The influence of parental age on the risk of Wilms' tumour

The Brazilian Wilms' Tumour Study Group carried out a hospital-based multic entre ease-control study of potential risk factors for the disease between April 1987 and January 1989. The parents of 109 cases of Wilms' tumour (WT) were interviewed when they were admitted to hospital for diagnosis and tre atment. Also interviewed were the parents of two controls per case, matched for age, sex and interviewer, who were admitted to the same or nearby hosp itals for treatment of non-neoplastic conditions. Odds ratios adjusted for family income and parental education were calculated by conditional logisti c regression. Among cases diagnosed before 25 months of age there was a mar ked gradient of increasing risk of WT with increasing maternal age at the t ime of the child's birth. There was no increased risk for cases diagnosed a fter 25 months of age. The effects of paternal age were less marked. Possib le explanations for these results are discussed.