Objective: To identify the main age of onset of different malignant tumors in childhood and to describe the distribution of the different tumors in each pediatric age group.
Material and methods: Descriptive survey was used. We reviewed the files of six Mexico City hospitals from 1980 to 1992. We included 4595 cases divided into 13 types of cancer. Peak age was defined when in that year we encountered a frequency equal to or below 10 % of the cases.
Results: Peak ages for hepatic, sympathetic nervous system, germ cell tumors, retinoblastoma and rhabdomyosarcoma were between 2 and 3 years of age. Wilms' tumor appeared between the first and fourth years; central nervous system tumors between 4 and 5 years; acute lymphoblastic leukemia between 2 and 4 years; non-Hodgkin's lymphomas between 3 and 6 years; Hodgkin's disease between 4 and 8 years; bone tumors between 10 and 14 years. In acute myeloid leukemia and carcinomas no age peak was found.
Conclusions: Lymphomas present an age peak different from that reported in developed countries. In neonates and infants, the most frequent tumor was retinoblastoma.