Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Testicular Cancer ?
    ### Response:
    Key Points
                    - Testicular cancer is a disease in which malignant (cancer) cells form in the tissues of one or both testicles.    - Testicular cancer is the most common cancer in men aged 15 to 34 years.    - Testicular cancer can usually be cured.
    