Metachronous bilateral Wilms' tumor: the importance of time interval to the development of a second tumor.

BACKGROUND: Information regarding survival and prognostic factors in children with metachronous bilateral Wilms' tumor is limited.
METHODS: A literature search of English language articles from 1950-1996 was performed. A total of 108 of 123 children with metachronous bilateral Wilms' tumor from 30 studies were evaluable for analysis. The children were classified according to the time interval to the development of a contralateral Wilms' tumor (< 18 months vs. > or = 18 months).
RESULTS: Kaplan-Meier analysis rates of overall survival for metachronous bilateral Wilms' tumor were 49.1% and 47.2% at 5 and 10 years, respectively. The median time interval to the development of a second tumor was 23.1 months. Of 106 children, 102 (96.2%) had a metachronous presentation of Wilms' tumor by 5 years. In children ages < 2 years and children ages 2-5 years, 95.2% and 93.9%, respectively, of contralateral tumors appeared within 60 months. For children ages > or = 5 years, all contralateral kidney tumors appeared by 54 months. Analysis of overall survival of patients with a time interval of < 18 months and > or = 18 months showed a 10-year survival of 39.6% and 55.2%, respectively (P = 0.024, log rank test).
CONCLUSIONS: Children with a metachronous bilateral Wilms' tumor who developed a contralateral tumor > or = 18 months from the initial diagnosis of Wilms' tumor had a better overall survival than children with a time interval of < 18 months. Children ages < 2 years at the initial diagnosis of Wilms' tumor did not have a longer period of risk for developing a contralateral kidney tumor than those ages > or = 2 years. Screening by abdominal ultrasound of the contralateral kidney for > 5 years after initial diagnosis of Wilms' tumor may not be necessary because > 95% of children had a time interval to the development of a second tumor of < or = 60 months.