Pfizer's drug tremelimumab and Bristol-Myers Squibb's ipilimumab are antibodies to a protein called CTLA-4 (cytotoxic T-lymphocyte antigen-4) that acts as an emergency brake to prevent killer T cells from attacking healthy tissue.

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In May 2012, the U.S. Preventive Services Task Force recommended against routine PSA screening (Prostate-Specific Antigen test to screen Prostate cancer) before being diagnosed as it did not benefit patients.

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