Before giving you your new blood stem cells in the form of bone marrow, peripheral blood stem cells (PBSC), or cord blood, it is necessary to prepare your body to receive the new blood forming cells. This process is called the preparative regimen or conditioning regimen.
The days you receive the preparative regimen are “minus” days (or – days). The number of days will vary, depending on your regimen. For example, you may receive treatment on day – 8 through day – 1. Someone else may receive treatment on day – 6 through day – 2. This part of the transplant process is the “countdown” to transplant day, or ‘Day Zero’.
There are 2 main types of preparative regimens:
- Standard intensity regimens – These are also called myeloablative regimens. These regimens use high doses of chemotherapy and sometimes radiation.
- Reduced-intensity regimens – These are also called non-myeloablative regimens. These regimens use relatively lower doses of chemotherapy with or without radiation.
Doctors choose the type of preparative regimen for patients based on their disease and overall health factors. Your transplant team can explain why a particular type of regimen is the best choice for your transplant.
Preparing your body for transplant
Download a copy of Your guide to the transplant process to help you understand what to expect during the transplant process.
- Standard intensity preparative regimens use high doses of chemotherapy and possibly radiation therapy. The high-dose treatment helps to destroy any remaining diseased cells in your body. For allogeneic transplants, which use cells from a family member, unrelated donor or cord blood unit, the preparative regimen also weakens your immune system. Weakening your immune system helps to prevent it from attacking your donated cells after the transplant.
- Doses of chemotherapy and radiation therapy in the preparative regimen can be higher than would be used to treat the same disease in a patient who was not getting a transplant. While these higher doses may cause more severe side effects, they also destroy more diseased cells.
- All preparative regimens are given in the days leading up to your transplant, and may last 2 to 10 days or even longer. The length of this treatment depends on your disease, your age, and any previous treatments you may have had.
- The preparative regimen may be given as an outpatient, which means you can leave the transplant center after each day of treatment. Or, you may need to stay in the hospital throughout the preparative regimen.
- All preparative regimens use chemotherapy. Some also include radiation therapy. A single radiation therapy treatment lasts from 10 to 20 minutes. Radiation therapy may happen all in one day, or it may be spread out over several days, depending on the total dose you will receive.
Common early side effects of the preparative regimen
High doses of chemotherapy and radiation therapy can cause side effects. You might have some side effects as soon as you begin your preparative regimen. Some go away quickly after your regimen stops. Others can last longer after you complete your regimen and receive your transplant. Side effects will be treated to make you more comfortable. Common side effects include:
- Lack of appetite
- Mouth sores
- Hair loss
- Skin rash
Serious early side effects
There are other less common side effects that can appear in the first month after the preparative regimen. While less common, some of these can be serious. Your transplant team will take steps to prevent these side effects or treat any side effects that develop. Some of these side effects include:
- Damage to the liver
- Lung damage
- Damage to the heart muscle
You will have your transplant of marrow, peripheral blood stem cells (PBSC) or cord blood cells shortly after completing your preparative regimen. To read about the next step of your transplant process, see Transplant day.