Colorectal cancer: how a new genetic risk test could reduce the frequency of colonoscopies

  • In the United States, it is recommended that people start getting screened for colorectal cancer with colonoscopies starting at age 45.
  • Guidelines recommend that colonoscopies be done every 10 years until age 75.
  • Researchers report that a new test for colorectal cancer that uses genetic risk factors could reduce the frequency of colonoscopies for people considered low risk.

Doctors may one day use a standardized risk score to assess patients’ susceptibility to colorectal cancer and to determine how often colonoscopy is needed.

A polygenic risk score (PRS) system for colorectal cancer is currently under development, researchers from the Finnish Institute for Molecular Medicine (FIMM) at the University of Helsinki reported at the annual conference of the European Society of Human Genetics this week.

The results have not yet been published in a peer-reviewed journal.

The score aims to identify those most at risk for colorectal cancer and whether they would benefit from early detection of the disease.

“In the future, risk-based approaches that consider genetic factors along with other relevant risk factors have the potential to personalize recommendations about how we might most effectively screen for colorectal cancer,” Dr. Max Tamlanderco-author of the study and doctoral student at FIMM, told conference attendees.

“People of different ancestry may have different risk factors and therefore may require different screening strategies,” said Dr. Liudmila Schaefermedical oncologist specializing in gastrointestinal cancers and founder of Doctor Connect.

“In order to improve the efficiency of colorectal cancer screening, there is a need for more personalized recommendations such as genetic profiles,” said Schafer, who was not involved in the study. Medical News Today.

The scoring system is being developed based on the medical and genetic records of more than 400,000 people in Finland.

“In the United States, genetic testing becomes the standard of care after a person is diagnosed with colorectal cancer,” said Dr. Jesse Houghtonsenior medical director of gastroenterology at Southern Ohio Medical Center Gastroenterology Associates.

“However, it is very rarely used to stratify patients by different screening strategies before a diagnosis, other than using a patient’s family history of colorectal cancer,” said Houghton, who was not involved in the study. ‘study. Medical News Today.

Currently, screening for colorectal cancer in the general population begins at age 60. In some other countries, screening – usually by colonoscopy – begins at age 50.

In the United States, the recommendation is to begin screening at age 45.

The new research suggests such routine screening could begin up to 16 years apart depending on whether a person is determined to be high-risk or low-risk based on their PRS scores.

People assessed to be most at risk for colorectal cancer could be asked to start screening earlier than current recommendations require.

On the other hand, patients assessed as low risk may need screening less frequently (in the United States, most people are advised to have a colonoscopy every 10 years).

“(The PRS test) would be very useful for stratifying patients along different screening pathways, or potentially eliminating screening altogether in patients with the lowest PRS scores,” Houghton said. “Earlier detection and cost savings would be two important benefits.”

Using PRS scores to adjust screening schedules could also benefit some people who are hesitant to have a colonoscopy.

On the other hand, people who need more screenings might have to pay for them out of pocket.

“When it comes to colon cancer screening, there are many barriers to getting a colonoscopy,” said Dr Bethany Malone, a colon and rectal surgeon based in Fort Worth, Texas. “One is bowel prep, which many dread. The other is insurance coverage.

For example, Malone said Medical News Today that although US colonoscopy guidelines were recently changed so that screening for most people is recommended at age 45, “many insurance companies do not yet cover screening colonoscopies in this age group” .

“Even with a genetic risk assessment, patients may still have barriers to shortened intervals for surveillance colonoscopies due to the high cost, which can reach several hundred dollars,” she said.

The researchers noted that most people who develop colorectal cancer do not have a family history of the disease or other significant risk factors.

“Many cases of colorectal cancer are related to epigenetics, which involves changes in gene expression that do not involve alterations in the underlying DNA sequence,” Schafer said. “However, there are still a lot of things we don’t know. For example, the role of the microbiome, the community of microorganisms living in our body, in colorectal cancer is not yet fully understood. Research is ongoing to determine if and how the microbiome might contribute to the development of this type of cancer.

The PRS score could be another tool to assess risk in these people, rather than simply basing screening recommendations on attained age, the researchers said.

“(A) PRS specific for colorectal cancer would be able to define more appropriate ages to start screening individuals based on their genetic risk,” Tamlander said.

“If this work continues in the future, we could potentially save millions of healthcare dollars by eliminating unnecessary colonoscopies in patients with low PRS scores, while preserving this procedure for patients most at risk,” added Houghton.

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