Supplement Use for Colorectal Cancer Prevention: Insights from NCCN Guidelines

Announcer:

Welcome to Clinician’s Roundtable on ReachMD. On this episode, we’ll hear from Dr. Reid Ness, who will be reviewing recommendations on supplement and aspirin use from the 2024 NCCN Guidelines for Colorectal Screening. Dr. Ness is an Associate Professor of Medicine at Vanderbilt University Medical Center in Nashville, Tennessee, faculty with the Vanderbilt Ingram Cancer Center, and the Chairman of the committee that developed the colorectal cancer screening guidelines. Here he is now.

Dr. Ness:

The NCCN Guidelines highlight mixed evidence around the use of vitamin D, calcium, and folate in reducing colorectal cancer risk. Specifically, it's well known that low levels of vitamin D have been associated with an increased risk of colorectal cancer. While supplemental vitamin D, calcium, and folate have been linked to a decreased risk of conventional adenoma as a precursor lesion for colorectal cancer, some evidence suggests that these agents may increase the risk of serrated polyps, another precursor lesion for colorectal cancer. So what do you do with this information? In general, if you find that your patients are deficient in a vitamin or micronutrient that is important, then they should be supplemented appropriately. Otherwise, I ask my patients to ingest a broad diet that's well balanced and full of lots of fresh fruits and vegetables, and in most cases, this will address most vitamin deficiencies unless they're due to an underlying pathologic illness.

So with regards to cancer risk, I would say that if you have a patient who has a known deficiency, of course that should be supplemented, or a patient who is at risk—let's say a person who has pancreatic insufficiency, has malabsorption secondary to celiac disease, or some other malabsorptive process or specific pathology that would lead to them specifically wasting certain vitamins and micronutrients or across the board—then supplementation is appropriate for the treatment of that primary illness.

The updated guidelines reflect the U.S. Preventive Services Task Force conclusion that evidence is insufficient to recommend low-dose aspirin for reducing colorectal cancer incidence or mortality in the general population. So when it comes to aspirin use, particularly in patients already taking it for cardiovascular reasons, the evidence that it can decrease the risk of colorectal cancer is mixed, and that's honestly to say the least. So there's been a long history of evidence from observational studies showing that colorectal cancer incidence and mortality can be decreased by the regular use of aspirin. This, though, has to be now balanced against the results of the ASPREE trial—which was published pre-COVID—which showed that in patients over age 70, the risk of overall mortality was increased by regular aspirin use, and specifically, this overall mortality was secondary to an increased risk of metastatic cancer, principally colorectal cancer; thus, we have extremely mixed results for the use of aspirin and its outcomes in colorectal cancer incidence and mortality for primary prevention.

Aspirin use has been associated with improved colorectal cancer survival and overall survival when employed for secondary prevention. There is evidence supporting the use of aspirin for colorectal cancer chemoprevention, specifically in Lynch syndrome patients. The results of the CAPP2 trial from 2020 showed that colorectal cancer instance was decreased by the regular use of high-dose aspirin. In our guidelines, we mentioned that this is an option to offer Lynch syndrome patients, but do not give it a hard recommendation.

Announcer:

That was Dr. Reid Ness talking about supplement and aspirin use considerations for colorectal cancer prevention. To access this and other episodes in our series, visit Clinician’s Roundtable on ReachMD.com, where you can Be Part of the Knowledge. Thanks for listening!