About 1 in 9 American men receive a diagnosis of prostate cancer at some point in their lifetime. Fortunately, since most prostate cancers are slow-growing and not aggressive, the majority of men with prostate cancer do not die from it.
Screening and diagnosis for prostate cancer
What is PSA?
Prostate-specific antigen (PSA) is a substance made by cells in the prostate gland (both normal cells and cancer cells.) PSA is usually found in semen, but can also be found in the blood. The chance of having prostate cancer increases as PSA levelsrise.
Most men free of prostate cancer have PSA levels under 4 nanograms per milliliter (ng/mL) in the blood. When prostate cancer develops, the PSA level usually rises above 4. However, a level below 4 does not mean that a man does not have cancer, and a level above 4 does not mean that the cancer is present. About 15% of men with a PSA below 4 will have prostate cancer on a biopsy. Men with borderline PSA levels between 4 and 10 have about a 1 in 4 chance of having prostate cancer. If the PSA is more than 10, the chance of having prostate cancer is over 50%.
If your PSA level is high, your physician will likely advise either observation and repeating the test or getting a prostate biopsy to find out if cancer is present. Not all physicians follow the same cutoff point when advising whether or not to do a biopsy. Some may recommend it if the PSA is 4 or higher, while others may recommend it at a 2.5 or higher. Other factors such as race, age, general medical condition, and family history may come into play when determining next steps.
Factors that could cause PSA levels to increase:
- An enlarged prostate: A non-cancerous enlargement of the prostate, known as benign prostatic hyperplasia (BPH), could raise PSA levels.
- Older age: PSA levels natural increase as you get older, even if no prostate abnormality of present.
- Prostatitis: An infection or inflammation of the prostate gland, may raise PSA levels.
- Ejaculation: This can cause PSA levels to rise for a short amount of time, and then drop again. Which is why some physicians suggest that men abstain from ejaculation for 2 days before testing.
- Riding a bicycle: Some studies have suggested that cycling may raise PSA levels, because the seat puts pressure on the prostate. Although, not all studies have found this to be true.
- Certain urologic procedures: Some procedures such as a prostate biopsy, catheterization or cystoscopy may result in higher PSA levels for a short period of time. Some studies have even suggested that a digital rectal exam (DRE) might also raise PSA levels. Physicians might advise drawing blood for the PSA test before doing the DRE, just to be safe.
- Certain medications: Testosterone may causePSA levels to rise.
Factors that could cause PSA levels to decrease:
- Obesity: Obese (severely overweight)men tend to have lower PSA levels.
- Aspirin: Recent studies have suggested that men who takeaspirin regularly might have lower PSA levels. If you take aspirin regularly (such as to help prevent heart disease), talk to your physician before you stop taking it for any reason.
- Herbal mixtures: Some mixtures that are soldas dietary supplements could also decrease PSA levels. It is important to let your physician know if you are taking any type of supplement, even ones that are not meant for prostate health.
- Certain medications: Drugs used to treat BPHor urinary symptoms, such as finasteride (Proscar or Propecia), or dutasteride (Avodart), could lower PSA levels.
For men who are unaware if they have prostate cancer,it is not always clear if lowering PSA is helpful or harmful. In some instances, the factors that lower PSA levels may also lower their risk of cancer. On the flip side however, it might lower PSA levels without affecting a man’s risk of cancer. This could actually be harmful if it were to lower the PSA from an abnormal level to a normal one, as it could result in not detectingor a delay in the detection of cancer. This is why it is important to talk with your physician about factors that could affect your PSA level.
What is the Gleason Score?
An important part of the prostate cancer diagnosis is not only understanding the stage of the cancer, but also the grade. The Gleason Score is the grading system used to help in determining the aggressiveness of an individual’s prostate cancer. Pathologists grade the cancer on a scale from 1-5, 1 being the lowest (appearing to be very similar to normal prostate tissue)and 5 being the highest (appearing to be very different from normal prostate tissue). The pathologist then assigns a grade to the most common tumor patterns and a second grade to the next most common tumor pattern. The two grades are then added together to get a Gleason Score.
For example, if the most common tumor pattern was a grade 3, and the second most common tumor pattern was a grade 4, the Gleason Score would be 3+4=7. The Gleason Scores ranges from 2-10 with 10 being the most aggressive. It is very uncommon to have a Gleason Score <6.
Digital Rectal Exam (DRE)
A digital rectal exam (DRE), is a procedure your physician will do in order to examine your prostate to check for abnormalities and prostate cancer. To perform the DRE, your physician will insert a gloved, lubricated finger into the rectum to feel for any bumps or abnormalities on the prostate that might feel like cancer.
The prostate gland is just in front of the rectum, and most cancers begin in the back part of the gland, which can be felt during a rectal exam. The exam can be uncomfortable, but it usually isn’t painful and only takes a short time to complete.
To perform a prostate biopsy, a probe about the size of a finger in inserted a short distance into the rectum. The probe can provide images at different angles to help your doctor estimate the size of your prostate and may detect abnormal growths.
During a prostate biopsy, trans-rectal ultrasound imaging is used to guide several small needles through the rectum wall into areas of the prostate. The needles usually remove a tiny amount of tissue from six or more areas of the prostate. The tissue samples are then analyzed in a laboratory and the results are sent back to the physician. From there, your physician can identify the grade of the cancer and help determine the aggressiveness or likelihood of spreading.