Measuring the amount of melanin in a hair sample independently predicts an individual's risk for melanoma, according to a report in the May 15 issue of the American Journal of Epidemiology.
Melanin is a natural substance 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, Dr Stefano Rosso told Reuters.
Rosso from the Piedmont Cancer Registry, Turin, Italy and associates note that hair concentrations of melanin can be measured by various means.
They used different methods to determine the melanin content in the hair of study participants in Europe and South American (2001-2002) who were enrolled in a large, multicenter skin cancer trial.
The study included 98 subjects with melanoma, who were matched with a comparison group of 98 without melanoma.
The researchers found that measuring 2,3,5-pyrroletricarboxylic acid (PTCA) levels, which forms after the oxidation of the pigment eumelanin, provided the strongest 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, the team reports.
Near infrared spectroscopy, which the researchers describe as "a less precise but faster and cheaper type of measurement of eumelanin," was associated with a two-fold increased risk of melanoma, but this was not statistically significant after controlling for other risk factors. Nevertheless, Rosso said, his group wants to develop near infrared spectroscopy further, so that it may be used to use directly measure melatonin.
The investigators point out that determination of the PTCA also provides the chance to study the role of melanin in the direct causes of skin tumors.
"We plan to further extend melanin measurement to squamous-cell carcinoma and basal-cell carcinoma in the same case-control setting."