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Colorectal Cancer Awareness Month: Why Screening Can Prevent, Not Just Detect
Every March, Colorectal Cancer Awareness Month highlights a cancer where finding and removing small growths can stop cancer before it starts. Here is what NCI says.
A plain-language summary based on public reporting and trusted sources, linked below.
Please note: this page is educational only — it is not medical advice, and it does not speculate about anyone’s health beyond reliable public reporting. For questions about your own health, talk with your healthcare team.
A campaign with an unusual promise
Most cancer awareness months ask you to find disease sooner. March asks something bigger: prevent it.
Colorectal cancer usually starts as a polyp, a small growth on the inside lining of the colon or rectum. Polyps are common and most never turn into anything. Some do, slowly, over years.
That slow timeline is the opening. A test that spots a polyp can also remove it in the same visit. The cancer that polyp might have become never exists. NCI lists polyp removal among the protective factors that lower colorectal cancer risk.
The five tests, and what each asks of you
NCI's screening summary describes five approaches. They are not interchangeable, and the trade-off is between effort and reach.
Fecal occult blood test. A stool sample checked for blood invisible to the eye. The older guaiac version uses a chemical that changes the color of a card. The newer fecal immunochemical test, or FIT, uses antibodies that detect human blood specifically. Done at home, no preparation.
DNA stool test. Checks stool cells for genetic changes linked to colorectal cancer. Also done at home.
Sigmoidoscopy. A thin lighted tube examines the rectum and the lower colon. It can take tissue samples and remove polyps. It does not reach the upper colon.
Colonoscopy. The same idea for the entire colon and rectum, with sedation and bowel preparation beforehand. It can find and remove polyps anywhere along the length.
Virtual colonoscopy. A CT scan builds a detailed picture of the colon's inner surface. It shows polyps but cannot remove them, so anything found means a real colonoscopy afterwards.
NCI adds one clear negative. Studies show a digital rectal exam does not work as a screening test for colorectal cancer, and screening this way does not reduce deaths from it. Our page on colonoscopy covers preparation and recovery in detail.
When to start
The US Preventive Services Task Force recommends screening every adult aged 45 to 75. Screening from 50 to 75 carries its top grade, A. Screening from 45 to 49 carries grade B.
From 76 to 85 the recommendation changes character. The Task Force says to screen selectively, weighing overall health, previous screening and personal preference, because the net benefit across everyone in that age band is small.
Intervals depend on the test. FIT or a high-sensitivity guaiac test is yearly. Stool DNA-FIT is every one to three years. CT colonography and flexible sigmoidoscopy are every five years. Sigmoidoscopy every ten years paired with yearly FIT is another option. Colonoscopy alone is every ten years.
Those recommendations apply to people at average risk without symptoms. A personal history of colorectal cancer, high-risk adenomas, ovarian cancer or inflammatory bowel disease changes the plan, as does an inherited syndrome.
The harms that March does not advertise
Honest screening advice includes the downside, and NCI states it directly.
False negatives happen. A normal result when cancer is present can cause someone to ignore later symptoms.
False positives happen too. An abnormal result with no cancer leads to more tests, which carry their own risks, and to real anxiety in between.
Colonoscopy itself carries rare but serious risks: tears in the colon lining, and bleeding. Both are more likely when a biopsy or polyp removal is done, and both may need hospital treatment. Sedation can cause heart or breathing problems.
Sigmoidoscopy has fewer complications, partly because it usually needs no sedation. Virtual colonoscopy has fewer physical harms than either, at the cost of not being able to treat what it finds. Our page on the benefits and harms of screening sets out how to weigh these.
What raises the risk, and what lowers it
NCI's prevention summary sorts the evidence rather than listing everything anyone has claimed.
Risk factors: age, a parent, sibling or child with colorectal cancer, which doubles a person's risk, personal history of the conditions above, inherited syndromes such as familial adenomatous polyposis and Lynch syndrome, drinking three or more alcoholic drinks a day, cigarette smoking, race, and obesity.
Protective factors: physical activity, aspirin, combination hormone replacement therapy, and polyp removal.
Unclear: non-aspirin NSAIDs, calcium, and diet. That last one surprises people, and it is what the evidence currently supports.
No effect: estrogen-only hormone replacement therapy, and statins.
If Lynch syndrome runs in your family, screening starts far earlier and runs more often. Our page on Lynch syndrome explains who should be tested.
When to get checked between screening rounds
Screening is for people with no symptoms. Symptoms are a separate route and should not wait for the next scheduled test. NCI lists these as reasons to see a doctor:
- Blood in the stool, bright red or very dark.
- A lasting change in bowel habits, in either direction.
- A feeling that the bowel does not empty completely.
- Stools that are narrower than usual.
- Persistent gas pain, bloating, fullness or cramps.
- Weight loss with no known cause, tiredness, or vomiting.
Age is not a reason to dismiss these. NCI reports that between 2012 and 2021 the rate of new colorectal cancers rose by about 2.4% a year in adults younger than 50, even as it fell overall.
The wider numbers
The American Cancer Society projects about 158,850 new colorectal cancers and 55,230 deaths in the United States for 2026, which is the estimate SEER publishes. It is the second leading cause of cancer death in the country.
Five-year relative survival for 2016 to 2022 was 65.4% overall: 91.3% while the cancer is still local, 75.2% with regional spread, and 16.9% once distant. Localized disease makes up 34% of diagnoses and distant disease 23%. These are population statistics from past years, not a forecast for any one person.
What this does not mean
Screening does not remove risk. It lowers it, and it can miss things.
A clear colonoscopy is not a permanent result. The interval exists because new polyps form.
And a campaign month is not a clinical recommendation. Which test suits a particular person depends on age, family history, previous findings, other illnesses and what they will actually complete. The best screening test is the one that gets done.
Sources
- NCI PDQ, Colorectal Cancer Screening (Patient Version) — https://www.cancer.gov/types/colorectal/patient/colorectal-screening-pdq
- NCI PDQ, Colorectal Cancer Screening (Health Professional Version) — https://www.cancer.gov/types/colorectal/hp/colorectal-screening-pdq
- NCI PDQ, Colorectal Cancer Prevention (Patient Version) — https://www.cancer.gov/types/colorectal/patient/colorectal-prevention-pdq
- NCI PDQ, Colon Cancer Treatment (Patient Version) — https://www.cancer.gov/types/colorectal/patient/colon-treatment-pdq
- US Preventive Services Task Force, Colorectal Cancer: Screening — https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/colorectal-cancer-screening
- SEER Cancer Stat Facts, Colorectal Cancer — https://seer.cancer.gov/statfacts/html/colorect.html
How this article was prepared
An AI-assisted editorial system helped prepare this page. No named medical reviewer has reviewed it unless one is listed.
The National Cancer Information Foundation publishes Cancer Explained. This page is for learning. It is not medical advice and does not suggest a test or treatment.
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Put the story in context
Prevention, possible warning signs, screening, and diagnosis
This story relates to Colorectal cancer & screening. The information below is general: it does not reveal anything else about a public person’s health, and not every point applies to every cancer. Personal advice depends on age, symptoms, family history, exposures, and medical history.
Prevention and risk reduction
Not every cancer can be prevented. Avoiding tobacco, protecting skin from ultraviolet radiation, limiting alcohol, staying active, and receiving recommended HPV or hepatitis B vaccination can lower the risk of certain cancers. A risk factor is not a prediction or a cause in one individual.
Symptoms and possible early signs
Possible signs vary and are often caused by conditions other than cancer. Changes worth discussing include a new lump, unexplained bleeding or weight loss, a persistent cough, lasting bowel or bladder changes, a changing skin spot, or symptoms that persist or worsen. Some early cancers cause no symptoms.
Screening and early detection
Screening looks for certain cancers before symptoms begin. Recommended tests exist only for some cancers and depend on age and risk. Screening can have benefits and harms; it is not the same as evaluating a new symptom, and there is no single routine scan or blood test that reliably screens for every cancer.
How cancer is diagnosed
Diagnosis may involve a history and exam, imaging, laboratory tests, and often a biopsy. Pathology can identify the cancer type and may test biomarkers that guide treatment. Symptoms, screening results, tumor markers, or online stories alone cannot confirm cancer.
Learn about this story’s cancer topic
A public story may encourage questions, but it should not be used to estimate your risk or choose testing. Contact a healthcare professional about a persistent or concerning change. Seek urgent care for severe or rapidly worsening symptoms.