Medical Device Daily
Researchers in Vancouver, British Columbia, have reported “initial success“ in detecting oral cancer using a customized optical device designed for dentists to visualize cancer lesions or precancerous lesions “in a completely new way.“
The development was reported by the National Institute of Dental and Craniofacial Research (NIDCR; Bethesda, Maryland), part of the National Institutes of Health, which funded the research.
Called a Visually Enhanced Lesion Scope (VELScope), the hand-held device emits a cone of blue light into the mouth that excites various molecules within the patient's cells, causing them to absorb the light energy and re-emit it as visible fluorescence.
“The natural fluorescence of the mouth is invisible to the naked eye,“ said Miriam Rosin, MD, a senior author on the paper and a cancer biologist at the British Columbia Cancer Research Center, in a statement. “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 changes in the natural fluorescence of healthy tissue generally reflect light-scattering biochemical or structural changes indicating developing tumor cells, the VELScope is designed to allow dentists to shine a light on 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.
The VELScope device – similar to devices currently being used to detect both lung cancer and cervical cancer, according to the NIDCR – was tested in 44 people, with the results published online in the Journal of Biomedical Optics.
In the testing, the researchers evaluated 50 tissue sites from the 44 people. All sites were biopsied, and pathologists classified seven as normal, 11 as severe dysplasia and 33 biopsies were oral squamous cells 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. Those numbers translated to 100% specificity, or the ability to correctly identify people with a disease, and 98% sensitivity, the ability of a test to correctly identify those who are well.
The correct distinction between normal and abnormal tissue was possible in all but one instance. The NIDCR said that the diagnoses were confirmed to be correct by biopsy and standard pathology.
In an online interview with the NIDCR web site, Rosin told the institute: “The earlier that you catch a suspicious sore, or lesion, in the mouth, the better the outcome will be for the patient.“
Unfortunately, she noted also that “the problem is the morbidity and mortality rates for oral cancer have remained fairly static for several decades,“ although they can be seen by the human eye.
She said “the lack of progress tells us three things: One, we need better screening tolls that more sensitively and specifically determine whether a suspicious lesion is precancerous and should be removed.“
Included in that list was outreach to the dental and medical communities to develop a more “seamless system to manage patients.“
“We can't allow anyone to get lost in the system,“ she said in the interview with NIDCR.
The NIDCR said that 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, because “looks alone can be deceiving“ when trying to diagnose cancer, based on the general appearance and staining patterns of tissue biopsy. In the web site interview, Rosin said that they can also be deceiving in the pathology lab.
“You can't just look at these lesions under a microscope and know definitively how they will behave in the future,“ she said. “To better characterize a mild or moderate dysplasia, you need access to molecular information. You need to know whether abnormal molecules are present in the cells that drive the abnormal growth.“
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.“
Ultimately, after Rosin's suggestion, Calum MacAulay, MD, the head of the British Columbia Cancer Research Center's cancer imaging program, agreed to begin the process of designing a hand-held device that would be user-friendly in a dentist's office, along with post-doctoral fellow Pierre Lane, the NIDCR said.
“We essentially refined and integrated [a] box-and-goggles concept into one device,“ said MacAulay, who also works with a corporate partner looking to commercialize the device. “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.“
Rosin's group is conducting a larger follow-up study to evaluate further the VELScope device.
“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.“