Dr. Roach: Leukemia not just one disease, but several
Dear Dr. Roach: What are the known causes of leukemia?
Dear B.B.: “Leukemia” comes from the Greek roots for “white blood” because an excess of white blood cells can be seen even without a microscope in a test tube of spun whole blood. It’s not one disease, but several.
White blood cells are the infection- and cancer-fighting blood cells. There are two main branches of white blood cells, called granulocytes and lymphocytes. Leukemias are named for the type of white blood cell affected and by the time course in which they appear — acute or chronic. For example, there is chronic lymphocytic leukemia. There are many subtypes.
Increasingly, leukemias are subtyped, and treatment is based more on their genetic mutations than by their microscopic appearance. Those mutations in DNA lead a normal white blood cell precursor to become cancerous. What, exactly, causes those mutations is not known with any precision, but it does appear that it is a single progenitor cell that develops a series of mutations that causes the cell to grow without the normal controls that limit cell division. The initial event might be exposure to a toxic chemical; an excess of radiation (or just bad luck that background radiation we are all exposed to hits exactly the wrong spot); a virus damaging DNA; or something else we don’t yet understand.
Some leukemias are curable now. Others, sadly, are not. Overall, survival rates for leukemia are improving over time, and today over 60% of people diagnosed with leukemia live longer than five years. Five years is a good sign that the person has achieved a long-term remission, but that still does not necessarily mean cure.
Dear Dr. Roach: I saw an ad for a new treatment for Alzheimer’s disease using Copaxone and Protollin. It is supposed to remove amyloid from the brain by 73%. Can this be true?
Dear M.B.: One of the abnormalities found in the brains of people with Alzheimer’s disease is a protein called tau. Like another protein, beta-amyloid, it is a misfolded normal brain protein. Beta-amyloid has long been suspected to be part of the underlying mechanism of Alzheimer’s disease, but treatments designed at removing beta-amyloid protein alone have so far not been successful at improving the memory and other brain problems in Alzheimer’s. Researchers have also looked at treatments aimed at tau protein, which correlates better with disease severity.
Preliminary studies in mice have shown that vaccines using one or more of several compounds, including those you mention, have been effective in both removing amyloid and tau proteins and preventing new deposition of these proteins. However, there is still not good evidence that these therapies will cause clinical improvement in people with Alzheimer’s. For now, I recommend against using these treatments outside of a clinical trial.
Until there is a successful clinical trial, we are left with only modestly effective treatments, such as donepezil (Aricept) and similar drugs, and memantine (Namenda), which slow down progression of Alzheimer’s. Factors that protect against development of Alzheimer’s disease include regular physical exercise, high social interaction, regular mental exercise and careful control of high blood pressure (if present). A Mediterranean diet and consumption of fatty fish or omega-3 fish oil have limited evidence of benefit in prevention of dementia.
Readers may email questions to ToYourGoodHealth@med.cornell.edu.