ALK-positive (or ALK-negative)
Tumor cells that produce a special enzyme called Anaplastic Lymphoma Kinase.   Approximately half of all cases of systemic ALCL cells show an unusual picture in their chromosomes known as t(2,5) translocation. This genetic change is linked to the production of a special protein (enzyme) called Anaplastic Lymphoma Kinase. The presence of this enzyme is termed ALK-positive (+ve). Absence of the enzyme is ALK-negative (-ve).

Anaplastic
Loss of differentiation of cells. Tumor cells lose some of the normal distinctive appearance of well developed "differentiated" healthy cells.

Antibody
Antibodies are Y-shaped proteins designed to attach specifically to the outside on the target cell. They are produced normally by the body in response to infections or foreign material (such as transplanted tissue). Antibodies can now also be produced in laboratories and are used in the treatment of a number of diseases. Antibodies have the ability target and bind to specific types of cells based on unique markers (antigens) found on the surface of cells. Once on the cell they can assist the body's natural defenses to kill the tumor cell or can signal the tumor cell itself to die.

Antibody-based therapies have now been shown to produce tumor shrinkage and increased survival in a number of cancers including breast cancer, colorectal cancer and some other forms of lymphoma know as B-cell lymphomas. These targeted therapies have proven to be effective and, in general, with toxicity profiles more tolerable than conventional chemotherapeutic regimens. New antibodies are currently being tested in clinical trials for systemic ALCL and primary cutaneous ALCL

Antibody-drug conjugate
Antibodies linked to drugs with antitumor activity. Antibody-drug conjugates, or ADCs, are designed to deliver the cell-killing payload directly to tumor tissue by utilizing the targeted antibody. This may result in fewer side effects than is traditionally expected with cancer chemotherapy.

Antigen
A protein or carbohydrate that the body regards as foreign and thus is capable of stimulating an immune response. This reaction often involves production of antibodies. Cancer cells have certain antigens that can be found by laboratory tests. They are important in cancer diagnosis and in monitoring response to treatment. Other cancer cell antigens play a role in immune reactions that may help the body's resistance against cancer.

B-cells
B-cells (B-lymphocytes) are part of the immune system. They originate in the bone marrow and mature into plasma cells that secrete antibodies, the proteins that recognize and attach to foreign substances known as antigens. B-cells play a key role in the development of certain forms of cancer and autoimmune disease.

Biopsy
A procedure to obtain tissue for diagnosis. Because the appearance of a lymph node is important in categorizing the type of lymphoma that may be present, surgical removal of an entire, swollen lymph node or nodes is necessary (lymph node biopsy).

Bone marrow transplant
A complex and sometimes risky treatment that may be used when cancer is advanced or has recurred, or as the main treatment in some types of leukemia or lymphoma. A portion of the patient's or donor's bone marrow is withdrawn, cleansed, treated and stored. The patient is given high doses of chemotherapy to kill the cancer cells. The drugs also destroy the remaining bone marrow, thus robbing the body of its natural ability to fight infection. The cleansed marrow is given by transfusion (transplanted) to rescue the patient's immune defenses.

Cancer
A group of diseases characterized by abnormal cells that grow and spread uncontrollably. A mass, or collection, of cancer cells called a malignant tumor frequently grows rapidly, invading and destroying nearby tissue. Cancer cells often travel to other body parts where they grow and replace normal tissue. This process, called metastasis, occurs as the cancer cells get into the bloodstream or lymph vessels.

CD30
A protein found on the surface of some cells, notably those of ALCL. CD30 only appears on a small number of other cell types in the body and thus provides a way to distinguish the tumor cells. This marker is widely used to diagnose ALCL.

Chemotherapeutic
A drug administered to stop the growth of or to kill cancer cells.

Chemotherapy
Treatment with anti-cancer drugs. Numerous drugs have been developed for this purpose and most act to injure the DNA of the cells. When the DNA is injured, the cells cannot grow or survive. Successful chemotherapy depends on the fact that malignant cells are somewhat more sensitive to the drugs than normal cells.

Chemotherapy is often used with surgery or radiation to treat cancer when the cancer has spread, when it has come back (recurred), or when there is a strong chance that it could recur.

Clinical trials
A planned study of a new drug or treatment approach or a new application of an existing drug or approach to evaluate safety, side effects and efficacy. Such trials are required to gain the information required by the Food and Drug Administration (FDA) to determine efficacy and safety before approving a drug for marketing. Federal guidelines for informed consent of participants must be followed.

Cutaneous
Pertaining to the skin.

Computed tomography (CT) Scan
An imaging test in which many x-rays are taken from different angles of a part of the body. These images are combined by a computer to produce cross-sectional pictures of internal organs. Except for the injection of a dye (needed in some but not all cases), this is a painless procedure that can be done in an outpatient clinic. It is often referred to as a "CT" or "CAT" scan.

Hematologic malignancy
Cancer of the blood or bone marrow, including leukemia and lymphoma.

Hodgkin Lymphoma (Hodgkin's disease)
A type of B-cell lymphoma that usually begins in the lymph nodes of the neck, axillae and chest. Diagnosis is often aided by the identification of characteristic tumor cells referred to as Reed-Sternberg cells. These are an unusual type of malignant B-cell.   Hodgkin lymphoma may be treated with radiation therapy if localized or with a four or more combination of chemotherapeutic drugs if widespread.

Ki-1
Former name of CD30, a protein present on the surface of some cells, notably those of ALCL.

Lymph nodes
Small structures, the size of beans, that contain large numbers of lymphocytes. These nodes are distributed throughout the body. In patients with lymphoma, the malignant lymphocytes grow and expand the lymph nodes so that they may be enlarged. This enlargement of lymph nodes can be seen, felt, or measured by computed tomography (CT) scan or magnetic resonance (MR) imaging depending on the degree of enlargement and location.

Lymphocytes
A type of white blood cell that is the essential cell type in the body's immune system. There are three major types of lymphocytes: B lymphocytes that produce antibodies to help combat infectious agents like bacteria, viruses and fungi; T lymphocytes that have several functions, including assisting B lymphocytes to make antibodies, and natural killer (NK) cells that can attack virus-infected cells or tumor cells.

Lymphoma
Lymphoma is a general term for a group of cancers that originate in the lymphatic system. Lymphoma results when a lymphocyte (a type of blood cell) undergoes a malignant change and accumulates because of exaggerated multiplication and/or a failure to die. This excess of lymphocytes interferes with the growth of normal blood cells and creates masses of tumors in lymph nodes. The two main types of lymphoma are Hodgkin's disease and non-Hodgkin's lymphoma.

Monoclonal antibody (mAb)
Genetically engineered antibodies of identical molecular structure that recognize and bind to a single, specific cell-surface antigen. Monoclonal antibodies are capable of selectively targeting specific cells, such as cancer cells, while bypassing most normal tissue. In therapeutic applications, they can be used alone, in combination with other therapies, or they can be used to deliver drugs, toxins or other payloads.

Non-Hodgkin Lymphoma
A cancer of the lymphatic system. What distinguishes non-Hodgkin lymphoma from Hodgkin lymphoma is the absence of a type of cell called the Reed-Sternberg cell. This cell is present only in Hodgkin lymphoma. The treatment methods for Hodgkin and non-Hodgkin lymphomas are very different.

Positron emission tomography (PET) Scan
A scan that creates an image of the body (or of biochemical events) after the injection of a very low dose of a radioactive form of a substance such as glucose (sugar). The scan computes the rate at which the tumor is using the sugar. In general, high-grade tumors use more sugar than normal and low-grade tumors use less. PET scans are especially useful in taking images of the brain, although they are becoming more widely used to find the spread of cancer of the breast, colon, rectum, ovary, or lung. PET scans may also be used to see how well the tumor is responding to treatment.

Primary
The original tissue source of the tumor before any spread of the disease.

Radiation therapy (radiotherapy)
Treatment with high-energy rays (such as x-rays) to kill or shrink cancer cells. The radiation may come from outside of the body (external radiation) or from radioactive materials placed directly in the tumor (internal or implant radiation). Radiation therapy may be used to reduce the size of a cancer before surgery, to destroy any remaining cancer cells after surgery, or, in some cases, as the main treatment.

Refractory
A disease that does not respond to a certain form of therapy.

Relapsed / Recurrent
A patient or disease that has fallen back into its previous condition after experiencing a partial recovery. Local recurrence means that the cancer has come back at the same place as the original cancer. Regional recurrence means that the cancer has come back in the lymph nodes near the first site. Distant recurrence is when cancer metastasizes after treatment to organs or tissues (such as the lungs, liver, bone marrow, or brain) farther from the original site than the regional lymph nodes.

Remission
A disappearance of evidence of a disease, usually as a result of treatment. The terms "complete" or "partial" are used to modify the term "remission." Complete remission means all evidence of the disease is gone. Partial remission means the disease is markedly improved by treatment, but residual evidence of the disease is present. Cure requires a complete remission, especially in progressive lymphomas.

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 and stem cell transplant
A variation of bone marrow transplantation in which immature blood cells called stem cells are taken from the patient's blood and later, in the lab, stimulated with growth factors to produce more stem cells which are returned to the patient by transfusion

Systemic
In cancer, this term means that the tumor that originated in one place has spread to distant organs or structures.

T-Cell
T cells received their name from the "t" in thymus, a gland in the chest that shrinks and disappears as people grow into adulthood. These cells are critical to a variety of immune functions. Uncontrolled proliferation after the malignant transformation of this type of cell gives rise to T-cell lymphoma.