Prostate cancer: What you need to know about the PSA test
Published on 7 October 2021
Screening for prostate cancer is now commonly done using a simple blood test. Learn about whether this test is for you depending on your age and risk factors.
Prostate cancer is the third most common cancer in men in Singapore. However, it is often a slower growing cancer compared to other malignancies. Screening may be one way of detecting the disease early and managing it when it is still localised. Here’s what you need to know about the test and its role in managing prostate cancer.
As with many cancers, early detection is the best way to beat the odds. When it comes to prostate cancer, there is a blood test to screen for high levels of prostate-specific antigens (PSA). Men with prostate cancer usually have a higher PSA level, explained Dr Wang Ziting, Associate Consultant, Department of Urology, National University Hospital (NUH) .
However, this is not always the case, so a more definitive diagnosis involves a biopsy. Small tissue samples from the prostate are extracted using a fine needle. These tissues are then microscopically examined to look for cancerous mutations.
Dr Wang noted that the advantage of PSA testing is that it allows the diagnosis of prostate cancer at an earlier stage when the cancer is still limited to the prostate and has not had time to spread (metastasize).
What happens if I opt for a PSA test?
|PSA blood test: Outcomes|
|PSA levels are within the normal range||PSA levels are higher than the normal range|
|What's next?||Re-testing is recommended in another 2-3 years, depending on the patient’s risk profile.||A second test may be done to confirm the levels.|
|The next step: A more definitive diagnosis|
If PSA levels are high, additional imaging may be ordered. For example: a magnetic resonance imaging (MRI) scan, computed tomography scan or bone scan.
MRI in particular is becoming a valuable way to detect cancer non-invasively and can help 20-30% of men who do not have cancer to avoid unnecessary biopsies.
But ultimately, a prostate biopsy is required for definitive diagnosis.
|What happens if prostate cancer is diagnosed?|
|Not all prostate cancers need treatment as this type of cancer grows slowly, typically requiring active surveillance.
For fast-growing prostate cancer, treatment includes radiotherapy, long-term androgen deprivation therapy and/or surgery.
So, should I have a PSA test?
A PSA test is useful to detect prostate cancer early. According to Dr Chan Ming Tow, Medical Officer, Department of Urology, National University Hospital, one in four men in Singapore have advanced disease by the time they are diagnosed with prostate cancer.
Early screening and diagnosis with screening can help detect prostate cancer early. However, there are some limitations to testing. When considering a PSA test, keep in mind that:
- Screening does not lower the risk of having prostate cancer
- PSA tests detect early-stage cancers that a digital rectal examination might miss
- Normal PSA levels are not a guarantee of being cancer-free, so a test every few years is helpful
- High PSA levels do not always signal cancer - and can be caused by infections and conditions such as benign prostatic hypertrophy
- PSA testing can result in false positives, and involve unnecessary blood tests, investigations, and psychological stress. It is thus useful to discuss and balance the pros of early diagnosis with the cons of over-investigations and over-treatment
If you are weighing the necessity of a PSA test, speak with your urologist to assess your risk factors, as well as what to expect from the PSA test and biopsy.
Dr Wang pointed out that new techniques are making prostate biopsies safer and more convenient. At NUH, a safer and more convenient prostate biopsy test known as transperineal prostate biopsy has been carried out since 2018. It is done under local – instead of general – anaesthesia, and has a lower risk of infective complications.