Second non-ocular tumors among survivors of retinoblastoma treated with proton therapy.

Abstract

10018 Background: The leading cause of death for patients with hereditary retinoblastoma is second malignancy. Proton radiation allows for significant sparing of non-target tissue. We sought to determine the risk of second malignancy for the largest and oldest cohort of retinoblastoma patients treated with proton therapy. Methods: We performed a retrospective review of patients treated at the Massachusetts General Hospital (MGH) between 1986 and 2011. Results: Fifty-two patients were identified (see Table). Forty-four patients (85%) were hereditary survivors. Patients were followed for a median of 6.9 years from the start of radiation therapy (range, 11.3 months to 24.4 years). The median age at follow-up was 9.0 years (range, 31.3 months to 24.5 years). Fifteen patients had more than 10 years of follow-up from the start of radiation therapy, and 20 patients were more than 10 years old at last follow-up. With 417.2 person-years of follow-up, we identified one secondary malignancy, an osteosarcoma of the distal femur. The cumulative incidence of second tumor was 5% at 10 years. No radiation-associated malignancies were reported. Conclusions: Retinoblastoma is highly responsive to radiation. The central objection to the use of radiation—the risk of second malignancy—is founded on studies of patients treated with relatively non-conformal techniques. We present the first series of patients treated with the most conformal of current available modalities. While longer follow up is necessary, our preliminary data suggest that the risk of radiation-associated malignancy is minimal with proton therapy. [Table: see text]