Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) ovarian cancer ?
    ### Response:
    Ovarian cancer is a disease that affects women. In this form of cancer, certain cells in the ovary become abnormal and multiply uncontrollably to form a tumor. The ovaries are the female reproductive organs in which egg cells are produced. In about 90 percent of cases, ovarian cancer occurs after age 40, and most cases occur after age 60.
    