Mutation and cancer: A model for wilms' tumor of the kidney

Statistical analysis of cases of Wilms' tumor supports a 2-mutation model previously reported for retinoblastoma. Comparison of data for familial, bilateral, unilateral, and unselected cases reveals that familial and bilateral cases have an early average age of diagnosis, with a distribution suggestive of a single-event process, while unilateral and unselected cases do not. Familial cases have an incidence of bilaterality higher than that of unselected cases and a pattern consistent with autosomal dominant inheritance. These findings suggest that Wilms' tumor may be attributed to a 2-mutational model; i.e., 2 mutations are required in all cases, but, in approximately 38%, one mutation has occurred in the germinal line of a parent and is inherited. Persons acquiring this germinal mutant develop an average of one second mutation each, which gives rise to tumor. Approximately 37% of gene carriers do not develop tumor, and 15% develop bilateral tumors. About 62% of cases of Wilms' tumor are non­hereditary, both of the mutations occurring in somatic cells. The association of Wilms' tumor with aniridia, hemihypertrophy, and genitourinary anomalies is fitted to the model. The familial pattern is noted to be similar to that of a delayed mutation,- new germinal mutations may be attributable to a vertically transmitted tumor virus resembling the virus causing embryonal renal sarcoma in chickens. —j Nat Cancer Inst 48: 313-324, 1972.