Bowel cancer can spread through the body in a number of different ways. When cancer cells break away from the primary tumour in the bowel, they can travel around in the blood stream or in lymph fluid. We know that there is a common pattern in the way that bowel cancer spreads in the body. The name given to this kind of bowel cancer is ‘metastatic’ and each new area of growth away from the primary tumour is known as a ‘metastasis’.
Advanced bowel cancer commonly causes metastatic spread to the liver and/or the lungs. Sometimes, it can also spread locally into the abdomen. Less commonly, it may spread to the bones and brain.
The lungs are the organs which allow us to breathe. As blood passes through the lungs oxygen is replenished and carbon dioxide is cleared. All the blood in the body (about five litres) passes through the lungs in about a minute and bowel cancer cells in the blood stream are likely to lodge in the lungs.
It is unusual to have lung metastases in isolation and it is more usual that liver metastases will grow first before lung metastases develop.
Lung metastases can grow as one or two isolated tumours or scattered across both lungs. The options for treatment will depend on the size and position of these tumours, especially in relation to how close they are to the large blood vessels that supply the lungs.
Metastases in the lungs are usually diagnosed using a combination of CT and PET scans. This combination of specialist imaging techniques can identify where the cancer is active, and which structures in the lung are involved. On its own, the CEA tumour marker blood test is not an accurate test for active metastases in the lungs.
Lung metastases do not usually give you any symptoms. However, your specialist team will want to know if you experience any unexplained symptoms that do not respond quickly to treatment.
Patients with lung metastases from bowel cancer may be offered surgical removal if spread is limited to the lungs, or if there is also spread to the liver and it has been, or can be treated. The treatment is likely to involve a range of different techniques, and will depend on your general health and circumstances.
If you are diagnosed with lung metastases, your case should be referred to a specialist multi-disciplinary team for thoracic conditions as part of your treatment plan. This should be done to ensure that you are offered the best possible treatment options as part of your overall bowel cancer pathway.
This team might include these specialists: