Thursday, April 12, 2007

Former Senator, Radio Host and Actor Fred Thompson has Indolent Lymphoma, an intermediate form of Non-Hogkin's Lymphoma

Senator Thompson said he has Indolent Lymphoma and BTW "Indolent" is a Non-Hodgkin's Lymphomas (NHLs) or the worst of the the two main lymphomas Hodgkins and Non-Hodgkins'! The diagnosis was made late in 2004, when he sought treatment for a 3.5 centimeter by 4 centimeter (roughly one inch by 1½ inch) lump under his left jaw and the biopsy came back positive for NHL.

There are many different types of Non-Hodgkin's lymphoma, depending on whether it's indolent (slow growing) or aggressive (fast growing), and which one of the 30 different types of lymphocyte is involved. Indolents encompass what were called low grade and some categories of intermediate grade NHL.
see flash animation
  • B lymphocyte
  • T lymphocyte
  • other cells
Animated diagram explaining non-Hodgkins lymphoma
Non-Hodgkin's lymphoma is a disease that affects the cells of the lymphatic system known as lymphocytes. Click on the picture to see an animated diagram explaining non-Hodgkin's lymphoma

Indolent NHLs have traditionally not been strongly responsive to conventional cancer therapies such as
chemotherapy and radiation therapy but now are more responsive to a newer therapy described as Monoclonal Antibody Therapy.
  • Monoclonal Antibodies are antibodies that have been bioengineered from part of a mouse antibody. The mouse antibody is changed so that it is very close in structure to a human antibody. For NHLs a new Mononclobnal treatment that Fred Thompson received was Rituximab
see flash animation

The aim of monoclonal antibody therapy is to target and destroy non-Hodgkin's lymphoma cells, leaving other cells unharmed. Click on the illustration to go to an animation explaining how monoclonal antibody therapy works

How monoclonal antibody therapy works
Initial treatment for indolent non-Hodgkin's lymphoma usually produces a remission, which may last for a number of years. However, almost all of these patients have a relapse, and the lymphoma recurs.
Unlike chemotherapy and radiotherapy, which act in a less specific way, the aim of monoclonal antibody treatment is to destroy the non-Hodgkin's lymphoma cells in a targeted way and to leave other types of cells unharmed.
All cells have protein markers on their surface, known as antigens. Monoclonal antibodies are designed in the laboratory to specifically recognise particular protein markers on the surface of some cancer cells. The monoclonal antibody then 'locks' onto this protein. This either triggers the cell to destroy itself or signals to the body's immune system to attack and kill the cancer cell.
For example, rituximab, the monoclonal antibody that is used in the treatment of non-Hodgkin's lymphoma, recognises a protein marker known as CD20. CD20 is found on the surface of the abnormal B cells that are found in some of the most common types of non-Hodgkin's lymphoma.
When rituximab locks onto CD20 on the surface of a B cell, the cell may be destroyed directly, but also the body's natural defences are alerted. Rituximab effectively targets the lymphoma cells for destruction by the body's immune system, which can now kill the cancer cells.
CD20 is also found on the surface of normal B cells, one of the types of white blood cells that circulate in the body. This means that these normal B cells, too, may be destroyed when rituximab is used. However, the stem cells in the bone marrow
that develop into B cells do not have CD20 on their surface.
Stem cells are therefore not destroyed by rituximab and can go on to replenish the body with healthy B cells. Although the number of mature, normal B cells is temporarily reduced by the treatment, they return to previous levels after the treatment.
Rituximab: Results in Previously Untreated Follicular (low grade) NHL:
Rituximab can be given concurrently with chemotherapy, or after completion of chemotherapy. At least three major trials have shown that the chance of progression is approximately halved with the addition of Rituximab to chemotherapy. The time to progression is also nearly doubled with the addition of Rituximab (from 1.4 to 2.4 years in one study). A recently trial also reported an improvement in survival of about 6% at the end of 3 years. More mature data on survival benefit is still awaited.


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