One
in ten women will die of breast cancer according to current statistics. While
health and awareness campaigns have improved early detection rates of the
disease, researchers like University of Cape Town's (UCT) Dr. Sahar
Abdul-Rasool, of the clinical laboratory science department, are working on the
clinical side to provide women with a more sensitive diagnostic test, one that
allows for earlier intervention.
An
Iraqi, Abdul-Rasool came to South Africa three years ago to begin her PhD in
hematology at the university’s molecular biology laboratory.
Abdul-Rasool
qualified with a bachelor’s degree in medicine and surgery from the University
of Baghdad, College of Medicine in 1987 and obtained her master’s degree from
Nahrain University Medical College in 1995, her thesis on the quantitative
histochemical study of skeletal muscle fiber. She has also lectured at
universities in Yemen and Libya.
Abdul-Rasool
is part of a collaborative team of researchers from UCT's clinical laboratory
sciences, surgery and anatomical pathology departments who are conducting an
important study to develop a more sensitive diagnostic test for breast cancer
that will provide earlier staging and testing.
According
to the researcher, if diagnosis and treatment of breast cancer are delayed until
the primary tumor has metastasized (spread) and the lymph nodes are palpable;
the five-year survival rate for women is 45% to 50%.
Much
of the current research into the disease concerns the sentinel lymph nodes in
the cancerous breast tissue. A sentinel node is the first lymph node in the
axilla (the armpit) to receive drainage from a cancer-containing area in the
breast. This is what doctors try to remove, sparing the wholesale removal of
tissue in the axilla (which contains fat, lymph nodes, lymph and blood vessels
as well as nerves), to prevent any cancerous cells from spreading.
New
insights have shown that wholesale removal of the axillary tissue does not
necessarily prevent breast cancer from spreading. It also often causes numerous
side effects like chronic pain and lymphedema (chronic swelling of the arm due
to blockage of the lymph vessels).
Sentinel
lymph node biopsy, however, provides doctors with a far more accurate way of
isolating the cancer.
"It
is the likely site for lymphogenic metastases [cancer cells spreading through
the lymphatic vessels]," Abdul-Rasool explained. Sentinel lymph node biopsy
involves a more delicate technique, and by lessening side effects in this way
the procedure is less complicated for the patient in the short and long term,
she said.
However,
it is known that breast cancer patients with no clinically-apparent signs of
metastases may already harbor nodal micro metastases; cancerous spread at a
molecular level.
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Staging
involves histopathological examination of the sentinel node to detect cancerous
spread to the surrounding or axillary nodes
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"If
you can detect and more accurately stage the cancer at this point, treatment is
more likely to be effective as the tumor burden is small and the host is still
immune-competent. Currently, staging involves histopathological examination of
the sentinel node to detect cancerous spread to the surrounding or axillary
nodes.
The
sentinel node is the most likely site for spread among the lymph glands and can
be identified with a 98 percent accuracy using radio-guided surgery.
"We're
already using this surgical technique at Groote Schuur Hospital (GSH),"
Abdul-Rasool added.
But
the method of examining the sentinel node is still costly and labor-intensive.
The team of researchers has now developed a specific and reproducible molecular
assay that can accurately detect the spread of cancerous cells in the sentinel
nodes.
The
team evaluated the gene expression patterns of 73 molecular markers in
sentinel node biopsy specimens gathered from patients at GSH.
Most
of these are cancer-testis antigens (CTAs); antigens normally present in testis tissue but abnormally expressed by cancerous cells.
"Breast
cancer has its own unique CTA profile and our aim was to find the perfect
combination of markers to ensure 100 percent detection and specificity."
The
results have been very encouraging. The researchers found that immunohistochemical analysis in the lab resulted in a 77 percent detection rate,
compared with 37 percent for histopathological examination.
"Immunohistochemical
analysis is considered essential in order not to miss sentinel node
micrometastases. Molecular analysis of breast tissue with breast tumor markers
MAM-A (mammaglobin-A) and MAGE-A3 (Melanoma antigen, family A, 3) were found to
allow specific and sensitive detection of breast cancer micrometastases with a
90 percent detection rate.
"However,
the clinical value of histologically negative but molecular positive sentinel
nodes can only be determined with long-term follow-ups with patients.
"This
work can revolutionize breast cancer diagnosis and staging, allowing for earlier
treatment, better prognoses and prolonged patient survival."
Abdul-Rasool
took her findings to Sydney where she presented her work at the prestigious
Leura V International Breast Cancer Conference in November 2004.
Her
supervisor, senior medical scientist Dr Gideon Hanekom, considers this asignificant achievement. It also vindicates Abdul-Rasool's initial thoughts
about choosing to train at an institution in Africa's southern-most tip.
"UCT
is a university with outstanding research capacity. Here I can fulfill my hopes
and ambitions regarding my scientific work," she said.
