Risk factors for essential thrombocythemia - A case-control study

BACKGROUND. Very little information is presently available regarding risk factors for essential thrombocythemia (ET). METHODS. A case-control study was performed to study the possible association between ET and selected behavioral, occupational, and environmental exposures. RESULTS. Thirty-nine patients aged 20 years or older and 156 controls were enrolled in 2 Italian Hematology Departments located in Rome and Pavia. Controls were recruited among outpatients seen in the same hospitals and matched 4:1. to the patients after stratification by age and sex. Odds ratio (OR) estimates suggest an association between ET and hair dye use (in particular the use of dark hair dye for periods longer than 10 years: OR = 5.3; 95% confidence interval [CI], 1.4-19.9), living in houses built with tuff (a material with a high concentration of gamma-emitting radionuclides and radon) for longer than 9 years (OR = 5.1; 95% CI, 1.2-22.1), and selected occupations (electrical worker and shoemaker, OR +infinity and 2.7; 95% CI, 0.5-16 respectively). CONCLUSION. Behavioral exposures such as hair dyes, living in a tuff house, and working as an electrician are significantly associated with ET development. The data are consistent with those observed in acute leukemias. (C) 1996 American Cancer Society.