Hodgkin’s lymphoma is a type of cancer that originates in white blood cells called lymphocytes, which are part of the body’s immune system. While initial treatments like chemotherapy and radiation are often effective, for some individuals, the cancer may return or not respond to these therapies. In such cases, a stem cell transplant can be a treatment option that offers a chance for long-term remission or even a cure. This intensive procedure aims to replace diseased bone marrow with healthy blood-forming cells.
What a Stem Cell Transplant Involves
A stem cell transplant involves replacing a patient’s immature blood cells. This procedure is necessary when the bone marrow, where they reside, has been damaged by disease or destroyed by high doses of cancer treatment. The goal is to restore the bone marrow’s ability to produce healthy blood cells.
There are two primary types of stem cell transplants relevant to Hodgkin’s lymphoma. An autologous transplant uses the patient’s own stem cells, which are collected and stored before high-dose chemotherapy. This is the more common type of transplant for Hodgkin’s lymphoma, as it avoids issues of immune rejection from a donor.
An allogeneic transplant uses healthy stem cells from another person, known as a donor. The donor may be a close relative, such as a sibling, or an unrelated individual whose tissue type closely matches the patient’s. Allogeneic transplants are less common for Hodgkin’s lymphoma and are considered if an autologous transplant has not been successful.
When a Transplant is Considered for Hodgkin’s Lymphoma
A stem cell transplant is considered for Hodgkin’s lymphoma patients when the disease has either returned after initial treatment (relapsed Hodgkin’s lymphoma) or has not responded adequately to initial therapies (refractory Hodgkin’s lymphoma). This approach allows doctors to administer higher doses of chemotherapy, sometimes with radiation, than the bone marrow could tolerate. The intense treatment aims to eliminate remaining lymphoma cells.
The rationale behind using a transplant in these scenarios is to provide a more potent treatment to overcome resistant cancer cells. While standard chemotherapy doses are limited by their toxic effects on bone marrow, a transplant provides a “rescue” by replacing the damaged blood-forming cells. This enables a more aggressive attack on the lymphoma.
Doctors consider several factors when deciding if a transplant is appropriate, including the patient’s overall health, age, and how well the lymphoma responded to previous treatments. For instance, patients with chemosensitive disease, meaning the lymphoma has responded to prior chemotherapy, have better outcomes with autologous transplants.
The Stem Cell Transplant Journey
The stem cell transplant journey begins with preparation, including the placement of a central venous catheter. This thin, flexible tube is surgically inserted into a large vein and is used for administering medications, fluids, and stem cells throughout the treatment process.
Stem Cell Collection
Following preparation, stem cells are collected. For an autologous transplant, the patient’s own stem cells are gathered, most commonly through apheresis. This involves administering daily injections of a growth factor, such as filgrastim, for several days to stimulate the bone marrow to release stem cells into the bloodstream.
Blood is then drawn from a vein, passed through a machine that separates the stem cells, and the remaining blood components are returned to the patient. This outpatient procedure usually takes about 3 to 4 hours per session and may require multiple sessions over 1 to 5 days to collect enough cells.
In some cases, if peripheral blood collection is not successful, stem cells may be harvested directly from the bone marrow through a surgical procedure under general anesthesia. For an allogeneic transplant, stem cells are collected from a matched donor, typically via apheresis, or less commonly from bone marrow harvest.
Conditioning Regimen
Once sufficient stem cells are collected, the patient undergoes a “conditioning regimen.” This phase involves high-dose chemotherapy, and sometimes radiation therapy, administered over several days.
The purpose of this intensive treatment is to destroy remaining lymphoma cells throughout the body, suppress the patient’s immune system to prevent rejection of the new stem cells, and create space in the bone marrow for the transplanted cells to engraft.
Stem Cell Infusion
On “Day Zero,” the stored or freshly collected stem cells are infused into the patient. This procedure is similar to a blood transfusion, with the stem cells delivered intravenously through the central line. Patients are closely monitored for any reactions during this time.
Engraftment and Recovery
After the infusion, the stem cells travel through the bloodstream to the bone marrow, where they begin to settle and multiply, a process called “engraftment.” During this period, the new stem cells start producing new white blood cells, red blood cells, and platelets.
The patient’s blood counts are very low, making them highly susceptible to infections and other complications. Most patients remain hospitalized for several weeks until their blood counts recover sufficiently to reduce the risk of serious complications.
Life After a Stem Cell Transplant
The recovery period following a stem cell transplant is extensive, often taking many months to a year or more to fully regain strength. In the short term, patients experience a weakened immune system due to the high-dose chemotherapy, making them highly vulnerable to infections from bacteria, viruses, and fungi.
This necessitates a period of isolation and strict precautions, often with daily hospital visits for monitoring and transfusions of red blood cells or platelets if counts remain low.
Common complications in the initial months include fatigue, nausea, vomiting, mouth sores, and hair loss, which are largely side effects of the intensive conditioning regimen. Infections are a significant concern, and patients often receive preventive antibiotics, antifungals, and antivirals.
Graft-versus-host disease (GvHD) is a serious potential complication specifically following allogeneic transplants, where the donor’s immune cells recognize the recipient’s body as foreign and attack various organs, including the skin, liver, and gastrointestinal tract. GvHD can manifest acutely, typically within the first 100 days, or chronically, appearing months or even years later.
Long-term recovery involves continued follow-up care to monitor for late effects and potential recurrence of the lymphoma. The immune system can take a year or more to fully reconstitute, and patients may require vaccinations to rebuild immunity to common diseases.
Possible late effects can include issues with the thyroid, heart problems, or the development of secondary cancers, though these vary by patient and transplant type. Support systems, including family, friends, and specialized support groups, play a significant role in navigating the physical and emotional challenges of recovery. While the transplant journey is demanding, it offers many Hodgkin’s lymphoma patients the potential for long-term survival and an improved quality of life.