Prostate Specific Antigen in Asian Men
Prostate Speficic Antigen or PSA Test for the prostate gland has been receiving much attention in Singapore as well as in Asia over the last decade. We attempt to answer some common questions and misconceptions posted by our patients.
S H HO UROLOGY AND LAPAROSCOPY CENTRE
Updated 19 Sep 09
What is a PSA test?
The PSA test measures the level of PSA in the blood. It is measured via a blood sample drawn by the doctor. The blood sample can be taken without any preparation and over anytime of the day.
PSA test is used as a tumour or cancer marker for prostate cancer.
How often should I have a PSA test?
Generally, PSA tests should not be done more frequently than once a year for men who do not have any symptoms or have any previously abnormal PSA readings.
What if my PSA reading is high?
A high or abnormal PSA reading suggest a problem in the prostate gland. It may be due to prostate enlargement related to aging, prostate infection or any inflammation in the prostate gland.
In 25% of cases, it is due to cancer of the prostate. The higher the PSA reading, the higher likelihood of significant prostate cancer. PSA levels of above 20 ng/mL in prostate cancer patients suggest spread of the cancer to areas beyond the prostate gland, such as the lymph nodes or the bones.
Can a specialist differentiate between cancer and non-cancer from a PSA reading?
The Urologist cannot differentiate between a cancer or non-cancer growth of the prostate by just looking at the PSA level. He will be aided by a digital rectal examination to detect lumps in the prostate to suggest prostate cancer. However, early prostate cancer does not manifest as a lump and the prostate gland would have a ‘normal’ feel.
It is much more important to determine the cause of PSA elevation rather than just bringing the PSA reading to normal level. PSA tests only acts as an indicator of problems in the prostate.
If the abnormal PSA reading is due to an infection, PSA will revert to normal upon treatment of the infection with a course of antibiotics.
Drugs such as Dutasteride and Finesteride, which are used to treat prostate enlargement would decrease PSA levels significantly but would not decrease the risk of prostate cancer.
It is a fact that the incidence of prostate cancer in the Asian population is much lower than the western population. Prostate cancer is the fifth commonest cancer in men in Singapore while it is the commonest cancer in American men.
The differences may have been due to differences in race, life-style and diet. Many health providers in America practise PSA screening which detects early and prostate cancer when it is not causing any symptoms.
However, in our 2004 study involving more than 3400 participants who do not have any symptoms and underwent PSA testing, the cancer detection rate was 1%. The incidence rate of 1% is similar to other population based studies conducted in America and Europe. It seem to suggest that the observed lower incidence in Asian men may be due to under detection.
Ministry of Health, Clinical Practice Guidelines 6/2003
- Executive Summary
Trends in Cancer Incidence in Singapore 1968 - 2002
- Singapore Cancer Registry
Summary of Topics
The conventionally accepted ‘normal’ PSA is any reading less than 4.0 ng/mL. Any reading that is above 4.0 ng/mL requires further evaluation to exclude prostate cancer.
There is a trend towards accepting a lower ‘normal’ range in younger patients in order to increase sensitiveness in cancer detection. Many centres in the world consider a PSA reading of above 2.5 ng/mL being abnormal in men who are below 50 years old.
Digital Rectal Examination of the Prostate
- to detect nodule or lump in the prostate
Summary of Topics
PSA (prostate specific antigen) is a protein or chemical substance produced by cells in the prostate gland of a man and distributed
in the blood. It is normal for a man to have some PSA detected in the blood. However, prostate cancer or benign prostate enlargement will
cause an abnormal increase in PSA levels.
The opinion amongst specialists is divided over the concept of routine screening for prostate cancer. Routine screening means annual
PSA test for all men above 50 years old, regardless if they have symptoms.
Ministry of Health in Singapore currently does not
recommend routine population based screening for prostate cancer with PSA testing.
Some studies have shown that routine screening
allows early detection of prostate cancer in men who do not have any symptoms at all. They are potentially curable if early prostate
cancer treatment is administered. Long term and large population based studies are underway to answer questions pertaining to screening.
These studies will be maturing in a few years.
You should be evaluated by the Urologist, who would perform a digital rectal examination of the prostate gland. He would most
likely proceed to perform a transrectal ultrasound and biopsy of the prostate gland.
Only after a biopsy can the Urologist determine
if the abnormal PSA is due to prostate cancer or other diseases of the prostate.