Background: External beam radiotherapy is standard treatment for medium and large, or visually threatening, intraocular retinoblastoma but markedly increases the risk of cosmetic deformities and second malignant neoplasms in children with germline RB1 mutations. Large tumors and those with vitreous seeds do poorly despite radiotherapy. Chemotherapy traditionally is ineffective for intraocular retinoblastoma, perhaps because many retinoblastomas overexpress the multidrug resistance protein, P-glycoprotein.
Objective: To avoid radiotherapy in the management of intraocular retinoblastoma by using chemotherapy and focal therapy.
Interventions: We shrank retinoblastomas in 40 eyes of 31 patients that conventionally should be enucleated or receive radiotherapy by using chemotherapy (ie, vincristine-teniposide, 8 eyes; additional carboplatin, 32 eyes) combined with the administration of cyclosporine, a known multidrug-resistance-reversal agent. We then consolidated these responses to chemotherapy by subsequent 532- and 1064-nm laser therapy and cryotherapy.
Results: At the median follow-up of 2 2/3 [corrected] years (range, 1/10-4 3/4 years), the results of treatment were excellent. The actuarial relapse-free rate was 89% in patients not previously treated (91% for 28 eyes) and 67% in patients treated after relapse from previous therapy (70% for 12 eyes). For the eyes with the worst prognosis (ie, vitreous seeds), the relapse-free rate was 88%, better than previously reported. Cyclosporine is nontoxic and did not enhance the expected toxic effects of chemotherapy. Most eyes required laser therapy, cryotherapy, or both for consolidation of tumor control.
Conclusions: This pilot study suggests that most retinoblastomas are curable by combining chemotherapy with cyclosporine therapy, laser therapy, and cryotherapy, without requiring external beam radiotherapy. We propose a randomized trial to clarify the role of cyclosporine.