[Epidemiological aspects of bilateral retinoblastoma]

Retinoblastoma (RB) is the most frequent solid tumor in the Instituto Nacional de Pediatría, México (INP). The bilateral presentation occurs in 25% of all patients. We present some epidemiological data of this form of the disease, in learn these epidemiological variables in our series. We reviewed the clinical charts from 1972 to 1994. We analyzed age, sex, timing of presentation of the second affected eye, positive family history, clinical staging, and the development of secondary malignancies. A total of 105 cases were detected from 412 RB total cases (25%). We observed a male predominance 1.6:1.0 p = 0.04 versus females. The clinical staging showed: retinal stage 9/102, ocular stage 58/102, orbital stage 26/102 and non classified 9/102 p < 0.00001. The asynchronous form is a rare presentation in our experience: 16/105 cases p = 0.00001 (15%). Only 16/105 patients had a positive family history of RB (15%). We found 2 of 105 cases with secondary malignancies (0.01%). The asynchronous form constitutes a rare presentation. We cannot explain the etiology for the high prevalence of bilateral disease. The frequency of secondary malignancies is lower than that reported in the literature.