Repeating PSA Test And Prostate Health
Prostate-specific antigen (also known as PSA) is a unique biological protein that is secreted by the cells of male prostate gland. As part of the normal metabolism, part of this secretion also seeps in the blood; thus forming the basis of PSA test.
PSA test measures the levels of prostate-specific antigen in the blood (nanograms per milliliter or ng/mL). FDA has approved PSA test as a reliable test to detect the progression of prostate cancer in 1986. Since early detection of prostate cancer is associated with an excellent prognosis, it is suggested that screening of prostate cancer by PSA test, should be started at the age of 50. In addition, males who are at risk of developing prostate cancer (such as African American males, ore men who have a strong family history of prostate cancer) should opt for early screening at the age of 40 or 45 years.
What Are The Indications Of Repeat PSA Test?
PSA test is usually performed as part of the workup for Prostate cancer. It has been observed that males with prostate malignancy produce significantly high levels of this protein. Although the sensitivity and specificity of PSA test is fairly high; it is imperative to keep in mind that:
- Certain non-cancerous lesions can also cause an elevation in the PSA levels. For example, conditions like benign enlargement of prostate gland (BPH) and prostatitis (or inflammation of prostate gland) are associated with a significant rise in the serum levels of prostate-specific antigen. Other conditions in which PSA levels are high (without malignancy) are; previous prostate biopsy, any injury or surgery involving prostate gland etc.
- A false decrease in the serum levels of PSA is also possible due to some drugs (hence a false-negative test is possible requiring the need of a repeat PSA test); these drugs include, finasteride, certain diuretics and dutasteride.
- It is not possible to ascertain just on the basis of PSA test if the rise in level is due to a malignancy or a benign condition. Consequently, it is also possible that the two conditions coexist; thereby making it necessary to perform other sophisticated tests.
- It is also possible to have a normal PSA test in some males who have active prostate cancer.
- Not every male with a high PSA levels have prostate malignancy. According to latest estimates, only 25% of males with abnormal PSA test have active prostate malignancy.
The normal PSA levels vary with the age of a person. Generally, PSA levels of 4.0 ng/mL or less are considered normal (or ideal) in an adult male. In other words, if PSA levels are higher than 4.0 ng/mL; your doctor may advise either of the following:
- A repeat PSA test to rule out any infection or inflammatory process
- Prostate biopsy to rule out malignancy
Besides cancer detection, other indications of conducting repeat PSA test are:
- As part of the screening process in males who are at high risk of developing prostate cancer (such as positive family history or abnormal findings on the digital rectal exam) in asymptomatic men.
- During active surveillance of prostate malignancy in patients who are not ideal candidates for surgery.
- To detect recurrence of prostate cancer in patients who have already received a treatment for prostate malignancy. It is believed that PSA levels begin to rise a couple of years in advance, before the onset of other clinical and radiological signs in case of a recurrence.
Repeat PSA Test And Impact On Overall Health
Research and clinical data indicates that repeat PSA test can influence physical and sexual health in males significantly. For example, data indicates that abnormal PSA test (requiring repeat testing) can cause erectile dysfunction, poor libido and declining sexual vigor due to anxiety and depression. Other adverse effects include:
- False-positive or false-negative test results cause agitation in patients. In addition, it may force physicians to perform other sophisticated/ somewhat invasive tests like prostate biopsies. Needless to say that, the risk of infection, bleeding and other complications is significantly high if invasive approach is used due to non-reliable results of PSA test.
- In situations, when the affected male has abnormal results of digital rectal exam but low PSA levels, false results may actually give hope to the patient that he does not have any malignancy; thereby causing more emotional turmoil once the final diagnosis is released.
However, the effects are not always devastating. According to a new study reported in European Urology journal (3), investigators explained that a repeat PSA test within 7 weeks from an initial assessment of 3.0–19.99 ng/ml (that was obtained from a sample of 54,087 men; age range 50 – 70 years) helped physicians in making a decision regarding further invasive testing to detect cancer (such as biopsy).
1. Barry MJ. Clinical practice. Prostate-specific-antigen testing for early diagnosis of prostate cancer. New England Journal of Medicine 2001;344(18):1373-1377.
2. Thompson IM, Pauler DK, Goodman PJ, et al. Prevalence of prostate cancer among men with a prostate-specific antigen level < or =4.0 ng per milliliter. New England Journal of Medicine 2004;350(22):2239-2246
3. Rosario, D. J., Lane, J. A., Metcalfe, C., Catto, J. W., Dedman, D., Donovan, J. L., … & ProtecT Study Group. (2008). Contribution of a single repeat PSA test to prostate cancer risk assessment: experience from the ProtecT study. european urology, 53(4), 777-784.