Stem cell transplants -- from bone marrow or other sources -- can be an effective treatment for people with certain forms of cancer, such as leukemia and lymphoma. Stem cell transplants are also used for multiple myeloma and neuroblastoma, and they’re being studied as a treatment for other cancers, too.
Why do cancer patients consider these transplants? While high doses of chemotherapy and radiation can effectively kill cancer cells, they have an unwanted side effect: They can also destroy the bone marrow, where blood cells are made.
The purpose of a stem cell transplant or a bone marrow transplant is to replenish the body with healthy cells and bone marrow when chemotherapy and radiation are finished. After a successful transplant, the bone marrow will start to produce new blood cells. In some cases, the transplant can have an added benefit; the new blood cells will also attack and destroy any cancer cells that survived the initial treatment.
Understanding Stem Cells
While you may have heard about embryonic stem cells in the news, the stem cells used in cancer treatment are different. They’re called hematopoietic stem cells.
What’s special about these cells? Unlike most cells, these stem cells have the ability to divide and form new and different kinds of blood cells. Specifically, they can create oxygen-carrying red blood cells, infection-fighting white blood cells, and clot-forming platelets.
Most stem cells are in the bone marrow, a spongy tissue inside bone. Other stem cells -- called peripheral blood stem cells -- circulate in the blood. Both types can be used in stem cell transplants for cancer treatment.
Who Is a Candidate For a Stem Cell Transplant or Bone Marrow Transplant for Cancer Treatment?
While stem cell transplants may be lifesaving, they’re not the right treatment for everyone. The process can be difficult and tedious.
Given that the risks can be serious, deciding whether to get a stem cell transplant for cancer treatment is not easy. Your doctor will need to consider your general physical condition, diagnosis, stage of disease, and treatments you have already had. You’ll need a number of tests to make sure that you’re healthy enough to undergo the procedure. You also need to make sure you understand the potential benefits and risks of stem cell transplants.
Keep in mind that stem cell transplants only seem to be effective in treating specific types of cancer. While they were once used for breast cancer, for instance, experts no longer recommend them. Studies found that they didn’t work better than standard treatments.
Where Do Transplanted Stem Cells Come From?
Stem cells for a transplant -- whether from peripheral blood cells or bone marrow -- can come from two places: your body or a matching donor’s body.
Autologous transplants involve stem cells taken from your body before you’ve received chemotherapy and radiation. The stem cells are frozen, then reintroduced to your body after treatment.
Allogenic transplants involve stem cells that come from another person whose tissue type "matches" yours. Most donors are relatives -- preferably and most often a sibling.
To find out if stem cells match, a potential stem cell donor will have their blood tested in a process called human leukocyte antigen testing (HLA testing). In those very rare cases where the donor is your identical twin -- and thus a perfect match -- it’s called a “syngeneic transplant.”
Another source of donated stem cells is blood taken from the umbilical cord or placenta after childbirth. Some people choose to store or donate this blood after having a baby instead of discarding it. The process of taking the blood doesn’t pose a risk to the mother or child. However, because only a small amount of blood is in the umbilical cord and placenta, cord blood transplants are generally only used in children or small adults.
Stem cells can also come from what is known as a matched unrelated donor (MUD). Your bone marrow and tissue typing is matched against an unknown donor via a bone marrow registry to find a compatible donor. Doctors will search bone marrow registries if the patient does not have a relative who “matches” their stem cells.
Collecting Bone Marrow or Stem Cells for Cancer Treatment
How would a doctor collect stem cells from you or a donor? That depends on whether you’re getting a peripheral blood stem cell transplant or a bone marrow transplant for cancer treatment.
Peripheral blood stem cells. In this approach, the stem cells circulating in the donor’s blood are harvested and stored. This technique has become more common than bone marrow transplants for cancer treatment. Peripheral blood stem cell transplants are as effective for some, but not all cancers, but the process of donating is simpler.
For a few days, the donor -- whether it’s you or another person -- will take special drugs called growth factors that temporarily increase the number of stem cells in the blood. Side effects of this drug include bone pain. Then, a health care professional will insert a catheter into a vein to filter the donor’s blood through a special machine. This device extracts the stem cells and circulates the blood back to the body.
The process usually takes two to four hours. The donor might need to repeat the process for a few days before enough stem cells have been collected. The stem cells are then frozen until the transplant. The risks are very low. Side effects during the procedure include faintness and cramps in the hands.
Bone marrow stem cells. Because harvesting bone marrow is more involved, it’s done in an operating room. The donor will be under either general anesthesia (and asleep) or regional anesthesia (which eliminates feeling from the waist down.) A doctor will then insert a needle into a bone -- usually in the hip -- and withdraw some of the bone marrow, which is then stored and frozen.
The process takes one to two hours and the risks are very low. The most serious danger comes from the anesthesia itself. The area where the needle is inserted might be sore or bruised for a few days. Donors might also feel tired for several days or weeks afterward.
Chemotherapy and Radiation Therapy
Before you get the stem cell transplant, you’ll get the actual cancer treatment. To destroy the abnormal stem cells, blood cells, and cancer cells your doctor will give you high doses of chemotherapy, radiation therapy, or both. In the process, the treatment will kill healthy cells in your bone marrow, essentially making it empty. Your blood counts (number of red blood cells, white blood cells, and platelets) will drop quickly. Since chemotherapy and radiation can cause nausea and vomiting, you might need anti-nausea drugs. Mouth sores are also a common problem that may need to be treated with pain medication.
Without bone marrow, your body is vulnerable. You won't have enough white blood cells to protect you from infection. So during this time, you might be isolated in a hospital room or required to stay at home until the new bone marrow starts growing. You might also need transfusions and medication to keep you healthy.
What Happens During the Stem Cell Transplant?
A few days after you’ve finished with your chemotherapy or radiation treatment, your doctor will order the actual stem cell transplant. The harvested stem cells -- either from a donor or from your own body -- are thawed and infused into a vein through an IV tube. The process is essentially painless. The actual stem cell transplant is similar to a blood transfusion. It takes one to five hours.
The stem cells then naturally move into the bone marrow. The restored bone marrow should begin producing normal blood cells after several days, or up to several weeks later.
The amount of time you’ll need to be isolated will depend on your blood counts and general health. When you are released from the hospital or from isolation at home, your transplant team will provide you with specific instructions on how to care for yourself and prevent infections. You’ll also learn what symptoms need to be checked out immediately. Full recovery of the immune system might take months or even years. Your doctor will need to do tests to check on how well your new bone marrow is doing.
There are also variations in the stem cell transplant process. One approach is called a tandem transplant, in which a person would get two rounds of chemotherapy and two separate stem cell transplants. The two transplants are usually done within six months of one another.
Another is called a “mini-transplant,” in which doctors use lower doses of chemotherapy and radiation. The treatment is not strong enough to kill all of the bone marrow -- and it won’t kill all of the cancer cells either. However, once the donated stem cells take hold in the bone marrow, they produce immune cells that might attack and kill the remaining cancer cells. This is also called a non-myeloablative transplant.
What Are the Risks of Stem Cell Transplant for Cancer Treatment?
The main risks come from the chemotherapy and radiation treatment before the stem cell transplant. When they destroy the bone marrow, the body is at risk of infection and uncontrolled bleeding. Even a common cold or the flu can be quite dangerous.
It can take some time before your blood counts are back to normal. In the short term, stem cell transplants can cause side effects like nausea, fatigue, hair loss, and mouth sores. Some types of chemotherapy and radiation can also cause, infertility, organ damage, and an increased risk of new cancers.
Some people who get stem cells from a donor develop graft-versus-host disease -- the blood cells produced by the new bone marrow mistakenly attack healthy cells in your body. This can cause potentially life-threatening damage to the organs. To prevent it, some people need to take drugs that suppress the immune system.
In other cases, the stem cell transplant just doesn’t work. The new stem cells die or are killed by your body’s remaining immune cells.
If you’re considering a stem cell transplant for cancer treatment, have a long talk with your health care providers. Make sure you understand all of the potential risks.
Will My Insurance Provider Cover My Stem Cell Transplant or Bone Marrow Transplant?
Don’t assume that your insurance company will cover all - or any - of the costs of a stem cell transplant or a bone marrow transplant. Many insurers require pre-certification letters of medical necessity.
So if you’re even considering a stem cell transplant or a bone marrow transplant, contact your insurer now and get the details. Make sure you completely understand your coverage. You might also be able to get financial help from local or federal programs. Talk to your doctor or a hospital social worker about your options.
Deciding on a Stem Cell Transplant for Cancer Treatment
Is a stem cell transplant or bone marrow transplant the right treatment for you? It’s not an easy decision to make. It’s tough to weigh the potential benefits with the serious risks -- not to mention the disruption to your life and the lives of your family members.
But when you’re feeling anxious, remember that tens of thousands of people have had stem cell transplants or bone marrow transplants for cancer treatment. These techniques are constantly being improved and refined, and they’re more effective now than ever before.
Try to remain confident, and take on an active role in your treatment. Do some research into various stem cell transplant or bone marrow transplantation techniques. Ask your doctors specific questions, especially if you are participating in a clinical trial. Get support from your family, and make sure they understand what getting a transplant will mean for them. The better you understand your options, the more confident you’ll be when you make your decision.