Optical biopsy studied as breast cancer treatment aid
Breast cancer is the leading cause of cancer-related death in women
aged 40-59 and was expected to total more than 45,000 deaths in the
United States last year, according to the American Cancer Society. A Los
Alamos National Laboratory-developed technology, the Optical Biopsy
System (OBS), may aid in not only the diagnosis of breast cancer, but the
success of the surgical treatment as well.
An OBS is a real-time probe based on white-light interaction with tissue, which can be
used either through an endoscope or a biopsy needle. The system consists of small
optical fibers that shine tiny bursts of light onto tissue and then collect the scattered
light traveling through the tissue. A computer then analyzes the scattered light.
OBS technology works because cancerous tissue scatters and absorbs light differently than normal tissue. A computer uses artificial intelligence and pattern
recognition codes to analyze the scattered light spectra and discern the spectra of
normal tissue from diseased tissue.
"Breast cancer is very complicated because breast tissue consists of a wide variety of
tissue types," said Irving Bigio, formerly with the Laboratory's Bioscience Division
and now at Boston University. "Types of cancer tissues from the breast vary greatly,
as do types of normal tissue, so it's
a difficult process doing diagnos-
tics." Bigio and Paul Ripley, a post
doc at the Laboratory from the
United Kingdom, are currently
working with doctors at the
University College of London
Medical School on the OBS clinical
breast cancer studies.
So far, data from the clinical studies
being conducted by the UK collabo-
rators are promising. The OBS data
agree with findings from standard
pathology more than 80 percent of
the time, based on two parameters: sensitivity and specificity. Sensitivity refers to the instrument's ability to find cancer when there is cancer, and
specificity refers to the instrument's ability to discern cancerous tissue
from healthy tissue.
"We're very encouraged by these results, although preliminary," said
Bigio." The fact that we're getting this level of agreement with results
from pathology means that the OBS has excellent potential for aiding
doctors during breast cancer surgery."
In another aspect of the research, Bioscience Division's Judith Mourant
is studying the properties of tissue that affect light scattering and make
systems like OBS predictors of cancerous tissue. Light scatters from an
object depending on its composition and shape. Consequently, one
might expect that the scattering of light from tissue would change when
the form and structure of the tissue changes. Mourant has had a
National Institutes of Health-funded program since 1996 to study how
changes in cell structure that accompany carcinogenesis affect light
scattering. "One of our first tasks was to determine what structures in
the cells scatter light. We now have strong evidence that light is
scattered by small, internal cellular structures," Mourant said.
The light scattering from these small, internal cellular structures is
particularly important when the light illumination point and the
scattered-light detection point are located close to each other on the
surface of the tissue. Further, Mourant has studied the light-scattering
properties of tumor-causing cells grown in a 3-D culture. She is now
using this information to develop more sensitive methods to noninva-
sively measure properties of tissue related to cancer-causing cells.
Mourant now is developing fiber optic probes that deliver and detect
polarized light, because this provides additional information than
garnered with traditional methods.
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