Searching for the Optimal CRC Surveillance Test

Q: Have you been doing any research on the reasons why more young people are getting colon cancer? 

We recently published work looking at the potential factors that may be driving the rising rates of early onset colorectal cancer. One hypothesis that’s been floating around is antibiotic exposure in early adulthood or childhood because of its effect on the microbiome. Using our large database at Kaiser Permanente Northern California, we did not find an association between oral antibiotic use during early adulthood and the risk of early-onset colorectal cancer.

You have the usual suspects like obesity and diabetes, but it’s not explaining all that risk. While familial colorectal cancer syndromes contribute to a small proportion of early-onset colorectal, these syndromes are not increasing across generations. I really do feel it’s something in the diet or how foods are processed and environmental factors that’s driving some of the risk of early onset colorectal cancer and this should be explored further. 
 

Q: In 2018, you issued a landmark study which found an association between a 10-year follow-up after negative colonoscopy and reduced risk of disease and mortality. Has there been any updates to these findings over the last 6 years? 

We recently saw a study in JAMA Oncology of a Swedish cohort that showed a negative colonoscopy result was associated with a reduced risk of developing and even dying from colorectal cancer 15 years from that examination, compared to the general population of Sweden. I think there’s some things that we need to be cautious about regarding that study. We have to think about the comparison group that they used and the lack of information regarding the indication of the colonoscopy and the quality of the examination. So, it remains uncertain whether future guidelines are going to stretch out that 10-year interval to 15 years.

Q: What other CRC studies are you working on now? 

We have several studies that we are working on right now. One is called the PREVENT CRC study, which is looking at whether a polygenic risk score can improve risk stratification following adenoma removal for colorectal cancer prevention and tailoring post-polypectomy surveillance. This is a large observational cohort study that we have teamed up with the Fred Hutchinson Cancer Center, Erasmus University, and Kaiser Permanente Northwest to answer this important question that may have implications for personalized medicine. 

Then there’s the COOP study, funded by the Patient-Centered Outcomes Research Institute. This is looking at the best surveillance test to use among older adults 65 years and older with a history of polyps. The trial is randomizing them to either getting a colonoscopy for surveillance or annual fecal immunochemical test (FIT) for surveillance. This is to see which test is best for detecting colorectal cancer among older adults with a history of polyps.  
 

Q: Do you think FIT tests could eventually replace colonoscopy, given that it’s less invasive? 

Although FIT and other stool-based tests are less invasive and have been shown to have high accuracy for detecting colorectal cancer, I personally do not think they are going to replace colonoscopy as the most popular screening modality in the United States. Colonoscopy remains the gold standard for detecting and removing precancerous polyps and has the highest accuracy for detecting colorectal cancer.