Stem Cell Transplants in Childhood Cancer

Although the most common (and most popular) methods to treat childhood cancer are through chemotherapy/radiation therapy, stem cell transplants have also been highly effective in cancer treatment. But in order for a stem cell transplant to be beneficial to a cancer patient, it is very important to know the “ins and outs” of the stem cell transplant process.

Although stem cell transplants are used to treat other types of childhood cancers besides leukemia (the most common type of childhood cancer), stem cell transplants are mostly used for treating leukemia due to the fact that leukemia is one of the only cancers that directly damages cells in the body (specifically blood cells) to the point of no regrowth.

A stem cell transplant involves placing stem cells (often from a donor with the same blood group as the cancer patient or from the cancer patient themselves) into a cancer patient’s body, in the hopes that the body will replace the damaged cells with the new stem cells that have been newly “transplanted” into the body.

But what exactly are stem cells? Stem cells are young, undeveloped cells that can mature into any type of body cell depending on their location (for example, stem cells located in the stomach mature into stomach cells). Stem cells mostly live in the bone marrow, which is why stem cell transplants are also known as bone marrow transplants. Specifically in leukemia, stem cell transplants aim to replace damaged red blood cells (carry oxygen from lungs to other body cells) and white blood cells (help to fight infections/viruses and are primarily located in the immune system).

There are two types of stem cell transplants: one using stem cells from the cancer patient themselves (autologous stem cell transplant), and one using stem cells from a donor (allogeneic stem cell transplant).

In the process of an autologous transplant, the stem cells are first “harvested” from your bone marrow or blood and then frozen. Once you are finished with the most intense rounds of chemotherapy and/or radiation, the stem cells are thawed and returned back into your body.

One advantage of an autologous transplant is that since the stem cells are from your body, there is a decreased risk of the cells being rejected by your body and causing more damage. On the other hand, one disadvantage of an autologous transplant is that the cancer cells that once are taken out of your body, have the possibility of going back into your body and doing the same damage again.

The process of an allogeneic transplant is very similar to the process of an autologous transplant. The stem cells are first “harvested” from your bone marrow or blood and then frozen. Once you are finished with the most intense rounds of chemotherapy and/or radiation, the stem cells are thawed and inserted into your body. The most common place to extract stem cells from in an allogenic transplant is the umbilical cord or placenta of a newborn baby. “Cord blood” is known to have a high number of stem cells that multiply really quickly.

One advantage of an allogeneic transplant is that the stem cells from the donor make their own immune cells, which have been shown to have a much higher success rate at killing off the cancer cells in the cancer patient’s body (this is often called the graft versus cancer effect). One major risk of allogeneic transplants is that the immune cells that are formed from the donor’s stem cells are often very strong, and may even kill the cancer patient’s healthy cells. This can pose a serious problem as cancer patients already struggle with low healthy blood plasma and cell count.

Even though stem cell transplants are shown to have the same or better effect in treating cancer as chemotherapy and/or radiation, stem cell transplants can often be much more expensive and have much lower success rates.

In an independent study conducted by the U.S National Marrow Donor Program, the predicted one-year survival rate of stem cell transplants was 62%. But do not be fooled by this statistic. This survival rate only applies to people who ever get the chance to have a transplant. Many people end up waiting for at least 6 months to one year before they even get a notice about their donor. And sometimes even with finding the right donor, the transplant still might not work due to the donor and the cancer patient having different virus antibodies. Some people even pass away while still being on the waiting list for finding a transplant donor.

Stem cell transplants are one of the most expensive medical procedures, costing about $87,000 to $300,000 (depending on what stage of cancer the patient is in). The cost of a stem cell transplant (that has relatively low chances of working) might be more of a financial burden to certain families than the payments of regular chemotherapy. There are certain medical insurances who cover the whole, half, or even just one-fourth the cost of the total transplant (it depends on the insurance company). But most medical insurances do not cover the whole transplant cost after twice and more often than not, cancer patients need at least three cell transplants. This still presents a major problem in our medical society today.

That being said, getting a stem cell transplant can still be a great treatment option if your oncologist recommends it to you. First, your oncologist will take blood samples of your HLA (human leukocyte antigen) cell proteins. HLA proteins are used by your body to recognize which cells are yours. Then, your oncologist will enter your HLA information into the data bank of the National Marrow Donor Program (NMDP) and contact you when the program notifies that they have found a matching donor. However, there is also a possibility that your HLA proteins match up with someone from your family. In that case, you can get stem cells needed for your transplant from one of your relatives. Unfortunately, approximately 7 out of 10 people end up having no relatives with matching HLA proteins (according to the AAMDS). But, it is worth asking your oncologist to take HLA protein samples of your immediate relatives.

There are many benefits and risks to choosing to go through a stem cell transplant. At the end of the day, the choice is up to you. You should pick whichever type of stem cell transplant (autologous or allogeneic) fits your needs and progression of your cancer treatment. You and your oncologist may even decide that a stem cell transplant is not right for you. Again, go with whatever treatment, whether that be conventional chemotherapy or stem a cell transplant, that your oncologist recommends and is best for you.

Sources:

https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/stem-cell-transplant.html

https://www.lls.org/treatment/types-of-treatment/stem-cell-transplantation

https://bloodstemcell.hrsa.gov/data/donation-and-transplantation-statistics

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5726064/

https://www.mskcc.org/news/msk-s-one-year-survival-rate-after-allogeneic-bone-marrow-transplant-exceeds-expectations?page=1

https://www.aamds.org/finding-stem-cell-donor