Epidemiological aspects on hairy cell leukaemia

Abstract: Non Hodgkin's lymphoma (NHL) has an increasing incidence in many Western countries. In Sweden, about 1800 new cases were reported to the Cancer Registry in 1996 including cases of chronic lymphatic leukaemia (CLL). Hairy cell leukaemia (HCL) is a rare subgroup of malignant lymphoma. About 25 new cases are diagnosed among males in Sweden yearly. The mean age at diagnosis is 55-60 years.To further evaluate the findings in a pilot-study conducted in Uppsala, where a large proportion of patients with HCL had worked in the areas of agriculture or gardening, a case-control study was initiated. The study included 121 male cases of HCL diagnosed between 1987 and 1992, and 484 controls matched for age, sex and county. The aim of the study was to investigate potential risk factors for HCL such as occupation, and different occupational exposures such as organic solvents, pesticides, exhausts and animals. Information was also obtained on previous medical history and medications.No significantly increased risk for HCL among farmers was found. An increased risk for HCL was seen for exposure to domestic animals and different subgroups of pesticides, as well as for exposure to organic solvents and exhausts. A decreased risk for hairy cell leukaemia was correlated with smoking. A previous history of certain diseases of the cardiovascular system was associated with a moderately reduced risk for HCL.Epstein-Barr virus (EBV) has been correlated with certain subtypes of malignant lymphomas. In a subgroup of the individuals in the study, levels of certain antibodies to EBV were analysed as risk factors for HCL. These levels were related to selfreported exposure to other potential risk factors. The results suggest the possibility of an interaction between EBV and self-reported occupational exposures.Organochlorines have been suggested as risk factors for NHL. Concentrations of 36 PCB-congeners, p,p' -ODE (a metabolite of DOT), hexachlorobenzene (HCB) and 4 congeners of chlordanes in blood were measured in a subgroup of included induviduals. These concentrations were analysed as risk factors for HCL, and were also related to the levels of certain antibodies to EBV. The possibility of an interaction between EBV and these exposures is suggested.