Introduction
Metastases can occur in the context of colon cancer. About one third of patients already have metastases in other organs when first diagnosed with colorectal cancer. The metastases can occur in various other organs.
These metastases occur most frequently in the liver and second most frequently in the lungs (about 15% of metastases). In addition, metastases may occur in the brain or in the bones (bone marrow) in rarer cases. If this is the case, metastases are often already present in other organs.
What is the life expectancy for metastases
Metastases generally indicate an advanced stage of cancer. Metastases mean that cancer cells detach themselves from the original site of degeneration and spread either via the lymphatic vessels or via the blood vessels to other organs in the body. In the other organs, the cells in turn multiply unchecked and lead to masses of space.
Since metastases restrict the functionality of other organs and weaken the body in addition to the primary tumour, life expectancy with metastases is drastically reduced in contrast to early stages of cancer. In colorectal cancer, metastases in distant organs mean that less than 10% of those affected are still alive 5 years after diagnosis, provided that no therapy is initiated. However, if the cancer is diagnosed in stages where there are no metastases, the probability of still being alive after 5 years is much higher and can be up to 90%.
Formation of metastases
The spread and formation of metastases occurs via different pathways. Firstly, intestinal cancer can spread via the lymphatic system. Depending on the location of the intestinal cancer, this is then possible along the large abdominal artery (aorta), in the lymph nodes and vessels of the pelvic wall or the groin.
If colorectal cancer has already progressed so far that it has broken into the blood vessel system, colorectal cancer cells can also spread via this route. The blood outflow from the colon is initially directed to the liver via the portal vein. For this reason, this is where metastases are most likely and quickest to be found.
Only after the blood has passed through the liver does it flow back towards the heart and then the lungs, where the second most frequent metastases form. If the colon cancer is located in the rectum, the blood does not flow through the liver but directly back to the heart and lungs. This means that cancer cells can also reach the lungs directly without the detour via the liver and form metastases here.
If the intestinal cancer breaks through into the abdominal cavity, the cancer cells can also spread directly here and form metastases. These then lie in the abdominal cavity and infiltrate the abdominal wall from the inside or other organs that are also located in the abdominal cavity. Depending on the location of the metastases, they are divided into three groups. A distinction is made between local metastases (close to the site of origin of the colon cancer), regional metastases (in the lymph nodes close to the original tumour) and distant metastases (in distant organs such as the liver and lungs via the bloodstream).
