blood cancers: Malignancies of the body's blood-forming and immune systems in which abnormal cells in excessive amounts interfere with the body's production of healthy blood cells, making the body unable to protect itself against infections. New cases of leukemia, lymphoma, Hodgkin's disease and myeloma account for 9 percent of cancer cases diagnosed in the United States, and about 59,200 persons die from the diseases each year.

bone marrow: A spongy tissue inside bones that produces blood cells.

bone-marrow transplant: An aggressive procedure that replaces a patient's marrow that has been destroyed as a side effect of giving high doses of cancer-fighting chemotherapy or radiation therapy.

Cell Therapeutics Inc.: A Seattle-based biotech company formed by two Hutchinson Center doctors hoping to profit from their research. Its research was used in The Hutch's breast-cancer study.

Cipro: The brand name for a common antibiotic; used by the Hutch and initially Cell Therapeutics as part of a mixture of drugs to protect vital organs from high doses of chemotherapy.

endocrinologist: A doctor who specializes in the glands and hormones that regulate growth, metabolism, sexual development and reproduction.

Genetic Systems Co.: A Seattle biomedical company that owned rights to some of the drugs being tested in Protocol 126.

graft: Tissue transplanted in a part of the body to repair a defect. The graft may be autologous (from another part of the patient's body), allogeneic (from a genetically nonidentical donor of the same species) or syngeneic (from a genetically identical twin).

graft-versus-host disease, or GVHD: An immune-system reaction that may occur after a bone-marrow transplant in which the donated bone marrow attacks the "foreign" cells of the recipient, whose immune system has been destroyed by cancer therapy and transplant preparation. GVHD shows up as dermatitis -- red, itchy, blistery skin, starting in the palms and soles -- to more severe forms of hepatitis (inflammation of the liver) and enteritis (inflammation of the intestine).

graft failure: A condition that occurs when transplanted white blood cells fail to reach or maintain the levels necessary to protect the host from infectious diseases. Indicates the host body has rejected the donor graft. Fatal 99 percent of the time in bone-marrow transplants.

Human Subjects Review Committee: Internal panel charged by federal law with protecting patient rights. Renamed Institutional Review Board.

immunologist: A doctor with special training and experience in the study of components of the immune system, tissues, organs and processes that identify material as abnormal or foreign and prevent it from harming the body.

Institutional Review Board, or IRB: A local board at research centers whose job is to review experiments for the protection of patients.

Lisofylline: A patented drug that Cell Therapeutics hoped would protect patients receiving high-dose chemotherapy from organ damage; it was derived from two other drugs, pentoxifylline and ciprofloxacin. Studies showed it to be ineffective.

leukemia: A malignancy of the blood-forming cells. Classified by cell type (myeloid or lymphoid) and speed of progression (acute is fast, chronic is slow). Characterized by abnormal increase in the number of white blood cells. Leukemias may be in remission, accelerated or blast crisis, indicating their speed of malignancy. Chronic Myelogenous Leukemia (CML) in first remission is the most curable. Incidence in the United States is estimated at 13 per 100,000 people per year. Cause is unknown. Risk factors include radiation and chemical exposure.

lymphoma: A malignancy of the lymphoid cells that constitute 20-30 percent of normal white blood cells.

matched-sibling donor: A brother or sister whose tissue type matches the patient's in six key measurements. Each sibling has a 25 percent chance of being a perfect match.

monoclonal antibodies: Artificially produced proteins of exceptional purity and specificity derived from hybrid cells capable of producing a continuous supply of identical antibodies. Like a key in a lock, antibodies lock in to particular antigens, or cell-surface identifying markers. Compared to "guided missiles."

neutropenia: An abnormal decrease in a type of white blood cell.

Office of Protection from Research Risks, or OPRR: The federal agency, now called the Office for Human Research Protections, responsible for policing abuses in experiments funded by the National Institutes of Health.

oncologist: A doctor with special training and experience in the study of tumors.

pentoxifylline: A drug used to treat leg cramps that Hutch researchers hoped would also help cancer patients. Initial research showed amazing results but follow up studies showed PTX was a failure.

Protocol 126: A Hutchinson Center experiment using monoclonal antibodies to identify and kill T-cells in 82 patients receiving bone-marrow transplants from tissue-matched sibling donors, 1981-1993.

Protocol 159: A Hutchinson Center experiment using monoclonal antibodies at the same time as Protocol 126. Dr. Frederick Appelbaum was principal investigator. The Hutch review board expressed concerns about both.

Protocol 681: A Hutchinson Center experiment to see how much high-dose chemotherapy doctors could safely give breast-cancer patients in combination with rescue drugs meant to protect vital organs. Four women were killed by the chemotherapy, including Kathryn Hamilton.

regimen-related toxicities (RRT): Deaths or injuries caused by treatment.

stem-cell transplant: A procedure in which doctors transplant primitive, immature cells that give rise to all other blood cells. Studies conclude that in many cases stem-cell transplants are safer and more effective than the old form of bone-marrow transplant. Currently most so-called bone-marrow transplants focus on stem cells obtained from the blood-making marrow in bone cavities, while so-called stem-cell transplants obtain the donor cells from peripheral blood in the veins.

T-cells: White blood cells that patrol the body to eliminate infected and cancerous cells and foreign materials. T-cells are named after the thymus gland, where they mature.

T-cell depletion: Destruction of 99.9 percent of T-cells in Protocol 126.

tissue typing: Procedure to determine the match between patient and donor marrow and other tissues, measured by proteins called Human Leukocyte Antigens or HLA on the surfaces of most cells in the body. If a patient and donor are matched, the transplant has a good chance to succeed.