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New Victories in Battle Against Blood Cancers

Posted on: Monday, 22 September 2003, 06:00 CDT

By Amanda Gardner, HealthDay Reporter

HealthDayNews -- An estimated 106,000 Americans will be diagnosed this year with either leukemia, lymphoma or myeloma, all cancers of the blood-forming cells.

Another 57,500 people will die of one of these diseases.

"Blood cancers are 2 to 3 percent of all cancers, and yet they represent over 10 percent of all deaths," says Alan Kinniburgh, vice president of research for the Leukemia & Lymphoma Society.

Dubbed "liquid tumors" by some, none of these cancers can be surgically removed. Traditionally, that has meant radiation and chemotherapy were a patient's only choices.

But thanks to breakthroughs in the area of molecularly targeted therapies -- drugs that attack diseased cells directly and produce fewer side effects -- researchers are making significant strides against some of the cancers. Some doctors even suggest that, one day, a pill may be enough for a cure.

That's a timely message because September has been designated Leukemia, Lymphoma and Myeloma Awareness Month.

Within each of these three major diseases are an array of other diseases, further subdivided into acute, rapid onset and chronic -- which comes on more slowly.

Leukemia, which accounts for about 30 percent of all cancers diagnosed in children under the age of 15, refers to cancer of the bone marrow and blood cells.

Lymphomas, the most common of blood cancers, are malignancies of the lymphocytes -- a type of white blood cell. The two main types of lymphomas are Hodgkin's disease and non-Hodgkin's disease.

Myeloma affects the plasma cells, or white blood cells found primarily in the bone marrow, and interferes with the body's immune system.

For the most part, no one knows what causes these different cancers. Exceptions are benzene, a widely used chemical found in everything from car emissions to furniture wax, and radiation in the case of some leukemias. And the Epstein-Barr virus has been linked to some lymphomas.

Increasingly, however, researchers are understanding how to treat and even cure these diseases.

Gleevec, one of the most successful of the new molecularly targeted drugs, offers a big breakthrough for people with chronic myeloid leukemia, or CML. The drug inhibits an enzyme that pushes cells to reproduce uncontrollably. Within three to four weeks of initiating treatment, patients' blood cell counts often return to near normal.

"It's made a huge impact on the way we treat CML," says Dr. Rene Castillo, a hematologist/oncologist with the Ochsner Clinic Foundation in New Orleans. "Most people feel that we can treat this disease with a pill."

"Gleevec is the standard practice for newly diagnosed patients," adds Kinniburgh.

Prior to Gleevec, a tricky bone-marrow transplant was the only possible cure for CML, Castillo says.

But Gleevec doesn't offer a cure for everyone with CML, and trials are under way to pinpoint its strengths and weaknesses.

"A lot of questions still need to be answered," Castillo says. "Is this going to change the natural history of the disease? Are we going to see people with longer disease-free intervals? We still don't know. We do know that it is going to take more than Gleevec to control CML because there are some patients who are starting to recur."

While Gleevec is the "poster child" of the new molecularly targeted drugs, other advances are being made.

A drug called Velcade, one of a class of medications called proteasome inhibitors, was approved earlier this year for multiple myeloma. It inhibits proteins that interfere with normal cell death, Kinniburgh explains, adding, "Velcade has been very effective in about 80 percent of patients."

These success stories notwithstanding, acute leukemia remains stubbornly difficult to treat, Castillo says, "despite better supportive care measures that get our patients through systemic chemotherapy."

Except for Gleevec and CML, leukemia treatments have not changed much in years. "Other leukemias are still lacking in breakthrough medications," Castillo says. "Although we can put patients in remission, most of the cancers have returned. We still need a lot of work in acute leukemia."

There have been more strides in the treatment of lymphomas. A new monoclonal antibody, another type of targeted therapy, seems to be able to prevent recurrence of the disease. It's part of a new approach called immunotherapy, which involves developing antibodies that attack part of the diseased cell's surface, causing the cell to die.

"These targeted therapies are starting to find their way into the armamentarium of treating tumors, although we still have a ways to go," Castillo says.

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On the Net:

Leukemia & Lymphoma Society

Leukemia information

Non-Hodgkin's Lymphoma information

Hodgkin's Lymphoma information

Myeloma information

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