Prostate-specific antigen (PSA) is a protein that forms in the prostate gland. A PSA test calculates PSA levels in the blood. While it cannot stage cancer by itself, it is a useful screening tool.

Prostate cancer is a common form of cancer that affects males. It is the most common cancer to receive a diagnosis in males worldwide. Prostate cancers may grow relatively slowly and can take up to 10 years for significant symptoms to develop.

Diagnosing prostate cancer early on enables a prompt treatment plan. This can increase the likelihood of successful treatment and reduce the chances of the cancer spreading and causing morbidity or mortality. PSA testing is the most common method of testing for prostate cancer, alongside transrectal ultrasound and prostate biopsies.

PSA testing is useful when working out the presence of cancer, how it is progressing, and whether PSA levels increase after treatment. However, PSA testing is relatively nonspecific, as a rise in PSA levels is not always due to a harmful tumor.

Read on to learn more about PSA levels and their role in monitoring prostate cancer.

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PSA is a protein that can form in both regular cells, as well as malignant cancerous cells in the prostate gland. These proteins enter the bloodstream, which enables a medical professional to measure PSA levels from a blood sample.

PSA testing measures the concentration of PSA in the blood. This can help when assessing for prostate cancer, particularly when making an initial diagnosis.

PSA levels alone cannot indicate stages of prostate cancer. A doctor may use PSA levels as a screening tool for people at risk of developing prostate cancer. A doctor may also use PSA levels to monitor prostate cancer and whether the treatment is effective. After successful treatment, PSA levels can also indicate if cancer has recurred.

Additionally, PSA levels can vary due to a range of factors, so it is best to use other tests to support the results of a PSA analysis.

There are four main stages of prostate cancer. Classification depends on where the cancer spreads to and, therefore, how curable it is. If cancer cells spread from the prostate, they usually go to the bones or lymph nodes.

The stages of prostate cancer are as follows:

  • Stage 1: The earliest and smallest tumor stage. Cancer is very localized.
  • Stage 2: As with Stage 1, cancer is still only present in the prostate and does not extend beyond the prostate.
  • Stage 3: Cancer extends beyond the prostate area and may reach the seminal glands but does not extend to the bladder or rectum.
  • Stage 4: The most advanced stage, where cancer extends beyond the prostate to areas such as the bladder, and may spread to the lungs, liver, or lymph nodes.

As stages of prostate cancer increase, a person’s outlook worsens, and the cancer becomes more difficult to treat.

Read on to learn more about the stages of prostate cancer.

As well as having malignant prostate cancer cells, other factors can increase PSA levels in the blood. This reduces the reliability of PSA testing when assessing prostate cancer.

Reasons for high PSA levels can include:

On the other end of the scale, 5-alpha reductase inhibitors can reduce PSA levels by 50% over 6–12 months. A doctor may prescribe these medications to help treat BPH.

Read on to learn more about other causes of elevated PSA levels.

Although testing PSA levels is not always a specific method, it is currently the most common tool when assessing prostate cancer. Data show that mortality from prostate cancer has decreased by 44% since PSA testing became more accessible at the start of the 1990s.

Other types of prostate cancer tests include:

  • imaging tests of the prostate, such as MRI, CT, or PET scans
  • digital rectal exam (DRE) in combination with another test, usually PSA testing
  • blood or urine tests in the process of risk stratification bioassay to check if a prostate biopsy is necessary
  • prostate biopsy test, which removes and analyzes prostate tissue
  • transrectal ultrasound-guided biopsy, which uses ultrasound to examine the prostate gland

Read on to learn more about prostate exams.

Diagnosing prostate cancer is important for containing and treating the cancer. Prostate-specific antigen (PSA) testing is a common diagnostic tool that measures PSA levels in the blood.

PSA is a protein that comes from the prostate gland and can develop into cancer cells. Therefore, identifying a high concentration of PSA in the blood can indicate the presence of prostate cancer. However, other factors, such as harmless prostate enlargement, can also increase PSA levels. As such, while PSA testing cannot stage prostate cancer, it is an important screening and monitoring tool.