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Prostate Cancer Testing & Diagnosis

If you have symptoms of prostate cancer or a prostate screening PSA blood test comes back with reason for concern, your physician is likely to do some additional testing. S/He will most likely ask more about your family history and perform a digital rectal exam. This is done to see if there are any hard or lumpy areas of the prostate where a tumor may be growing. 

A biopsy may also be recommended to take a small tissue sample that can be examined under a microscope for cancer cells. A core needle biopsy is most commonly performed on men to test for prostate cancer. This is done by inserting a needle into the prostate to remove the necessary cells for testing. There are typically several areas of the prostate tested during this procedure. 

The physician, typically a urologist, who performs the biopsy may also want to look at the prostate using a transrectal ultrasound, an MRI, or a fusion of both of these imaging tools.

Prostate Cancer Grade, if Cancer Is Found

If cancer cells are found, the pathologist studies tissue samples from the prostate under a microscope to report the grade of the tumor. The grade tells how much the tumor tissue differs from normal prostate tissue and how rapidly it’s likely to grow. Tumors with higher grades tend to grow faster than those with lower grades. They are also more likely to spread. Doctors use tumor grade along with your age and other factors to recommend treatment options.

The Gleason Score for Prostate Grades

  • The primary system used to establish a grade for prostate cancer is the Gleason score. Gleason scores range from 2 to 10. To come up with the Gleason score, the pathologist uses a microscope to look at the patterns of cells in the prostate tissue. The most common pattern is given a grade of 1 (most like normal cells) to 5 (most abnormal). If there is a second most common pattern, the pathologist gives it a grade of 1 to 5, and adds the two most common grades together to make the Gleason score. If only one pattern is seen, the pathologist counts it twice. For example, 2 +2 = 4. 
  • Cancers with a Gleason score of 6 or less may be called well-differentiated or low-grade.
  • Cancers with a Gleason score of 7 may be called moderately-differentiated or intermediate-grade.
  • Cancers with Gleason scores of 8 to 10 may be called poorly-differentiated or high-grade.

Grade Groups for Prostate Cancer

Recent cancer research shows that simply adding the two numbers together doesn’t tell the whole story. The primary number (where the most abnormal cells were found) has an impact on outcomes. For example, men with a Gleason score 3+4=7 cancer tend to do better than those with a 4+3=7 cancer. And men with a Gleason score 8 cancer tend to do better than those with a Gleason score of 9 or 10.

A Gleason score can also lead a man to believe his cancer is worse than it really is. For example, a man with a Gleason score of 6 could easily assume his cancer is moderate grade because 6 is in the middle of 2 and 10. But actually, a Gleason score of 6 means the cancer is actually low grade.

Because of this, doctors have developed Grade Groups, ranging from 1 (slowest growing) to 5 (most likely to grow quickly):

  • Grade Group 1 = Gleason 6 (or less)
  • Grade Group 2 = Gleason 3+4=7
  • Grade Group 3 = Gleason 4+3=7
  • Grade Group 4 = Gleason 8
  • Grade Group 5 = Gleason 9-10

The Grade Groups will likely replace the Gleason score over time, but both are currently in use.