What is a stem cell transplant?

A stem cell transplant uses young blood cells, called stem cells, to replace bone marrow that has been destroyed by cancer treatment. Over time, these stem cells grow and become new, healthy bone marrow.

Before transplant, your bone marrow is destroyed with high-dose chemotherapy. Sometimes the whole body is treated with radiation, too. This makes room for the healthy stem cells that are put back in your body. It also kills any non-Hodgkin lymphoma cells in your body.

When might a stem cell transplant be used?

A stem cell transplant is a complex treatment. It can cause very serious side effects. Because of this, it's most often used only when non-Hodgkin lymphoma is no longer responding to other treatments, or it has come back after treatment.

Rarely, a stem cell transplant may be part of the first treatment for certain hard-to-treat types of non-Hodgkin lymphoma.

Types of stem cell transplants

There are 2 kinds of stem cell transplants:

• Allogeneic transplant. This means the stem cells come from another person, called a donor, whose cell type is a lot like yours. A donor may be a close relative, such as a brother or sister. Or a stranger may match and be a donor.

• Autologous transplant. This means the stem cells are collected from your own body and frozen. It's done before you get high-dose chemotherapy.

Autologous transplants are often preferred over allogeneic transplants. This is because of the lower risk of serious side effects. But autologous transplants can cause problems, too. For instance, they may be less likely to fully destroy the lymphoma cells. An allogeneic transplant might be done if an autologous transplant didn’t work. Discuss the risks and benefits of each with your treatment team.

How stem cells are collected

Stem cells may be collected in 1 of these ways:

• From the blood. This is the most common source of stem cells for a transplant. You or your donor may get injections of a growth factor medicine for several days. This helps stimulate stem cell production. The method for collecting stem cells from the blood is called apheresis. It’s a lot like giving blood, but it takes longer. A thin, flexible tube (catheter) is used to take blood out of a vein. The blood goes into a machine that removes the stem cells. Then the rest of the blood is returned to you (or the donor). Apheresis is done as an outpatient procedure and takes a few hours. You may have a strange taste in your mouth during the process. This is from the preservative used to save the stem cells. This process may need to be done every day for a few days to collect the right amount of cells.

• From the bone marrow. Stem cells may also be taken from your (or your donor's) bone marrow. It's done in an operating room after medicines are used to put you into a deep sleep so you don't feel pain. A large, hollow needle is put into the back of the hip (pelvic) bone to remove the thick liquid marrow. The hip bone may be sore, bruised, or achy for a few days afterwards. The removed stem cells are filtered. Then they might be given to you right away, or they're frozen until they're needed.

• From umbilical cord blood. Stem cells may also be collected from umbilical cord blood. After a baby is born, the blood from the placenta and umbilical cord is collected. The blood would be thrown away otherwise, and collecting it doesn't put the baby or mother at risk. This blood has a lot of stem cells in it. The blood is frozen and stored until it's needed by someone with a matching tissue type.

Having the transplant

• You might need to be in the hospital for the transplant. Your healthcare team will go over the details with you. They will also talk about ways to lower your risk for infections. 

• You'll get high-dose chemotherapy and maybe radiation. It may last a few days.

• After this treatment, you'll get the stem cells through a central venous catheter (a thin tube that goes into a large vein). It's a lot like a blood transfusion. It doesn't hurt. If the cells were frozen, they'll be thawed right before you get them.

• Over time, the stem cells will go into your bone marrow. There, they start to multiply and make new blood cells.

• You'll have to wait for your stem cells to start multiplying. This process is called engraftment. You may have to limit your time around other people during this time to help keep you from getting infections. You might also need to take medicine to help prevent infections.

• You'll see your treatment team every day for the first month or so. They'll watch your blood counts closely. You may need antibiotics, platelets, or blood transfusions until your new stem cells start to work.

Side effects

Stem cell transplant can lead to many kinds of side effects. Side effects you might have depend on the treatments used to get you ready for transplant and the type of transplant you have. Your treatment team will talk with you about what you might expect. Many side effects can be managed. There may even be things you can do to help prevent some of them.

Short-term side effects

Most of the short-term side effects of a stem cell transplant are from the high doses of chemotherapy or radiation. They should get better over time as you recover. Common side effects include:

• Low blood cell counts

• Infection

• Feeling very tired

• Easy bruising and bleeding

• Upset stomach, or nausea

• Vomiting

• Loss of appetite

• Mouth and throat pain and sores

• Diarrhea

• Hair loss

• Fever or chills

• Shortness of breath

• Tightness or pain in the chest

• Pneumonia or other lung problems

• Low blood pressure

• Coughing

• Weakness

• Acute graft-versus-host disease (see below)

Long-term side effects

Some side effects of a stem cell transplant may be long-lasting. Others might not show up until years later. Long-term side effects and problems can include:

• Shortness of breath, often caused by radiation damage to the lungs

• Stopped or irregular menstrual periods, which may mean ovary damage and infertility

• Infertility. Talk to your healthcare team before treatment about ways to protect your fertility if having children is important to you.

• Weight changes

• Vision problems such as blurriness or cloudiness, caused by damage to the lens of the eye (cataracts)

• Bone pain, caused from damage due to lack of blood supply (called aseptic necrosis)

• Problems with metabolism, caused by damage to the thyroid gland

• Damage to other organs, such as the heart, kidneys, lungs, liver, bones, joints, and nervous system

• Another cancer, such as leukemia, years later

• Cancer that comes back (relapses)

Graft-versus-host disease (GVHD)

Another possible side effect is graft-versus-host disease (GVHD). It can only happen with an allogeneic transplant.

GVHD can happen within a few weeks after transplant. This is common and is called acute GVHD. Medicines are often used to help prevent or limit this. Chronic GVHD starts later, usually more than 3 months after transplant. When this happens, medicines that suppress your immune system may be needed until the symptoms get better.

In GVHD, the immune system cells in the donor's stem cells attack your body. The cells can attack your skin, liver, gastrointestinal (GI) tract, mouth, or other organs. Symptoms depend on the part of your body that's being attacked. They can include things like:

• Skin rashes and redness with itching (most common sign). The rash can be everywhere. It often starts on the palms of the hands and the soles of the feet.

• Upset stomach, or nausea

• Vomiting

• Mouth and throat sores

• Belly cramps and swelling

• Severe watery diarrhea

• Appetite loss and trouble eating

• Extreme tiredness (fatigue)

• Breathing problems

• Cough or wheezing

• Yellow-colored skin and/or eyes, called jaundice

• Muscle weakness and pain

• Joint stiffness

• Weight loss