RB1 and breast cancer: About 40% of retinoblastomas are hereditary and hereditary retinoblastoma survivors are at risk for second malignancies like osteosarcoma, melanoma, and epithelial malignancies like lung, bladder, and breast cancer.10, 11 Somatic alterations in RB1 are known to occur in various malignancies including lung, breast, bladder, and prostate cancer.