Glossary
Diagnostic Tests
PCA-3
PCA-3 is a urine test to detect prostate cancer. Values above 35 indicate a higher chance that prostate cancer will be diagnosed if a random biopsy is performed. Extremely low or extremely high PCA-3 levels carry greater weight (suggesting lower and higher risk of cancer respectively) but unfortunately this test is far from perfect.
PSA
Prostate Specific Antigen better known as PSA helps find prostate cancer when it is still small and confined to the prostate gland. Elevated PSA levels in the blood may indicate that prostate cancer is present. However there are several non-cancerous reasons for an elevated PSA. The most common non-cancerous cause of an elevated PSA is a condition called benign prostatic hypertrophy (BPH). BPH is enlargement or swelling of the prostate and may be associated with urinary difficulties. Other reasons for non-cancerous PSA elevations are laboratory errors, prostate infection, and recent sexual activity. Since these causes can be temporary and reversible, the first step toward determining the reason for a rise in PSA is simply to repeat the blood test after a course of antibiotics or after abstaining from sexual activity for a day or two. Often, the PSA will drop back into the normal range with these simple measures.
Not everyone has the same normal range for PSA. The normal range for PSA varies because as men get older their prostate glands enlarge due to BPH. The enlarged gland makes more PSA and an allowance has to be made for this fact. The normal range of PSA varies somewhat from lab to lab but here are some general guidelines: For age less than 50 the PSA should be less than 2.0. Between ages of 50 to 60, the PSA should be less than 3.0; between ages 60 to 70, the PSA should be less than 4.0; and for age over 70 the PSA should be less than 5.0.
These age-related, normal ranges for men can partially account for the increased PSA from large prostates in aging men. However, just as with any other physical characteristic, some men have glands that are much larger than average. Your physician has the ability to detect an oversized gland during a digital rectal exam. If the increased PSA level is proportionate to the degree of prostate enlargement your doctor may reasonably conclude that no further testing is necessary.
A PSA level that remains elevated after the simple measures outlined above may warrant referral to a specialist for an ultrasound with a biopsy. Before making the referral some additional factors need to be considered. These factors are (a) race: African American men are more prone to develop prostate cancer than other races, (b) family history: men who have a father or brother with prostate cancer have a higher incidence of the disease, and (c) The results of another related but different blood test called free-PSA.
The ultrasound is a finger-sized wand inserted into the rectum while the patient lies on his side. Ultrasound is a scanning tool using sound waves. The ultrasound helps the physician localize the prostate gland for biopsy. Typically six to twelve small core samples about the thickness of a pencil lead are removed with a spring-loaded biopsy tool.
The biopsy material that is removed from the prostate is sent to a pathologist, a physician specializing in evaluation and diagnosis of this material. When cancer is present the biopsy results yield valuable information about the extent and grade of the cancer. The grade of the cancer (called the Gleason Score) is one of the most important indicators of the cancer's aggressiveness. Noting how many of the cores have cancer in them and what percentage of each core is replaced by cancer provides additional information about the extent of the cancer.
Not everyone with a normal biopsy is cancer-free. Studies show that it is possible for the biopsy to miss the cancer. This can occur up to 20% of the time and it happens much more commonly in men with large prostate glands. So it is not unusual to request a second biopsy if your doctor has a strong suspicion that cancer is present.
Sometimes there are reasons to do a biopsy even when the PSA is in the normal range. Men who have been checking their PSA faithfully from year to year will notice that the PSA usually does not vary much. Many younger men have PSA levels consistently below 1.0. When such individuals see a sudden jump in PSA, up to 2.5 for example, they should look at this as a possible indication of cancer. Also, biopsy may be warranted if an abnormality is felt with digital rectal examination.
Everyone should know his own PSA level! Tracking PSA from year to year is a powerful method to detect prostate cancer at an earlier stage. Take responsibility - keeping track of your own PSA from year to year is a fairly simple proposition. PSA variations occur from laboratory to laboratory so the measurements will be more consistent and reliable by using the same laboratory from year to year. Abnormal urinary symptoms such as burning, urgency, or increased urinary frequency at the time of the blood test need to be brought to the attention of your physician because they could indicate an underlying prostate infection that could elevate the PSA level.
PSA is a remarkable tool that has transformed the management of prostate cancer over the last 20 years since its FDA approval in 1988. Powerful tools require proper understanding for correct application. This small essay constitutes a preliminary introduction to a vast field of clinical and scientific endeavor.
Other Tumor Markers
A variety of blood tests including LDH, ALP, CEA, PAP and CTC help determine if prostate cancer is progressing or regressing. These blood tests are generally of little value in men with localized disease. However, the accuracy of PSA may diminish when prostate cancer metastasizes or becomes castration resistant. "Cross checking" with additional blood tests, usually on a monthly basis, can aid in the earlier determination of the pace and direction the disease. In men with recurrent disease we generally check these markers twice a year to see if they are elevated above the normal range. If any are elevated above the normal range we check them monthly.
Small Cell Markers
A rare, aggressive type of prostate cancer called small cell may be signaled by an increase in the blood of CGA and NSE. You need to be aware, however, that common anti-acid medications such as Prilosec, Prevacid and Nexium can elevate blood levels of CGA. If the presence of a small cell prostate cancer is confirmed, chemotherapy is usually the best treatment. Rather than Taxotere, the most commonly used chemotherapy for prostate cancer, small cell cancer usually responds better to other medicines such as adriamycin, VP-16 or Vincristine.
