Due to the high risk of complications, bone marrow transplants are only recommended in certain situations where other treatments have failed.
Bone marrow transplants are usually only recommended if:
- the recipient of the transplant is in relatively good health despite their associated condition - which is why they are often carried out when cancer is in remission
- stem cells are available from a brother or sister or, less commonly, another family member, or an unrelated donor, with the same or similar tissue type, which reduces the chances of bone marrow being rejected
- the associated condition is not responding to other forms of treatment, or it is felt that there is a high risk of the condition returning without a transplant
- it is felt that the benefits of a transplant outweigh the risks
Tissue type
All human tissue carries a special genetic marker or code which is known as a human leukocyte antigen (HLA).
For a transplant to be successful, the transplanted tissue should ideally come from someone with an identical or very similar HLA tissue type.
If the transplanted tissue has a different HLA type, your immune system might treat it as a foreign object and reject it.
Alternatively, the cells from the transplanted tissue may regard the rest of your body as a foreign object and start attacking it. This is known as graft versus host disease (GvHD).
Your tissue type is inherited from both of your parents. If you have a brother or sister who is willing to be a donor, they will need to be tested to see if their HLA type is the same as yours. There is a 1 in 4 chance of each full sibling - that is, those who share both of the same parents - being an exact match.
Bone marrow registry
If you are an only child, or if your siblings are not suitable donors, a search of the NHS Blood and Transplant registry will be carried out. It holds a database of all the people willing to donate stem cells and their HLA type.
It may take several years before a suitable donor can be found. However, in some cases waiting without treatment may be considered too dangerous or it may not be possible to find a full match. In such cases, stem cells from a partially matched donor may be used instead.
This will increase the risks of complications, but your treatment team may recommend it if they feel that the benefits outweigh the risks.
