A stem cell transplant can be an important part of treatment for some people with blood cancer. It is used most commonly for certain types of leukemia, lymphoma, and multiple myeloma, but it is not required for everyone with these diseases.
A stem cell transplant involves giving healthy blood-forming stem cells after intensive treatment. Depending on the cancer and treatment plan, the stem cells may come from the patient or from a donor.
The purpose is to restore the body's ability to produce healthy blood cells after intensive cancer treatment and, in some donor transplants, to provide an additional immune-based effect against the cancer. Understanding how a transplant works and why it may be recommended can help patients make sense of this important part of blood cancer treatment.
What Is a Stem Cell Transplant?
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
A stem cell transplant, also called a hematopoietic stem cell transplant or sometimes a bone marrow transplant, replaces blood-forming stem cells that have been damaged or destroyed by intensive cancer treatment. Blood-forming stem cells are immature cells that develop into the three main types of blood cells:
- Red blood cells, which carry oxygen
- White blood cells, which help fight infections
- Platelets, which help control bleeding
These stem cells are found mainly in the bone marrow and can also be collected from the bloodstream. In selected situations, stem cells may also come from umbilical cord blood.
Why Is a Stem Cell Transplant Used for Blood Cancer?
High doses of chemotherapy, sometimes combined with radiation therapy, can destroy cancer cells but can also severely damage the healthy blood-forming cells in the bone marrow.
A stem cell transplant allows doctors to use intensive treatment while providing a way to restore blood-cell production afterward.
With an allogeneic transplant, where the stem cells come from a donor, there can also be an additional anti-cancer effect. Donor immune cells may recognize and attack remaining cancer cells. This is known as the graft-versus-leukemia or more broadly graft-versus-tumor effect.
This immune effect can be particularly important in certain blood cancers, although it also contributes to some of the risks associated with donor transplantation.
Which Blood Cancers Can Be Treated With a Stem Cell Transplant?
Stem cell transplantation may be considered for several blood cancers, but its role differs considerably between diseases.
Leukemia
Stem cell transplantation can be used in selected people with acute leukemias and certain other leukemias. Whether it is recommended depends on factors such as the leukemia subtype, genetic and molecular characteristics, disease risk, response to initial treatment, and whether the disease has returned.
For some high-risk leukemias, an allogeneic transplant may be considered after the disease has responded to initial treatment. It is not automatically required for every person with leukemia.
Lymphoma
Both autologous and allogeneic transplants can have a role in lymphoma, depending on the subtype and treatment history.
An autologous transplant may be considered for selected people whose lymphoma has returned or has not responded adequately to earlier treatment. Some people with particular high-risk or relapsed lymphomas may be considered for an allogeneic transplant.
The exact role of transplantation depends heavily on the lymphoma subtype, previous treatments, response to treatment, and the patient's overall health.
Multiple myeloma
Autologous stem cell transplantation is an established treatment option for many patients with multiple myeloma who are suitable for intensive treatment.
In an autologous transplant, the patient's own stem cells are collected and stored before high-dose chemotherapy. They are then returned after the intensive treatment to help the bone marrow recover.
Not every person with multiple myeloma is a candidate for transplant. Age, overall health, organ function, disease characteristics, and treatment response all influence the decision.
The Two Main Types of Stem Cell Transplant
The most important distinction is where the stem cells come from.
Autologous stem cell transplant
In an autologous transplant, the patient's own healthy blood-forming stem cells are collected before intensive treatment.
The basic sequence is:
- Stem cells are collected from the patient's blood or, less commonly, bone marrow.
- The collected cells are stored, often by freezing them.
- The patient receives high-dose chemotherapy and, in selected situations, radiation therapy.
- The stored stem cells are returned through an intravenous infusion.
- The stem cells travel to the bone marrow and begin producing new blood cells.
The major advantage is that there is no need to find a donor match and there is no graft-versus-host disease from donor immune cells. However, the transplant does not provide the same donor immune effect against cancer that can occur with an allogeneic transplant.
Allogeneic stem cell transplant
In an allogeneic transplant, the stem cells come from another person. The donor may be a relative or an unrelated donor who is a suitable genetic match.
Before the transplant, the patient receives conditioning treatment to destroy cancer cells, suppress the immune system, and prepare the bone marrow to receive the donor cells.
The donor stem cells are then infused into the patient. Once they establish themselves in the bone marrow, they begin producing new blood cells.
An allogeneic transplant can provide an important graft-versus-cancer effect, but it also carries additional risks, including graft-versus-host disease (GVHD).
How Is a Donor Match Determined?
For an allogeneic transplant, doctors assess compatibility between the patient and potential donors using markers called human leukocyte antigens (HLAs).
These markers help the immune system distinguish the body's own cells from foreign cells. A closer HLA match generally improves the chances of successful transplantation and can reduce certain complications, although other factors are also important.
A potential donor may be a sibling, another family member, or an unrelated volunteer donor. The availability of a suitable donor depends on the patient's individual circumstances and the donor-search process.
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
What Happens Before a Stem Cell Transplant?
A transplant requires careful preparation. Before proceeding, the medical team assesses whether the potential benefits of transplantation outweigh its risks. The evaluation may include:
- Detailed review of the blood cancer and its subtype
- Assessment of the disease's response to treatment
- Blood tests and other laboratory investigations
- Heart and lung evaluation when appropriate
- Kidney and liver function testing
- Infection screening
- Assessment of general physical condition
- Donor and HLA testing for an allogeneic transplant
What Is Conditioning Treatment?
Conditioning refers to the treatment given immediately before the stem cell infusion. It commonly involves high-dose chemotherapy and may sometimes include radiation therapy. The goals can include:
- Destroying remaining cancer cells
- Making space in the bone marrow for the new stem cells
- Suppressing the immune system when necessary to help donor cells establish themselves
What Happens on Transplant Day?
The day the stem cells are infused is often called Day 0. The stem cells are usually given through a central venous catheter or another intravenous line. The process is generally similar to receiving an intravenous blood product rather than undergoing surgery.
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
After infusion, the stem cells travel through the bloodstream to the bone marrow. Over time, they begin producing new blood cells. The period after the infusion is often the most closely monitored part of the transplant process because blood counts can remain very low while the new stem cells become established.
What Is Engraftment?
Engraftment is the process in which the transplanted stem cells settle in the bone marrow and begin producing new blood cells.
As the new marrow starts functioning, white blood cell, red blood cell, and platelet counts gradually recover. The timing varies between patients and depends on factors such as the type of transplant, conditioning treatment, disease, and overall health.
Until adequate blood-cell production is restored, patients may require close monitoring and supportive care, including blood or platelet transfusions and treatment or prevention of infections.
What Are the Risks of a Stem Cell Transplant?
Stem cell transplantation is a complex treatment and can cause significant short- and long-term complications. The risks depend on the type of transplant, conditioning regimen, age, underlying disease, general health, and other factors. Possible early complications include:
- Infections
- Bleeding due to low platelet counts
- Anemia
- Nausea and vomiting
- Mouth sores
- Loss of appetite
- Severe fatigue
- Organ-related complications
With an allogeneic transplant, graft-versus-host disease is an additional important complication. It occurs when donor immune cells recognize the recipient's tissues as foreign and attack them. GVHD can affect the skin, liver, digestive tract, and other organs.
How Long Does Recovery Take?
Recovery after a stem cell transplant is gradual. The initial hospital or closely supervised recovery period focuses on blood-count recovery, infection prevention, management of side effects, and monitoring for complications.
Even after blood counts recover, the immune system may take considerably longer to return to normal. Recovery is generally longer after an allogeneic transplant than after an autologous transplant.
Some people can gradually resume normal activities within months, while others require a longer recovery period. The timeline depends on the type of transplant, complications, underlying cancer, and overall health.
Does a Stem Cell Transplant Cure Blood Cancer?
A stem cell transplant can potentially produce long-term remission and, for some blood cancers, may contribute to a cure. However, it is not a guaranteed cure for every patient.
The outcome depends on the type and biology of the cancer, disease status at the time of transplant, response to previous treatment, transplant type, patient characteristics, and complications.
In donor transplantation, the graft-versus-cancer effect can help eliminate remaining malignant cells. At the same time, the treatment carries substantial risks, which is why transplant specialists carefully balance potential benefits against possible complications.
What Happens After the Transplant?
Follow-up remains an important part of transplant care. The medical team monitors blood counts, infections, medication effects, organ function, and signs of complications.
For allogeneic transplant recipients, monitoring for acute and chronic GVHD is particularly important. Immunosuppressive medicines may be required to reduce the risk or severity of GVHD.
Vaccination schedules and other preventive measures may also need to be reviewed because immune recovery can take time.
Over the longer term, follow-up focuses on cancer surveillance, management of late effects, general health, and gradual recovery of physical and emotional wellbeing.
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
The Bottom Line
A stem cell transplant can be a powerful treatment option for selected people with blood cancer, particularly certain leukemias, lymphomas, and multiple myeloma. It works by restoring blood-forming stem cells after intensive treatment and, in donor transplantation, may also provide an immune response against remaining cancer cells.
The two main approaches are autologous transplantation, which uses the patient's own stem cells, and allogeneic transplantation, which uses cells from a donor. Each has different potential benefits and risks.
Whether a transplant is appropriate depends on much more than the diagnosis alone. The cancer subtype, disease status, previous treatment response, overall health, organ function, donor availability, and potential risks all need to be considered together. For this reason, stem cell transplantation is best understood as one component of a broader, individualized blood cancer treatment plan.
