Tumour types and their distribution in the colon | Colon Cancer

Tumour types and their distribution in the colon

90% of colon carcinomas originate from the glands of the colon mucosa. They are then called adenocarcinomas. In 5-10% of cases, the tumours produce particularly large amounts of mucus, so that they are then called mucinous adenocarcinomas. In 1% of the cases a so-called seal ring carcinoma is diagnosed, which looks like a seal ring under the microscope due to an accumulation of mucus in the cell and therefore bears this name. The location of the carcinomas (malignant cancer) is divided according to their frequency:

  • 60% in the rectum (“rectum”; )
  • 20% in the sigmoid colon (large intestine section in the left lower abdomen)
  • 10% in the caecum (bag-like initial part of the colon)
  • 10% in the remaining colon.

Causes

The risk of developing intestinal cancer (colon carcinoma) increases steadily with age. Particularly from the age of 50 onwards, an increase in the incidence of the disease becomes apparent. Colorectal adenomas are benign growths of the mucous membrane (polyps), which, above a certain size (> 1 cm), have a tendency to develop cancer (degeneration).

There are different histological forms of differentiation of the polyps: The tubular adenoma has the lowest risk and the villous adenoma the highest risk of degeneration. The mixed tubullo-villular adenoma has a medium risk of degenerating into a malignant cancer (carcinoma). Origin and development of colorectal cancer:View from the perspective of a colonoscopy

  • Intestinal lumen / opening
  • Intestinal mucosa
  • Haustren = small “normal” sacs in the area of the colon

View from the perspective during a colonoscopy

  • Colon polyps Colon polyps can be the precursor of colorectal cancer.

View from the perspective during a colonoscopy

  • Colorectal cancer Colorectal cancer extends into the intestinal tube and threatens to close it completely

Eating habits are also increasingly being blamed for the development of tumours. Food rich in fat and meat, especially the consumption of red meat (pork, beef etc.) is a risk factor.

It is suspected that the low-fibre diet leads to a longer intestinal passage and that various carcinogenic substances from the food have a greater damaging effect on the mucous membrane due to the longer contact time. The consumption of fish on the other hand reduces the risk of cancer. Excessive calorie intake, overweight and lack of exercise are counted among the cancer-promoting factors, as are nicotine and alcohol consumption.

After many years of ulcerative colitis (chronic inflammatory bowel disease), the risk of developing colon cancer increases fivefold due to the constant inflammation of the intestinal mucosa. In the other chronic inflammatory bowel disease, Crohn’s disease, the risk of developing bowel cancer is only slightly increased. In rare cases, cancer of the colon may be inherited.

In familial polyposis coli (FAP), the loss of a gene leads to hundreds or thousands of polyps in the colon, which very often degenerate in the course of the disease. About 1% of colon cancers are caused by FAP. This genetic disease can lead to colon cancer at a young age, so that, depending on the findings, a prophylactic total colonectomy (colectomy) is recommended at a very young age.

and removal of the colon

Hereditary non-polyposis colorectal carcinoma (HNPCC) is not only the cause of colon cancer, but also of other tumors such as ovarian cancer, breast cancer, uterus cancer. This disease can cause colon cancer before the age of 45, which does not arise from polyps. These carcinomas are responsible for about 5-10% of colon cancer.

Some other rare syndromes are also associated with an increased risk of colon cancer, such as Gardner’s syndrome, Peutz-Jeghers syndrome, Turcot syndrome and juvenile familial polyposis. In rare cases, colorectal cancer may be inherited. In familial polyposis coli (FAP), the loss of a gene leads to hundreds or thousands of polyps in the colon, which very often degenerate in the course of the disease.

About 1% of colon cancers are caused by FAP. This genetic disease can lead to colon cancer at a young age, so that, depending on the findings, a prophylactic total colonectomy (colectomy) is recommended at a very young age. and removal of the colon Hereditary non-polyposis colorectal carcinoma (HNPCC) is not only the cause of the development of colon cancer, but also of other tumours such as ovarian cancer, breast cancer, uterus cancer.

This disease can cause colon cancer before the age of 45, which does not arise from polyps. These carcinomas are responsible for about 5-10% of colon cancer. Some other rare syndromes are also associated with an increased risk of colon cancer, such as Gardner’s syndrome, Peutz-Jeghers syndrome, Turcot syndrome and juvenile familial polyposis.

Some other rare syndromes are also associated with an increased risk of colorectal cancer, such as

  • Gardner Syndrome
  • Peutz-Jeghers syndrome, Turcot syndrome and
  • Juvenile familial polyposis. Colon cancer is the third most common cancer in men and the second most common cancer in women (in Germany). People over 40 years of age have a significantly higher risk than younger people.

Overweight people and people with alcohol & cigarette consumption also have a significantly higher risk. As far as nutrition is concerned, it has long been known that food rich in fibre and vegetables has a protective effect and food rich in meat and fat increases the risk. In addition to genetic factors, risk associations with other diseases have also been found: Glandular tumours (colorectal adenomas), chronic inflammatory diseases (Crohn’s disease, ulcerative colitis), diabetes mellitus type II and other malignant diseases such as breast, stomach and ovarian cancer.

Various forms of metastasis can be described: growing into it (infiltrating). – Tumor spread via the lymphatic tract (lymphogenic metastasis)The lymph vessels drain the lymph fluid (interstitial fluid) from all parts of our body and thus also from a colon cancer. If the tumour is connected to a lymph vessel through its growth, it can happen that some tumour cells detach from the tumour cell cluster and are carried along with the lymph stream.

Numerous lymph nodes are located in the course of a lymph vessel. They are the seat of the immune system, which has the task of intercepting and fighting germs (bacteria). The tumour cells settle in the nearest lymph nodes and multiply again.

This leads to a lymph node metastasis. In the case of colon cancer, lymph nodes located in the course of an artery supplying the intestine are particularly affected, so that it is advisable to remove the blood-supplying vessels together with the lymph nodes during the operation. – Tumor spread via the bloodstream (hematogenic metastasis)If the tumor grows and connects to a blood vessel, cells can also break away and be spread throughout the body via the bloodstream.

The first station where the blood flows through the liver (liver metastases) is where the carcinoma cells can settle and form daughter ulcers (distant metastases). Deep-seated rectal carcinomas also connect to vessels which, bypassing the liver, lead through the inferior vena cava to the heart. The next organ in which tumour cells can settle and form distant metastases is the lung (lung metastases).

As the disease progresses, cells can also detach from the liver metastases and spread further into the lung. – Tumour spread through local growth (per continuitatem)The tumour can grow into other neighbouring organs as it spreads. For example, rectal carcinoma in particular can grow (infiltrate) into: the bladder (vesica) the uterus (uterus) the ovaries (ovaries) the prostate into other loops of the large and small intestine.

  • The bladder (vesica)
  • The womb (uterus)
  • The ovaries (ovaries)
  • The prostate gland
  • Into other large and small intestinal loops
  • The bladder (Vesica)
  • The womb (uterus)
  • The ovaries (ovaries)
  • The prostate gland
  • Into other large and small intestinal loops

Almost every tumour can spread to other regions via the blood and lymphatic system. This leads to tumour cells settling in a place far away from the site of the actual tumour. This process is known as metastasis.

Colon cancer can also spread in different ways. It can metastasize via the lymphatic system to various lymph node regions or lead to tumor cell deposition via the bloodstream, particularly in the liver and lungs. Therefore, when making a diagnosis of colorectal cancer, an X-ray of the thorax must always be taken to detect any lung metastases and an ultrasound or computer tomography of the upper abdomen to detect any liver metastases.

Depending on whether it is a single (isolated) metastasis or numerous (multiple) metastases, removal can be attempted or only palliative (not cure-oriented but primarily symptom-relieving) therapy is used. The diagnosis (see Diagnosis and therapy of colorectal cancer) determines the stage of the tumor, which is decisive for further therapy planning. However, an exact assessment of the tumour stage is often only possible after the operation, when the tumour has been removed and the surgical specimen (resected) and lymph nodes have been examined (histologically) under a microscope.

  • Stage 0: This is a so-called carcinoma in situ, in which only the uppermost mucosal layer (mucosa) shows cancer cell changes. – Stage I: In this stage the tumour also affects the second mucous membrane layer (Tela submucosa) Ia and the muscle layer (Tunica muscularis) Ib. – Stage II: The tumour has reached the last layer of the intestinal wall (subserosa).

No lymph nodes are affected. – Stage III: Here the cancer cells have infiltrated the lymph nodes. – Stage IV: Daughter tumours (metastases) have formed in other parts of the body.