The american cancer society recommends that all men over 50 be screened annually with two standard tests : the prostate specific antigen , or psa , which measures a protein in the blood , and the digital rectal exam , or dre , which entails a physical exam the prostate 美国癌症学会建议所有超过50岁的男人每年都要进行两种标准检测的进行筛选:包括测量血液中蛋白的前列腺特异抗原检测( psa )和检查前列腺器质的指状直肠检测( dre ) 。