<prompt> Which is the most common second malignancy in survivors of retinoblastoma?Optic gliomaOsteosarcomaThyroid cancerNasopharyngeal carcinoma  <response>: Osteosacrcomas are the most common second malignancy in survivors of retinoblastoma. Ref: Cancer in Children and Adolescents By William Larkin Carroll, Page 384; Manual of Pediatric Hematology and Oncology By Philip Lanzkowsky, 5th Edition, Page 947 