Novel light device distinguishes cancerous lesions from normal tissue in skin

Researchers report promising results for the viability of a portable, handheld device using a specialised light technique that may enhance the differential diagnosis of non-melanoma skin cancers, inflamed scar tissue and normal skin in vivo. Recently published in Lasers in Surgery and Medicine (August 2008 issue), the peer-reviewed professional journal of the American Society for Laser Medicine and Surgery, the retrospective study discussed the advantages of using Raman microspectroscopy to examine and classify pathologic skin cells.

In his article entitled "In Vivo Nonmelanoma Skin Cancer Diagnosis Using Raman Microspectroscopy," author Chad A. Lieber, PhD, a biomedical engineer and head of the bio-optics laboratory at CHOC Research Institute, Children’s Hospital of Orange County, Orange, CA, explains how his research team (from Vanderbilt University in Nashville, TN) utilised the Raman technique to noninvasively classify nonmelanoma skin cancers.

According to Dr Lieber, Raman spectroscopy is an optical technique that probes the vibrational activity of chemical bonds using interactions with laser light. As such, each molecule has a spectral "fingerprint" characteristic of its modes of vibration. In medical diagnostics, these spectral fingerprints can be used to differentiate samples according to their chemical consistency – such as distinguishing cancerous tissue from normal tissue. This molecular specificity could presumably allow detection of subtle changes in the body well before conventional signs of problems might arise.

"Skin cancer is more common than any other cancer, and early detection is critical to keeping the cancer localized and minimizing its threat of spreading," said Dr Lieber.

"The current gold-standard for diagnosing skin lesions is invasive and error-prone; these drawbacks beg the need for a more streamlined diagnostic technique. Today, people can check their blood pressure at monitors available in every drugstore – if people could check for skin cancer just as readily I think more skin cancers would be detected in their earliest and most treatable stages."

In their study, Dr Lieber and his colleagues measured the Raman spectra of 21 suspected non-melanoma skin cancers in 19 patients, along with nearby normal skin. Based on these optical "fingerprints", the researchers constructed a diagnostic algorithm to see if they could determine the proper pathological diagnosis. Their results demonstrated that all of the basal cell carcinomas (9/9), squamous cell carcinomas (4/4), and inflamed scar tissue (8/8) were correctly predicted, and 19 out of 21 normal tissues were correctly classified. "We are very pleased with the diagnostic outcomes of the study," Dr Lieber noted.

The study also found that Raman microspectroscopy could successfully detect abnormal tissue much deeper in the skin, opening the door to the possibility that this technology could be used as an important screening tool to detect changes brewing beneath the skin before it even raises a red flag.

"Cancers communicate via chemical signalling that evades traditional diagnostics, so we’re hopeful that one day this device could listen in to cancer’s conversations deep within the skin’s surface and alert us to potential problems that could then be addressed even sooner," Dr Lieber concluded.

(Source: American Society for Laser Medicine and Surgery: In Vivo Nonmelanoma Skin Cancer Diagnosis Using Raman Microspectroscopy. Lasers in Surgery and Medicine, Lieber CA.: August 2008)