Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Colorectal Cancer ?
    ### Response:
    Various drugs are under study as possible treatments for colorectal cancer. A 2005 study found that patients who took the drug AvastinTM with their standard chemotherapy treatment had a longer progression-free survival than those who did not take Avastin, but the evidence is mixed on whether or not Avastin can extend life.
    