Screening and Diagnosis of Prostate Cancer Digital rectal examination (DRE) and PSA (Prostate Specific Antigen) blood test are the two most important tests in screening for prostate cancer. What is Prostate Specific Antigen (PSA) Prostate Specific Antigen (PSA) is a protein made by the prostate that enters the blood stream. PSA is reported in nanograms per milliliter (ng/ml) units. Elevated PSA levels may indicate the presence of prostate cancer. However, PSA elevation may occur in a number of non-cancerous situations, as well, such as infection, prostatitis and benign prostatic enlargement (BPH). Therefore, urologist may use other tests associated with the PSA before recommending a prostate biopsy to diagnose prostate cancer. Free PSA and Prostate Cancer Some of the PSA in the blood stream is attached to other proteins; these are called “Bound PSA”. The rest circulate freely, without being bound to other proteins. The freely circulating PSA is called “Free PSA”. Total PSA is the amount of “Free PSA” plus “Bound PSA”. Researchers have discovered an association between the percent of Free PSA in the blood stream and prostate cancer.  The lower the amount of Free PSA, the higher is the chance for prostate cancer.  In general, if the Free PSA is less than 25%, then a prostate biopsy is recommended. The risk of having prostate cancer based on the percent of Free PSA is listed below:              % Free PSA                             % Risk for Prostate Cancer     Less than 10%                        56% chance of having cancer     11% - 15%                              28% chance of having cancer     16% - 20%                              20% chance of having cancer     21% - 25%                              16% chance of having cancer     More than 25%                        8% chance of having cancer PSA Velocity How fast the PSA rises over time is also a risk factor for prostate cancer. A rate of 0.75 ng/ml or higher per year is associated with higher risk of cancer, prompting the need for biopsy. Age-Based PSA The normal range for PSA is related to a person’s age. In general, a PSA greater than 4.0 ng/ml is considered abnormal. However, age-based PSA can be used to fine-tune the need to proceed with a biopsy. Normal PSA ranges are listed below based on age of the patient.               Age                                PSA Ranges (ng/ml)     40 – 49                                0 – 2.5     50 – 59                                0 – 3.5     60 – 69                                0 – 4.5     70 – 79                                0 – 6.5 Digital Rectal Exam An abnormal DRE and/or abnormal PSA do not automatically establish the diagnosis of prostate cancer. Abnormal test results may prompt the urologist to recommend a prostate biopsy. A prostate biopsy is performed to establish or confirm the diagnosis of prostate cancer. A digital rectal exam involves palpation of the prostate by placement of the physician’s index finger into a patient’s rectum. The physician will feel for size, symmetry and texture of the prostate. Although only the back side of the prostate can be felt through the rectum, most prostate cancers occur in this region. A PSA test does not replace the value of a digital rectal exam. About 15% of patients with prostate cancer have a normal PSA profile, but have an abnormal DRE. Prostate Size- A normal prostate is about the size of a walnut. Enlargement of the prostate by itself is not a sign of cancer. Texture- A normal prostate has a texture that feels like the palm of the hand, yielding evenly to palpation. Hard, firm, or nodular areas are indications of an abnormal prostate texture. Symmetry- A prostate is considered normal when both sides of the prostate are the   same size and texture. Suspicious Findings On DRE For Prostate Cancer Include: Prostate nodule: Firm or hard area on the prostate that is round and elevated (like a pea or small marble). Asymmetry of prostate: One side larger than the other. Induration: A flat, firm area of the prostate.