American Journal of Epidemiology Advance Access originally published online on March 5, 2007
American Journal of Epidemiology 2007 165(10):1170-1177; doi:10.1093/aje/kwm018
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ORIGINAL CONTRIBUTIONS |
Is 2,3,5-Pyrroletricarboxylic Acid in Hair a Better Risk Indicator for Melanoma than Traditional Epidemiologic Measures for Skin Phenotype?
1 Oncology Prevention Center, Piedmont Cancer Registry, Turin, Italy
2 Granada Cancer Registry, Andalusian School of Public Health, Granada, Spain
3 Department of Preventive Medicine and Public Health, Faculty of Medicine, University of Seville, Seville, Spain
4 Regional Cancer Registry, Southern Portugal Regional Institute of Oncology, Lisbon, Portugal
5 Doubs Cancer Registry, Faculty of Medicine and Pharmacy, University of Besançon, Besançon, France
6 A. H. Roffo Institute of Oncology, University of Buenos Aires, Buenos Aires, Argentina
7 Dermatology Clinic, Hiller
d Hospital, Hillerd, Denmark
8 Dermatology Center, Buxtehude Hospital, Buxtehude, Germany
9 Department of Epidemiology, Murcia Health Council, Murcia, Spain
10 Department of Dermatology, University Federico II of Naples, Naples, Italy
11 Department of Dermatology, Infermi Hospital, Biella, Italy
12 Herault Cancer Registry, Centre Epidaure, Montpellier, France
13 Ragusa Section, Italian League against Cancer, Ragusa, Italy
14 Regional Agency for Public Health of Tuscany, Florence, Italy
15 Institute for Macromolecular Studies, National Research Council, Biella, Italy
Correspondence to Stefano Rosso, Oncology Prevention Center, Piedmont Cancer Registry, Via San Francesco da Paola, 31, Torino 10123, Italy (e-mail: stefano.rosso{at}cpo.it).
Received for publication May 3, 2006. Accepted for publication November 1, 2006.
This study aims to assess type of melanin as a risk indicator for skin tumors, in a sample of melanoma cases and controls within a larger multicenter study (Helios 2), held in Europe and South America in 2001–2002. In each case and control, the melanin content in hair was assessed by three methods: 1) the amount of 2,3,5-pyrroletricarboxylic acid (PTCA); 2) the absorbance ratio with ultraviolet spectroscopy; and 3) the spectra of near-infrared spectroscopy. Statistical analysis was performed in a Bayesian setting, defining priors for confounders and effect modifiers from the larger study data set. Subjects with values of PTCA of less than 85 ng/mg carried an increased risk (26 vs. seven discordant pairs: odds ratio = 4.4, 95% confidence interval: 1.52, 14.54), adjusted by hair color, eye color, and number of nevi (n = 
40). The absorbance ratio showed a weaker and nonsignificant odds ratio of 1.5. After correction by misclassification, near-infrared spectroscopy was associated with an odds ratio of 2.3 (95% confidence interval: 1.36, 4.22). The amount of PTCA is thus a strong and independent risk indicator for melanoma. Incorporating PTCA determination into epidemiologic studies is therefore recommended.
melanins; melanoma; skin neoplasms; spectroscopy, near-infrared
Abbreviations: HPLC, high-performance liquid chromatography; NIR, near-infrared; PTCA, 2,3,5-pyrroletricarboxylic acid