Wilms' tumour and parental age: a report from the National Wilms' Tumour Study.

Age distributions of parents at birth of patients registered in the National Wilms' Tumour Study were compared to those of the general population. An increasing incidence of sporadic Wilms' tumour with increasing paternal age was found, with a relative risk of 2.1 of tumour in children of fathers over 55 compared to children of fathers younger than 20. A similar effect for maternal age was found, with a relative risk of 1.4 in children of mothers over 40 compared to children of mothers younger than 20. The maternal age effect was much weaker among patients registered later in the study; in the later, more completely ascertained cohort, paternal age appears to be the major contributor to the parental age effect. Little difference in paternal age distribution was found between patients with bilateral and unilateral tumour and between male and female patients. In contrast, patients with reported associated congenital anomalies, patients with evidence of nephrogenic rests, and patients with early or late age-of-onset of tumour had parents who were, on average, substantially older than the remainder. These findings lend support to the idea that many Wilms' tumours result from new germline mutations. Further, the histologic composition of such tumours may be sufficiently distinct as to provide a valuable diagnostic indicator of the etiology of these tumours.