Thermotherapy for retinoblastoma

Objective: To evaluate the results of thermotherapy for retinoblastoma. Design: Prospective nonrandomized analysis of the treatment method. Participants: A total of 188 retinoblastomas in 80 eyes of 58 patients who were treated with thermotherapy. Main Outcome Measures: Tumor response and ocular adverse effects. Results: Of 188 retinoblastomas treated with thermotherapy, mean tumor base was 3.0 mm and tumor thickness was 2.0 mm. Complete tumor regression was a chieved in 161 tumors (85.6%), and 27 tumors (1.49%) developed recurrence. Using univariate analysis, the predictors of local tumor recurrence were ma le sex (P =.005), no color change ("no visible take") in tumor after treatm ent (P =.01), increasing number of treatment sessions (P =.002), and previo us use of chemoreduction (P =.02). By multivariate analysis, the most impor tant predictors of local tumor recurrence were male sex (P =.01) and previo us use of che moreduction (P =.03), the latter likely reflecting the fact t hat these tumors were initially larger with more ominous findings, and requ ired chemoreduction therapy to reduce them to a size amenable to focal trea tment with thermotherapy. When evaluating thermotherapy variables as a func tion of tumor size, it was apparent that larger tumors (greater than or equ al to 3.0-mm base) required greater energy and time than did smaller tumors (<3.0-mm base). Comparison of treatment variables for larger vs smaller tu mors was as follows: number of treatment sessions, 3.3 vs 2.3; spot size, 1 .7 vs 1.3 mm; power, 540 vs 370 mW; treatment duration, 49 vs 14 minutes; a nd coupling of thermotherapy with chemotherapy, 79% vs 48% of cases (P less than or equal to.001 for each variable). Complications of thermotherapy in the 80 eyes included focal iris atrophy in 29 eyes (36%), peripheral focal lens opacity in 19 eyes (24%), retinal traction in 4 eyes (5%), retinal va scular obstruction in 2 eyes (2%), and transient localized serous retinal d etachment in 2 eyes (2%). There were no cases of corneal scarring, central lens opacity, iris or retinal neovascularization, or rhegmatogenous retinal detachment. All eyes with focal lens opacity demonstrated adjacent focal i ris atrophy. By multivariate analysis, the predictors of thermotherapy-indu ced focal iris atrophy were increasing number of treatment sessions (P =.00 1) and increasing tumor base (P =.02). Conclusions: Thermotherapy is used for relatively small retinoblastomas wit hout associated vitreous or subretinal seeds. This treatment provides satis factory control for selected retinoblastomas, with 86% of tumors demonstrat ing lasting regression. Tumors that measure 3.0 mm or larger in base at the time of thermotherapy require more intense treatment than smaller tumors a nd are at greatest risk for ocular complications such as focal iris atrophy and focal paraxial lens opacity.