Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Clear cell renal cell carcinoma ?
    ### Response:
    Clear cell renal cell carcinoma is a cancer of the kidney.  The name "clear cell" refers to the appearance of the cancer cells when viewed with a microscope.[5258]  Clear cell renal cell carcinoma occurs when cells in the kidney quickly increase in number, creating a lump (mass).
    