic of fecal immunochemical testing (FIT) as a means of screening for CRC.
In that article, “Are You FIT to Be Tested?,” we posed several questions to Steven Jacobsohn, M.D., a gastroenterologist and member of our editorial board. The two key takeaway messages were: (1) Screening with FIT has been shown to decrease incidence and mortality from colorectal cancer and has increased public compliance with screening recommendations. (2) The U.S. Multi-Society Task Force on Colorectal Cancer considers FIT one of the two top screening options, the other being colonoscopy. More recently, however, there was a lot of coverage about a controversial study reporting that colonoscopy did not reduce colorectal cancer as much as expected and did not prevent deaths from the disease. Dr. Jacobsohn gave us his perspective on the research in this guest editorial.
Screening for CRC is known to significantly reduce morbidity and mortality from the disease. The Wellness Letter wanted to look at other prevention strategies besides screening. We spoke with two leading gastroenterologists from NYU Langone Health in New York City: Aasma Shaukat, M.D., M.P.H., and Peter Liang, M.D., both of whom have published widely on colorectal cancer prevention.
The Wellness Letter: Besides keeping up with screenings, what kind of lifestyle factors play a role in preventing colorectal cancer?
Dr. Shaukat: A healthy lifestyle includes a few components, starting off with maintaining a healthy weight. Related to that obviously is having a prudent diet, and also engaging in physical activity. When we talk about a healthy weight, that’s not about people having just a few extra pounds. By healthy weight, we mean a body mass index, or BMI, below 30. That’s the cutoff for being defined as obese. In fact, high BMI or obesity is one of the emerging factors associated with early-onset colon cancer.
WL: What are the latest recommendations on diet?
Dr. Shaukat: There is more and more evidence in favor of what’s considered a prudent diet. Essentially that’s a diet that’s high in fiber, high in fruits and vegetables—along the lines of the Mediterranean diet. What’s also important is what is not good. Red meat is the main item to reduce or limit. And this kind of diet has so many other benefits beyond just colorectal cancer prevention.
Dr. Liang: These are really things that many patients already know. They’ve been told by their primary care physician, or they know from what they’ve read and heard, that the foods that are good for you in general are also good for cardiovascular disease and for colorectal cancer prevention. And within the red meat category, meat that is processed—such as cured or smoked—increases the risk even more.
WL: How about dairy products?
Dr. Shaukat: There are no conclusive data on that.
WL: And physical activity?
Dr. Liang: Yes. Physical activity has been shown to be protective against colorectal cancer, and physical inactivity or sedentary behavior is an independent risk factor. But again, if you think about it, the same things are helpful for you in terms of cardiovascular disease and overall health. So exercise has multiple benefits, including for colorectal cancer prevention.
WL: What about taking aspirin?
Dr. Liang: Taking aspirin for prevention of colorectal cancer, or precancerous polyps, has been found to be effective in a select group of people—those who should be taking aspirin for prevention of cardiovascular disease. That’s because it’s been studied for colorectal cancer prevention only in people who are already taking aspirin for heart disease. In other words, the primary outcome in most of the trials is cardiovascular disease, because it’s a much more common occurrence. There is no recommendation to take aspirin for colorectal cancer prevention alone in the absence of needing to take it for cardiovascular disease.
Dr. Shaukat: The downside is the gastrointestinal toxicity. Aspirin is not completely harmless. It can cause ulcers, gastritis, and bleeding anywhere in the gastrointestinal tract. And at some point, that risk with long-term use outweighs the benefits. So I would recommend that people have a conversation with their physician about whether or not to take aspirin for the prevention of either cardiovascular disease or colorectal cancer, especially given that the guidelines for aspirin use for cardiovascular prevention have recently changed.
WL: What’s the status of calcium and vitamin D as a preventive strategy?
Dr. Liang: There is some research suggesting that these are effective, but the randomized controlled trials have not borne that out. There are still some ongoing studies, especially for vitamin D, that may or may not change what the recommendations will be in the future. But as of now, based on the available evidence, we would not recommend either calcium or vitamin D alone or in combination to prevent colorectal cancer.
WL: Before we end, let’s please clear up what seems to be a misconception—that some populations are more biologically predisposed to develop colon cancer.
Dr. Liang: If you look at the data, they do show that colon cancer incidence is higher for Black individuals compared to White individuals, and Black individuals also have a higher risk of dying from colon cancer. So that might lead one to think there might be racial differences in the biology of the cancers. Maybe Black individuals get more aggressive cancers or cancers that are more resistant to treatment. Actually, we believe most of the differences have to do with factors related to the social determinants of health. Black individuals generally have less access to care, are less likely to have health insurance, and are less likely to get advice on prevention strategies—there’s a variety of reasons.