Where your DNA places you among other people, and the studies behind it.
Not tailored to your result, and not medical advice
Limit Processed and Red Meat: In a meta-analysis of prospective cohort studies, colorectal cancer risk was about 18% higher for each extra 50 g of processed meat eaten per day (RR 1.18, 95% CI 1.10 to 1.28) and about 17% higher for each extra 100 g of red meat (RR 1.17, 95% CI 1.05 to 1.31). The proposed mechanism is fairly specific to this food group: heme iron in red meat drives endogenous formation of N-nitroso compounds in the gut, nitrite used in curing adds further exposure, and meat cooked at high temperature forms heterocyclic amines. The authors note that red meat but not white meat shows a dose-response relation with nitroso compound formation in humans. Risk rose roughly linearly with intake up to around 140 g a day, after which the curve approached a plateau. PLOS ONE (PMC)
Move More and Sit Less: A Lancet Oncology review of the pooled evidence puts colon cancer risk roughly 20-25% lower in the most physically active people, in a dose-response pattern, along with about 15% lower risk of colonic adenomas and 35% lower risk of advanced adenomas. Sitting appears to contribute separately from exercise: the same review reports 54% higher colon cancer risk for time spent watching television, and about 24% higher for occupational sitting and for total sitting time. That pattern suggests breaking up long sedentary stretches matters alongside a scheduled workout. Colorectal cancer is also named there as one of the three malignancies with the most consistent evidence linking them to being overweight or obese. Lancet Oncology (PMC)
Keep Alcohol Intake Low: A dose-response meta-analysis of published studies estimated colorectal cancer risk about 7% higher at 10 g of alcohol a day, roughly one standard drink (RR 1.07, 95% CI 1.04 to 1.10), 38% higher at 50 g a day, and 82% higher at 100 g a day. Compared with non-drinkers and occasional drinkers, moderate drinkers at 2 to 3 drinks a day had 21% higher risk and heavy drinkers at 4 or more had 52% higher risk. The moderate-drinking association was stronger in men than in women, and heavy drinking showed a stronger association in Asian populations. The relationship is graded rather than a threshold effect, so the relevant quantity is total ethanol over time. Annals of Oncology (PubMed)
Treat Fiber Claims With Caution: This is where the honest answer is weaker than the usual headline. Observational studies have long linked high-fiber diets to lower colorectal cancer risk, but a Cochrane review pooling five randomised trials in 3,641 people with a history of adenomatous polyps found no difference in polyp recurrence between the higher-fiber and control groups (RR 1.04, 95% CI 0.95 to 1.13). The reviewers graded this as low-quality evidence, flagged a dropout rate above 16% that left the result unstable, and noted that polyps are only a surrogate for cancer, so their conclusion was an absence of evidence over a two to eight year window rather than a verdict against fiber. Fiber-rich whole foods remain a reasonable part of a diet for other reasons, but the idea that adding fiber prevents colorectal cancer has not been confirmed in randomised trials. Cochrane Database of Systematic Reviews (PMC)
Take Persistent Bowel Symptoms Seriously: In a systematic review of 81 studies covering nearly 25 million patients, the most common presenting features of colorectal cancer diagnosed under age 50 were rectal bleeding in 45%, abdominal pain in 40%, and altered bowel habits in 27%. Rectal bleeding carried the strongest association with a diagnosis of any red flag examined, and iron deficiency anemia was also linked to a higher likelihood. The same review found the interval from first symptom to diagnosis averaged about 6.4 months, commonly because bleeding was attributed to hemorrhoids without further evaluation. Symptoms like these are worth raising with a clinician rather than waiting to see whether they settle on their own. JAMA Network Open (PMC)
How much of this is genetic?
Genetics explains 35% of why people differ in this trait. The rest is environment, daily habits and chance.
Heritability estimate: Lichtenstein et al., NEJM 2000
Background and further reading
Colorectal cancer arises in the colon or rectum, usually developing slowly over years from benign growths called adenomatous polyps. It is one of the most common cancers worldwide, with incidence rising sharply after age 50, though cases in younger adults have been increasing. When detected early it is highly treatable, and screening programs are designed to find and remove polyps before they become cancerous. Most cases occur in people with no strong family history, reflecting a mix of common inherited variants, lifestyle, and chance.
Genetic Basis: Twin and family studies estimate that inherited factors account for roughly a third of the variation in colorectal cancer liability, with the remainder attributable to environment and lifestyle. The vast majority of this genetic contribution is polygenic, spread across many common variants each with a small effect, identified through large genome-wide association studies at loci such as 8q24, SMAD7, GREM1, and BMP4. A polygenic score sums these small effects. Importantly, it does not capture rare high-penetrance syndromes such as Lynch syndrome (mismatch-repair genes MLH1, MSH2, MSH6, PMS2) or familial adenomatous polyposis (APC), which carry much larger individual risks and are assessed separately through clinical genetic testing and family history.
Environmental and Lifestyle Factors: Colorectal cancer is one of the more preventable cancers, and modifiable factors substantially shape whether inherited tendency translates into disease. Diets high in red and processed meat, heavy alcohol use, smoking, obesity, and physical inactivity are consistently associated with higher risk, while diets rich in fiber, whole grains, and dairy are associated with lower risk. Age and personal or family history of polyps also matter. Because early polyps are removable, participation in age-appropriate screening is the single most impactful step most people can take, independent of any genetic score.
The published research behind your score, and the variants it draws on.
24 published scores from 12 studies
The colorectal cancer score combines 24 polygenic scores drawn from 12 published studies.
These traits are influenced by some of the same genes and variants as this one
Content updated August 2026.
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