Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) head and neck squamous cell carcinoma ?
    ### Response:
    Squamous cell carcinoma is a cancer that arises from particular cells called squamous cells. Squamous cells are found in the outer layer of skin and in the mucous membranes, which are the moist tissues that line body cavities such as the airways and intestines.
    