Colon cancer is the most common cancer in the gastrointestinal tract. Colon carcinoma refers to malignant tumours of the large intestine.

Malignant bowel tumours account for around 14% of all malignant neoplasms in adults. In Germany, around 27,000 men and 30,000 women are diagnosed with carcinomas of the colon every year.

It is the third most common carcinoma in men and the most common in women. With a mean age of onset of almost 70 years, colon carcinoma is predominantly a disease of older people, with a particularly marked increase after the age of 50.

The vast majority of malignant tumours in the bowel develop in the large intestine, the so-called colon. Around 95% of all bowel tumours are carcinomas (also known as colon carcinoma or adenocarcinoma of the colon). The remaining 5% are neuroendocrine tumours, squamous cell carcinomas, lymphomas and small cell carcinomas.

Colon carcinomas usually develop from polyps of the colon mucosa. Around 64% of carcinomas are found in the sigmoid colon and rectum, 20% in the left colon, 6% in the transverse colon and around 10% in the right colon.

Most colon carcinomas develop from polyps as part of a so-called adenoma-carcinoma sequence over the course of 5-10 years. In addition, there are familial syndromes with an increased risk of carcinoma, which account for around 5-6% of colorectal carcinomas.

Exogenous (external influences): Low physical activity, obesity, possibly dietary factors (red meat, alcohol consumption)

Endogenous (internal influences): Ulcerative colitis, Crohn's disease, colorectal intraepithelial neoplasia = adenomas

Genetic (hereditary): Positive family history (1st degree relatives with colorectal carcinoma (CRC) or adenomas), hereditary (inherited) cancer syndromes.

As a rule, colon carcinomas rarely cause symptoms in the early stages and are therefore usually discovered by chance. Occasionally, abdominal pain, intestinal discomfort or constant fatigue occur. However, these symptoms are often due to harmless causes. If occult blood is found in the stool as part of a screening examination using a stool test, this leads to a colonoscopy being carried out, which can result in a diagnosis of colon cancer. Visible blood in the stool or a black discolouration of the stool can also be an indication of colon cancer.

If colon carcinoma is suspected, various examinations are necessary, e.g. physical examination, laboratory tests (blood), ultrasound examination, colonoscopy and computer tomography (CT). If necessary, further examinations such as X-ray examination, magnetic resonance imaging (MRI) or skeletal scintigraphy may also be required.

Medical history and physical examination

In a detailed discussion, all complaints and previous illnesses (including family hereditary diseases) are asked about and documented. This is followed by a thorough physical examination.

Laboratory tests

Your blood and urine will be analysed. The blood tests provide information about the patient's general condition and certain organ functions. Changes in the blood such as anaemia, changes in blood proteins, an increase in certain enzymes or an increase in blood cell count may indicate tumour disease. One tumour marker for colon carcinoma is the so-called CEA. This marker is particularly important for monitoring the progression of colon cancer. A normal CEA value after colon cancer surgery and an increased CEA value during the course of the disease indicates a recurrence of the colon cancer.

Ultrasound examination (sonography)

Sonography is a painless and radiation-free examination to detect colon cancer metastases in the liver or lymph nodes in the abdominal cavity.

Colonoscopy (colonoscopy)

A colonoscopy is performed to investigate the cause of abdominal complaints or to find a possible source of bleeding in the bowel in the event of anaemia or blood in the stool. During this examination, biopsies can also be taken from conspicuous areas of the intestinal mucosa to clearly identify the colon tumour.

CT colonography ("virtual colonoscopy")

Computed tomography (CT)

Computed tomography is a painless, special X-ray examination (with contrast medium) that illuminates the body layer by layer. This usually allows the size of the tumour and the exact spread of the tumour and any existing metastases, e.g. in the liver, lungs or lymph nodes, to be determined.

Magnetic resonance imaging (MRI)

MRI is not an X-ray examination, but is based on the effects of magnetic fields. However, this examination is only carried out in exceptional cases, e.g. in the case of contrast agent intolerance or impaired kidney function, sometimes in addition to computer tomography.

Skeletal scintigraphy (bone scintigraphy)

By administering a small amount of radioactive substance into the bloodstream, tumour metastases in the bones can be visualised. A special camera recognises the radioactively enriched areas in the diseased bone. This is a gentle examination in which the radiation decays quickly.

In order to be able to determine the most suitable therapy, the exact extent to which the tumour has spread must be determined using the diagnostics described above before starting therapy, i.e. the tumour stage is determined. The TNM classification is used for this purpose (see table below).

T stands for the size and extent of the primary tumour, N stands for the number of affected regional lymph nodes and M stands for the occurrence and localisation of distant metastases (tumour metastases).

An exact assessment of the TNM stage is often only possible after tumour surgery.
Two further criteria are decisive for further therapy. Microscopic examination of the tumour tissue provides an indication of the malignancy of the tumour. This involves comparing the similarity of the cancer cells with the organ cells (see table below).

On the other hand, it is of decisive importance whether the tumour could be completely removed. The so-called R classification is used for this purpose (see table below).

The UICC classification is used for the stage-appropriate treatment stratification of patients with colorectal cancer. There is also the Dukes classification:

The treatment methods depend on the stage of the tumour. The earlier colon cancer is detected, the more favourable the prognosis for the patient. Whether the tumour has spread to other organs, i.e. whether and in how many organs there are metastases, plays a key role. It is also important how many metastases are found in the affected organ.

Curative (healing) surgery

As a rule, only the earlier stages of the tumour can be cured by surgical therapy. As a rule, an en bloc resection (removal as a whole) of the tumour-bearing section of bowel and the regional lymph drainage area is performed. The mortality rate for this operation is less than 3%, even in older patients. In the event of complications such as intestinal obstruction (ileus) and tumour perforation, etc., the surgical procedure must be adapted, e.g. as an extended en-bloc resection. Local surgical tumour removal (excision) or endoscopic resection is only indicated in the early stages (pT1, G1-G2 without lymph vessel infiltration and with complete removal in healthy tissue). Curative resection of individual distant metastases or liver metastases confined to one lobe of the liver can be discussed and should be performed if possible, as this can significantly improve the prognosis.

Palliative (symptom-relieving) surgery

Approximately 25% of all colorectal cancer patients already have lymph node or distant metastases at the time of diagnosis. In the case of obstructing carcinomas without the possibility of complete resection, a bypass anastomosis or an artificial bowel outlet (anus-praeter anastomosis) is performed if a complete resection of the tumour is not possible.

Metastatic surgery and special local ablative procedures

Curative resection of solitary distant metastases or liver metastases confined to one lobe of the liver is now standard practice. This can reduce symptoms and prolong survival.

Secondary resection after chemotherapy

Even if the size or location of the metastases does not permit primary surgery, in certain cases chemotherapy can be used to reduce the size of the metastases. Due to the high response rates of combination chemotherapy (> 50%; see below), approx. 20%-30% of metastases can be removed secondarily (resectable). In the case of partial remissions, resectability must always be checked in good time as long as metastases are still recognisable.

Local ablative (ablative) procedures

Local ablative procedures such as radiofrequency ablation or laser-induced thermotherapy (LITT) are similarly effective as surgical therapy for solitary distant metastases.

Palliative endoscopic procedures

In the case of narrowing (stenosing) colon carcinomas, if surgery is not possible, the passage can be restored using endoscopic procedures. This may include procedures such as dilatation, argon plasma coagulation, cryotherapy and laser therapy as well as implantation of a metal mesh stent.

Chemotherapy

Cytostatic drugs are intended to kill fast-growing tumour cells in the body. Stage-dependent adjuvant (post-operative) and palliative chemotherapy is a recognised component of the treatment of colon carcinomas. Significant progress has been made in recent years with the introduction of new chemotherapeutic agents. The introduction of antibodies and so-called small molecules, which block the effect of tumour-specific growth factors (e.g. epidermal growth factor (EGF)) or angiogenic cytokines (vascular growth factor (VEGF)), in combination with chemotherapy, can achieve further improvements in therapy.

Systemic chemotherapy should be initiated at an early stage. If successful, the therapy can also be interrupted and resumed if the tumour progresses. Whether a real break or a lighter chemotherapy is given during the "break" is discussed individually with the patient. At the University Hospital, innovative treatment options are available for many types of tumour as part of studies. We are constantly endeavouring to improve the treatment of patients through current studies.
Current studies can be found here LINK.

Palliative radiotherapy

Colon carcinomas are relatively insensitive to radiation. For this reason, radiotherapy is almost only used at an advanced stage to relieve pain, particularly in the case of bone metastases.

If a recurrence (reappearance of the tumour in the former tumour area) occurs, it should be surgically removed if possible. If metastases have also formed or the recurrent tumour is too large (has grown together with other organs), a decision must be made on a case-by-case basis as to whether surgery or another therapy is appropriate. If the tumour is at an advanced stage, palliative (symptom-relieving) and supportive (supportive) treatment can be carried out.