That’s why global organizations recommend that people start screening at age 45\u2014even without symptoms.<\/p>\n
Symptoms that may prompt a referral for diagnostic testing<\/h2>\n
Many patients have no symptoms in the early stages, but the following should be checked:<\/p>\n
- \n
- Persistent changes in bowel habits<\/li>\n
- Blood in the stool<\/li>\n
- Sudden weight loss<\/li>\n
- Unusual weakness and fatigue<\/li>\n
- Feeling of incomplete bowel emptying<\/li>\n
- Long-term abdominal pain and bloating<\/li>\n
- If these symptoms are present, the doctor will usually prescribe one or more diagnostic procedures.<\/li>\n<\/ul>\n
![\"\u0631\u0648\u0634\u200c\u0647\u0627\u06cc](\"https:\/\/bonyadhamdeli.com\/wp-content\/uploads\/2025\/11\/Untitled-design-2-9.png\")
<\/h2>\nThe most important methods for diagnosing colorectal cancer<\/h2>\n
Diagnostic methods for this cancer are divided into several main groups:<\/p>\n
Endoscopic methods<\/p>\n
Colonoscopy<\/p>\n
Sigmoidoscopy<\/p>\n
Stool sampling-based methods<\/p>\n
FIT<\/p>\n
FOBT<\/p>\n
FIT-DNA<\/p>\n
Imaging methods<\/p>\n
CT colonography (virtual colonoscopy)<\/p>\n
Blood tests and tumor markers<\/p>\n
Biopsy<\/p>\n
New methods based on genetics and biological fluids<\/p>\n
We will explain each one in detail below.<\/p>\n
Colonoscopy: The most accurate and important diagnostic method<\/h2>\n
What is a colonoscopy?<\/h3>\n
Colonoscopy is an advanced endoscopic procedure that uses a long, thin tube equipped with a camera to examine the entire colon.<\/p>\n
Benefits of colonoscopy<\/h3>\n
\u2714\ufe0f The most accurate method for diagnosing colorectal cancer<\/p>\n
Ability to view the entire colon<\/p>\n
Detection of millimeter-sized polyps<\/p>\n
Polyps can be removed in the same session<\/p>\n
Simultaneous biopsy<\/p>\n
Complete examination of the colon<\/h3>\n
This feature makes colonoscopy the gold standard of diagnosis. No other method has the same accuracy.<\/p>\n
Accuracy rate<\/h3>\n
Above 95% for detecting large lesions<\/p>\n
Between 80 and 90% for small polyps<\/p>\n
Who is it recommended for?<\/h3>\n
People over 45<\/p>\n
People with a family history<\/p>\n
Patients with symptoms<\/p>\n
Sigmoidoscopy; a lighter version of colonoscopy<\/h2>\n
Sigmoidoscopy examines the last part of the large intestine (rectum and sigmoid colon).<\/p>\n
Advantages<\/h3>\n
- \n
- Simpler and faster<\/li>\n
- Less need for anesthesia<\/li>\n
- Lower cost<\/li>\n
- Limitations<\/li>\n<\/ul>\n
This procedure examines only the last third of the intestine, so lesions in the upper sections may not be detected.<\/p>\n
Suitable for initial screening, but not a complete replacement for colonoscopy.<\/p>\n
Stool tests to detect colorectal cancer<\/h2>\n
These tests are especially useful for annual screening and do not require anesthesia or sophisticated equipment.<\/p>\n
a) FIT test (fecal immunochemical test)<\/h3>\n
This test checks for the presence of hidden blood in the stool.<\/p>\n
Advantages:<\/p>\n
Quick and inexpensive<\/p>\n
No diet required<\/p>\n
More accurate than FOBT<\/p>\n
Accuracy:<\/p>\n
About 70% for active cancers<\/p>\n
b) FOBT test (fecal occult blood test)<\/h3>\n
This is the traditional and older version and is less accurate.<\/p>\n
Important drawback:<\/p>\n
Foods consumed and some medications can affect it.<\/p>\n
c) FIT-DNA test (known as Cologuard)<\/h3>\n
This is the most advanced stool test.<\/p>\n
What does it check for?<\/p>\n
Hidden blood<\/p>\n
Genetic changes associated with cancer<\/p>\n
Accuracy:<\/p>\n
Between 92 and 95%
\nSuitable for home screening with high accuracy.<\/p>\nCT colonography (virtual colonoscopy)<\/h2>\n
This method uses CT images to create a 3D image of the colon.<\/p>\n
Benefits<\/h3>\n
- \n
- Non-invasive<\/li>\n
- No anesthesia<\/li>\n
- Viewing of large sections of the intestine<\/li>\n<\/ul>\n
Limitations<\/h2>\n
- \n
- If polyps are seen, you will need to have another colonoscopy<\/li>\n
- Less accurate than a real colonoscopy<\/li>\n<\/ul>\n
Used as an alternative for people who are unable to have a colonoscopy.<\/p>\n
Blood tests and tumor markers<\/h3>\n
The most well-known blood marker for colorectal cancer is CEA (carcinoembryonic antigen).<\/p>\n
Important points:<\/p>\n
- \n
- This test is not sufficient for early diagnosis<\/li>\n
- It is mostly used to monitor treatment and recurrence<\/li>\n
- High levels of CEA can be a sign of tumor growth<\/li>\n<\/ul>\n
The blood test alone does not prove cancer, but it is an important complement to imaging methods.<\/p>\n
Biopsy: The only definitive way to diagnose colorectal cancer<\/h2>\n
A biopsy means removing a tissue sample from the intestine and examining it under a microscope.<\/p>\n
Why is a biopsy definitive?<\/h2>\n
Because the cells are directly observed and the pathologist determines whether the cells are cancerous.<\/p>\n
How is it done?<\/h3>\n
It is usually done during a colonoscopy and is painless.<\/p>\n
New and promising methods for diagnosing colorectal cancer<\/h3>\n
Modern medicine is moving towards methods that:<\/p>\n
\u2714 Are non-invasive<\/p>\n
\u2714 Have very high accuracy<\/p>\n
Can detect cancer before a tumor forms<\/p>\n
Some of these techniques:<\/p>\n
1. Liquid Biopsy<\/h3>\n
Identifies tumor DNA in the blood.<\/p>\n
The future of cancer diagnosis!<\/p>\n
2. Advanced molecular tests<\/h3>\n
Investigates mutated genes associated with cancer.<\/p>\n
3. Artificial intelligence in colonoscopy<\/h3>\n
Algorithms detect tiny polyps faster than humans.<\/p>\n
Who should have regular screening?<\/h2>\n
High-risk groups include:<\/p>\n
- \n
- People over 45<\/li>\n
- People with a family history of colon cancer<\/li>\n
- People with precancerous polyps<\/li>\n
- Patients with inflammatory bowel disease (IBD)<\/li>\n
- Smokers<\/li>\n
- People with a sedentary lifestyle<\/li>\n<\/ul>\n
If you are in this category, a colonoscopy is necessary every 5 years or as recommended by your doctor.<\/p>\n
The best detection method for each group<\/h2>\n
Asymptomatic individuals<\/p>\n
FIT annually<\/h3>\n
- \n
- FIT-DNA every 3 years<\/li>\n
- Colonoscopy every 10 years<\/li>\n
- Individuals with gastrointestinal symptoms<\/li>\n<\/ul>\n
Colonoscopy<\/h3>\n
CT colonography if endoscopy is not possible<\/p>\n
High-risk individuals<\/h3>\n
Regular colonoscopy from a younger age (30\u201340 years)<\/p>\n
![\"\u0631\u0648\u0634\u200c\u0647\u0627\u06cc](\"https:\/\/bonyadhamdeli.com\/wp-content\/uploads\/2025\/11\/Untitled-design-1-10.png\")
<\/h1>\nDifferences between screening and diagnosis methods in colorectal cancer<\/h2>\n
Many people think that “screening” and “diagnosis” are the same concept, when in fact the two are completely different.<\/p>\n
\ud83d\udd38 What is screening?<\/h3>\n
Screening is the examination of \u201chealthy, asymptomatic\u201d people to detect changes in the colon before they develop into cancer.<\/p>\n
Screening methods include:<\/p>\n
FIT<\/p>\n
FIT-DNA<\/p>\n
FOBT<\/p>\n
Regular colonoscopy<\/p>\n
CT colonography in some situations<\/p>\n
\ud83d\udd38 What is diagnosis?<\/h3>\n
Diagnosis is when symptoms are present or the screening is abnormal and the doctor needs to do a more detailed examination.<\/p>\n
Diagnostic methods include:<\/p>\n
Colonoscopy<\/p>\n
Biopsy<\/p>\n
Detailed imaging<\/p>\n
Supplementary laboratory tests<\/p>\n
This important distinction helps people know which test is most appropriate for them.<\/p>\n
What factors affect the accuracy of the tests?<\/h2>\n
The accuracy of the tests is not constant and depends on various factors:<\/p>\n
1. The quality of bowel preparation<\/h3>\n
In colonoscopy, if the bowel is not completely emptied, small polyps will not be seen.<\/p>\n
For this reason, doctors usually ask the patient to:<\/p>\n
Have a liquid diet the day before<\/p>\n
Use bowel cleansing solutions<\/p>\n
2. Doctor’s experience<\/h3>\n
It has been proven worldwide that doctors with more experience have a higher diagnosis rate.<\/p>\n
3. Type and quality of laboratory testing<\/h3>\n
Especially in FIT and DNA tests, newer devices are more accurate.<\/p>\n
4. Patient’s age and family history<\/h3>\n
People with a family history usually form polyps earlier, so the tests should be more sensitive and with a shorter interval.<\/p>\n
The role of lifestyle in choosing the type of diagnostic test<\/h2>\n
The choice of diagnostic method does not depend only on age and family history; lifestyle also has an impact.<\/p>\n
\ud83d\udd39 People with little activity and obesity<\/p>\n
are at higher risk and should choose more detailed tests such as colonoscopy.<\/p>\n
\ud83d\udd39 People who smoke or drink alcohol<\/p>\n
are at higher risk and screening should start at a younger age.<\/p>\n
\ud83d\udd39 People with a low-fiber diet<\/p>\n
These people are more likely to form polyps.<\/p>\n
\ud83d\udd39 People with a high-fiber diet<\/p>\n
can use less invasive tests such as FIT, but it is still recommended to have a colonoscopy every 10 years.<\/p>\n
The role of genetics in the diagnosis of colorectal cancer<\/h2>\n
The presence of certain genes increases the risk of cancer. The most important ones are:<\/p>\n
- \n
- APC<\/strong><\/li>\n
- MLH1<\/strong><\/li>\n
- MSH2<\/strong><\/li>\n
- PMS2<\/strong><\/li>\n
- MUTYH<\/strong><\/li>\n<\/ul>\n
People with genetic mutations should:<\/p>\n
\u2714 Start screening earlier (even from the age of 25\u201330)<\/p>\n
\u2714 Have a colonoscopy every year or every two years<\/p>\n
Currently, genetic tests can determine a person’s risk, but a colonoscopy and biopsy are needed to definitively diagnose cancer.<\/p>\n
The importance of early diagnosis for less invasive treatments<\/h2>\n
Early diagnosis not only increases the chances of cure, but also prevents the patient from having to undergo difficult and burdensome treatment.<\/p>\n
If cancer is diagnosed at an early stage:<\/p>\n
Light surgery is performed<\/p>\n
The patient does not need chemotherapy<\/p>\n
The recovery period is shorter<\/p>\n
The patient’s quality of life is maintained<\/p>\n
But if it is diagnosed late:<\/p>\n
Needs extensive surgery<\/p>\n
Chemotherapy<\/p>\n
Radiotherapy<\/p>\n
Heavy costs<\/p>\n
That is why doctors emphasize:
\nRegular screening = saving lives<\/p>\n<\/div>\nCan home tests replace colonoscopy?<\/h2>\n
The short answer is: No.<\/p>\n
But they can be a great complement.<\/p>\n
Home tests are suitable for:<\/p>\n
\u2714 People without symptoms<\/p>\n
\u2714 Routine screening<\/p>\n
\u2714 People who do not want to have a colonoscopy at this time<\/p>\n
But if:<\/p>\n
The test is positive<\/p>\n
Or there is a family history<\/p>\n
Or there are suspicious symptoms<\/p>\n
In any case, a colonoscopy should be done.<\/p>\n
The role of AI in colorectal cancer diagnosis<\/h2>\n
In recent years, AI technology has rapidly entered the field of colorectal cancer diagnosis.<\/p>\n
Applications:
\n\ud83d\udd38 Detection of tiny polyps in colonoscopy<\/p>\nAI analyzes camera images in real time and identifies hidden polyps.<\/p>\n
\ud83d\udd38 Increase the accuracy of doctors’ diagnosis<\/p>\n
Studies have shown that the use of AI reduces the rate of missing polyps by 50%.<\/p>\n
\ud83d\udd38 Analysis of DNA and genetic tests<\/p>\n
Algorithms can better recognize genetic mutation patterns.<\/p>\n
This will revolutionize the future of diagnosis methods.<\/p>\n
Should young people also use colorectal cancer screening methods?<\/h2>\n
Unfortunately, global statistics have shown that the incidence of colorectal cancer in young people (under 45 years of age) is increasing.
\nPossible causes:<\/p>\n- \n
- Poor diet<\/li>\n
- Obesity<\/li>\n
- Inactivity<\/li>\n
- Consumption of processed foods<\/li>\n<\/ul>\n
Therefore:<\/p>\n
Young people should use FIT tests or colonoscopy, especially if they have symptoms.
\nIf there is a family history, screening should start 10 years earlier than the age of the affected person in the family.<\/p>\nImportant tips for preparing before a colonoscopy<\/h2>\n
Proper preparation can increase the accuracy of diagnosis by up to 30%.<\/p>\n
Most important tips:<\/p>\n
- \n
- Reduce high-fiber foods three days before<\/li>\n
- Drink plenty of fluids<\/li>\n
- Consume only clear liquids the day before the colonoscopy<\/li>\n
- Take your doctor’s prescribed medications exactly<\/li>\n
- Failure to follow these tips may result in a repeat test.<\/li>\n<\/ul>\n
Can new methods detect cancer before a tumor forms?<\/h2>\n
Yes.
\nSome modern methods, such as DNA and fluid biopsies, can detect genetic changes in cells before a tumor forms.<\/p>\nThis means:
\n\u2714 More effective prevention
\n\u2714 Much earlier detection
\n\u2714 Lower treatment costs<\/p>\nBut these technologies are not yet available in all countries.<\/p>\n
Summary<\/h2>\n
Colorectal cancer screening methods range from simple stool tests to the most advanced endoscopic procedures.<\/p>\n
But the gold standard remains colonoscopy, a procedure that not only detects but can remove precancerous polyps on the spot.<\/p>\n
Frequently Asked Questions<\/h2>\n
1. What is the most accurate way to diagnose colorectal cancer?<\/p>\n
Without a doubt, a colonoscopy.<\/p>\n
2. Can the FIT test detect cancer 100% of the time?<\/p>\n
No. If it is positive, a colonoscopy must be performed.<\/p>\n
3. Is a colonoscopy painful?<\/p>\n
It is usually performed under short-term anesthesia and the patient does not feel any pain.<\/p>\n
4. Is it possible to have colorectal cancer without symptoms?<\/p>\n
Yes. That is why screening is essential from the age of 45.<\/p>\n
5. What is the best home test for diagnosis?<\/p>\n
The FIT-DNA test is the most accurate home test.<\/p>\n
\n
- MLH1<\/strong><\/li>\n
- APC<\/strong><\/li>\n