Bowel cancer 

The large intestine is the last part of your digestive system and is about 1.5 metres long. The large intestine lies in your belly neatly around your small intestine. In the large intestine, fluid and salts are extracted from the food mash, creating stool. The stool is pushed to the end of the large intestine by squeezing movements. In addition, there are trillions of bacteria, viruses, yeasts and fungi in the intestines that do a great job for you. Together they are called the microbiome. The microbiome helps keep your intestinal wall healthy. It also supports your immune system. Here you can find more information about digestion and the microbiome. 

People who are overweight and have a lot of body fat and belly fat have an increased risk of developing bowel cancer. It is therefore important to maintain a healthy weight, and underweight must also be prevented. 

A Western diet increases the risk of bowel cancer. This form of cancer is less common in non-Western countries. Bowel cancer also appears to be less common among vegetarians. 

You can follow the guidelines for a healthy diet. Choose healthy products and vary your diet! That way you will get all the nutrients your body needs. Eat enough fibre every day. You can find fibre in plant-based products such as vegetables, fruit, whole grain products, legumes, nuts and seeds. Fibre is known to reduce the risk of bowel cancer. 

In addition, the advice is to eat no more than 500 grams of meat per week, with a maximum of 300 grams of red meat, such as beef and pork. Processed meat, meat products and fatty meats are not included in the food pyramid. Due to the negative effects on health, it is advised not to eat meat products, processed meat and fatty meats too often. 

Regular exercise can protect against bowel cancer. Exercise for at least 30 minutes every day. This should be moderately intensive exercise such as walking, cycling or gardening. Take the stairs instead of the lift, cycle to work or go for a half hour walk after dinner. Reduce the amount of time you spend sitting. If you are overweight, 60 minutes of exercise per day is recommended. 

Bowel cancer is more common in smokers than in non-smokers. (Excessive) alcohol consumption also increases the risk of bowel cancer. 

Recommendation: Do not smoke and preferably do not drink alcohol, or limit your alcohol intake to a maximum of 1 glass per day* 

You also have a greater chance of getting bowel cancer if you suffer from chronic inflammation of the colon, such as ulcerative colitis or Crohn’s disease. The risk of developing bowel cancer increases about ten years after diagnosis. That is why people with chronic intestinal inflammation regularly undergo a colonoscopy. 

The cancer can return in people who have previously had bowel cancer. That is why people continue to be monitored for a number of years after treatment for bowel cancer and rectal cancer. 

In most cases, heredity does not play a role in bowel cancer, but in some cases it does. Some families have a remarkably high incidence of bowel cancer. In that case, the doctor will suggest testing for a hereditary predisposition to bowel cancer. A hereditary predisposition means that you have a greater chance of developing bowel cancer than someone without a hereditary predisposition.  

Conditions that can increase the risk of bowel cancer: 

• Lynch syndrome
• Familial adenomatous polyposis (FAP or AFAP)
• MUTYH-associated polyposis (MAP) 

The doctor can detect these conditions with genetic testing. The doctor will then look for an error in the APC gene, for example. The doctor can also test for microsatellite instability (MSI). 

The cause of why there is a high incidence of bowel cancer in families is not always found. People from families with a high incidence of bowel cancer regularly undergo a colonoscopy. 

Blood or mucus in your stool can be caused by bowel cancer. The blood does not always have to be red, dark (almost black) stool can also mean that there is blood in your stool. If there is blood in your stool, go to the doctor. The doctor can then investigate what the cause is. 

Take a look at our poo test to discover what is and isn’t healthy. 

Changes in stool can be caused by bowel cancer. For example, going to the toilet more or less often than normal. Or diarrhoea one time, constipation the next and then diarrhoea again. If your stool looks different from what you are used to, this can also be caused by bowel cancer. 

A reduced appetite is one of the warning signs of bowel cancer. But a reduced appetite can also be related to something else, such as stress or other (bowel) disorders. 

A persistent, uncomfortable feeling in the abdomen is a signal that something is wrong with your digestion, for example with your intestines. There may be a tumour in the intestines that can cause the uncomfortable feeling. It can also have another, more innocent reason. For example, you may be suffering from constipation or have eaten something wrong. Abdominal pain can also be caused by serious conditions such as chronic inflammatory bowel disease (IBD), coeliac disease or gallstones. 

An urge to defecate that is not satisfied can also be a symptom of bowel cancer. You feel the need to defecate, but no faeces are produced. 

Bowel cancer can cause you to lose weight. You lose weight without knowing why. This could be due to the tumour in your intestines. 

A tumour in your intestines can cause you to lose blood. This loss of blood can cause anaemia. Anaemia can make you feel tired and dizzy. 

These symptoms can be related to bowel cancer, but can also have another cause. Go to your doctor if you are worried. Or if any of these symptoms do not go away after two weeks. Or if the symptoms keep coming back. 

Everyone suffers from intestinal complaints or problems with bowel movements from time to time. If these complaints recur regularly or persist for more than two weeks, it is advisable to see your doctor. It is also advisable to see your doctor if you are over 50 and have intestinal complaints for the first time. 

If several people in your family have or have had some form of bowel cancer, there is a chance that the bowel cancer is hereditary. This chance is also present if one family member develops bowel cancer at a (very) young age. If you are worried that bowel cancer in your family is hereditary, you can discuss this with your doctor. 

Discuss your symptoms and concerns with your family doctor. The doctor will listen to your symptoms, examine you and decide whether further investigation is necessary. Sometimes the doctor will perform a digital rectal examination: an examination via the anus (the back passage). During this examination, the doctor inserts a finger into the anus to examine the inside of the rectum. If necessary, the doctor will refer you to a gastroenterologist (gastroenterology and liver doctor) at the hospital. 

There are various types of colonoscopy. During a colonoscopy, the doctor uses a flexible tube with a tiny light and a camera. This tube is inserted through the anus and ‘looks’ inside the intestine. During the examination, the doctor can detect polyps and tumours. A major advantage is that the doctor can also perform minor procedures immediately. For example, polyps can be removed during the examination. The doctor can also take a small piece of tissue (biopsy) from a tumour or a ‘suspicious’ spot in the intestinal mucosa. These polyps and biopsies are then examined in the laboratory for abnormal or malignant cells. If malignant cells are found, it is a case of bowel cancer.

Many people are very anxious about an intestinal examination. Discuss your fears with the doctor beforehand. Usually you can choose to be put to sleep (sedation). This will make you sleepy and less aware of the examination. 

Types of examination:

• During a colonoscopy, the doctor will primarily examine the large intestine. During a sigmoidoscopy, the doctor will examine the last part of the large intestine, where the sigmoid colon is located. The sigmoid colon is a part of the large intestine. During a proctoscopy, the doctor will examine the inside of the rectum and the anus. The rectum is the last part of the large intestine. It is the storage place for faeces and is closed off from the outside world by the anus. The anus is the opening through which faeces leave the body. 
• Is an internal examination not possible or not sufficient? For example, if your physical condition is not good enough for an examination or because the doctor was unable to examine the entire intestine. In that case, the doctor can perform a CT colonography. This is a special type of CT scan of the large intestine. This scan allows the doctor to look inside your large intestine through your abdominal wall. The disadvantage of this test is that it uses X-rays and that a colonoscopy is still needed to take biopsies. 

You will always have a blood test if you might have bowel cancer. The doctor will have a number of substances in your blood tested. For example, haemoglobin, to check if you are anaemic. Anaemia is common in bowel cancer. They will also check if there is CEA in your blood. CEA is short for carcinoembryonic antigen. CEA is a tumour marker. This means that this substance is produced in the body when cancer is present. Healthy people also have CEA in their blood. However, if there is more CEA in the blood than normal, it could be caused by bowel cancer or another type of cancer. However, that is not always the case. Smoking and other factors can also increase the amount of CEA. 

Once bowel cancer has been diagnosed, it is necessary to determine how far the tumour has grown into the surrounding tissue. An examination will also be made to see if there are any metastases in the lymph nodes, liver or other organs. Various additional examinations are possible:  

• CT scan
  A CT scan allows the doctor to examine whether the bowel cancer has metastasised. Bowel cancer can spread to the lymph nodes, the liver, the peritoneum or the lungs. A CT scan of the abdomen can show any metastases in the liver, the lymph nodes along the body artery (aorta) or on the peritoneum. If more research into metastases is needed, the doctor can order an ultrasound of the liver or an MRI scan of the abdomen. Bowel cancer can also spread to the lungs. The doctor investigates this with a CT scan of the chest. If there are metastases in the lungs, an additional scan may be necessary, such as a PET-CT scan.
• Examination of a metastasis (biopsy or puncture)
  The doctor may also take a biopsy or puncture of something that may be a metastasis. This is sometimes necessary if it cannot be clearly seen on a scan, or to make the correct diagnosis. The doctor will then use a needle to remove a piece of tissue or some cells. The tissue is then examined in the laboratory.
• Liver ultrasound for bowel cancer
  Bowel cancer often spreads to the liver. Usually you will get a CT scan to see if there are any metastases in the liver. If the doctor wants to take a closer look at the metastases, he or she can do an ultrasound of the liver, for example. 

Sometimes the doctor will choose to test for the mismatch repair proteins. Your body has these proteins to repair errors in your DNA. Sometimes it is necessary to know whether these proteins are working properly in you. The test results are important for determining heredity, but also for your expectations and the choice of treatment.  

If the proteins do not work properly in you, we call this ‘microsatellite instability’ (MSI). Another name for this is MMR deficiency (dMMR). If you have a tumour because the proteins are not working properly, we call this an MSI tumour. This can mean the following for you: 

• There will be additional testing for hereditary factors. An MSI tumour can be an indication of hereditary bowel cancer. 
• You may not receive chemotherapy after the operation. MSI tumours may be less sensitive to chemotherapy. 
• You may receive immunotherapy. This is only if the bowel cancer has spread to other organs. Immunotherapy usually works well with MSI tumours. 

If the proteins are working properly, the tumour is ‘proficient MMR’ (pMMR) or ‘microsatellite stable’ or MSS. 

There are two reasons for your doctor to examine your DNA for faulty cancer cells. The examination may be necessary to determine the right treatment. The doctor can also use DNA testing to determine whether or not the bowel cancer is hereditary. This examination is also known as a genetic examination.  

The doctor can use various types of tissue for the DNA research: 

• Tissue removed during the biopsy during the examination (the colonoscopy) 
• Tissue from a metastasis, removed during a puncture 
• Tissue from the tumour, removed during surgery 

Sometimes your doctor will also use blood for additional DNA research. The piece of tumour or blood is examined in the laboratory to see if there are any errors in the DNA of the cancer cells. An error in the DNA is called a mutation. 

Some DNA mutations are common in bowel cancer. These include the RAS mutation, the BRAF mutation and the APC mutation. 

• RAS mutation : In the case of metastatic bowel cancer, the doctor will examine the tumour for a RAS mutation. This means there is a fault in the RAS gene. Whether or not the tumour has a RAS mutation determines the treatment. If you have the RAS mutation in your cancer cells, certain targeted therapies will not work. These are the drugs called EGF inhibitors. Approximately half of all people with bowel cancer have this error in their cancer cells. In healthy cells, the RAS gene ensures that the cells divide and grow. If there is an error in the RAS gene, the RAS protein is always ‘on’. This causes the cells to grow and divide uncontrollably, allowing the cancer cells to continue growing. 
• BRAF mutation in bowel cancer: In the case of metastasised bowel cancer, the doctor will examine the tumour for a BRAF mutation. If the tumour has a BRAF mutation, this will determine the treatment. If the tumour has this mutation, you can receive a specific type of targeted therapy. This involves medication called BRAF inhibitors and EGF inhibitors. Approximately 8% of colorectal tumours have a fault in the BRAF gene. In healthy cells, the BRAF gene ensures that cells divide and grow. If there is a fault in the BRAF gene, the cells divide and grow uncontrollably. This allows the cancer cells to continue growing and a tumour develops. 

In addition to removing the tumour, the surgeon also removes a piece of healthy tissue and some of the fat with lymph nodes near the tumour on both sides of the tumour. These lymph nodes are examined in a laboratory for the presence of cancer cells. Depending on the results, the doctor will determine whether there is reason to recommend additional chemotherapy. 

Chemotherapy involves the administration of drugs that inhibit cell division with the aim of killing cancer cells. These drugs are also known as cytostatics. There are different types of chemotherapy. A drug that is almost always used for bowel cancer is 5-fluorouracil (5-FU), often in combination with other cytostatics. A disadvantage of combining cytostatics is that people often suffer more from side effects. 

Patients with advanced bowel cancer that has spread to other parts of the body can be treated with targeted therapy in the form of monoclonal antibodies. These antibodies can inhibit tumour growth in various ways. The antibodies are usually added to chemotherapy, but are sometimes given separately.  

RAS test 

A RAS test is done before or during the targeted therapy. The result of this DNA test determines whether or not treatment with EGFR inhibitors will have an effect. EGFR inhibitors are specific monoclonal antibodies that inhibit the division of cancer cells. Just over half of people with bowel cancer have a fault in the RAS gene, which means treatment with antibodies will not work. 

In this case, the diagnosis is not ‘bowel cancer’, but there is suspicion of cancer. Often it involves a polyp with abnormal cells, which are usually still benign and very superficially present. This is called dysplasia. This is a precursor to cancer. Polyps can almost always be removed during a screening examination of the intestine (colonoscopy). Large polyps or polyps that are difficult to remove because of their shape sometimes require surgery.  

The removed polyp is examined in a laboratory for the presence of malignant or abnormal cells. If a polyp is malignant, we refer to it as bowel cancer. The type of polyp, its size and the location where it was found determine the further treatment. 

In stage 1 bowel cancer, the tumour is located inside the intestinal wall. Treatment for stage 1 bowel cancer is usually a colonoscopy or surgery. Sometimes the tumour can be removed during a colonoscopy. The removed tissue is then sent to the laboratory for examination. The examination sometimes shows that surgery is still necessary. The surgeon can also remove the tumour during surgery. 

In stage 2 bowel cancer, the tumour has grown through the intestinal wall and into the fatty tissue around the bowel or another organ. Stage 2 bowel cancer is usually treated with surgery, possibly followed by chemotherapy. The surgeon removes the tumour during the operation. The surgeon also removes the lymph nodes near the tumour. Sometimes the doctor will suggest chemotherapy after the operation for people with stage 2 bowel cancer. This is only necessary if there is an increased chance that the tumour will return after the operation. Chemotherapy reduces the chance of the cancer returning.

In stage 3, there are metastases in the lymph nodes around the tumour. There are no metastases in other parts of the body. In stage 3 Bowel cancer, you will usually undergo surgery, usually followed by chemotherapy. During the operation, the surgeon removes the tumour and the lymph nodes near the tumour. After the operation, the doctor will suggest adjuvant (additional) chemotherapy. This chemotherapy is intended to kill any metastases that you cannot see but may be present. This reduces the chance of the metastases returning. Whether your doctor suggests chemotherapy depends on your condition and how you recover from the operation.

Stage 4 bowel cancer means that there are metastases elsewhere in the body, for example in the liver or on the peritoneum. The possible treatments depend on how many metastases there are and where in the body they are located. Your doctor will discuss this with you.

Possible treatments for metastatic bowel cancer are:

• Surgery to remove metastases in the liver or lungs in the case of one or a few metastases.
• Heat ablation with RFA or MWA in the case of one or a few metastases in the liver or lungs.
• Radiation therapy in the case of one or a few metastases in the liver or lungs.
• In the case of metastases in the peritoneum: CR/HIPEC.
• In the case of many metastases in the body: chemotherapy, sometimes together with targeted therapy.

The treatment is usually intended to prolong life and reduce symptoms. The starting point is a good quality of life. If there are not many metastases, a cure is sometimes possible. Treatment also has consequences, so it is important that you weigh up the advantages and disadvantages of the treatment with your doctor.

Approximately 1 in 4 people with bowel cancer have metastases in the lymph nodes near the tumour (and no metastases in other organs) at the time of diagnosis. These metastases are called ‘regional metastases’ because they are in the region of the tumour. If possible, the surgeon will remove these metastases during the bowel surgery and the doctor will suggest chemotherapy after the operation.  

Metastases in the liver are common in bowel cancer. Most people with metastatic bowel cancer have liver metastases. If there are metastases in the liver, you do not have liver cancer. It is bowel cancer cells in the liver. Your doctor will tell you what treatment you can receive for liver metastases. This depends on how many metastases there are and how big they are.  

Bowel cancer can also spread to the peritoneum. The peritoneum surrounds the organs in the abdominal cavity. This can happen if the tumour grows through the intestinal wall and cancer cells detach and enter the abdominal cavity. The cells can end up on the peritoneum.  

Your doctor will tell you what treatment you can receive for metastases on the peritoneum. This depends on how many metastases there are and how large they are. Your physical condition is also important. HIPEC treatment is sometimes possible for peritoneal metastases. 

Metastases of bowel cancer in the lungs also occur. If there are metastases in the lungs, then you do not have lung cancer. It is bowel cancer cells that have ended up in one or both lungs. Your doctor will tell you what treatment you can receive for metastases in the lungs. This depends on how many metastases there are and how big they are.  

Quite soon after the operation you may experience diarrhoea or loose stools. The diarrhoea often disappears by itself after a few weeks. Your stools may remain looser than they were before the operation. If you suffer a lot from the diarrhoea or if it has not gone away after a few weeks, discuss it with your doctor or dietician. You may need medication or advice about what you should and should not eat and drink. Check out the tips that can help with diarrhoea. 

Constipation often occurs in people with bowel cancer. The stool cannot pass through the intestines. Constipation can be caused by the tumour itself, but can also occur as a result of surgery.

After the operation, the surgeon connects the pieces of intestine. At the site of the seam, the stool can sometimes have difficulty passing. This can be caused by a narrowing of the scar at the site of the seam. Or if the piece of intestine cannot squeeze together as well. The blockage can cause pain in your stomach or make you feel nauseous. Or you may vomit. It is important to drink enough fluids to prevent blockages. Drink at least 1.5-2 litres a day. It is also important to eat enough fibre, for example from fruit and vegetables and wholemeal products. And if possible, it is important to get enough exercise.

If this does not help the constipation to go away, more guidance may be necessary. Let your doctor or dietician know if you suffer from constipation. They can guide you and give you tips.

An empty urge to defecate is common in people with bowel cancer. It feels like you need to defecate, but nothing happens. The feeling can be caused by the tumour itself that you can feel. Or if faeces somewhere in the intestines causes a blockage. The tumour in the intestine can also prevent faeces from moving forward. This can feel like you need to go to the toilet.

Many people who have or have had bowel cancer have to go to the toilet more often than before their operation. This is very normal and very unpleasant. And there are various causes for it. You may suffer from false urges caused by the tumour. Or it may be difficult to tell whether you need to pass wind or really need to defecate. You may suffer from this permanently. It is always good to discuss these symptoms with your doctor or dietician. They can refer you to a pelvic floor physiotherapist, for example, if necessary.

Do you suffer from any of these problems, or do you have other complaints? You can read more about many complaints on the website voedingenkankerinfo.nl. You will also find general tips that may help.

• pain caused by the tumour itself, if the tumour is pressing against something in the body 
• abdominal pain or cramps if the tumour is causing constipation 
• pain caused by metastases 

You may also experience pain as a result of the treatment:

• pain from the scar after surgery 
• pain if the tumour has damaged nerves, or if nerves were damaged during surgery. 

You may also experience pain if you spend a lot of time in bed, for example pain from bedsores.