Hematopoietic Stem Cell Transplant

A hematopoietic stem cell transplant (HSCT) is a procedure in which a patient's bone marrow is replaced before being replenished with either the patient's own bone marrow, or with an outside donor's bone marrow. In cancer, it is performed in order to rid a patient of cancer cells in their body and to rebuild their immune system with the replenished, healthy marrow, which goes about the business of producing every type of blood cell necessary for the body.

An hematopoietic stem cell transplant is also know as a bone marrow transplant and a stem cell transplant. These terms refer to the same procedure.

Pre-transplant preparative regimen

Cancer patients are prepped for a hematopoietic stem cell transplant by receiving high-dose chemotherapy and radiation. The purpose is to kill every last cancer cell in the patient's body; but what happens in the process is that all the cells in the bone marrow are destroyed. For this reason, the patient will have either banked his or her own bone marrow beforehand (called an autologous stem cell transplant) if their bone marrow is free of cancer, or he or she will receive the bone marrow of a donor (allogeneic stem cell transplant).

One way or the other, replenishing the bone marrow is meant to rebuild the patient's immune system within a body that should be completely free of cancer. To this end, HSCTs are designed to be curative procedures. However, because they are serious procedures with significant risks to the patient's health and well-being, they are generally considered the last line of defense against a refractory cancer.

Hematopoietic Stem Cell Transplant Side Effects

Transplant patients will possibly have to endure some difficult side effects with hematopoietic stem cell transplant stemming from the high-dose chemo and radiation, including nausea and vomiting, diarrhea, mouth sores, hair loss, infertility, some organ toxicity (depending on the dose and type of chemotherapy), and possibly, down the road, a secondary cancer developing from the preparative regimen.

Hematopoietic Stem Cell Transplant Patients

Because an HSCT patient temporarily does not have an immune system to speak of, they generally stay in hospital rooms which are as sterile as possible, and their direct physical contact with others is extremely limited. The patient may require transfusions of red blood cells or platelets. Every step and effort must be taken in order to avoid the possibility of infection. The hospital stay itself can last for anywhere between several weeks to several months, and follow-up returns to the hospital are extremely frequent after discharge. They include a seemingly endless array of exams, scans and blood draws.

Hematopoietic Stem Cell Transplant Risks

HSCT patients face a number of significant risks, the chief among them being a disease known as graft-versus-host-disease (GVHD). This can be acute (occurring within the first 100 days of the transplant) or chronic (occurring after the 100 days). In GVHD, the transplanted marrow begins to attack the patient's organs (it is only possible in an allogeneic SCT). Please see the links at the bottom of this article for longer discussions of GVHD.

About one percent of allogeneic SCTs end in graft failure, meaning the transplant failed to rebuild the immune system.

Finally, there is a significant risk of death from complications related to hematopoietic stem cell transplant, whether it be from preparative treatments, GVHD, or any of the myriad infections that are possible post-transplant. In sum it is a serious procedure that each patient must discuss at length with his or her medical team as well as his or her loved ones.

Sources

UpToDate.com, HSCT Patient Information

The National Marrow Donor Program