The need for a stem cell transplant arises when the body requires a restoration of the blood-forming stem cells. These cells are often destroyed by high dosage of chemotherapy drugs and intensive energy from radiation therapy. You can learn more about the interrelation of stem cells and chemotherapy in cancer treatment at Chemotherapy and Stem Cells.
Stem Cell Transplant are most often used in blood-related cancer diseases such as leukemia and lymphoma. Sometimes they are also used to treat conditions of neuroblastoma and multiple myeloma. There are 2 main types of stem cell transplant, namely:
- Autologous: stem cells are taken from the person who will get the transplant before the procedure takes place.
- Allogenic: stem cells are taken from a match or unrelated benefactor who donates them.
Types of Leukemia
It is important to know that leukemia is not like other kinds of cancer that starts in specific body organs that can spread to the bone marrow. Leukemia starts with the blood-forming cells in the bone marrow itself and travels to the bloodstream when leukemia cells are already crowding out normal cells within the bone marrow. When leukemia cells get to spill into the bloodstream, it causes the number of white blood cells to increase within the body.
NOT ALL LEUKEMIAS ARE THE SAME. There are specific types of this disease and it is important to get informed because it will allow your doctor to choose the best treatment for each individual type.
Acute or Chronic Leukemia
These refer to the state of maturity or immaturity of the leukemia cells. In chronic leukemia, cells are only partly matured. Cells in this condition may look fairly normal but they don’t serve their functions in fighting against infections like what normal white blood cells do. Problems caused by chronic leukemia can take longer years to be recognized, consequently, they are harder to cure than that of acute leukemia.
In acute leukemia, cells cannot mature properly. In this case, without any treatment, patient who suffers from this condition can only live in a few months because immature cells continue to propagate and build up. Specific types of acute leukemia may respond positively to treatments but other types have less positive reaction towards it.
Kinds of Chronic Leukemia
Chronic Myeloid Leukemia (CML), also called myelogemous leukemia, starts in certain blood-forming cells specifically in immature cells of myeloid cells (the cells that make red blood cells (RBC), platelets, and most types of white blood cells (WBC) except lymphocytes. CML takes place when genetic change occurs in the body. This change creates an abnormal gene called BCR-ABL. This gene fusion is formed when pieces of chromosomes 9 and 22 break off and trade places. The ABL gene from chromosome 9 joins the BCR gene in chromosome 22 which forms the BCR-ABL gene, which turns into a CML cell. When leukemia cells spill over the blood, it may stay on other organs of the body including the spleen. Most cases of CML happen to adults and rarely to children.
Chronic Lymphocytic Leukemia (CLL) is a blood and bone marrow disease which is the most common type of leukemia in adults. Common form of CLL starts in B lymphocytes. Usually, it occurs after middle age and rare on children. This type of leukemia starts in the bone marrow with a specific type of WBC called lymphocytes. However, there are some rare types of leukemia that have the same characteristics as the CLL. These include:
- Prolymphocytic Leukemia (PLL): In this type, cancer starts in the immature version of normal cells called prolymphocytes which are either from B or T lymphocytes. PLL may happen (tends to be aggressive) to someone who has already an existing condition of CLL but is also possible to people with no CLL. Both B-PLL and T-PLL are more aggressive than CLL.
- Large Granular Lymphocyte (LGL): Cancer cells are large with either features of T lymphocytes or natural killer (NK) cells which are also another type of lymphocytes. Though LGL leukemia slowly grows, its small amount can still be aggressive.
- Hairy Cell Leukemia (HCL): This type only accounts for about 2% of all leukemias. Its name was derived as to how it may be seen on the microscope, with fine projections on their surface which make them look “hairy.” Cancer cells n this type are from type B lymphocytes but are different from those in CLL.
Kinds of Acute Leukemia
The term acute connotes the quick progression of the leukemia cells without treatment and can cause death in a few months. There are two types of acute leukemia, the acute lymphocytic leukemia (ALL) and the acute myeloid leukemia (AML).
The ALL, also known as acute lymphoblastic leukemia starts from the immature version of lymphocytes. This type of cancer can reach other parts of the body which includes the lymph nodes, liver, spleen, central nervous system (brain and spinal cord), and testicles.
The AML, also called by names of (1) acute myelocytic leukemia, (2) acute myelogenous leukemia, (3) acute granulocytic leukemia and (4) non-lymphocytic leukemia. Most AML build up from undeveloped white blood cells (excluding lymphocytes) but some cases may also from other types of blood-forming cells.
Stem Cell Transplant Treatment for Leukemia
In Autologous Transplant
The danger on this type occurs when cancer cells have also been collected along with the healthy stem cells. This means that cancer cells may just be injected into your bloodstream again after high dosages of chemotherapy and radiation.
Another disadvantage of this transplant is that the body’s immune system cannot be strengthened. It is because it continually weakened by chemo and radiation. Consequently, cancer cells can escape the immune system’s defense just like they did before.
In Allogeneic Transplant
Risks in adopting this type occur when the grafted (transplanted) stem cells fail to fight against the cancer cells. It is because they weren’t able to settle in the bone marrow.
This is the reverse of the graft-versus-cancer effect. It’s where donor stem cells are able to make their own immune system that potentially kills the patient’s cancer cell.
Furthermore, there is a risk of infection even if the donor has been checked prior the transplant. This may happen due to the body’s recent infection in which the immune system had successfully stabilized. Infections may surface after the transplant because the immune system has been suppressed by medicines called immunosuppressive drugs.
This type of transplant is most commonly used to treat specific types of cancer. It is used to leukemia, lymphomas, multiple myeloma, myelodysplastic syndrome, and another type which is the aplastic anemia.