Prostate-specific antigen (PSA) is a substance made by cells in the prostate gland (both normal cells and cancer cells). PSA is mainly found in semen, however a percentage is also discovered in the blood.
Two tests are frequently used to screen for prostate cancer
- Digital rectal exam (DRE): A doctor or nurse inserts a gloved, lubricated finger into the rectum to estimate the size of the prostate and feel for lumps or other abnormalities.
- Prostate particular antigen (PSA) test: Measures the level of PSA in the blood. PSA is a substance made by the prostate. The levels of PSA in the blood can be higher in men who have prostate cancer. The PSA level may likewise rise in other conditions that affect the prostate.
When prostate cancer establishes, the PSA level usually goes above 4. Still, a level below 4 does not ensure that a man does not have cancer. About 15% of men with a PSA below 4 will have prostate cancer on a biopsy.
Men with a PSA level between 4 and 10 have about a 1 in 4 chance of having prostate cancer. If the PSA is more than 10, the opportunity of having prostate cancer is over 50%.
If your PSA level is high, your doctor might recommend either waiting a while and duplicating the test, or getting a prostate biopsy to discover if you have cancer. When thinking about whether to do a prostate biopsy to search for cancer, not all doctors use the exact same PSA cutoff point. Some may encourage it if the PSA is 4 or greater, while others may recommend it starting at a lower level, such as 2.5 or 3. Other factors, such as your age, race, and family history, might impact this choice.
Elements that might impact PSA levels
A variety of aspects aside from prostate cancer can likewise raise PSA levels:
- A bigger prostate: Conditions such as benign prostatic hyperplasia (BPH), a non-cancerous augmentation of the prostate that impacts lots of men as they get older, can raise PSA levels.
- Older age: PSA levels usually go up slowly as you get older, even if you have no prostate problem.
- Prostatitis: This term describes infection or inflammation of the prostate gland, which can raise PSA levels.
- Ejaculation: This can make the PSA go up for a brief time, and then go down once again. This is why some doctors recommend that men avoid ejaculation for a day or more prior to testing.
- Riding a bicycle: Some research studies have actually recommended that biking might raise PSA levels (perhaps because the seat puts pressure on the prostate), although not all studies have actually found this.
- Particular urologic treatments: Some treatments done in a doctor's workplace that impact the prostate, such as a prostate biopsy or cystoscopy, can lead to greater PSA levels for a short time. Some studies have actually suggested that a digital rectal examination (DRE) might raise PSA levels somewhat, although other studies have actually not discovered this. Still, if both a PSA test and a DRE are being done during a doctor check out, some physicians advise having actually the blood drawn for the PSA before having the DRE, just in case.
- Certain medications: Taking male hormonal agents like testosterone (or other medicines that raise testosterone levels) may cause an increase in PSA.
Special types of PSA tests
Some doctors might think about using different types of PSA tests (gone over below) to help choose if you need a prostate biopsy, however not all doctors settle on how to use these other PSA tests. If your PSA test outcome isn't really normal, ask your doctor to discuss your cancer risk and your requirement for more tests.
Percent-free PSA: PSA takes place in 2 significant forms in the blood. One kind is attached to blood proteins, while the other distributes free (unattached). The percent-free PSA (fPSA) is the ratio of how much PSA circulates totally free compared to the overall PSA level. The portion of complimentary PSA is lower in men who have prostate cancer than in men who do not.
This test is often used to assist decide if you must have a prostate biopsy if your PSA results are in the borderline range (like between 4 and 10). A lower percent-free PSA indicates that your chance of having prostate cancer is greater and you ought to probably have a biopsy.
Numerous doctors recommend biopsies for men whose percent-free PSA is 10% or less, and recommend that men think about a biopsy if it is in between 10% and 25%. Using these cutoffs detects most cancers and assists some men avoid unnecessary prostate biopsies. This test is widely used, however not all medical professionals agree that 25% is the best cutoff point to decide on a biopsy, and the cutoff may change depending upon the overall PSA level.
Complexed PSA: This test directly measures the amount of PSA that is attached to other proteins (the part of PSA that is not "complimentary"). This test might be done instead of examining the total and totally free PSA, and it could offer the very same quantity of info as the other tests done independently. This test is being studied to see if it offers the exact same level of precision.
Tests that integrate different types of PSA: Some newer tests, such as the prostate health index (phi) and the 4Kscore test, integrate the outcomes of various types of PSA to obtain a total score that reflect the opportunity a man has prostate cancer. These tests may be useful in men with a slightly raised PSA, to help determine if they ought to have a prostate biopsy. Some tests might be used to help identify if a man who has already had a prostate biopsy that didn't find cancer ought to have another biopsy.
PSA speed: The PSA velocity is not a different test. It is a step of how quick the PSA increases in time. Normally, PSA levels increase slowly with age. Some research has actually found that these levels go up much faster if a man has cancer, but research studies have actually disappointed that the PSA velocity is more helpful than the PSA level itself in finding prostate cancer. For this reason, the ACS guidelines do not recommend using the PSA speed as part of screening for prostate cancer.
PSA density: PSA levels are higher in men with bigger prostate glands. The PSA density (PSAD) is often used for men with big prostate glands to attempt to change for this. The doctor measures the volume (size) of the prostate gland with transrectal ultrasound (talked about in If Prostate Cancer Screening Test Results Aren't Normal) and divides the PSA number by the prostate volume. A higher PSA density suggests a greater likelihood of cancer. PSA density has actually not been revealed to be as beneficial as the percent-free PSA test.
Age-specific PSA ranges: PSA levels are normally higher in older men than in younger men, even when there is no cancer. A PSA result within the borderline variety might be very worrisome in a 50-year-old man but cause less concern in an 80-year-old man. For this reason, some doctors have actually recommended comparing PSA results with arise from other men of the very same age.
However due to the fact that the effectiveness of age-specific PSA ranges is not well proven, many medical professionals and professional companies (as well as the makers of the PSA tests) do not advise their use at this time.