If the cancer has spread to another part of the body it is called metastatic bowel cancer or secondary (advanced) cancer
If the cancer in the bowel is not detected and removed at an early stage, part of the tumour can break off from the main bowel tumour and spread, usually via the lymphatic system or bloodstream, to nearby lymph nodes or other parts of the body.
Your cancer may be advanced when it is first diagnosed. Or it may come back some time after you are first treated.
If the cancer has broken through the wall of the bowel and cancer cells have spread into surrounding tissues in the abdomen and pelvis, this is known as local spread.
Metastasis spread (secondary)
If the cancer has spread to another part of the body (for example, the liver or lungs) it is called metastatic cancer or secondary (advanced) cancer.
The liver is second only to the lymph nodes as the most common part of the body for bowel cancer cells to spread to. The liver is a common site for bowel cancer cells to spread to as the liver receives most of its blood supply from the portal vein (the vein that carries blood from the intestines and spleen to the liver).
If your bowel cancer has spread in this way, you have metastatic bowel cancer in your liver – not liver cancer.
Your treatment is dependent on where the cancer started and therefore the treatment you have must work on bowel cancer and not liver cancer cells.
The next most common part of the body for bowel cancer cells to spread to is the lungs.
Treatment for metastatic bowel cancer
If your cancer is advanced when it is first diagnosed you may be offered chemotherapy to keep it under control. You may have just one drug or a combination of drugs.
Some people with bowel cancer that has spread receive a targeted therapy which is a different type of treatment to chemotherapy. Ask your oncologist about the choices available to you, and the combination option.
In some circumstances you may have surgery.
The choice of treatment depends on:
- The type of cancer you have
- The size and number of secondaries and where they are in the body
- The treatment you had already had
Surgery for metastatic bowel cancer
Surgery can be used in some situations to treat advanced bowel cancer:
- To slow the cancer
- When the bowel is blocked
- To remove secondary cancer
- Surgery to control the cancer
Sometimes when there is a recurrence of bowel cancer in the bowel, it is possible to remove it. This is unlikely to cure the cancer because there are usually cancer cells elsewhere in the body.
Removal of the bowel tumour may however relieve any symptoms you may have. It may also be some time before the cancer starts to grow anywhere else.
Surgery for blocked bowel
Sometimes bowel cancer can grow so that it completely blocks the bowel. This is called a bowel obstruction. The waste from the food you have digested cannot get past the blockage. This can cause a number of symptoms such as feeling bloated and full, pain, feeling sick, vomiting, or constipation. To relieve symptoms, it is sometimes possible to unblock the bowel by putting in a stent.
To put the stent in, the surgeon puts a flexible tube with a light at the end (called an endoscope) into the bowel through your back passage through a procedure known as a colonoscopy. The surgeon uses the endoscope to see where the blockage is and pushes the stent through it. The stent expands and holds the bowel open so that bowel motions can pass through again. The surgeon leaves the stent in the bowel to keep it open. As well as relieving symptoms, this procedure gives doctors time to plan an operation to remove the blocked part of the bowel.
Another way to remove an obstruction is to operate and remove the affected part of the bowel, provided you are fit enough. It may be possible to close up the bowel again during the operation or you may need to have a colostomy.
Surgery to remove small metastatic cancers
If bowel cancer spreads, it often goes to the liver or lungs. Sometimes when the cancer metastases in the liver or lungs are small and there are only one or two, you can have surgery to remove them.
This is not suitable treatment in every situation and is done more often for liver metastases than for lung metastases. If you have this type of surgery, you may also have chemotherapy before and after the operation.
To decide if this treatment is suitable for you, your doctor will look at:
- Your general health
- How advanced your cancer was when you were diagnosed
- How quickly your cancer came back
- How many secondaries you have and their size
- Where they are in the liver or lungs
- How close they are to major blood vessels
Chemotherapy for metastatic bowel cancer
Chemotherapy to shrink a cancer and control symptoms is called palliative chemotherapy.
Treatment with chemotherapy at this stage is unlikely to cure your cancer, but it can help you live longer and may shrink the cancer.
For secondary bowel cancer, the aim of chemotherapy is to help you feel better. If however, you are unhappy about the side effects, you do not have to continue with the treatment.
How do you know if chemotherapy is working?
Your oncologist will arrange a scan before you start treatment and again three months later. Your oncologist can measure the tumour on the scan and so will be able to see how well the treatment is working. The tumour may have become smaller or larger or remained the same size.
If it has remained the same size, your oncologist will want to talk to you about whether or not it is worth continuing with your treatment.
If the tumour has become bigger, despite your treatment, your oncologist will stop the chemotherapy and may suggest trying a different treatment.
If it has become smaller, you may have a break and then have more treatment.