Risk factors for Wilms' tumour : analysis of a case-control study

The Brazilian Wilms' Tumor Study Group carried out a case-control study of Wilms' tumour (WT) to identify risk factors for the development of WT. Two controls per case, matched for sex, age (${ pm12}$ months), hospital and interviewer, were chosen. Controls were children admitted to hospital for conditions other than neoplasms. Pediatricians interviewed parents of 109 cases and 218 controls.Increasing levels of parental education and family income were associated with the diagnosis of WT, probably the result of selecting a hospitalized control group. The positive association between high family income and WT was strongest among the cases diagnosed early, and absent among the cases diagnosed late.Parental occupational exposure to pesticides or herbicides before the pregnancies of the subjects was identified as a risk factor, with a significant trend for increasing risk with increasing cumulative frequency of use.Also identified as risk factors were maternal consumption during the pregnancy of coffee in excess of 2 cups/day and of dipyrone, an analgesic (both among the lowest income group), and of alcoholic beverages (among the most educated)