If you have been found eligible for a stem cell transplant to treat your cancer, the first step consists of finding whether one of your family members is a potential donor. The transplant team will carry special blood studies on you and your family members to find out the best tissue type match. The standard test carried out is called tissue typing, also known as human leukocyte antigen (HLA) type. HLA are proteins found on the surface of most cells in your body, and they constitute your tissue type (different from your blood type). You inherit these HLA proteins from both your parents. The transplant team will try to match these proteins to find your optimal donor. The closest the tissue type matching is the less likely the risk of GVHD and transplant rejection is.
The search for a good match usually starts with your brother or sister whose chance of being a perfect match is 1 out of 4. If your sibling is not a good match, the search is then extended to your parents, half siblings, and extended family. If none of your relatives are found to be a good match, the transplant team will use the transplant registries.
For some types of cancer, an autologous transplant is possible which means you can be your own donor and your own marrow stem cells are used. In autologous transplant, you don’t have to worry about GVHD; however there is an increased risk of cancer coming back.
If no matched stem cell donor can be found, the transplant team might consider the umbilical cord blood registries. The umbilical cord blood contains high levels of stem cells. The advantage of using this source is that it doesn’t have to be a perfect tissue match with you. However only a limited number of cells can be collected and they may not be enough for your treatment.