Blood and Marrow (Stem Cell) Transplant

A stem cell transplant restores blood-forming stem cells. It is used in people whose own stem cells have been destroyed. That destruction comes from the high doses of chemotherapy or radiation therapy used to treat certain cancers, blood disorders, and autoimmune disorders.

Blood-forming stem cells are vital because they grow into different types of blood cells. White blood cells fight infection. Red blood cells carry oxygen. Platelets help blood clot.

Stem cell transplants may also be called bone marrow transplants, or peripheral blood stem cell transplants. The name depends on where the cells come from.

A transplant rebuilds your blood-forming cells after high-dose treatment wipes them out.

Stem cell transplants usually do not work against cancer directly. Instead, very high doses of chemotherapy, and maybe radiation, destroy the cancer cells. The transplant then restores your body's ability to make new blood cells.

There is one important exception. In leukemia, a transplant that uses donor stem cells can work against cancer directly. The effect is called graft-versus-tumor, or graft-versus-leukemia. It happens when white blood cells from your donor attack cancer cells that remain in your body. That improves the chances that the transplant succeeds.

In a transplant, you receive healthy blood-forming stem cells through a needle in your vein. The cells can come from the bloodstream (a peripheral blood stem cell transplant). They can come from the bone marrow (a bone marrow transplant). Or they can come from umbilical cord blood (a cord blood transplant). Once in your bloodstream, the cells travel to the bone marrow. There they take the place of the cells that were destroyed.

Transplants can be:

• Autologous — the stem cells come from you. The cells will match, but there is a small risk that cancer cells could be transplanted.
• Allogeneic — the cells come from someone else, related or not, if they are a close enough match. It is important that they match closely so your immune system does not see them as foreign.
• Syngeneic — the cells come from your identical twin.

There are also mini-transplants. These are a type of allogeneic transplant that uses lower treatment doses. And there are tandem transplants, a type of autologous transplant with two rounds of high-dose chemotherapy and two transplants.

Which type is right for you depends on many things. Your type of cancer. How advanced it is. Whether you can use your own cells. Whether matching donor cells are available. And your overall health.

To decide if a donor's cells are a match, they are tested for their HLAs (human leukocyte antigens). HLAs are sets of proteins, or markers, found on most cells in your body. Each person has a different set. The more HLAs you and the donor share, the better the chance your body will accept the cells. Most often, the best match for an allogeneic transplant is a brother or sister.

The high doses of treatment before a transplant can cause bleeding, a higher risk of infection, and feeling tired. Short-term problems can include nausea, vomiting, fatigue, loss of appetite, mouth sores, hair loss, and skin reactions. Long-term problems can include infertility, cataracts, new secondary cancers, organ damage, and bone and muscle weakness.

If you have an allogeneic transplant, you might develop graft-versus-host disease. It happens when white blood cells from your donor (the graft) see your body's cells (the host) as foreign and attack them. That can damage the skin, liver, intestines, and other organs. It can be acute (within the first 3 months) or chronic (3 months or later). It can be treated with steroids, or with other drugs that suppress the immune system. The risk can be lowered too — with a closer match, with immune-suppressing drugs, or by removing certain donor cells.

A stem cell transplant can take a few months to complete. It starts with high-dose chemotherapy, and maybe radiation, for a week or two. Then come a few days of rest. Then you receive the stem cells. The day you receive them is often called day zero. Getting the cells is like a blood transfusion and takes 1 to 5 hours.

After that comes the recovery phase, when doctors check your blood counts often. Even after blood counts return to normal, the immune system takes longer to recover. That is several months for autologous transplants, and 1 to 2 years for allogeneic or syngeneic transplants. Allogeneic transplants are done at a hospital with a specialized transplant center, and you may need to stay near the hospital during recovery.

A transplant is a months-long process, and your team will follow your blood counts and recovery closely.

While your counts are low, your body may not be able to mount the usual signs of illness. A small change can be the only warning you get, so the threshold for phoning the transplant unit is deliberately low. Use the 24-hour transplant number you were given, not a general clinic line.

• Call 911 or go to an emergency department if you have shaking chills, breathing that has become hard work, chest pain, or bleeding that will not stop — from the nose, gums, bowel or a line site. Sudden severe headache, a seizure, or confusion also belong here.
• Call the transplant team's urgent number at once, at any hour, and expect to be seen in an emergency department, if your temperature reaches 100.4°F (38°C) or higher, even once and even if you feel reasonably well. After a transplant your white cells cannot mount a normal defence, so fever counts as a medical emergency and antibiotics are meant to start within hours (CDC).
• Call your transplant team the same day if you get a spreading rash or reddened palms and soles, watery diarrhoea that keeps coming, persistent vomiting, or yellowing of the eyes or skin. In an allogeneic transplant, that group of signs is how graft-versus-host disease usually announces itself, and it is treatable when caught early.
• Call your transplant team within a day or two if mouth sores are stopping you eating or drinking, new bruises appear without a knock, your central line site looks pink or feels tender, or you notice dry gritty eyes, a dry mouth or tightening skin months down the line. Those later signs can be chronic graft-versus-host disease.

Anyone living with you should know where the transplant number is kept. Fever after a transplant is one of the few things that genuinely cannot wait until morning.

• National Cancer Institute — Stem Cell Transplant
• National Cancer Institute — Infection and Neutropenia during Cancer Treatment
• MedlinePlus — Graft-versus-host disease
• CDC — Fever and Cancer Treatment