|
Gene Expression Profiling Distinguishes Lymphomas
Burkitt’s lymphoma and diffuse large B-cell lymphoma (DLBCL) cells may look
similar under a microscope, but each cancer requires different treatments. A
multinational team of researchers, including several from NIH’s National Cancer
Institute, now report that gene expression profiling, a molecular technique that
analyzes many genes at once, can distinguish these immune cell tumors more accurately
than current diagnostic methods.
 |
|
Burkitt’s lymphoma under the microscope.
Photo courtesy of Dr. Louis Staudt. |
|
Burkitt’s lymphoma and DLBCL are types of non-Hodgkin’s lymphomas — malignancies
of a type of white blood cell, B lymphocytes. Healthy lymphocytes help destroy
bacteria, viruses and other infectious agents invading the body. An estimated 58,800
people will be newly diagnosed with these cancers in the U.S. this year, and about
19,000 will die of them. Both lymphomas can occur in the same age group and patients
have similar symptoms, so it’s often difficult for doctors to tell them apart.
A correct diagnosis is crucial, however; when Burkitt’s patients are misdiagnosed
and treated with the therapy recommended for DLBCL, their survival rate drops from
about 80% to 20% or less.
A panel of experts evaluated 71 samples from previously untreated patients who’d
been diagnosed with Burkitt’s lymphoma or the related atypical Burkitt’s lymphoma.
Using the latest diagnostic methods, they reclassified the samples as Burkitt’s
lymphoma, atypical Burkitt’s lymphoma, DLBCL or high-grade lymphoma. The panel
reclassified nearly a third of the samples, a sign of how difficult it is to
make an accurate diagnosis.
The researchers tested the samples using DNA microarrays to simultaneously measure
the activity of over 2,500 genes. The results appear in the June 8, 2006, issue
of the New England Journal of Medicine. Among the samples declared to
be Burkitt’s lymphoma by the review panel, molecular profiling reached the same
diagnosis 100% of the time. However, 17% of the samples that the panel reclassified
were revealed to be Burkitt’s lymphoma by molecular profiling. Of those reclassified
as DLBCL, molecular profiling showed that 35% were actually Burkitt’s lymphoma.
In clinical practice, such misdiagnoses could result in inappropriate treatment
for these patients.
This experimental test still requires further development before it’s available
for clinical use. In the meantime, researchers see it as a valuable tool to help
them understand the molecular mechanisms causing these diseases and uncover novel
targets for therapy.
|
