Computer Simulation Aims to Solve Colonoscopy’s Right-Side Problem

drawing of a colonoscope in a colon

In the U.S., colonoscopy is the most commonly used method for colon cancer screening. Unlike other screening tests used to detect early-stage colon cancer, colonoscopy can often prevent it by removing polyps from the colon before they become cancerous. 

Widespread uptake of colonoscopy (and other colon cancer screening tests) has led to a steep decline in colon cancer incidence rates. But some studies suggest that colonoscopy may not be as effective against cancers that develop in the right side of the colon. 

Amy Knudsen, PhD, a researcher at Massachusetts General Hospital and Harvard Medical School in Boston, Mass., is creating a computer model to help explain why this happens. Knudsen and her team started the project in 2015 with funding support from the American Cancer Society.

“One possible explanation is that polyps that develop in the right side of the colon may be biologically different from those that develop in other parts of the colon,” she says. “It might also be harder for doctors who perform colonoscopy to find right-sided polyps, and when they do, to completely remove them.” 

Knudsen’s computer model allows her and her team to create detailed simulations of the development of colorectal cancer and the effectiveness of colonoscopy. For example, the model can simulate what happens if a colon polyp is not completely removed during a colonoscopy. It can also look at how a polyp’s shape, size and location impact the ability of colonoscopy to detect it.

Knudsen explains that she and her team have also recently added new features to what is called the “natural history” portion of the model. This is the part of the model that simulates what happens to patients when they are not screened for colon cancer. For instance, they have added hyperplastic polyps, a type of polyp that does not progress to colon cancer, to the model. This is allowing them to explore screening strategies in which the doctor leaves in place any small polyp located in the left side of the colon or in the rectum to be examined at the next colonoscopy. This spares the patient the small risk of complications that may arise from polyp removal.

Next steps include modifying the model to simulate “sessile serrated polyps,” which are polyps that are particularly difficult to detect during a colonoscopy and that are most commonly located in the right colon. Knudsen plans to then use the model to evaluate the effectiveness of screening strategies that combine colonoscopy with other screening tests that could together offer adequate protection throughout the entire colon. 

“Ultimately, we hope that the results from our study will guide the development of new screening tests for colorectal cancer, highlight important areas of focus for quality-improvement efforts in colonoscopy, and inform future screening recommendations,” she says.

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