What is PSA?
- PSA – Prostate Specific Antigen is a protein produced by the prostatic epithelium and periurethral glands. PSA is secreted into seminal fluid in high concentration and it is also found in low concentration in blood.
- PSA levels under 4 ng/ml are generally considered normal, while levels over 4 ng/ml are considered abnormal.
- PSA levels between 4 and 10 ng/ml indicate a risk of prostate cancer higher than normal. When the PSA level is above 10 ng/ml, risk of prostate cancer is much higher.
- An elevated PSA does not always indicate cancer, nor does normal PSA means that you do not have cancer (a false negative result).
- PSA is not a perfect test.
- The blood test does not tell you whether or not you have prostate cancer.
- Some men with prostate cancer do not have an elevated PSA, and many men with an elevated PSA do not have prostate cancer.
- PSA levels may be high if you have prostate cancer, prostate gland is enlarged (BPH) or there is inflammation in the prostate (prostatitis).
- PSA levels may be lower in patients who take Proscar or Avodart.
Several other ways to look at PSA have been developed to avoid the short comings of PSA (false positive and false negative).
Age – specific reference ranges: PSA increases with age primarily because of increase in prostate size, and age-adjustment of PSA is a means of accounting for this size increase with age. Age-adjustment of PSA – compared to the use of a single PSA cutoff for all ages – may lead to increased cancer detection in younger men thus avoiding false negative PSA.
Age 40 to 50 years 0 to 2.5 ng/ml
Age 50 to 60 years 0 to 3.5 ng/ml
Age 60 to 70 years 0 to 4.5 ng/ml
Age 70 to 80 years 0 to 6.5 ng/ml
The rate of rise of the PSA over time is called PSA velocity
A change in PSA of more than 0.5 ng/ml per year indicates presence of prostate cancer.
The vast majority of men (80%) with elevated PSA have serum levels in the range of 4.0 to 10.0 ng/ml
In these men, the most likely reason for elevated PSA is BPH not prostate cancer.
The ratio of PSA tp prostate gland volume measured by is ultrasound called the PSA density.
Total and Percent Free PSA:
Approximately 90% of the PSA in the blood is bound to protein and lesser amount is free (not bound to protein)
Studies have suggested that patients with prostate cancer have lower percentage of Free PSA than patients with benign disease. If your serum PSA is between 4-10 ng/ml your free PSA should be at least 25% of Total PSA value.
“PSA is the single test with the highest positive predictive value for cancer”
If the results of digital rectal examination of prostate or blood test (PSA) suggest that you may have prostate cancer, we would suggest that you should consider Transrectal Ultrasonography and Ultrasound guided Biopsy of the Prostate.
What is Transrectal Ultrasound?
Transrectal ultrasound is the examination of prostate using a machine called ultrasound. We insert a finger like probe into the rectum to examine the prostate. Ultrasound creates a picture of prostate using high-frequency sound waves. These sound waves come out of the probe and are transmitted through body tissues. The sound waves then bounce off the tissue and return to the probe. These returning sound waves are called echoes and are translated and recorded into photographic images.
Transrectal Ultrasonography provides excellent visualization of the prostate and abnormalities that may be present in the prostate. We can also easily guide the biopsy needle under ultrasound guidance into the prostate where cancer is suspected.
The ultrasound machines in our offices are capable of doing color doppler studies and three dimensional (3D) reconstruction of the gland. Usually there is increased blood flow within the cancerous lesion or adjacent to the lesion and color doppler helps us precisely guide the biopsy needle into the lesion for accurate biopsy.
Transrectal ultrasonography is also used to estimate the prostate volume accurately to calculate PSA density.
Transrectal ultrasonography also provides images sensitive enough to defect capsular involvement and extention of cancer into the seminal vesicles (staging of cancer).
What is biopsy and how is it done?
Once we find an abnormal area in the prostate on ultrasound, we need to remove small pieces of prostate for pathological examination called prostate biopsy.
While the ultrasound probe is in the rectum, a biopsy needle is inserted through the probe and under the ultrasound guidance, biopsies are performed. Six to twelve tine pieces of tissue are taken from the prostate. These pieces of prostate tissue are then sent to a Laboratory where a pathologist who is an expert in prostate cancer examined these pieces under the microscope to determine.
- Whether cancer is present
- Evaluate microscopic features of cancer (Gleason Score)
- Whether suspicious lesions are present (PIN)
- Or the biopsy is negative for cancer
- Whether inflammation is present
What happens if my biopsies comes back negative?
Just because your biopsies are negative, does not mean that you do not have cancer in your prostate. You need to be seen on a regular basis for digital rectal examination and PSA testing. If there is significant change in your PSA, we may suggest repeat biopsies. The average risk of finding cancer in a repeat biopsy following a benign diagnosis is about 18%.
What is prostate intraepithelial neoplasia (PIN) or atypical or suspicious cells on biopsy?
In about 10% of prostate needle biopsy reports, the pathologist will tell us that the final diagnosis is neither benign nor malignant. They describe this condition as
- High Grade Intraepithelial Neoplasia (High Grade PIN)
- A premalignant condition
- Biopsy should be repeated soon
- 25% risk of cancer on repeat biopsy
- Low Grade Intraepithelial Neoplasia
- Repeat biopsy is not indicated unless there is a rise in PSA
- Repeat biopsy should be done as risk of having cancer is about 40%
In these difficult cases, pathologist will use specific stains to determine the exact diagnosis.