Hair analysis may reveal cancer risk

Measuring the amount of melanin in a hair sample can predict an individual's risk for melanoma. Melanin is the natural black pigment that gives colour to the hair, skin and iris of the eye, and also protects the skin from damaging rays of the sun. Determining the amount of melanin as an indication of an individual's skin type could be used to advise patients how often they should be screened for skin cancer and to also provide individualised patient advice. Italian researchers from the Piedmont Cancer Registry, Turin, used three different methods to determine the melanin content in the hair of study participants, which included 98 subjects with melanoma. These were matched in age and sex with a comparison group of 98 patients without melanoma. The melanin content in hair was assessed by three methods - amount of 2,3,5-pyrroletricarboxylic acid (PTCA), absorbance ratio with ultraviolet spectroscopy and the spectra of near-infrared spectroscopy. It was found that measuring PTCA levels, which form after the oxidation of the pigment eumelanin, provided the best results. After accounting for the effects of hair colour, eye colour and number of moles, the researchers found that the subjects with a PTCA concentration below 85 ng/mg had more than four times the risk of developing melanoma. Near infrared spectroscopy, which the researchers described as a less precise but faster and cheaper type of measurement of eumelanin, was associated with a two-fold increased risk of melanoma, but was not statistically significant after controlling for other risk factors. Determination of the PTCA also provides the chance to study the role of melanin in the direct causes of skin tumours. The researchers plan to further extend melanin measurement to squamous-cell carcinoma and basal-cell carcinoma in the same setting.