The topic of transplants for cancer is quite complicated but let me spell out some of the most common types of transplants and terminology discussed for cancer these days. First of all, transplants in cancer setting are carried out usually for blood cancers (but sometimes of other cancers of solid organs). For blood cancers the term is hematopoietic Stem Cell transplants. The goal with these are to replace the cancerous blood cells that are frequently part of the immune system with new cells that are not defective. The ultimate goal is to take the new transplanted cells from a donor put them into a sick person after the cancer has been removed as much as possible so that the new stem cells (from the donor) can repopulate the whole bone marrow and immune system and much of the blood system of the sick person. So, in general these transplants remove the bad cells and replace them with good cells in hopes that the good cells will completely take over and he/she will have no more cancer. Ok, sounds simple…well it’s not. No way. Here are some issues that are important.
1. Allogeneic transplants: These occur when the donor who is giving the stem cells to the sick patient is someone else. This is very common as the donor is healthy and if there is a good match (genetic match) with the recipient than the bone marrow stem cells can be used. If it is a relative the chances of finding a genetic match is usually better. We call that a haploidentical sibling transplant.
2. Allogeneic peripheral Blood Stem Cells transplant: This is the same thing as above in that the donor is someone else (either a relative or a complete stranger who donates his/her bone marrow). However the difference is that above the donation was bone marrow taken from within the bone cavities, in this case the doctor removes the blood and uses that as the donor material . The stem cells from the blood are removed after the patient is given a drug called GCSF. The blood is taken from the patient and put into a machine that will remove the stem cells from the blood and the blood is returned to the patient with the stem cells removed. This is not so painful and does not require going into the bone. This is called peripheral blood as it circulated all over the body and is not directly from the bone marrow.
3. Autologous transplant: In some cases the person with the cancer can be given drugs that remove the cancer temporarily or if the cancer that the person has in only in the periphery and not in the bone marrow, then he or she can donate their own bone marrow stem cells to themselves. This is termed autologus…from self. So, in this case the donor is an EXACT genetic match since the donor and the recipient is a match. However, the doctor must be VERY careful to make sure there is no cancer cell in the bone marrow or blood product that is going back into the patient. This is usually the most safe type of procedure in terms of complications as I will explain below. This does not work for everyone and only works if the cancer is not present in the material that is being given to the patient.
4. Cord blood transplant: more recently scientist have discovered that the cord blood is full of stem cells that can be used for transplant. Cord blood comes from the umbilical blood that the baby and mother can donate when the baby is born. Collection of this blood causes no harm and no pain and many people are starting to donate and put into donation centers. For some reason that people do not know, the cord blood stem cells often do not need to be matched 100% when given to a sick patient. Usually the person with cancer can tolerate some – of the cord blood. However, one limitation of cord blood is the volume. So, at the moment children who are smaller can get cord blood as a product but it is hard for larger adults.
Complications: In order to prepare for a transplant the patient needs to be treated for his/her cancer as aggressively as possible so as to keep the cancer cells as low as possible. This means that the patient is put on chemotherapy and drugs to kill off as much of the cancer as possible. This can make patients very sick. Then after that, many patients need to undergo radiation treatment. This is to help the new cells that are being donated take over the sick persons body after the transplant. The radiation kills of any remaining active immune response so that the patient does not destroy the donors new cells that are placed inside of him or her. Then the patient undergoes the transplant and this is a very complex and difficult procedure. Most patients will get very sick, develop rashes, get infection, vomit, and so forth for some time. As the new cells that are given need some time to develop and expand, patients are usually very susceptible to infection…and they need to be closely monitored for at least a month. They are usually on a lot of drugs to make sure their immune system doe snot destroy the new graft. The new stem cells from the donor is called a graft once it starts to replace the old bone marrow cells. Sometimes a patient can develop something called graft vs. host disease where the graft (the new material from the donor) starts to reject the host. There are certain things one can do to help reduce this, but in the end its up to the body.
Anyhow, there are more issues related to cancer transplants but I hope this helps a bit. It is not an easy subject to understand but it happens very often in the clinics. Please do visit my web page and see some education products I have to offer. I will have an audio of this topic coming soon! www.cancermadesimple.com