Risk factors for recurrent retinoblastoma after intravenous chemotherapy.

PURPOSE To analyze the risk factors and estimate the risk period for tumor recurrence in intraocular retinoblastoma (RB). METHODS Retrospective study of 60 RB patients. RESULTS The mean age at presentation with RB was 16 months (median 11 months; range 1-84 months). Tumor was unilateral in 13 (22%) and bilateral in 47 (78%) patients. Of 83 eyes with intraocular RB, group B (n = 27; 33%) tumors were more common based on International Classification of Intraocular Retinoblastoma. All cases received intravenous chemotherapy as a primary treatment. Over a mean follow-up period of 57 months (median 38 months; range 12-185 months) post-primary treatment, 44 (73%) patients developed tumor recurrence. The mean interval between the completion of primary treatment and first tumor recurrence was 5 months (median 3 months; range 1-24 months). The total duration of treatment for complete tumor control including treatment of tumor recurrences was 20 months (median 19 months; 2-58 months). By multivariate analysis, the factors predictive of tumor recurrence were multiple tumors (p = 0.008) and retinal detachment (p = 0.003) at presentation. Kaplan-Meier estimate of tumor recurrence at 6 months, 1 year, 3 years, and 5 years was 20%, 31%, 68%, and 73%, respectively. There was no tumor recurrence beyond 5 years since primary treatment. CONCLUSION Multiple tumors and retinal detachment at presentation are risk factors for tumor recurrence in RB. Close follow-up is mandatory for at least 5 years since the initiation of treatment for RB.