Second malignant neoplasms in children with retinoblastoma: the St. Jude Children's Research Hospital experience.

A retrospective review of 172 children with primary diagnosis of retinoblastoma (RB) was completed at St. Jude Children's Research Hospital to evaluate the incidence of second malignant neoplasm (SMN) development. Sixty-five patients presented with bilateral RB and 107 with unilateral RB. During follow-up, which ranged from 6 to 340 months (median = 170 months), 6 children (3.5%) developed SMN. All patients who developed SMN presented with bilateral disease (n = 5) or asynchronous bilateral disease (n = 1); two patients had a family history of RB. All had received irradiation. Four patients developed osteogenic sarcoma within this irradiated volume, one developed a basal cell carcinoma in the temporal region (within the irradiation field), and one was diagnosed with a lower extremity Ewing's sarcoma. Time to development of SMN ranged from 125 to 194 months post-irradiation. Initial irradiation total dose ranged between 32 and 45.76 Gy. Three patients were treated with anterior field irradiation and three received lens-sparing techniques (anterior/lateral n = 2, lateral n = 1). At last follow-up, 4/6 patients had died of SMN. The crude incidence is 3.5% with an estimation of risk using the density method of 24% at 20 years for SMN development. The specifics of the treatment associated with these second malignancies and the possible reasons for the reported incidence of SMN will be discussed.