When should a Prostate-Specific Antigen (PSA) test be ordered on a patient?

From the Guidelines

A PSA test should be ordered for men aged 55-69 after a thorough discussion of benefits and risks, and for men with risk factors, including family history of prostate cancer, African American race, or known genetic mutations, starting at age 40-45. The decision to order a PSA test should be based on a shared decision-making process between the patient and the healthcare provider, taking into account the patient's general health, life expectancy, and preferences 1. The test is also appropriate for men with symptoms of prostate disease, such as difficulty urinating, increased urinary frequency, or pelvic pain. PSA testing is also indicated for monitoring patients with previously diagnosed prostate cancer. The test measures a protein produced by prostate cells, with levels above 4.0 ng/mL generally considered elevated, though this threshold varies by age and other factors. It's essential to note that PSA can be elevated due to non-cancerous conditions like prostatitis, benign prostatic hyperplasia, or recent ejaculation, which is why results must be interpreted in clinical context. Routine PSA screening remains controversial due to concerns about overdiagnosis and overtreatment of clinically insignificant cancers. Asymptomatic men older than 75 years or those who have a life expectancy less than 10 years should not be offered prostate cancer screening due to the substantial harms associated with prostate cancer screening and treatment relative to questionable benefits 1. The American College of Physicians recommends that clinicians inform men between the age of 50 and 69 years about the limited potential benefits and substantial harms of screening for prostate cancer, and base the decision to screen on the risk for prostate cancer, a discussion of the benefits and harms of screening, the patient's general health and life expectancy, and patient preferences 1. The American Cancer Society guideline for the early detection of prostate cancer states that men who have at least a 10-year life expectancy should have an opportunity to make an informed/shared decision with their healthcare provider about whether to be screened for prostate cancer with serum prostate-specific antigen (PSA), with or without DRE, after receiving information about the benefits, risks, and uncertainties associated with prostate cancer screening and therapy 1. Some key points to consider when discussing PSA testing with patients include:

• The potential benefits and harms of screening
• The patient's general health and life expectancy
• The patient's preferences and values
• The risks and uncertainties associated with prostate cancer screening and therapy
• The possibility of overdiagnosis and overtreatment of clinically insignificant cancers. It is crucial to weigh the potential benefits of PSA testing against the potential harms and to make an informed decision based on individual patient factors.

From the FDA Drug Label

In clinical studies, finasteride tablets reduced serum PSA concentration by approximately 50% within six months of treatment. This decrease is predictable over the entire range of PSA values in patients with symptomatic BPH, although it may vary in individuals For interpretation of serial PSAs in men taking finasteride tablets, a new PSA baseline should be established at least six months after starting treatment and PSA monitored periodically thereafter

A PSA test should be ordered on a patient:

• Before starting finasteride treatment to establish a baseline PSA value
• At least six months after starting finasteride treatment to establish a new baseline PSA value while on treatment
• Periodically thereafter to monitor for any changes in PSA levels that may indicate the presence of prostate cancer 2

From the Research

Indications for PSA Ordering

• A PSA test should be ordered on a patient when the digital rectal examination (DRE) is suspicious for cancer, even in the absence of abnormal transrectal ultrasonography findings 3.
• The PSA level is considered abnormal when it is greater than 4 μg./l. or 4 ng./ml., and a biopsy should be considered in such cases 3, 4.
• The use of PSA in conjunction with DRE enhances early prostate cancer detection, and the combined use of both methods provides a more complete evaluation of the prostate gland for malignant involvement 3, 5.

Digital Rectal Examination and PSA

• DRE is recommended in combination with PSA for detection of prostate cancer, but its use as a screening test has limited data to support it 6.
• The positive predictive value of a suspicious DRE is appreciable in men with low serum PSA, and the majority of cancer cases detected by DRE have features of clinically important and potentially curable disease 4.
• However, the cancer detection rate of DRE is significantly lower than that of PSA, and the combination of DRE and PSA does not provide a significant benefit over PSA alone 6.

Clinical Considerations

• Digital rectal examination has a statistically significant effect on the serum PSA concentration, but the clinical significance of this effect is minimal, and the serum PSA concentration in the immediate post-DRE period is accurate and does not compromise clinical use of the tumor marker 7.
• The screening strategy combining DRE and PSA is not different from that of PSA alone in terms of cancer detection rate and positive predictive value, suggesting that DRE could be potentially omitted from prostate cancer screening and early detection strategies 6.