Abstract
Abstract: :
Purpose: To determine which small retinoblastoma tumors can be treated with transpupillary thermotherapy (TTT) alone, and to clarify the minimum amount of treatment required to prevent recurrence. Methods: 91 tumors in 22 eyes of 24 patients were treated with TTT as the primary treatment modality at a single institution from 1995 until 2002. TTT was applied only when a tumor first appeared or if growth of that tumor subsequently occurred. Treatment was performed while patients were under general anesthesia using the Iris diode laser (810 nm) on continuous mode with a 1.2-mm spot size. Results: Mean patient age at diagnosis was 3 months (range 0-19 months), and mean initial tumor base was 0.67 dd (range 0.1 dd -1.5 dd). Mean follow-up from first TTT treatment was 21 months (range 2-59 months). Eighty-four tumors (92%) were cured with TTT alone. Seven tumors (8%) required between one and five salvage treatments, with 4 patients receiving cryotherapy, 3 patients receiving systemic chemotherapy, 2 patients receiving external beam radiation, and 1 patient receiving periocular chemotherapy. All seven tumors that required salvage treatment were cured without the need for enucleation. Twenty-one eyes were preserved (95%), with one eye of one patient enucleated secondary to growth of other tumors. The mean number of treatment sessions required until cure was 1.7 (median, 1 session, range 1-6), with 64% of the tumors requiring only one session. The mean power used was 420 mW, the mean total duration for all sessions combined was 320 sec, and the mean total energy used for all treatments combined was 139.6 Joules. Univariate analysis revealed that the predictors of tumor recurrence were: male sex, increasing age at diagnosis, posterior and inferior tumor location, increasing initial tumor base diameter, and increasing total energy used. Multivariate analysis revealed that the predictive combination of variables included: male sex, increasing age at diagnosis, and increasing total energy used. The predictors of need for salvage treatment on univariate analysis were: male sex, inferior tumor location, increasing initial tumor base diameter, and increasing total energy used. Multivariate analysis indicated that the most important combination of variables were male sex and increasing total energy used. Conclusions: Retinoblastoma tumors smaller than 1.5 dd in base diameter can be successfully treated with TTT alone. Treatment can be implemented only when growth is observed, and can be employed at low power settings for a short duration.
Keywords: retinoblastoma • clinical (human) or epidemiologic studies: out • clinical (human) or epidemiologic studies: sys