A prostate cancer blood test is a medical diagnostic test that is used to screen men for the possibility of prostate cancer. The patient’s blood is examined for the presence of prostate-specific antigen (PSA). A higher than normal amount of PSA can indicate the presence of prostate cancer or other benign (non-cancerous) prostate problems. Doctors recommend that patients begin receiving a periodic prostate cancer blood test when they reach the age of 50. Men with a history of prostate cancer in their family are recommended to begin testing for PSA levels when they are between 40 and 45 years of age.
To perform a prostate cancer blood test, a doctor will draw a blood sample from the patient. The sample is sent to a laboratory for analysis, and to determine the level of PSAs in the bloodstream. A healthy male will have a PSA level of 4 ng/ml, and younger males often have a PSA range between 2.5 and 3 ng/ml. If the test results show a PSA level of 4 ng/ml or higher, there is a possibility that the patient has a prostate problem, such as cancer, prostatitis or benign prostatic hyperplasia. A PSA level higher than 4 does not necessarily indicate prostate cancer, as the prostate often becomes larger as a man ages, and PSA levels can increase naturally as a part of this process. Certain infections and the patient’s race can lead to PSA levels that are higher or lower than the range considered to be normal.
If a doctor administers a prostate cancer blood test and believes the results could indicate cancer, he or she will often recommend follow-up tests to confirm a diagnosis. These will often include imaging tests, transrectal ultrasound, x-rays and cytoscopy. If the doctor suspects cancer is present after these additional tests, he or she will recommend a biopsy. This involves removing a small piece of the prostate, often with a needle, in order to examine a sample under a microscope. If prostate cancer is diagnosed, treatment of the condition will begin.
A prostate cancer blood test is not perfect, and can often return either a false-positive or false-negative result. In a false-positive result, the levels of PSA are elevated even though no cancer is present; this can lead to extra or unnecessary tests and treatments. In a false-negative result, the levels of PSA are lower than normal, in spite of the patient actually having cancer. This can lead to delayed treatment of reproductive cancers. Research is being done by the National Cancer Institute and other health organizations to determine the overall efficacy of the prostate cancer blood test, and whether testing methods can be improved.