<prompt> Screening of prostate Ca commonly done byDRE Digital rectal examUSGMRIPSA  <response>: Screening for carcinoma prostate is done by measurement of PSA prostate specific antigen . It is a organ specific protease produced from the prostatic epithelium, secreted in the semen to cleave and liquefy the seminal coagulum formed after ejaculation. It is sensitive for carcinoma prostate but not specific. Normal value is 4 ngml of plasma. Value 10 ngml is significant. Cancer detection rate is 2-4. About 30 of men with elevated PSA will have prostate cancer confirmed by biopsy. But about 20 of those with clinically significant prostate cancer have PSA level within normal range. Reference : page 1043, 1044 SRBs manual of surgery 5th edition and page 1354 Bailey and Loves sho practice of surgery 25th edition 