White light reflectance reveals skin cancer

17 Jun 2002

Reflected light from skin could provide a low-cost tool for diagnosing skin cancer. British scientists from the Institute of Cancer Research and Royal Marsden Hospital have developed a system, based on white light reflectance, for differentiating between benign and malignant tumors in the skin.

Cancers cause structural and biochemical changes to tissue and these influence the scattering and absorption of reflected light. The scattering depends on features such as the cell size, while the absorption is dependent on the chemical composition. Reflected light for tumor analysis was first proposed by an Italian research group in 1991.

The UK technique is based on a xenon lamp, which gives a pure source of light from the ultraviolet (320 nanometers) to the infrared (1100 nanometers). This wide range of wavelengths allows a large amount of information to be collected about the lesion, and compensates for the misleading effects of freckles and other skin pigmentations.

The researchers recorded spectra of patients' skin before surgeons removed suspicious lesions. The spectra were then compared with the pathological results and analyzed by multivariate discriminate analysis. Vincent Wallace, a member of the team, says that, in the well-defined cases, there were very pronounced differences between the spectra of the benign tissue and that of the malignant tissue. Some diagnoses are more subtle but he says that their system examines seven separate features of the reflectance spectra and that this gives enough information to determine whether or not a tumor is malignant.

Wallace, who now works at the Beckman Laser Institute in California, hopes that the Royal Marsden Hospital will look at commercializing the system. "It would be nice to take this to the next stage," he says. "The components cost less than USD 5000, which is very inexpensive for any medical device." He adds that the system would be used in conjunction with other techniques, such as image analysis, to provide a more complete and accurate diagnostic tool.

The group's research was published in the March 2000 issue of the journal Physics in Medicine and Biology.

SH