May 11, 2009
New technique may help detect potential breast cancer spread
A new phase III clinical trial of early stage breast cancer patients
has shown that a molecule designed to home in on nearby lymph nodes is
just as accurate as current techniques, but faster, more specific and
easier to use.
"These results will really enable molecular
biology to enter the operating room for lymph node detection," said
breast surgeon Anne Wallace, MD, professor of clinical surgery at the
UC San Diego School of Medicine and the Moores UCSD Cancer Center, and
one of the study leaders. Wallace described her team's results May 7,
2009 at the 3rd International Symposium on Cancer Metastasis and the
Lymphovascular System in San Francisco.
When a woman has
breast cancer, doctors want to be sure that the disease has not spread
to her lymph nodes, the first place a cancer may go. The lymphatic
system is a network of vessels, ducts and glands that usually carry
disease-fighting cells throughout the body, but also can act as a
conduit for cancer cells to access the bloodstream.
According
to Wallace, the presence or absence of cancer in lymph nodes is an
important predictor of breast cancer prognosis, and as a result, the
appropriate treatment. But finding the right lymph nodes to test and a
standardized method of doing so hasn't been easy.
Wallace
and David Vera, PhD, professor of radiology at the UC San Diego School
of Medicine, were instrumental in the early development and testing of
the molecule, called Lymphoseek®, a radiopharmaceutical that binds to
the receptor on lymph node white blood cells called macrophages. The
radioactive portion of the molecule essentially lights up, enabling
detection of such nearby "sentinel nodes" that are the most likely
candidates to biopsy for possible cancer.
The trial, led by
research teams at the Moores UCSD Cancer Center, the Moffit Cancer
Center in Tampa, FL and other centers, along with the Dublin, OH-based
Neoprobe Corporation, which developed Lymphoseek, compared the
molecule's ability to detect nearby sentinel lymph nodes to that of the
standard method using blue dye and a radioactive tracer substance.
In
the trial, the Moores Cancer Center team, which also examined the
technique separately in melanoma patients, looked at 46 early stage
breast cancer patients. Each patient received Lymphoseek, and a short
time later, blue dye – which can also be detected and imaged as it
enters the lymph nodes.
The surgeons removed the detected
lymph nodes, which were subsequently sent to pathologists to determine
whether cancer was present. The researchers found that more than 98
percent of sentinel lymph nodes containing blue dye also had
Lymphoseek. Twenty-eight percent of the lymph nodes were positive for
cancer, 100 percent of which were detected by Lymphoseek.
"The
advantage in Lymphoseek is that we now have an agent that is tested and
designed specifically for detection of sentinel lymph nodes," Wallace
said, noting that blue dye is not specific for this use, lasts a
shorter time in the body and may not always go to only sentinel nodes.
"Lymphoseek is easier to use, takes less time to find lymph nodes and
is cleared faster from the body. This could standardize the process of
lymph node mapping and make the process easier, particularly for less
experienced surgeons."
According to Wallace, these results
could lead to other research on receptor binding imaging for different
types of cancers, and propel the field of imaging cancer based on
molecular profiling.
Contact: Steve Benowitz
sbenowitz@ucsd.edu
619-543-6163
SOURCE:
University of California - San Diego
