CLINICAL-FEATURES OF HEMATOPOIETIC MALIGNANCIES AND RELATED DISORDERSAMONG BENZENE-EXPOSED WORKERS IN CHINA

Previous occupational cohort studies of benzene-exposed workers have f or the most part used only death certificates to validate diagnoses of workers developing leukemia and other hematopoietic and lymphoprolife rative malignancies and related disorders (HLD). In a follow-up study of 74,828 benzene-exposed workers and a comparison group of 35,805 non exposed workers from 12 cities in China, we sought to characterize cli nicopathologically and to confirm diagnoses of ail cases of HLD. Using medical records, laboratory hematology results, and histopathology, U .S. and Chinese expert hematopathologists, blinded to exposure status, carried out a detailed review using standardized evaluation forms. Ke y among the findings were a notable diversity of malignant and nonneop lastic hematopoietic and lymphoproliferative disorders, documentation of excess myelodysplastic syndromes among benzene workers, and widespr ead dyspoiesis involving all hematopoietic cell lines. As sophisticate d clinicopathologic characterization and corresponding classification schemes for HLD become increasingly widespread, it is recommended that future epidemiologic investigations of benzene workers incorporate si milarly detailed morphologic evaluation. In extending follow-up of thi s cohort of young workers, we will continue to use ail available clini cal, laboratory hematology, and pathology data as well as cytogenetic and biochemical markers to characterize various HLD outcomes. These ca reful surveillance mechanisms should also provide additional insight i nto carcinogenic mechanisms of benzene and allow comparison of the mol ecular pathogenesis of HLD induced by benzene versus chemotherapy, rad iation, or other exposure.