Stem cell transplant is used to facilitate high-dose chemotherapy. Stem cell therapy does not fight cancer. It helps the body recover after the high-dose chemotherapy which is used to treat cancers including multiple myeloma, non-Hodgkin's lymphoma, Hodgkin's disease and relapsed testicular cancer.
Before high-dose chemotherapy and stem cell transplantation are used, medical oncologists administer multiple cycles of standard chemotherapy over several months. The standard chemotherapy is used to either reduce residual cancer cells or to determine if the patient will benefit from high-dose chemotherapy and stem cell transplantation.
The first step in the high-dose chemotherapy/stem cell transplant process is a thorough evaluation to determine the patient's likelihood of benefiting from the treatment.
The patient's medical records are reviewed. Previous chemotherapy results, scans and other factors are considered to determine if the patient is likely to benefit from high-dose chemotherapy and stem cell transplantation. At this time the doctor will order other tests to establish whether the patient is physically able to go through the high-dose chemotherapy and stem cell transplant process.
MUGA scan or echocardiogram
These tests measure how well the patient's heart pumps blood.
A MUGA (MUltiple Gated Acquisition) scan uses a radioactive substance injected into the patient's bloodstream and a gamma camera to produce a moving image of the heart as it beats.
An echocardiogram uses ultrasound to produce a moving image of the heart. It is similar to sonograms used to form images of babies in the womb.
Electrocardiograms use sensors placed on various parts of the body to chart the heart's electrical activity.
CT or PET scan
CT (computed tomography) makes multiple x-rays scans and assembles them together to form very accurate images of structures within the body. Sometimes a contrast dye is injected to enhance clarity and definition. CT scans can determine location of tumors precisely.
PET (positron emission tomography) uses a radioactive material injected into the body and a gamma camera to detect the metabolic activity of cells. PET scans are not as precise at determining tumor location, but are extremely accurate at establishing tumor activity.
Frequently a combination PET/CT scan is used to simultaneously determine tumor location and activity.
Pulmonary function test
A Pulmonary function test (or PFT) determines how much air is taken into the lungs when the patient inhales, how much is let out with each exhale and how quickly breath is exhaled. This helps doctors determine whether there any problems with the patient's lungs.
Chest x-rays are used to evaluate lung condition.
Blood tests are used to determine if the patient's liver and kidneys are functioning properly. Blood is also tested for previous infection and for exposure to viruses including hepatitis and HIV.
Bone marrow aspirate and biopsy
In some cases a bone marrow aspirate and biopsy is needed to evaluate the bone marrow for disease. In this procedure a local anesthetic is used as a needle is inserted into the pelvic bone and a sample of marrow and bone tissue is withdrawn for biopsy.
Since high-dose chemotherapy can cause infertility in both women and men, patients who are considering having children in the future are counseled about the risks of infertility and possible variations in treatment that may preserve fertility. In cases in which there are no possible variations patients may want to consider reproductive options such as egg harvesting or sperm banking.
Mobilization of stem cells
The patient's bone marrow must produce and release an unusually large number of stem cells before the stem cells can be collected. Patients are given medications to increase stem cell production and release. Calcium supplements are given for a few days prior to stem cell harvesting to minimize the effect of calcium loss which occurs during stem cell harvesting.
Harvesting stem cells
An apheresis catheter is inserted into a large vein in the patient's shoulder. (The port-a-cath which some patients may have had inserted for standard chemotherapy is not large enough for stem cell collection.)
The apheresis catheter is inserted under anesthesia at Fort Sanders Regional Medical Center, across the street from Thompson Cancer Survival Center.
Stem cells are harvested at Thompson Cancer Survival Center in three- to four-hour sessions every day until enough stem cells have been collected. It usually takes one to four days to collect enough stem cells.
In the stem cell harvesting process blood is removed from the patient's body, circulated through an aspheresis machine and returned to the patient's body. The aspheresis machine separates out the stem cells and retains them in plastic bags. Although all of the patient's blood goes through the aspheresis machine several times in each session, only about one-half cup is inside the machine at one time.
Stem cell harvesting is an outpatient procedure, and a nurse is present during the entire procedure. Blood counts are monitored, and blood pressure and pulse rate are checked before and after the procedure.
The patient must sit or lie still throughout the procedure, and may feel dizzy, light-headed, cold or numb around the lips or fingertips.
Processing and storing stem cells
The frozen stem cells are put into a liquid nitrogen freezer where they are preserved until time for transplantation.The bags of collected stem cells are taken to Thompson's stem cell processing laboratory where the stem cells are counted and examined to be sure they are not damaged and that they are sterile.
Next the stem cells are mixed with a preservative called DMSO. Then the bags of cells are placed in aluminum containers and put into a slow-rate freezer where they are gradually taken to a temperature of -90°.
The frozen stem cells are put into a liquid nitrogen freezer where they are preserved until time for transplantation.
High-dose chemotherapy (also called conditioning chemotherapy) is administered over a one- to six-day period, depending on the patient's specific diagnosis.
Whenever possible, high-dose chemotherapy therapy is given on an outpatient basis at Thompson Cancer Survival Center. When inpatient high-dose chemotherapy is necessary it is done under the supervision of Thompson physicians at Fort Sanders Regional Medical Center.
Like all chemotherapy, high-dose chemotherapy may have side effects. These will vary depending on the medicines used for the patient's specific cancer. A Thompson physician and nurse discuss the probable side effects of high-dose chemotherapy with each patient.
Transplantation of stem cells
After high-dose chemotherapy, patients rest for a day or two to allow the drugs to be cleared from their systems.
Patients receive stem cell transplants either as outpatients at Thompson Cancer Survival Center or as inpatients at Fort Sanders Regional Medical Center. In either case, the process is the same:
Recovery and follow-up
- Before the transplant begins patients are examined by a Thompson physician and a nurse.
- The patient receives medication to help prevent side effects.
- A processing laboratory staff member brings the still-frozen bags of stem cells to the patient's bedside, the bags are removed from the aluminum containers and the bags of stem cells are thawed one at a time in warm water.
- The cells are removed from the bags and transfused through the vein. Each bag takes approximately five minutes to transfuse.
- The DMSO used as a preservative causes some patients to sense a taste and smell similar to garlic during the transfusion and for a day or two afterward. Some patients may become nauseated. Other side effects are also possible.
High-dose chemotherapy severely disables the patient's immune system. The stem cells which were harvested from the patient before high-dose chemotherapy and transfused back into the patient after high-dose chemotherapy were not damaged by chemotherapy. It takes these undamaged stem cells approximately ten to fourteen days to graft to the bone marrow and begin producing new red, white and platelet blood cells.
Until engraftment occurs, patients are susceptible to infections (because of the lack of white blood cells), bleeding (because of lack of platelets) and fatigue (because of lack of red blood cells).
The transplant team watches the patient closely while waiting for engraftment. Antibiotic, antiviral and antifungal medicines are given to the patient during this period to prevent infections.
After the engraftment is complete the patient can gradually return to normal activities. Initially exposure to infection should be avoided. The transplant team provides complete guidelines.
When patients return home, their personal physician, and medical oncologists resume caring for them. These doctors are kept fully informed of all aspects of patient care during the high-dose chemotherapy/stem cell transplant process, so they are completely aware of their patients' conditions and any special medical needs.