Prostate-specific antigen (PSA) is a naturally occurring protein made in the prostate gland. Testing for elevated levels of it can be a useful but imperfect tool in screening for prostate cancer.
PSA levels can fluctuate throughout life. Elevated PSA results cannot confirm prostate cancer on their own but can indicate the need for further testing. PSA levels can also help measure how far along prostate cancer is and whether treatments are having any effect.
Let’s break down the role of PSA in the prostate, how testing works, and what PSA looks like in different stages of cancer.
Who can get prostate cancer?
Anyone with a prostate can get prostate cancer. The prostate is usually not removed during any gender affirming surgeries, as this can cause problems with urination and nerve damage.
The prostate gland is commonly described as walnut-shaped and is located behind the bladder and in front of the rectum. It surrounds the urethra, the tube that passes urine and semen out of the body.
The prostate gland makes a protein called prostate-specific antigen, or PSA. A healthy person’s prostate should circulate a small amount of PSA in the blood.
Several health factors and conditions related to the prostate can cause the gland to produce more PSA than is typical.
These include:
- Prostatitis: Prostatitis is inflammation and swelling in the gland and surrounding areas, often due to bacterial infection. It can be very painful.
- Benign prostatic hyperplasia: Also called prostate enlargement, this condition can cause frequent and strained urination and increased urination at night, among other symptoms. It is
not cancerousTrusted Source . - Prostate cancer: Prostate cancer occurs when malignant cells grow in the prostate’s tissues. The gland swells and isn’t able to function properly. In rare instances, prostate cancer can spread elsewhere in the body. In general, a higher PSA level indicates a
higher chanceTrusted Source of prostate cancer. - Urinary tract infection (UTI): Most UTIs are caused by bacteria. They can occur alongside other health issues in the prostate. A 2020 study found that
34.6%Trusted Source of people with prostate cancer experienced UTIs.
Certain medications can lower PSA as a side effect. This may interfere with prostate cancer screening and the accuracy of a PSA level test. These include:
- nonsteroidal anti-inflammatory drugs (NSAIDs) like naproxen and ibuprofen
- statins, which are medications that lower cholesterol
- thiazide diuretics, which treat high blood pressure
- finasteride (Proscar, Propecia) and dutasteride (Avodart), medications commonly used to treat hair loss and enlarged prostate
Not all researchers are in agreement, however. More research is needed.
A simple test can check the level of PSA in your blood. A nurse or healthcare worker will draw blood, usually from a vein in your arm, using a needle. The blood is then sent to a lab for analysis.
PSA testing is only one tool in deciding whether further testing is needed. Only a tissue biopsy can definitively diagnose cancer.
If your doctor believes your PSA test results require further investigation, they will likely order a prostate tissue biopsy as the next step.
During this biopsy, your doctor will use a thin needle to take several small samples of tissue from your prostate to be analyzed. This can show the presence of malignant cells. Ultrasound and MRI technology may be used to guide a biopsy. According to a 2021 study, this method is best for detecting cancer at an earlier stage.
There is no universal scale for judging PSA levels. Results are usually given in nanograms of PSA per milliliter of blood (ng/mL). According to
Additionally, a PSA number can change with age.
However, scientists found this method wasn’t totally reliable. Some with higher PSA levels have healthy prostates, and some with regular PSA levels can have cancer. This is why PSA level testing is not the only method for detecting and diagnosing prostate cancer. But it is an important tool.
Checking PSA levels regularly can help establish a personal baseline. If levels rise over time, this can indicate the need for further screening. Repeat testing may also be done if prostatitis is suspected.
If you already have prostate cancer, regular PSA level testing can track disease progression and response to treatment.
Organizing prostate cancer into stages is done to communicate how far along the disease is and to help plan treatment. Stages range from 1 to 4, with higher numbers indicating more advanced disease.
Prostate cancer, like many other cancers, is described based on the American Joint Committee on Cancer‘s TNM (tumor, node, metastasis) staging system. This staging system is based on the size or extent of the tumor, the number of lymph nodes involved, and whether the cancer has spread (metastasized) to distant sites or organs.
The cancer’s stage is further determined based on two additional factors: the PSA level and the Gleason scale.
The role of PSA in staging
Prostate cancer causes cells to become malignant and multiply uncontrollably. This can lead to overproduction of PSA and higher levels of PSA in the bloodstream.
However, some with prostate cancer do not exhibit elevated PSA levels. And certain noncancerous conditions, like a prostate infection or benign enlargement, can also cause high PSA levels.
PSA levels are just one factor used in determining the stage of prostate cancer. Another diagnostic tool is called the Gleason scale. This rates the extent of abnormality in your prostate cells after biopsy.
At a certain point in prostate cancer’s late-stage progression, Gleason and PSA become less useful. When a tumor is large enough, doctors no longer need these numbers to predict its growth or malignancy.
Overview of stages
Here’s a breakdown of how prostate cancer staging works per
| Stage | Features of cancer | PSA level |
|---|---|---|
| 1 | Cancer is only in half of the prostate and has not spread to the surrounding tissues. | 10 ng/mL or less |
| 2A | Cancer is found in | between 10 and 20 ng/mL |
| 2B and 2C | Cancer is found in one or both sides of the prostate. | Less than 20 |
| 3A | Cancer is found in one or both sides of the prostate. | 20 or greater |
| 3B and 3C | Cancer is found in one or both sides of the prostate. It | any PSA |
| 4A | Cancer is found in one or both sides of the prostate. It has spread to nearby glands, tissues, or organs. The cancer has | any PSA |
| 4B | Cancer is found in one or both sides of the prostate. It has spread to nearby glands, tissues, or organs. Cancer has additionally spread farther to bones or distant lymph nodes. | any PSA |
Your doctor will weigh
- cancer severity
- life expectancy
- impacts on your quality of life
- your overall functionality, and any coexisting health conditions
- whether other treatments have been or should be tried first
If the cancer is relatively localized (limited to one area of the prostate), it can be treated with:
- observation and monitoring
- prostatectomy (removal of part or all of the prostate)
- radiation therapy (using special X-rays
to kill cancer cellsTrusted Source ) - other medications to treat symptoms
Should your prostate cancer become more widespread, your doctor may also recommend hormone treatment. This is also called androgen deprivation therapy (ADT).
ADT can be very effective at slowing or stopping cancer growth, but it
People who are generally in good health and expected to be functional post-treatment will likely be offered surgery. However, if the disease is widespread, extending past the prostate to other tissues and organs, surgery may no longer be an option.
PSA level testing can sometimes result in “false positives” for prostate cancer. This can lead to unnecessary invasive procedures and create stress about cancer in those with low cancer risk.
There are several sets of guidelines for who should get screened for prostate cancer. The
- annually for those at high risk starting at ages 40 to 45
- annually for those at low or average risk starting at 45
- every 2 to 4 years for those at low to average risk between the ages of 55 to 69
- less frequently or not at all at ages 75 and above
The AUA points out that those between the ages of 70 and 80 who are in otherwise good health should be involved in the decision regarding testing.
Older men, Black men, and men with a history of prostate cancer in their family are most at risk of developing it. The majority of cases are diagnosed
Prostate cancer is one of the most common types of cancer. According to the National Cancer Institute, it made up
Multiple diagnostic tools are used together to screen for and diagnose prostate cancer. This includes PSA level testing, prostate tissue biopsy, and imaging. These tools are also used to monitor disease progression and how you’re responding to treatment.
Prostate cancer has a very positive outlook, especially when caught before the final stages. Treatment options have progressed rapidly, and the 5-year survival rate for all types of prostate cancer is
Speak with a doctor about your risk factors and to learn more about the pros and cons of PSA level testing.
