Why Genetics Are the New Baseline for Colorectal Cancer Prevention

Key Takeaways While standard guidelines suggest starting colorectal cancer screenings at 45, rising rates in younger adults make your personal genetic risk an important data point for potential early detection. Genetic insights for colorectal cancer range from high-impact variants (impacting risk for conditions like Lynch syndrome) to polygenic risk scores (PRS) that calculate the combined effect of thousands of small genetic markers. 23andMe is conducting a study to improve PRS accuracy for the Black and African American community to try to ensure equitable access to genetic information about colorectal cancer.

Is age 45 actually the right time for your first colonoscopy? While standard guidelines offer a baseline for colorectal cancer screening, your genetics offer a potential path for further precision. As we see a significant shift in colorectal cancer trends among younger adults, understanding your inherited risk factors is a critical tool for early detection and personalized care.

As we observe Colorectal Cancer Awareness Month, we’re looking at how your genetic data can help you move beyond the one-size-fits-all model and take better control of your health.

The Changing Face of Colorectal Cancer

The traditional milestone for your first colonoscopy used to be age 50. Recently, experts lowered it to 45. Why? Because the landscape of this disease is shifting.

According to the American Cancer Society, an estimated 158,850 people in the U.S. will be diagnosed with colon or rectal cancer in 2026, making colorectal cancer the fourth most common cancer. Perhaps most startling is that 45% of new cases are now occurring in adults under 65, a massive jump from just 27% in 1995. While the overall number of cases in young people is still relatively low, the rates of colorectal cancer in people between the ages of 20 and 40 is increasing at about 3% per year. This trend of younger adults being diagnosed means that for some, waiting until a standard screening age might already be too late.

The Genetic Spectrum: More Than One Way to Measure Risk

Standard screening guidelines already note that some people who are at higher risk (for example, due to a family history or having certain health conditions) should have their first colonoscopy before age 45. But many people don’t know they have higher risk, and genetics can unlock some of that knowledge. 23andMe offers a tiered look at your genetic risk to help you and your doctor move from a one-size-fits-all approach to more precise prevention.

• The MUTYH Report: Our MUTYH-Associated Polyposis Genetic Health Risk* report looks at specific variants in the MUTYH gene linked to a particular form of hereditary colorectal cancer. While having two variants significantly increases risk, even carriers of a single variant might benefit from sharing that information with their healthcare provider.
• High-Impact Variants: Particularly impactful genetic variants can also be found through sequencing, such as the clinician-ordered exome sequencing available through our Total Health™ service. This looks at over 100 high-impact genes, including some associated with significantly increased risk of developing colorectal cancer (specifically related to Lynch syndrome, MUTYH-associated polyposis, and APC-associated polyposis).
• Polygenic Risk Scores (PRS): Most cancer risk isn’t caused by a single variant or gene, but by the combined effect of thousands of small genetic variations. Our Colorectal Cancer PRS** report uses these markers to calculate whether you have an increased genetic likelihood for the most common forms of the disease.

Closing the Data Gap: Equity in Research

Precision medicine works best when the science behind it reflects the diversity of the people it serves. Historically, genetic research has been disproportionately centered on people of European descent. This has created a gap that we are working to close.

The stakes are especially high for the Black community. Black and African Americans are 15% more likely to develop colorectal cancer and 35% more likely to die from it than non-Hispanic white Americans.

Science shouldn’t have a blind spot like this. We have an ongoing study specifically designed to improve our Colorectal Cancer PRS report for our Black and African American members. Because of our currently limited data, the PRS driving this report failed to meet our performance standards for members of certain communities; these members are thus not able to receive a personalized genetic result. This study hopes to change that. Our goal is to work toward a future where preventive medicine is equitable and accurate for all.

Taking Control of Your Timeline

Colorectal cancer is one of the most preventable cancers, and when caught early it’s often more treatable. By understanding your genetic predisposition you’re equipping yourself with the knowledge needed to help lead the conversation with your doctor. Whether you are 25 or 55, knowing your risk allows you to advocate for the screenings you may need.

* The 23andMe PGS test uses qualitative genotyping to detect select clinically relevant variants in the genomic DNA of adults from saliva for the purpose of reporting and interpreting genetic health risks, including the 23andMe PGS Genetic Health Risk Report for MUTYH-Associated Polyposis. Your ethnicity may affect the relevance of each report and how your genetic health risk results are interpreted. The test is not intended to diagnose any disease and does not describe a person’s overall risk of developing any type of cancer. It is not intended to tell you anything about your current state of health, or to be used to make medical decisions, including whether or not you should take a medication, how much of a medication you should take, or determine any treatments. Warnings & Limitations: The 23andMe PGS Genetic Health Risk Report for MUTYH-Associated Polyposis is indicated for reporting the Y179C and G396D variants in the MUTYH gene and an increased risk for colorectal cancer.  The two variants included in this report are most common in people of Northern European descent.  This report does not include variants in other genes linked to hereditary cancers and the absence of variants included in this report does not rule out the presence of other genetic variants that may impact cancer risk. The PGS test is not a substitute for visits to a healthcare professional for recommended screenings or appropriate follow-up. Results should be confirmed in a clinical setting before taking any medical action. For important information and limitations regarding genetic health risk reports, visit  https://www.23andme.com/test-info.

** The 23andMe Colorectal Cancer PRS report is based on a genetic model that includes data and insights from 23andMe consented research participants and incorporates more than 1,700 genetic variants to provide information on the likelihood of experiencing colorectal cancer. The report does not describe a person’s overall likelihood, does not account for lifestyle or family history and has not been reviewed by the US Food and Drug Administration. The Colorectal Cancer PRS report is not intended to tell you anything about your current state of health, or to be used to make medical decisions or determine any treatment.