Novel Device Shows Great Potential in Detecting
Oral Cancer
Researchers supported by the National Institute of Dental and
Craniofacial Research, part of the National Institutes of Health,
report today their initial success using a customized optical device
that allows dentists to visualize in a completely new way whether
a patient might have a developing oral cancer.
Called a Visually Enhanced Lesion Scope (VELScope), this simple,
hand-held device emits a cone of blue light into the mouth that
excites various molecules within our cells, causing them to absorb
the light energy and re-emit it as visible fluorescence. Remove
the light, and the fluorescence of the tissue is no longer visible.
Because changes in the natural fluorescence of healthy tissue
generally reflect light-scattering biochemical or structural changes
indicative of developing tumor cells, the VELScope allows dentists
to shine a light onto a suspicious sore in the mouth, look through
an attached eyepiece, and watch directly for changes in color.
Normal oral tissue emits a pale green fluorescence, while potentially
early tumor, or dysplastic, cells appear dark green to black.
Testing the device in 44 people, the results of which are published
online in the Journal of Biomedical Optics, the scientists
found they could distinguish correctly in all but one instance
between normal and abnormal tissue. Their diagnoses were confirmed
to be correct by biopsy and standard pathology.
“The natural fluorescence of the mouth is invisible to the naked
eye,” said Dr. Miriam Rosin, a senior author on the paper and a
cancer biologist at the British Columbia Cancer Research Center
in Vancouver, Canada. “The VELScope literally brings this natural
fluorescence to light, helping dentists to answer in a more informed
way a common question in daily practices: To biopsy or not to biopsy.”
Because developing tumors in the mouth are often easily visible,
public health officials have long advocated early detection of
oral cancer. But determining whether a suspicious sore is benign
or potentially cancerous has remained scientifically problematic. “A
major reason is looks alone can be deceiving,” said Rosin, referring
to the common practice of diagnosing cancer based on the general
appearance and staining patterns of tissue biopsy. “What’s been
badly needed in screening for oral cancer is a way to visualize
the biological information within and let it tell you whether or
not a lesion is likely to become cancerous.”
Rosin said the VELScope goes a long way toward answering this
unmet need. “Historically, the problem in developing a fluorescence-reading
instrument has been largely organizational,” said Rosin, a leader
of the British Columbia Oral Cancer Prevention Program. “No one
scientific discipline possesses sufficient expertise to build such
a sophisticated imaging device, and the needed interdisciplinary
groups weren’t forming to tackle the problem.”
This lack of communication changed a few years ago when Rosin
broached the subject to Dr. Calum MacAulay, the head of the British
Columbia Cancer Research Center’s cancer imaging program and who
has extensive training in physics, pathology, and engineering imaging
devices. Based on these discussions, MacAulay and post-doctoral
fellow Pierre Lane agreed to begin the technologically challenging
process of designing a hand-held device that also would be user
friendly in the dentist’s office.
Starting with a crude, light-emitting box and a pair of goggles
that their group had previously cobbled together to visualize skin
cancer, Lane and MacAulay gradually progressed to the one-step
device reported today. “We essentially refined and integrated the
box-and-goggles concept into one device,” said MacAulay, who also
works closely with a corporate partner that would like to commercialize
the VELScope. “The box was molded into the lightweight, hand-held
structure, a flexible cord attaches the examination light, and
the goggles became the view finder that allows dentists to directly
evaluate lesions in real time.”
In their study, the scientists evaluated 50 tissue sites from
44 people. All sites were biopsied, and pathologists classified
seven as normal, 11 had severe dysplasia, and 33 biopsies were
oral squamous cell carcinoma. Reading the fluorescence patterns
of the 50 sites, the group correctly identified all of the normal
biopsies, 10 of the severe dysplasias, and all of the cancers.
These numbers translated to 100 percent specificity and 98 percent
sensitivity. Sensitivity refers to how well a test correctly identifies
people who have a disease, while specificity characterizes the
ability of a test to correctly identify those who are well.
Rosin said her group is now engaged in a larger follow-up study
in Vancouver that will further evaluate the VELScope. “Laboratories
are developing similar devices to detect lung and cervical cancer,” said
Rosin. “That means that the same basic technology is now being
used to evaluate three tumor sites, and we can begin hopefully
to pool our data and fine tune the characteristics and meaning
of the changes in fluorescence.”
The American Cancer Society (ACS) estimated last year that about
20,000 Americans were diagnosed with various oral cancers. The
ACS also estimated that just over 5,000 Americans died from these
cancers in 2005.
The National Institute of Dental and Craniofacial Research
is the nation's leading funder of research on oral, dental, and
craniofacial health. For more information, visit the Web site
at http://www.nidcr.nih.gov/.
The National Institutes of Health (NIH) — The Nation's
Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and
Human Services. It is the primary federal agency for conducting
and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both
common and rare diseases. For more information about NIH and
its programs, visit http://www.nih.gov. |