Prostate cancer is one of the most common malignancies found in American men, affecting nearly one in six in the United States. According to the American Cancer Society, prostate cancer is the second-leading cause of cancer death among men. Fortunately, improvements in the screening and treatment of prostate cancer have resulted in more men getting tested for the disease and a decreasing death rate. The prostate-specific antigen (PSA) test and digital rectal examination (DRE) are two of the most common methods used to detect prostate cancer, and many men over the age of 50 now undergo these tests as part of a yearly physical examination.
An elevated PSA level is the single most accurate predictor of prostate cancer, and this test detects cancer roughly 5 to 10 years earlier than the DRE. Clinical studies have shown many benefits of PSA testing, including the fact that most cancers detected with the PSA test are curable, and serial PSA testing of a population results in the virtual elimination of advanced prostate cancer at the time of diagnosis. The PSA blood test determines the level of an antigen normally produced by prostate cells in a patient’s blood. This antigen is not found in large amounts anywhere else in the body, although small amounts normally leak into the bloodstream and can be seen with a blood test. Greater levels of PSA are associated with enlargement or inflammation of the prostate or prostate cancer. Mild to moderate increases in PSA, however, do not necessarily mean cancer. They could point to other problems such as benign prostate hyperplasia (ie, enlargement of the gland) or prostatitis (ie, infection or swelling of the prostate), neither of which are life threatening. There is no current evidence linking these conditions to prostate cancer, although a man could have either or both and develop prostate cancer as well.
An abnormal PSA level is 4.0 ng/ml or higher, although a higher level of PSA does not necessarily mean cancer. A number of factors can affect PSA results, including prostate size, infection, and the age of the patient. Recent ejaculation has also been found to affect results, which is why men should abstain from sex for two days before taking the PSA test. Even DREs and biopsies of the prostate may influence PSA levels, though the increase in PSA resulting from a DRE is not thought to be significant.
Recent improvements in the use of the PSA test have resulted in greater accuracy in detecting prostate cancer. One is to assess PSA in relation to prostate size (ie, PSA density). PSA density considers the size of a man’s prostate when determining his PSA level. PSA density is determined by dividing the PSA value by prostate size (as observed on transrectal ultrasound). This measurement helps physicians decipher BPH from prostate cancer. A high PSA density indicates a greater chance of cancer, because an elevated PSA level is less likely from prostate enlargement.
The DRE is a brief but effective screening tool for prostate cancer. To perform a DRE, the patient either kneels on the examination table, lies on his side, or bends over the table. The physician then inserts a gloved, lubricated finger into the rectum and palpates the prostate gland. Although most of the prostate cannot be felt, the back wall of the gland will give the doctor a good idea of the prostate’s overall health. During this procedure the doctor looks for any abnormalities such as lumps, hard nodules or firmness.
It is important to note that neither of these screening tools is 100% effective. The most reliable way to detect prostate cancer in its early stages is to have both of these tests performed yearly.