Colorectal cancer is one of the most preventable cancers: it usually develops slowly, over years, from benign polyps. Screening finds and removes these polyps before they progress, or detects cancer at an early, curable stage. For average risk, screening generally starts around age 45; earlier and more often when there is a family history or other risk factors. The main tests are the faecal immunochemical test (FIT) and colonoscopy; the right choice and frequency are individualised, based on national guidelines and your personal profile.
Colorectal cancer is one of the most common cancers — and, at the same time, one of the few we can genuinely prevent. The reason is simple: in most cases it does not appear overnight, but develops slowly, over years, from a benign polyp. This time window is exactly what makes screening so effective.
Why screening matters so much
Screening has a dual aim: on the one hand to find and remove polyps before they can turn into cancer (prevention), and on the other to detect a cancer early, when it usually causes no symptoms and is far more easily curable (early diagnosis). When colon or rectal cancer is diagnosed at an early stage, the chances of a complete cure are very high.
Who should be screened, and from when
- Average risk: people without particular aggravating factors. Screening generally starts around age 45 and continues to about 75, depending on overall health.
- Family history: if a first-degree relative had cancer or advanced polyps, screening starts earlier — often around 40, or 10 years before the age at which the youngest relative was diagnosed — and is repeated more often.
- Hereditary syndromes (e.g. Lynch syndrome, familial adenomatous polyposis): these require a much earlier start, a specialised programme and genetic counselling.
- Chronic inflammatory bowel disease or a personal history of polyps/cancer: an individualised surveillance programme is followed.
The main tests
Faecal immunochemical test (FIT). A simple, non-invasive test done at home that detects hidden blood in the stool. It is repeated every year. It is easy and widely available; if it is positive, colonoscopy is needed for further investigation.
Colonoscopy. Considered the reference test: it allows direct inspection of the whole large bowel and, crucially, the removal of polyps in the same session. For average risk it is repeated roughly every 10 years if normal. It requires preparation (cleansing of the bowel) and is usually done under light sedation.
Stool DNA test (FIT-DNA). A non-invasive test that combines blood detection with DNA markers; it is repeated every 1–3 years. A positive result also leads to colonoscopy.
There are other methods too (such as CT colonography or sigmoidoscopy) used in selected cases. The key message is that the best test is the one that actually gets done: all of them reduce risk, as long as the programme is followed properly.
Risk factors
Some factors do not change — age, family and genetic history, chronic inflammatory bowel disease. Others, however, relate to lifestyle and are modifiable: a diet high in processed and red meat, obesity, smoking, excessive alcohol and a sedentary life. A healthy diet, physical activity and not smoking reduce risk — but they do not replace screening.
Screening in Greece
Greece runs organised prevention programmes (such as the "Prolamvano" programme) offering a free stool test (FIT) to specific age groups. Check the eligibility and process with your doctor or the official health authorities.
If a polyp is found
Finding a polyp does not mean cancer. In the vast majority of cases the polyp is removed during colonoscopy and sent for histology. Depending on the type and number of polyps, your doctor will set the appropriate follow-up schedule. More in the article "I was found to have a polyp on colonoscopy".
The key message
Screening for colorectal cancer saves lives, because it acts before the problem appears. The right test, the age to start and the frequency are individualised based on your personal profile and national guidelines. Talk to your doctor about which programme suits you.
From what age does screening start?
For average risk, screening generally starts around age 45 and continues to about 75, depending on health status. With a family history or other risk factors it starts earlier. The exact recommendation is individualised.
FIT or colonoscopy?
Both are acceptable. FIT is a non-invasive stool test done every year; if it is positive, colonoscopy follows. Colonoscopy is done roughly every 10 years for average risk and can remove polyps at the same time. The choice depends on your risk profile, preferences and national guidelines.
Do I need screening if I have no symptoms?
Yes — that is exactly the point. Most early cancers and polyps cause no symptoms, which is why screening is done preventively, before any complaint appears.
How often is it repeated?
It depends on the test and the findings: FIT usually every year, colonoscopy roughly every 10 years if normal, or sooner if polyps are found. Your follow-up schedule is set by your doctor.
I have a family history — what changes?
Screening usually starts earlier and is repeated more often, frequently with colonoscopy. Hereditary syndromes (e.g. Lynch syndrome, familial adenomatous polyposis) require a specialised programme and genetic counselling.