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Sanctuary Sites: These are areas in which it is difficult to get a sufficient concentration of chemotherapy to destroy leukemia cells. In acute lymphoblastic leukemia, the coverings (meninges) of the brain and spinal cord and the testes are notable sanctuary sites.

Secondary Leukemia: A leukemia arising as a result of previous chemotherapy, radiotherapy, or both. This can occur after treatment of lymphoma or other cancers such as breast or ovarian cancer.

Septicemia: The presence of bacteria or fungi in the blood usually as a result of spread from another site of infection such as skin, bowel, or urinary tract. It is usually associated with high fever, shaking chills, and heavy sweating. It is more likely to occur in patients with marked deficiencies of white blood cells.

Serum: The liquid portion of the blood after it clots. The blood is collected in sterile tubes without an anticoagulant and allowed to clot. The liquid portion or serum is removed after the clot forms. Most chemical tests are performed using serum.

Solitary Myeloma: Tumor present in one bone as determined by marrow examination and imaging studies of bones.

Somatic Mutation: The alteration of a gene in the cell of a specific tissue. If the mutation occurs in a gene that normally controls cell growth or cell life-span, referred to as proto-oncogene, the mutated gene may become a cancer-causing gene or oncogene. This change is called “somatic” to distinguish it from a germ cell mutation, which can be passed from parent to offspring. Cases of leukemia, lymphoma or myeloma are caused by a somatic mutation in a primitive marrow (blood-forming) or lymphatic system cell. If the mutation results from a major abnormality of chromosomes such as a translocation, it can be detected by cytogenetic examination. Sometimes the alteration in the gene is more subtle and requires more sensitive tests to identify the oncogene.

Spleen: An organ of the body in the left upper portion of the abdomen just under the left side of the diaphragm. It contains clusters of lymphocytes and also filters the blood of old or worn out T-cells. It is often affected in lymphocytic leukemias and lymphomas. Enlargement of the spleen is referred to as “splenomegaly.” Removal of the spleen by surgery is referred to as “splenectomy.” Removal of the spleen is used to treat certain diseases. Most of the functions of the spleen can be performed by other organs, such as the lymph nodes and liver.

Splenectomy: Surgical removal of the spleen. This procedure is occasionally done in leukemia or lymphoma as part of a patient's treatment if the disease is unresponsive to drug therapy and an enlarged spleen is causing severe difficulty.

Splenomegaly: Enlargement of the spleen.

Staging: A formal assessment of the spread of disease through the body. It is especially useful in assessing the lymphomas. It may be important in determining the type of treatment selected. It is also useful in cooperative clinical trials so that assessment of treatment results can be examined by the stage of disease of the patient treated.

Stem Cell: These are primitive cells in marrow that are required to make red cells, white cells and platelets (see “hematopoiesis”). Generally, the stem cells are largely found in the marrow but some leave the marrow and circulate in the blood. Using special techniques, the stem cells in blood can be collected, preserved by freezing and, later, thawed and used for stem cell therapy. (See Hematopoiesis)

Stem Cell Transplantation: This is a technique that was developed to restore the marrow of patients who had lethal injury to that site. Such injury can occur because of primary marrow failure, destruction of marrow by disease, or intensive chemical or radiation exposure. As first designed, the source of the transplant was the marrow cells of a healthy donor who had the same tissue (HLA) type as the patient. Usually, the source was a brother or sister. Donor programs have been established to identify unrelated donors who have a matching tissue type. This approach requires screening tens of thousands of unrelated individuals of similar ethnicity. The transplant product is a very small fraction of the marrow cells called “stem cells.” These stem cells not only reside in the marrow but also circulate in the blood. They can be harvested from the blood of a donor by treating the donor with an agent or agents that cause a release of larger numbers of stem cells into the blood and collecting them by hemapheresis. The stem cells circulate in large numbers in fetal blood also, and can be recovered from the placental and umbilical cord blood after childbirth. The harvesting, freezing and storing of “cord blood” has provided another source of stem cells for transplantation. Since blood as well as marrow is a very good source of cells for transplantation, the term “stem cell transplantation” has replaced “bone marrow transplantation” as the general term for these procedures. If the donor is an identical twin, the transplant is called “syngeneic,” the medical term for genetically identical. If the donor is a non-identical sibling, the transplant is called “allogeneic,” indicating it is from the same species and in practice nearly always matching in tissue type. The term “matched-unrelated” is applied to the donor recruited from large volume screening programs searching for the rare individual who is very similar in tissue type to the patient. The important technique of harvesting a patient's marrow, freezing it and returning it to them after they have received intensive chemotherapy and or radiotherapy for their underlying disease has been referred to as autologous (self) or auto-transplantation. This term is a well-entrenched misnomer since transplantation implies transferring tissue from one individual to another. This technique would better be referred to as autologous marrow infusion. (See Autologous Stem Cell Infusion)

Stem Cell Harvest: The collection of primitive cells capable of restoring blood cell production. These cells can be obtained from the marrow or blood of a donor. If the donor is another individual, such as a sibling, parent, or unrelated person, the stem cells are called allogeneic (syngeneic if an identical twin is the donor). In some cases in which a donor is not available or the recipient too old to receive an allogeneic stem cell transplant, the patient's own stem cells may be harvested and used to restore blood cell production after very intensive therapy for a blood cell cancer. This procedure is referred to as Autologous or self-transplantation. In the latter case, normal stem cells can be obtained when a patient is in remission. This approach has been used in acute leukemia, chronic myelogenous leukemia, myeloma, and lymphoma. In some cases tumor cells remain in the marrow and sometimes can be eradicated by treatment of the stem cell harvest with a chemical or immune treatment to minimize tumor cells.

Subcutaneous Injection: An injection into tissue immediately under the skin.

Syngeneic Human Transplantation: The transplantation from an identical twin donor to an identical twin recipient. Thus there is no genetic or, therefore, immune disparity and no likelihood of host versus graft (rejection) or graft versus host reaction. One exception to this rule is syngeneic transplantation for aplastic anemia in which an acquired autoimmune abnormality of T-lymphocytes in the recipient can attack donor cells. In this case the recipient usually receives pretreatment (Conditioning) to destroy the auto-reactive lymphocytes.