Raman-based method found feasible as post-ablation diagnostic tool

February 2, 2015

Ablation of non-melanoma skin cancer (NMSC) with a high-powered CO2 laser offers the advantage of highly precise tissue removal. Read and learn why and how.

Ablation of non-melanoma skin cancer (NMSC) with a high-powered CO2 laser offers the advantage of highly precise tissue removal, but confirming complete cancer removal can be problematic. With this in mind, a research team led by Andrew Terentis, Ph.D., associate professor of chemistry and biochemistry at Florida Atlantic University, undertook a study to explore the feasibility of using Raman spectroscopy as an in situ diagnostic method to differentiate NMSC from normal tissue following laser ablation.

The researchers took 25 samples from 11 patients undergoing Mohs micrographic surgery to remove NMSC tumors. Laser treatment was performed with a SmartXide DOT fractional CO2 laser at a wavelength of 10.6 mm. Raman spectra were collected from both untreated and CO2 laser-treated samples using a 785 nm diode laser. Principal Component Analysis (PCA) and Binary Logistic Regression (LR) were used to classify spectra as originating from either normal or NMSC tissue, and from treated or untreated tissue.

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The study found that partial laser ablation did not adversely affect the ability of Raman spectroscopy to differentiate normal from cancerous residual tissue. The spectral classification model correctly identified SCC tissue with 95 percent sensitivity and 100 percent specificity following partial laser ablation, compared with 92 percent sensitivity and 60 percent selectivity for untreated NMSC tissue. The main biochemical difference identified between normal and NMSC tissue was high levels of collagen in the normal tissue, which was lacking in the NMSC tissue.

“I think the most important finding of this study for dermatologists and their patients is that it demonstrates the feasibility of a potentially much faster and more accurate mode of skin-cancer treatment based entirely on laser technology, whereby cancerous tissue is diagnosed using a Raman laser and the cancerous tissue is removed in a very precise, localized fashion using an ablation laser,” Dr. Terentis tells Dermatology Times. “This type of Raman-based technique for skin-cancer diagnosis and treatment, although not yet fully developed, may one day obviate the need for a more costly and time-consuming treatment method like Mohs micrographic surgery, at least in some, if not all, clinical cases.”

The study was an Editor’s Choice article in the December issue of Lasers in Surgery and Medicine.

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