What does an elevated Prostate Specific Antigen level mean? What is Prostate Specific Antigen (PSA)? PSA is a protein that is produced mainly by the prostate organ in males. Together with a physical examination of the prostate, it is used to look for and assess the risk of prostate cancer. Generally, the higher the PSA level, the greater the risk of prostate cancer. However, other conditions can cause a high PSA level as well. For patients already diagnosed with prostate cancer, the PSA level aids in monitoring one’s disease progression as well as the treatment response.
Who Needs to Test for PSA? The decision for PSA testing is made jointly with your doctor: • Early screening can start at 40 years of age for those with cancer gene mutations (e.g. BRCA 1 /2) or a significant family history of prostate cancer • If you are 50-69 years old, individualised informed decision-making regarding prostate cancer screening should be discussed • Testing after 75 years of age should only be done in selected healthy men to detect the small numbers of potentially aggressive cancers Do note that it is not recommended to be tested during a regular health screening, especially if you have no risk factors or symptoms suggestive of prostate cancer.
What affects my PSA level? Common causes of a high PSA include: • Benign enlargement of the prostate (BPH) • Inflammation of the prostate (prostatitis) • Urinary tract infection • Recent use of/currently on urinary catheter Do medications affect my PSA level? 5-alpha reductase inhibitors such as dutasteride (Avodart®; combination with tamsulosin in Duodart®), finasteride (Proscar®) can decrease the PSA level by almost half. Patients on oral ketoconazole, which is a commonly-used medication for the treatment of fungal infections, can have their PSA levels reduced as well. Hence, the PSA level measured while on these medications needs to be adjusted accordingly for the true value.
How do I measure my risk of prostate cancer with my PSA levels? PSA level (ng/ml)
Risk of Prostate Cancer (%)
>4-10.0 >10.0
22-27 ≤ 67
What Are My Options? Repeat PSA Testing This is recommended especially if there are causes that can increase your PSA reading (see above), and if the PSA level is close to the upper limit of the threshold. Transrectal Ultrasound-Guided (TRUS)/Transperineal (TP) Prostate Biopsy This is recommended to obtain tissue samples of the prostate for analysis under the microscope to look for prostate cancer cells. It is performed as a day surgery procedure in the Urology Clinic under local anaesthesia.
Magnetic Resonance Imaging (MRI) of the Prostate This is an adjunct used to determine the risk of prostate cancer, but it should not be used as a screening tool for prostate cancer.
PSA doubling time (PSA-DT) This measures the increase in PSA over time. However, does not provide additional information compared to PSA alone and has limited use for the diagnosis of prostate cancer.
MRI provides detailed imaging of the prostate to look for suspicious features suggestive of prostate cancer, but it cannot rule out prostate cancer completely on its own.
Free/Total PSA ratio This may be used for PSA values 4-10ng/ml to determine the risk of prostate cancer. However, it has limited clinical value.
It is important to note that even with a normal MRI result, one can still have prostate cancer. With the benefit of MRI imaging, suspicious areas can be targeted for biopsy (MRI-targeted biopsy) to improve the detection rate of prostate cancer. Other PSA-related tests PSA velocity (PSAV) This is the rate of change of PSA over time. However, alone, it does not significantly increase the predictive accuracy of high PSA levels and hence is not recommended for the diagnosis of prostate cancer.
Prostate Health Index (PHI) This is a blood test that is indicated for PSA levels between 4-10ng/ml. A higher PHI value is associated with a higher risk of aggressive prostate cancer. What is recommended? If you have never had a prostate biopsy before and your PSA level is persistently high, a prostate biopsy is highly recommended to rule out prostate cancer. This can be done with or without the aid of an MRI prostate before the biopsy. If you have had previous prostate biopsies which were negative for prostate cancer, an MRI of the prostate is recommended to look for suspicious areas in the prostate which might have not been biopsied previously.
Yishun Health is a network of medical institutions and health facilities in the north of Singapore, under the National Healthcare Group. Admiralty Medical Centre • (65) 6807 8000 • www.admiraltymedicalcentre.com.sg Khoo Teck Puat Hospital • (65) 6555 8000 • www.ktph.com.sg Yishun Community Hospital • (65) 6807 8800 • www.yishuncommunityhospital.com.sg The information is correct at the time of printing and subject to revision without further notice.
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