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Prostate screenings: What the numbers mean

Prostate cancer

Prostate cancer, the most common non-skin cancer found in American men, is second only to lung cancer in male cancer deaths. However, with screening improvements in recent decades, there is now a 10-year survival rate for this slow-growing cancer.

What are the screening tests?

Primary care doctors will conduct a two-part screening:

  1. Digital rectal exam of the prostate
  2.  PSA screening (blood test) to measure the prostate-specific antigen, an enzyme made in the prostate — those with a higher than normal PSA have a 30 percent chance of prostate cancer  

When should men start PSA screenings?

The American Cancer Society recommends men have their first baseline screening at age 50. If your PSA is low — less than 4 ng/mL (nanograms per milliliter) — and you are at normal risk, screenings can be done every two to four years.

Who is at higher risk?

You are considered at higher risk for prostate cancer and should have annual screenings starting between age 40 and 45 if:

  • Your father or a brother has had prostate cancer
  • You are African-American
  • You have had an abnormal digital rectal exam

What does a high PSA screening level mean?

Seventy percent of the time, PSA levels between 4 and 10 ng/mL do not mean you have cancer. There are several non-cancerous reasons for a higher than normal PSA:

  • Benign Prostate Enlargement (BPE) is the enlargement of the prostate gland, and occurs in almost all men as they age.
  • Inflammation or infection of the prostate will raise the PSA level.
  • Recent sexual activity before the PSA can affect the level.
  • Men who have had a recent prostate biopsy, catheter, or other procedure may have a higher PSA.

How high is too high?

A PSA of less than 4 ng/mL is normal or low. Above 10 ng/mL, the chances of having cancer get proportionately higher, from 40 percent to 60 percent.  But for PSAs between 4 and 10 ng/mL, there is a gray area, with 30 percent of men being diagnosed with prostate cancer. There have been refinements in how to more accurately diagnose the incidence of cancer in this gray area.  Urologists use the following predictive values to evaluate results in this range:

  1. The absolute PSA number (between 4 and 10 ng/mL).
  2. PSA velocity – the rate at which your PSA level rises from year to year. A more rapidly rising PSA level could be an indication of prostate cancer growth.  

In order to avoid performing a biopsy on all men with a total PSA level between 4 and 10 ng/mL, urologists may conduct the following blood tests:    

  1.  A free PSA test measures the proportion of PSA that is not attached to a protein. The higher amount of free PSA (more than 25 percent), the lower the chance of cancer. If the free PSA level is less than a quarter, urologists will recommend a biopsy, with ultrasound guidance.   
  2. The 4Kscore test calculates the patient’s risk percentage for aggressive prostate cancer — results can determine whether a biopsy is needed.

At what age should a man stop having screenings?

Incidental prostate cancer is very common after age 80, with almost 60 percent of men diagnosed. With people now living well into their 80s and 90s, it is important to discuss the benefits of this screening with your physician as you age. 

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