Colon cancer screening

The large intestine is the part of the bowel that extends from the end of the small intestine to the anus, and it is divided into the cecum, the colon, and the rectum. In the large intestine, water and mineral salts are absorbed, and the digestive processes are completed. Colon cancer is a malignant tumour that most often originates from a mucosal tumour located in the large intestine. Most colon cancers develop from initially benign tumours, or polyps, as a result of a gradual process of carcinogenesis.

Colon cancer is a common disease that affects women and men almost equally. Almost 1,000 people in Estonia develop colon cancer every year.

Colon cancer is a major global health problem, ranking among the top three most common types of cancer that cause cancer death. The incidence of colon cancer has also increased year by year in Estonia: while 680 people were diagnosed with colon cancer in 2000, now almost 1,000 people are diagnosed with colon cancer each year.

It is difficult to detect colon cancer in a timely manner if people seek medical attention too late, i.e. only when they have complaints or symptoms. Nearly a third of cancer cases have already spread from the intestine to other organs by the time they are discovered. This makes treatment more complicated for both the patient and the doctor, which is why early detection of cancer and timely treatment are important.

The development of colon cancer is a gradual process that depends on the interaction of several factors. This means that the development of cancer requires the interaction of several carcinogenic factors, usually over many years. The gradual process reflects the emergence and accumulation of mutations acquired during life. Initially, it is a benign tumour in the intestinal mucosa. However, over time, the benign tumour, or polyp, may enlarge and undergo structural changes. Not all polyps develop into colon cancer. The regression of polyps is also possible, but approximately every twentieth polyp will progress and may develop into cancer.

Because colon cancer develops slowly and gradually, the risk of developing cancer increases with age. The risk of developing the disease increases significantly from the age of 50. 90% of colon cancer cases occur in people over 50 years of age.

Most colon cancer cases are first detected in people over 70 years of age. The higher the average life expectancy and the more older people there are in the population, the higher the incidence of colon cancer.

• In addition to age, important risk factors for colon cancer include dietary habits, the presence of previous benign colon tumours or polyps, the presence of colon cancer in close relatives (for example, one case of colon cancer or a significant polyp in a close relative doubles the risk), and obesity.
• Smoking also increases the risk, as does excessive consumption of red meat (the effect of the latter factor has not been conclusively proven in high-quality scientific studies). People who exercise more and eat fewer calories have a slightly lower risk of developing colon cancer.
• The risk is increased, among other things, by certain comorbidities and previous surgeries – people who have previously had surgery for either polyps or colon cancer have a slightly higher risk of developing colon cancer.
• In 75% of cases, colon cancer affects people who do not have a hereditary predisposition, meaning there is no history of cancer in the family. Approximately 25% of colon cancer cases are associated with a family history, but the exact number, location, nature, and mechanism of gene defects may not be known. About 2–5% of cases have been proven to be caused by specific gene changes.

The risk of developing colon cancer increases from the age of 50!

The process of cancer development is usually slow. It is believed that it takes at least 10–15 years from the onset of precancerous changes to the development of cancer. There are genetic syndromes characterised by an unusually rapid development of cancer – for example, Lynch syndrome, or hereditary nonpolyposis colon cancer. In this case, cancer may develop significantly faster than usual, for example, within a year or two in a previously visually healthy intestinal mucosa.

Polyps, or cancerous growths, can also occur in younger people – especially if there is a hereditary predisposition. Most often, the incidence of polyps increases in people aged 50 and older. According to various reports, about one in five people over the age of 50 have some kind of polyp in their intestines.

The likelihood of polyps occurring is somewhat lower in women than in men. The reason is probably both gender characteristics and environmental influences. Men tend to have more harmful habits, are on average less health-conscious, pay less attention to themselves, and seek medical attention later. The role of hormones is highly speculative – female hormones may offer some protection.

As polyps also develop from the accumulation of lifestyle factors, it can be speculated that they would not develop if people behaved health-consciously. However, the accumulation of genetic mutations is an inevitable process that accompanies ageing.

Factors that reduce the risk of developing colon cancer have also been studied – for example, the use of nonsteroidal anti-inflammatory drugs (NSAIDs, including aspirin, celecoxib, etc.), the use of cholesterol-lowering drugs, an active lifestyle, and a normal body weight. The use of estrogens and calcium supplements also somewhat reduces the risk of colon cancer.

The effectiveness of NSAIDs in preventing and also reducing polyps has been proven, but there is a question of side effects, for example, on the gastric mucosa and cardiovascular system. In addition, there is still limited knowledge about the exact doses and duration of treatment.

Colon cancer develops slowly and early colon cancer has no symptoms. The relatively long latency period offers a good opportunity for the early detection of the tumour. A polyp, or benign tumour, that is detected early and properly removed prevents the development of colon cancer.

Colon cancer causes complaints when the tumour is very large or has spread outside the colon. This may mean that treatment results will deteriorate and treatment will become more complicated. However, localised colon cancer, i.e. a tumour confined to the bowel wall, would be easier to treat safely and effectively.

Typical symptoms of colon cancer include rectal bleeding, altered bowel habits (constipation, occasional diarrhoea, painful/strong urges to defecate or urinate that do not necessarily lead to defecation or urination), abdominal or back pain, anaemia, and a tumour that can be felt.

The cancer may also have spread from one location to another or metastasised to other organs.

The success of colon cancer treatment is determined by the extent and complexity of the tumour, as well as the presence or absence of distant metastases, that is, cancer spread to other organs.

The general rule is that all tumours that are at least a centimetre or larger in diameter must be treated or completely removed.

Colon cancer screening is a proven effective method for detecting this form of cancer in its early stages, when the cancer has not yet spread to other organs. The development of colon cancer is slow, and identifying early changes in the bowel helps to detect the disease in time and start modern treatment, which has good results.

To diagnose colon cancer, either a stool test (faecal occult blood test) or a colonoscopy is performed.

Faecal occult blood test

Faecal occult blood tests are most commonly used because they are simple, fast, safe, painless, and more affordable. A person can take the stool sample required for a faecal occult blood test at home. The faecal occult blood test is an important screening test for the early detection of colon cancer. It allows for early detection of possible intestinal occult blood. A person can obtain the necessary materials and information for a faecal occult blood test from their family physician or nurse.

A faecal occult blood test is not a blood test! Occult bleeding is bleeding from the gastrointestinal tract that the person is unaware of (even 100 ml per day can go unnoticed). Even healthy people pass blood in their stools every day (0.5–1.5 ml in 24 hours).

Other causes of gastrointestinal bleeding may include aspirin, NSAIDs, gum disease, gastritis and oesophagitis, gastroduodenal ulcers, vascular ectasias, haemorrhoids, portal hypertensive gastropathy, and parasites in the gastrointestinal tract. Aspirin and anticoagulant therapy can cause bleeding, but usually so little that it does not cause a positive occult blood test.

Bleeding due to a tumour may be intermittent and the blood may be unevenly distributed in the stool. Therefore, it is necessary to take a stool sample from several places and sometimes several times.

If a properly performed test shows the presence of occult blood in the stool, a colonoscopy should be performed.

Colonoscopy

Colonoscopy is an examination of the large intestine that allows a doctor to examine the large intestine using a flexible, tubular examination instrument, or endoscope, equipped with a video camera. It allows the doctor to look for visible changes in the large intestine.

Colonoscopy is a painless procedure!

Colonoscopy is more accurate than an X-ray of the large intestine and, if necessary, allows for the taking of biopsies, or tissue samples, during the examination, which can later be examined under a microscope. It is a very important and high-quality examination that provides the most reliable answer.

Cancer screening is primarily a good opportunity to make sure you are healthy.

Screening as primary prevention helps to prevent cancer. Cancer only begins to cause complaints and symptoms when the cancer has spread to other organs in the body, and by then, it is significantly more difficult to treat. Screening helps to detect tumours at a stage when they can be treated and to prevent tumours from spreading to other parts of the body.

Research shows that colon cancer screening is effective. It allows to detect colon cancer at an earlier stage or before it develops, i.e. in a precancerous state, when a person has low- or high-risk benign tumours, or polyps. Thus, screening results in more polyps and stage I–II colon cancer being diagnosed, and fewer stage III–IV colon cancer being diagnosed.

Population-based screening programmes are used in several countries to reduce colon cancer incidence and mortality. In most countries, the faecal occult blood test is used as a screening method, with colonoscopy only being used in people with a positive test result. In addition, the occult blood test is more sensitive for large polyps and incipient cancers.

Estonia was one of the last countries in Europe where colon cancer screening was not available until 2016. However, this programme has also been introduced in other countries relatively recently.

With the aim of assessing the impact of implementing colon cancer screening on public health and the related health costs, the Health Insurance Fund commissioned the health technology assessment report ‘Cost-effectiveness of colon cancer screening’ from the Institute of Family Medicine and Public Health of University of Tartu.

The cost-effectiveness report compared different testing methods and found that the most effective is to use a faecal occult blood test first, and if faecal occult blood is found in the sample, a colonoscopy should be performed.

Therefore, the method chosen for colon cancer screening in Estonia is a faecal occult blood test, followed by colonoscopy if necessary. People aged 60–68 are invited to the screening.

Successful colon cancer screening helps to prevent a third of colon cancer deaths. By launching screening in Estonia, it is possible to prevent 33–74 deaths from colon cancer within the group of people participating in the screening within ten years and gain a total of 71–136 quality years of life for people aged 60–69.

Colon cancer screening is an effective method for detecting colon cancer at an earlier stage or before it develops, i.e. in a precancerous state, when a person has low- or high-risk benign tumours, or polyps.

Screening can reduce mortality from colon cancer by 13–33%, but screening has no effect on overall mortality. There are 750 new cases of colon cancer in Estonia each year, and although it ranks high among cancers, it still accounts for a small proportion of overall mortality.

Screening tests are generally effective when a sufficient number of people at risk participate. European quality guidelines say that the minimum participation rate should be 45% and 65% is recommended.

Screening is voluntary and the Health Insurance Fund considers it important to inform insured persons about both the positive and negative aspects of screening. Thanks to information materials, raising awareness, and explanatory work, the patient can make an informed choice.

Family physicians play a very important role in colon cancer screening. If you have any questions, contact your family physician. They will explain how important it is to participate in the screening and what will happen next, as well as advise you throughout the process and answers any questions that arise.

Men and women aged 60–68 participate in the screening every two years.

To participate in colon cancer screening, contact your family physician and register for an appointment with a family nurse.

At the appointment, you will receive the kit necessary to take a stool sample. The kit includes a sample container, information material, a questionnaire, and a postage paid envelope. The sample can be taken at home and then sent by mail to the laboratory. The postage for sending the sample is prepaid and there are no additional costs.

There is no need to wait for an invitation to participate in the screening. People in the target group can also contact their family physician and express their desire to participate in the screening.

The person takes a stool sample in accordance with the instructions and fills out the questionnaire included in the kit, where they must write their name and the date the sample was taken, and send it to the laboratory by mail in a postage paid envelope.

Please note!

You will receive the result of the occult blood test 10 working days after posting the sample from your family medicine centre or the health portal terviseportaal.ee.

Once the sample has reached the laboratory, it is analysed and the result is entered into the health information system.

If the test result is negative, you should be screened again in two years. If your health condition changes, you should definitely contact your family physician.

If the test is unsuccessful, or if there is no test result, you must return to your family medicine centre to repeat the test.

If the test result is positive, you will be sent for further tests. There is no reason to worry, because a positive result does not mean anything else besides that there is a need for additional testing. The family physician issues a referral for a colonoscopy.

The person registers for a procedure at an endoscopy clinic either by phone or through the health portal.

A medical specialist performs a colonoscopy in an endoscopy room. If necessary, a biopsy will be taken during the colonoscopy or polyps will be removed and sent for histological examination. The medical specialist will schedule an appointment in 30 days.

If the person does not come to the appointment at the agreed time, they will be contacted by the endoscopy office.

At the next appointment, the doctor performing the colonoscopy will decide, based on the histology results, what treatment the patient needs and, if necessary, issue a referral to an oncologist or surgeon.

To perform a colonoscopy, the large intestine must be clean of faeces. For this, oral lavage solutions are used. Thorough preparation is important to improve visibility for the doctor.

A low-fibre diet is recommended for 48 hours before a colonoscopy. Suitable foods include boiled or steamed white fish, boiled chicken, eggs, cheese, bread, margarine, cookies, and potatoes. It is not recommended to eat foods rich in fibre such as red meat (beef, pork, lamb), red fish (salmon, trout), fruits, vegetables, mushrooms, nuts, and whole grains.

The day before the colonoscopy, breakfast should be chosen from the foods allowed the previous day. After that, do not eat until the colonoscopy, but make sure to drink enough (for example, tea, coffee, sparkling or still water, or broth). Jellies and ice cream are also allowed. Milk can be added to coffee and tea.

When preparing for a colonoscopy, drink a bowel lavage solution in accordance with the recommended dosage and administration method of the manufacturer, and depending on whether your colonoscopy is performed in the morning or evening. It is recommended to stay near a toilet when drinking the lavage solution, as the need to use the toilet may arise quickly.

Some people may have problems with the amount of the solution (about four litres) and its salty taste, which can cause a feeling of nausea. It helps to drink the solution cold or add juice for flavour.

You also need to be careful with some medicinal products. For example, you must stop taking iron supplements one week before a colonoscopy. Aspirin up to 100 mg per day is allowed. Warfarin therapy can be safely stopped 3–4 days before colonoscopy and resumed immediately after colonoscopy.

During colonoscopy, you must lie on your back or turn to your right or left side if necessary. The colonoscope is passed through the anus into the large intestine and the colonic mucosa can be observed by dilating the large intestine with air. If necessary, a medicinal product to help you relax will be injected into a blood vessel (vein) before the procedure. You may experience some discomfort due your bowel stretching.

Colonoscopy lasts for 30–40 minutes, or sometimes longer, depending on the location of the intestinal loops in the abdominal cavity and the connections between them.

After the colonoscopy, you can return to your regular life. As the large intestine is thoroughly cleansed before the procedure, you may not feel the need to defecate the next day.

Contraindications for colonoscopy include acute heart and lung diseases, gastrointestinal perforation, bowel obstruction, severe bleeding, hernia, and the like. The decision on whether a patient can undergo a colonoscopy or whether the procedure should be postponed is made by the family physician.

Screening colonoscopy is a painless procedure with minimal risks. Bowel examinations are performed by experienced and appropriately trained doctors.

Screening always involves some risk. There is no direct health harm caused by taking a faecal occult blood test, but every screening method always carries the risk of false positive and false negative results. In the event of a false positive result, the person will proceed to a colonoscopy, which carries a risk of health damage.

Side effects associated with preparing for a colonoscopy procedure include bloating and abdominal pain. Complications from colonoscopy are rare (according to studies, they occur in up to five per cent of patients). The risk of complications is reduced by the fact that doctors with extensive colonoscopy experience are selected to perform screening tests.

The colonoscopy procedure is primarily associated with the risk of bleeding and/or gastrointestinal perforation, both during the preparation and execution phases. Bleeding that may occur after a biopsy is taken is minimal and does not require blood transfusions or surgery. However, a perforation in the colon wall, or gastrointestinal perforation, may lead to surgery.

Bleeding during colonoscopy occurs in 1.64 cases per 1,000, gastrointestinal perforation in 0.85 cases per 1,000, and death in 0.074 cases per 1,000 people.

The risk of health harm from colonoscopy is higher in patients with comorbidities and in the elderly. To mitigate the risk, a patient with a positive occult blood test result visits their family physician before undergoing a colonoscopy, who can assess their health status.

In the case of a false negative occult blood test, however, it may happen that a person actually needs to have a colonoscopy, but it is not performed. At the same time, the occult blood test chosen for screening is a very good method because of its sensitivity, and should provide fairly accurate answers. In addition, the medical specialist (colonoscopist) may not notice a change that is important to the patient (dangerous polyp, cancer). The causes may lie in the endoscopy, poor bowel preparation, or patient-related factors. This problem may occur in up to two cases per 100 procedures.

Theoretically, the risk increases just by going to the doctor – the anticipation and fear of the screening test, along with the possibility of an unpleasant result, can also cause worry and stress.

Polyps that are at least a centimetre in diameter must be removed when discovered. The quality of polyp removal is important – if it is removed completely, i.e. within healthy tissue, the risk of polyp recurrence is extremely low (assuming that these are benign changes). In the case of dysplasia, a precancerous condition, or cancer, the polyp may recur after removal.

Colon cancer is treated either surgically (openly through a large abdominal incision) or laparoscopically (observing the abdominal cavity with a laparoscope through a small incision made through the skin and muscles).

Radiation therapy and chemotherapy also play an important role in the comprehensive treatment of colon cancer. Together with surgical treatment, they improve the treatment outcomes of the disease. In some cases, patients have been cured without surgical treatment as a result of radiation therapy and chemotherapy.

Modern knowledge and experience make it possible to surgically treat even advanced colon cancer that has spread to other organs, such as the liver or lungs. The first successful surgical removal of liver metastases was performed as early as 1952. Surgical treatment of metastatic colon cancer has now become routine for those patients whose general condition and comorbidity profile make surgical treatment appropriate. The success of treatment has also been increased by the use of surgical treatment combined with advanced chemotherapy.

In addition, there is increasing talk of an immunological predisposition to colon cancer. Whether a tumour can be managed with immune system control or not depends largely on the immune status of the host and the nature of the tumour. This, in turn, largely determines the overall treatment outcomes of colon cancer.

Surgical techniques have become significantly more patient-friendly. The trauma of surgical treatment, including open surgical treatment, has decreased, and post-operative recovery has been significantly accelerated. Accelerated post-operative recovery programmes are available, allowing the patient to return to daily activities more quickly and safely.

In the case of rectal cancer, it is increasingly possible to restore bowel continuity and avoid the creation of a stoma (a surgically created opening in the front wall of the abdomen through which faeces or urine involuntarily pass into a collection bag attached to the abdomen for this purpose).

In the past, surgical treatment of rectal cancer meant the need for an artificial anus for up to half of patients. Today, the proportion of such cases has decreased significantly, usually reaching 10–25 per cent of all treated rectal cancer patients.

Colon cancer is becoming a chronic disease that requires treatment but can be controlled over many years.

Chemotherapy for colon cancer has developed greatly over the last 20 years. A number of new so-called precision medicines have been introduced into colon chemotherapy, which have improved the ability to control the disease. The curative effect of chemotherapy has not improved significantly, but the time to control the disease has become about four to five times longer than 20 years ago – from half a year to an average of three years.