SAN ANTONIO, Dec. 17 /PRNewswire/ -- A powerful tool of molecular
biology may be able to ensure that breast cancer patients receive a correct
evaluation of lymph node status during initial surgery. Speaking at the
29th Annual San Antonio Breast Cancer Symposium, Peter Blumencranz, MD,
from Morton Plant Mease Healthcare, reported the development of a new
assessment system based on reverse transcriptase-polymerase chain reaction
(RT-PCR). This new system, called the GeneSearch(TM) Breast Lymph Node
(BLN) assay, is being proposed as a more accurate replacement for
techniques currently in use, including frozen section and touch prep
cytology.
When patients undergo surgery for breast cancer, lymph nodes suspected
of harboring metastases are removed and sent to a pathologist for
assessment while the patient is still under anesthesia. In frozen section
evaluation, the lymph node is frozen and sliced, and the slice is examined
under a microscope. For touch prep cytology, the node is cut open, and the
cut surface touched to a slide, leaving behind a small sampling of cells
that can be examined microscopically.
Both techniques are very fast, but their accuracy is limited. After
initially being classified as "node-negative" on the basis of these
techniques, a patient may ultimately be reclassified as node-positive once
the node is examined more carefully. She must then undergo additional
surgery and anesthesia in order to have an axillary dissection, which can
be financially costly, as well as psychologically burdensome for the
patient.
The BLN assay analyzes a full 50% of the lymph node, compared with
about 5% in even the most meticulous standard approaches. The node is
ground and analyzed with special probes that identify specific proteins
associated with breast cancer cells. This technique is so powerful that it
can detect the presence of proteins from a single cancer cell.
The BLN assay is a rapid, closed-tube system that takes approximately
30 minutes to run (roughly equivalent to the amount of time it takes to
obtain a frozen section in many institutions). Because the results of the
assay are an objective "yes" or "no" for the presence of metastases, it can
be easily administered by a trained technician, freeing up the valuable
time of experienced pathologists. Only half of the lymph node is used,
leaving the other half available for more intense study in those cases
where the answer is "yes."
Two clinical trials in the US and Europe have validated the use of the
BLN assay. These studies showed that the assay was much more accurate in
detecting both micro- and macrometastases in suspicious lymph nodes,
compared with frozen section and particularly with touch prep cytology.
This high degree of accuracy means that the number of call-backs for
secondary axillary node surgery can be reduced, decreasing both cost and
patient anxiety.
SOURCE San Antonio Breast Cancer Symposium
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