Colon cancer

Colon cancer is the generic term for carcinomas of the digestive tract.
It is also referred to as bowel cancer or, when it has started in the large intestine, it is referred to as colorectal cancer or rectal cancer.

Alarm signs can include blood in the stool, severe abdominal pain, weight loss, loss of performance and fatigue. However, in the early stages, colon cancer is usually asymptomatic. Therefore, regular screening at an older age is advisable, especially if there are risk factors for colon cancer. The classic diagnostic tool here is a colonoscopy.

What is colorectal cancer?

Colon cancers are carcinomas, which are malignant growths of the gastrointestinal tract.

They most frequently start in the rectum and colon, and in lesser cases in the small intestine or appendix. Depending on the location, they are referred to as colon carcinoma, rectal carcinoma or collectively as colorectal carcinoma.

Moreover, the symptoms can vary depending on the localisation of colon cancer. Treatment requires various procedures in order to leave the very complex function of the intestinal tract as intact as possible.

Colon cancer usually develops from benign colon polyps over months or years and can be asymptomatic for a long time. This makes early detection and treatment considerably more difficult. Therefore, it is all the more important to attend regular check-ups and maintain a healthy lifestyle. This is important to prevent the development of colon cancer as much as possible.

At what age does colon cancer become more common?

Colon cancer is more common over the age of 50. More than half of those affected are even over the age of 70 when the disease first occurs. The reason for this is that the body’s defences against cancer decline with age and mutations accumulate.

However, younger people can also be affected, especially if they are predisposed to risk factors. If there are known cases of colon cancer in the family or other risk factors, it makes sense to talk to your doctor about starting regular screening.

Causes of colon cancer

There are a number of risk factors that are clearly associated with the occurrence of colon cancer. The causes include:

Types of colon cancer

The types of colon cancer can be subdivided according to their localisation in the bowel. You can find out more about the types of colon cancer in the following list.

Small colon cancer

Small colon cancer is a carcinoma in the section of the small intestine and accounts for around 25% of colon cancer cases.

Due to the anatomical location of the small intestine (in the deep centre of the abdomen), diagnosis is more difficult than with other forms of colon cancer.

It is usually treated surgically by partial resection of the affected section.

Appendix cancer

Appendix cancer, also known as cecal carcinoma, is a very rare form of colon cancer. Here, an ulcer develops in the appendix, the small pouch between the small and large intestine. It is usually discovered by chance during an appendectomy and can be treated either surgically or with chemotherapy.

Colon cancer

In colon cancer, the large intestine, which is the significantly shorter part of the colon, is affected. It is the second most common type of cancer in women and the third most common in men and often metastasises to surrounding organs and tissue.

It is also treated surgically and, in the case of metastases, with chemotherapy or radiotherapy.

Sigmoid carcinoma

Sigmoid carcinoma describes a colon carcinoma in the area of the sigmoid colon, the part of the intestine connecting the descending colon to the rectum. The sigmoid colon derives its name from the Greek sigma: σ, because it is curved in the form of an S.

The sigmoid colon is the part of the large colon closest to the rectum. It’s an important filter that absorbs water from the stool and pushes the rest to the rectum and anus to leave the body.

Therefore, around 30% of all colon carcinomas occur in the area of this curve.

Rectal carcinoma

Rectal carcinoma, also known as rectal cancer, is the second most common site of colon carcinoma at 25%. It can be diagnosed by colonoscopy or by digital rectal examination.

Anal carcinoma

Anal carcinoma, also known as anal cancer, is a rather rare cancer in the area of the anus. Due to its location, it can usually be diagnosed earlier and it metastasises less frequently.

Moreover, the symptoms differ from other forms of colon cancer and are characterised by problems with bowel movements and sometimes even incontinence.

Colon cancer symptoms

Colorectal cancer often remains asymptomatic in the early stages.

The first symptoms of colon cancer can be changes in bowel movements, blood in the stool, stomach pain, weight loss, fatigue and chronic constipation.
It also differs significantly in its symptoms depending on the region affected.

For example, left-side colon cancer (sigmoid, rectal and anal carcinoma) results in more changes in bowel habits or blood in the stool, while the right side colon cancer shows less symptoms.

In the advanced stages of colon cancer, symptoms such as weight loss, nausea, fatigue and pain can also occur. In addition, if metastasis occurs, other organs are also affected, causing the symptoms to spread.

Frequent or infrequent bowel movements

Colon cancer can classically lead to changes in bowel movements. Whether constipation or diarrhoea, frequent or infrequent bowel movements occur varies greatly from person to person and depends on the size and location of the tumour.

Again, if these changes occur with other symptoms, a detailed examination and diagnosis by a doctor should be carried out.

Blood in the stool

Blood in the stool is a symptom that can occur with colon cancer as well as haemorrhoids and other diseases.

A red coating on the stool or an overall red discolouration is usually recognisable.

However, small bleedings that are not visible to the eye can also be visualised by a stool test and are ideally suited as a screening tool.

It should always be regarded as an alarm signal and a doctor should be consulted.

Mucus in the stool

Mucus in the stool is considered a rather unspecified symptom and should be clarified by appropriate diagnostics by a doctor if it occurs frequently.

Pencil stool

Pencil stool is a term for the shape and consistency of faeces. It is characterised by a long, thin stool that looks like a pencil.
It can indicate a narrowing of the digestive tract, for example due to colon cancer, and should be clarified by a physician.


Flatulence is not a classic symptom of colon cancer, but can occur as a result of constipation, as the stool remains in the bowel for a long time and can block the passage of gases.

In the case of persistent flatulence or in combination with other symptoms, clarification and diagnosis by a doctor is advisable.

Weight loss

Weight loss in colon cancer is multifactorial. Increased energy consumption by the cancer cells, reduced appetite and the inability to fully absorb nutrients are factors that can lead to weight loss.

If unexplained weight loss or other symptoms occur, medical clarification should be sought.

Intestinal obstruction

Intestinal obstruction is a medical emergency and should be treated immediately. It leads to obstruction of the intestinal canal, which results in dilation and, in the worst case, perforation of the intestine and can end in life-threatening blood poisoning.

The symptoms are sudden onset of nausea, vomiting, cramp-like abdominal pain and fatigue.

Colon cancer can be a possible trigger for this and should be investigated by a specialist following appropriate surgical treatment.

Anal itching

Anal itching is a non-specific symptom of various diseases and irritations of the rectum. If this unpleasant sensation occurs frequently or even in combination with other alarm signs of colon cancer, a medical examination is indicated.

Back pain

Back pain is not a typical symptom of colon cancer, but can occur especially in advanced stages. This occurs when metastases form in surrounding tissues such as the bones or on the intervertebral discs and nerves.

If back pain occurs in combination with other colon cancer symptoms, a thorough examination is indicated.

Stages of colon cancer

As with all cancers, colon cancer is categorised into different stages depending on size, metastasis and tissue depth. They serve as a rough therapy guideline and provide information about possible treatment prognosis.

Stage 0 - colorectal cancer in situ

Stage 0, also known as in situ growth, is characterised by degenerate cell growth that has not yet spread to surrounding tissue.

Stage 1 - early stage

In stage 1, the tumour is already small to medium sized and the cancer may have already penetrated the basal lamina of the original tissue.
However, there are still no distant metastases or lymph node involvement.

Stage 2 - early stage with infiltrative growth

In stage 2, there is already infiltrative growth in surrounding tissue. In other words, the tumour has left its place of origin.
However, there are still no distant metastases or lymph node involvement.

Stage 3 - Regionally advanced stage

The regionally advanced stage is characterised by tumours of all sizes, infiltrative growth to surrounding organs and lymph node involvement. Distant metastases are still excluded.
From stage three onwards, the prognosis for treatment is significantly worse.

Stage 4 - terminal stage - colorectal cancer with metastases

The final stage is also characterised by distant metastasis. In colon cancer, the metastases typically affect the lungs and liver.
Stage 4 has the worst prognosis and requires different therapeutic measures.

Metastases in colorectal cancer

Metastases in colon cancer are secondary tumours that have spread from the original tumour in the bowel to other parts of the body.

Colorectal cancer can spread in different ways, including lymphatic spread, where cancer cells travel via the lymphatic system to nearby lymph nodes and other organs, and haematogenous spread, where cancer cells metastasise via the blood to more distant organs such as the liver, lungs or bones.

The most common metastasis of colorectal cancer is liver metastases, followed by lung metastases. Other frequently affected organs can be the brain, bones and adrenal glands.

The presence of metastases indicates that the colorectal cancer is at an advanced stage, which makes treatment more difficult and worsens the survival prognosis.

Diagnosis and detection of colorectal cancer

Colorectal cancer is often asymptomatic in the early stages and can therefore hardly be detected without special examination methods. As a result, the cancer continues to grow and can metastasise.

Comprehensive diagnostics are therefore essential to enable colorectal cancer to be detected in good time.


Colonoscopy is a screening tool that is recommended from the age of 50, once every ten years. A camera is inserted rectally, which enables an assessment of the bowel and helps to detect colon cancer at an early stage.

It is also possible to remove existing bowel polyps during the colonoscopy and thus reduce the risk of colon cancer.

Blood values and tumour markers

There are various tumour markers and changes in blood values that can indicate colon cancer. However, they are often only significantly elevated in advanced stages and are therefore more suitable for confirming a suspicion than for regular screening.

Stool test

A stool test is suitable for detecting tumour bleeding at an early stage, as it enables even the smallest amounts of blood to be reliably detected. This test is recommended regularly from the age of fifty and should be carried out every two years in addition to a colonoscopy.


Ultrasound is a non-invasive and relatively inexpensive examination method that is often used as part of the diagnostic process for colon cancer.

However, it can have its limitations, particularly when assessing deeper structures and differentiating between benign and malignant tumours. In such cases, further imaging techniques such as CT, MRI or endoscopic examinations may be required to make an accurate diagnosis.


MRI enables detailed images of the inside of the body without the radiation exposure of a CT scan. This allows structural changes in the bowel to be recognised, metastases to be excluded and other diseases to be differentiated.

As a whole-body MRI scan is very costly and time-consuming, it is only used in cases of concrete suspicion or in tumour follow-up care.


Like MRI, CT allows detailed images of the internal organs to be taken.
The advantage of CT over MRI is the shorter examination time and sometimes better image quality. The disadvantage is the increased radiation exposure.

Colon cancer self-test

Colon cancer self-tests are an option for home screening. They test for blood in the stool and are therefore not only effective for colon cancer, but also for haemorrhoids, polyps and other diseases.

Manufacturers such as Coloalert even offer tests that detect non-bleeding tumours, as they also detect tumour DNA.

Nevertheless, they are no substitute for professional examinations by a doctor and should only be used as a supportive measure.

In the event of a positive test result, a medical examination should be carried out immediately.

Treatments for colon cancer

As with other cancers, the type of treatment depends largely on the wishes and needs of the patient and the stage of the disease.

In addition to the conventional treatments such as resection, radiotherapy and chemotherapy, there are also newer approaches such as immunotherapy, cryotherapy and mistletoe therapy, which can significantly improve the therapeutic outcome.

We will take a closer look at some of these approaches below.

Colorectal cancer surgery

Surgical removal is still the treatment of choice for colon cancer. Particularly in the early stages, a purely surgical procedure is sufficient to completely remove the cancer.

Depending on the section affected, the surgical procedures differ in complexity and risks. In most cases, the affected section of the bowel is cut out and both ends are sutured together.


Radiotherapy is used particularly for locally advanced cancer, as it makes resection more difficult.

In the case of locally advanced colon cancer, surgical removal is difficult, which is why radiotherapy is often chosen. It can be carried out using both external and internal radiation sources, which ensure that the degenerated cancer cells continue to mutate and then die.

Typical side effects are fatigue, vomiting, nausea and unwanted mutations in healthy tissue can occur.


Chemotherapy is used in advanced stages of colon cancer to combat cancer cells that have already migrated and thus stop the cancer from spreading.
Chemical agents are used to inhibit cell division and the cancer cells die.

As chemotherapy can be very stressful and has a number of side effects, it is crucial to develop an appropriate treatment plan. For example, certain complementary therapies can help reduce the side effects significantly.


The aim of immunotherapy is to support the body’s own immune system so that it can recognise and destroy the cancer cells. So-called checkpoint inhibitors are used for colorectal cancer, which block all the proteins that slow down the immune system and thus stimulate the immune system to fight cancer cells.

Patient selection is important, as not every tumour can be successfully treated with immunotherapy.


Cryotherapy is a treatment method for early-stage colon cancer that cannot be surgically removed or for patients who are not suitable for surgery.
Liquid nitrogen is applied locally to the cancer endoscopically in order to kill the cells through the cold.

The advantages include minimal side effects, such as localised bleeding and pain, which usually subside within a few days, as well as the avoidance of long recovery periods that would be necessary after surgery.

Laser procedure

Laser therapy is a rarely used procedure in which the cancer cells are heated and killed by electromagnetic radiation.
It is used when colon cancer is located in hard-to-reach areas that cannot be reached with conventional surgery.

Mistletoe therapy

Mistletoe therapy is based on the use of extracts from the mistletoe plant, in particular Viscum album, to stimulate the immune system and improve the quality of life of cancer patients.

Research shows that ingredients of mistletoe activate the immune system and strengthen the body’s own defences against cancer cells. A number of processes in the body are found to be positively upregulated by the mistletoe ingredients.

Mistletoe therapy is therefore often used in combination with other treatment methods to improve the therapeutic outcome of cancer.

It is administered either orally or by injection. It can lead to mild side effects such as redness and swelling in some patients.

If you are interested, you should contact your doctor and consult other experts if necessary.

Effect of mistletoe extract on tumor response in neoadjuvant chemoradiotherapy for rectal cancer: a cohort study

Systematic evaluation of the clinical effects of supportive mistletoe treatment within chemo- and/or radiotherapy protocols and long-term mistletoe application in nonmetastatic colorectal carcinoma: multicenter, controlled, observational cohort study

Targeting inflammation in cancer-related-fatigue: a rationale for mistletoe therapy as supportive care in colorectal cancer patients

A Specific Mistletoe Preparation (Iscador-Qu®) in Colorectal Cancer (CRC) Patients: More than Just Supportive Care?

Chances of cure for colorectal cancer

The chances of cure and survival depend on a number of factors. These include the stage of the disease, the type of treatment and the patient’s general state of health.

For localised colon cancer, the five-year survival rate is 90%. If metastases are already present, the prognosis is lower.

In the early stages, complete resection of the tissue is usually possible and the patient is considered cured. Nevertheless, regular tumour screening should be maintained.

Integrative measures, such as the additional use of hyperthermia, can improve the chances of cure and life expectancy. Moreover, complementary therapies can reduce the side effects of conventional therapies and improve the quality of life.

Colorectal cancer screening

Recommendations for colorectal cancer screening and colonoscopies may vary depending on the guidelines of different medical societies and individual risk. In general, most guidelines start colorectal cancer screening at age 50.

For individuals with an increased risk of colorectal cancer due to family history or other risk factors, such as the presence of colon polyps, screening may begin earlier. In some cases, it is recommended that people start screening from the age of 35.

The recommended method of colon cancer screening for people at average risk is colonoscopy. During this examination, a flexible tube is inserted into the colon to look for signs of cancer or colon polyps.

Colonoscopy not only enables the early detection of colon cancer, but can also remove precancerous polyps before they develop into cancer.

It is important to discuss individual risk factors with a doctor to determine when colorectal cancer screening should begin for an individual and which screening options are most appropriate.

Med. pract. Dana Hreus M.A.

In the treatment of colon cancer, an integrative approach is advantageous in order to increase the chances of a cure and minimise side effects.

Med. pract. Dana Hreus M.A.

Frequently asked questions and answers about colon cancer

Colorectal cancer is a complex disease that can lead to unanswered questions and uncertainty for many patients. The most frequently asked questions and answers are listed below.

Do not hesitate to ask your doctor if you are still unsure.

Unfortunately, the majority of symptoms usually only become apparent in the advanced stages of colon cancer. The first signs can be digestive problems, tiredness and weight loss.

Therefore, colonoscopy and blood tests are more reliable when it comes to recognising colon cancer.

Bleeding caused by colon cancer often shows characteristic blood deposits in the stool. In some cases, it also spreads and leads to a red colour.

Sometimes the amount of blood is so low, that there is no discoloration, but blood may still be present in the stool. In this case, stool tests enable early detection of bleeding.

The danger of colon cancer lies mainly in its spread to other organs. Liver and lung metastases in particular are common and lead to loss of liver and lung function and ultimately to death.

However, treatment also harbours a risk of death, whether due to complications from surgery or due to the weakened immune system after chemotherapy.

Yes, precancerous polyps are a preliminary stage of colon cancer and can transform into colon cancer over time.

Therefore, it is best to perform a colonoscopy, which can recognise the polyps and remove them in time so that colon cancer does not develop in the first place.

No, more than half of all cases occur in patients over the age of 70.

Nevertheless, it is possible to develop the disease at the age of 30 if various risk factors are present. Therefore, if you have risk factors, it may be worth talking to your doctor about early colon cancer screening.

Colon cancer can be hereditary, as genetic factors also play a role in its development. If there are known cases in your family, it is worth consulting a doctor for clarification.

Yes, colon cancer can lead to constipation by causing a narrowing in the bowel, making it difficult for faeces to pass.

As constipation is a very vague symptom, you should pay attention to possible accompanying symptoms and consult a doctor if they occur frequently.

Common sites of metastasis of colon cancer are the liver and lungs, but the brain, bones and lymph nodes can also be affected.

Distinguishing between irritable bowel syndrome and colon cancer can be difficult, as the symptoms overlap considerably. However, bleeding and incomplete bowel evacuation are symptoms that speak in favour of colon cancer.

Diagnostic equipment such as a colonoscopy, CT scan or stool test is necessary for a precise diagnosis. Please consult your doctor to make the correct diagnosis.

Yes, as a chronic inflammatory bowel disease, ulcerative colitis can lead to the development of colon cancer.

The growth rate of colon cancer varies greatly from person to person and depends on the stage, type of tumour and many other factors.

If the patient does not want a colonoscopy, stool tests and imaging procedures such as CT and MRI can provide information about possible changes in the gastrointestinal tract.

However, these examination techniques are less sensitive for smaller changes and precancerous polyps. Moreover, the CT and MRI are too expensive for normal screening procedures. Therefore, a colonoscopy is still considered the gold standard.

In most cases, colon cancer should be operated on as quickly as possible to prevent it from spreading, minimise the risk of complications and improve the general prognosis.

The decision depends on various individual factors and should always be discussed with an experienced doctor.

Yes, pencil stools can indicate colon cancer, as they can be a sign of possible obstructions in the bowel canal.

If pencil stools occur regularly, a medical examination should be carried out to rule out serious causes.

Haemorrhoids are vascular cushions in the rectum and anus that contribute to healthy continence. If they become irritated and swollen, they can cause pain and bleeding during bowel movements. Therefore, these symptoms are similar to colon cancer.

If you have symptoms, it is worth consulting a doctor to rule out colon cancer and treat the haemorrhoids.

Further information

The information listed contains relevant topics and serves to improve understanding.