Bone marrow transplants are used to treat more than 70 diseases, ranging from blood cancers like leukemia and lymphoma to genetic conditions like sickle cell disease and severe immune deficiencies. The procedure replaces damaged or diseased bone marrow with healthy blood-forming stem cells, either from the patient’s own body or from a donor. Who actually needs one depends on the specific diagnosis, how the disease has responded to other treatments, and whether the patient is physically strong enough to endure the process.
Blood Cancers: The Most Common Reason
The majority of bone marrow transplants are performed for hematologic malignancies, meaning cancers that start in the blood or bone marrow. The most common include acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), chronic myelogenous leukemia, non-Hodgkin’s lymphoma, Hodgkin lymphoma, and multiple myeloma.
Not everyone with these cancers needs a transplant. It typically becomes part of the treatment plan when the cancer is classified as high-risk, when it has relapsed after initial chemotherapy, or when it stops responding to standard drugs. Timing matters significantly. When transplants are delayed until the disease becomes drug-resistant or reaches an advanced crisis stage, only about 10 to 20 percent of patients can be saved. Transplanting earlier, when the disease is in remission or still responding to treatment, produces far better outcomes.
For multiple myeloma specifically, a transplant using the patient’s own cells remains a standard step in treatment for eligible patients. For high-risk AML, a transplant using donor cells has become the standard approach based on decades of clinical evidence.
Non-Cancerous Conditions
A bone marrow transplant can also be the only cure for several serious diseases that aren’t cancer. These conditions share a common thread: the bone marrow itself is failing, producing defective blood cells, or producing immune cells that don’t work properly.
- Aplastic anemia: The bone marrow stops producing enough new blood cells, leading to fatigue, infections, and uncontrolled bleeding.
- Sickle cell disease: Red blood cells form an abnormal shape that blocks blood flow, causing pain crises and organ damage. A donor transplant can replace the faulty marrow with cells that produce normal red blood cells.
- Other bone marrow failure syndromes: A group of inherited conditions where the marrow gradually loses its ability to produce healthy blood cells.
- Primary amyloidosis: An abnormal protein builds up in organs and tissues, often originating from defective cells in the marrow.
For many of these conditions, a transplant is considered curative, meaning it can eliminate the disease entirely rather than simply managing symptoms.
Children With Genetic and Immune Disorders
Bone marrow transplants play a particularly important role in pediatric medicine, where they can correct genetic problems that would otherwise be fatal in early childhood. Children born with severe combined immunodeficiency (SCID), sometimes called “bubble boy disease,” have immune systems so compromised that even common infections can be life-threatening. A transplant from a healthy donor gives them a functioning immune system.
Other childhood conditions treated with transplants include chronic granulomatous disease (a genetic defect that prevents immune cells from fighting certain infections), inherited metabolic disorders like adrenoleukodystrophy, and certain brain and solid tumors. Rheumatologic disorders that don’t respond to conventional treatment are occasionally treated with transplant as well.
Your Own Cells vs. a Donor’s Cells
There are two main types of transplant, and the choice between them depends on the disease being treated.
An autologous transplant uses your own stem cells. Before high-dose chemotherapy, doctors collect and freeze your healthy stem cells. After chemo destroys the diseased marrow, your cells are infused back to rebuild it. This approach is standard for multiple myeloma and for certain lymphomas that relapse more than 12 months after initial treatment.
An allogeneic transplant uses cells from a donor, either a family member or an unrelated volunteer. This is the preferred approach when the bone marrow itself is the source of the problem, as in leukemia, aplastic anemia, sickle cell disease, or immune deficiencies. Donor cells not only rebuild the marrow but can also attack any remaining cancer cells, an effect called graft-versus-disease.
Donor matching relies on a set of genetic markers called HLA types. Most European transplant centers look for a 10/10 match across five specific gene locations, while the U.S. National Marrow Donor Program recommends at minimum an 8/8 match across four locations. Siblings have roughly a 25 percent chance of being a full match. When no family match exists, registries of millions of volunteer donors are searched for unrelated matches.
Who Is Healthy Enough for Transplant
Having a disease that could benefit from a transplant is only half the equation. The procedure involves intense chemotherapy or radiation to destroy the existing marrow before new cells are infused, and this conditioning phase is extremely hard on the body. Your heart, lungs, liver, and kidneys all need to be functioning well enough to tolerate it.
Before being approved, you’ll go through an extensive evaluation: blood tests, imaging scans, heart and lung function tests, a bone marrow biopsy, and a psychosocial assessment to gauge your mental readiness and support system. The evaluation process can take several days.
Age used to be a hard cutoff, with transplants rarely offered to patients over 55 or 60. That line has shifted. Mayo Clinic, for example, now considers selected patients over 65 depending on their overall physical fitness. Reduced-intensity conditioning regimens, which use lower doses of chemotherapy, have made transplants accessible to older or frailer patients who wouldn’t have tolerated the full-strength approach.
When Newer Therapies Replace Transplant
For some cancers, a newer treatment called CAR-T cell therapy has begun to replace bone marrow transplant in specific situations. CAR-T involves engineering a patient’s own immune cells to recognize and attack cancer, then infusing them back into the body.
In large B-cell lymphoma, CAR-T therapy has proven superior to the traditional approach of salvage chemotherapy followed by autologous transplant for patients who relapse within 12 months of their first treatment. Three CAR-T products are now approved for patients whose lymphoma returns after transplant or who weren’t eligible for one. For patients who relapse later, beyond 12 months, salvage chemotherapy followed by autologous transplant remains the standard, since CAR-T hasn’t been tested head-to-head in that group through randomized trials.
In multiple myeloma, CAR-T therapy is currently approved for patients who have already gone through at least four prior lines of treatment. The vast majority of patients in the clinical trials that led to approval, over 90 percent, had already undergone and progressed past a transplant. Clinical trials are now underway comparing CAR-T directly against autologous transplant as a first-line option, which could reshape how myeloma is treated in coming years.
CAR-T also originated as a treatment for relapsed B-cell ALL and continues to serve as an important option when that leukemia doesn’t respond to standard chemotherapy. Still, for many diagnoses and disease stages, transplant remains the most established and effective path to long-term survival.
Survival After Transplant
Outcomes vary widely depending on the disease, the type of transplant, and how early it’s performed. The first two years after transplant carry the highest risk, with complications like graft-versus-host disease (where donor cells attack the recipient’s body), infections, and organ damage posing the greatest threats.
For patients who make it past that two-year mark, the long-term picture improves substantially. In a large study of childhood transplant survivors who used their own cells, five-year survival rates (conditional on reaching the two-year milestone) were approximately 89 percent for Hodgkin lymphoma, 95 percent for AML, and 96 percent for neuroblastoma. Adult outcomes vary more depending on age and disease complexity, but survival rates across all transplant types have improved steadily over the past two decades as supportive care and donor matching have gotten better.