Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Retinoblastoma ?
    ### Response:
    Key Points
                    - Retinoblastoma is a disease in which malignant (cancer) cells form in the tissues of the retina.    - Retinoblastoma occurs in heritable and nonheritable forms.     -  Treatment for both forms of retinoblastoma should include genetic counseling.
    