Relationship between PSA and prostate cancer

• the value of PSA testing in asymptomatic men is unclear
  • estimates suggest that, using a PSA screening cut-off concentration of 4ng/mL or more, 13% of men with cancer will be missed but go on to present with the cancer in the next 4 years
    • of the men identified with cancer by screening, a proportion will never develop clinically significant disease
    • the PSA test does not clearly differentiate men who do and do not have prostate cancer
      • in a study involving 300 symptomatic men aged at least 50 years, prostate biopsy revealed cancers in around 11% of those with a PSA concentration of up to 4ng/mL, in around 26% with a concentration of 4.1-10ng/mL, and in around 64% with a concentration of 10ng/mL or more (2,3)
      • however the study did provide evidence that a combination of measurement of the serum PSA concentration and rectal examination, with ultrasonography performed in patients with abnormal findings, provides a better method of detecting prostate cancer than rectal examination alone
        
        
• a more recent review states (4):
  • PSA aims to detect localised prostate cancer when treatment can be offered that may cure cancer or extend life. It is not usually recommended for asymptomatic men with less than 10 years life expectancy
  • evidence suggests PSA screening could reduce prostate-cancer related mortality by 21%
  • about 3 in 4 men with a raised PSA level (>=3ng/ml) will not have cancer. The PSA test can also miss about 15% of cancers
  • Before a PSA test men should not have:
    • an active urinary infection
    • ejaculated in previous 48 hours
    • exercised vigorously in previous 48 hours
    • had a prostate biopsy in previous 6 weeks
• PSA is a continuous parameter, with higher levels indicating greater likelihood of prostate cancer. Many men may harbour prostate cancer despite having low serum PSA The table demonstrates the occurrence of Gleason > 7 prostate cancer at low PSA levels, precluding an optimal PSA threshold for detecting non-palpable but clinically significant prostate cancer Risk of Prostate Cancer in relation to low PSA values (5)

Open Image in Modal

Reference:

1. Drug and Therapeutics Bulletin (2004); 42(11):81-5.
2. Catalona WJ et al. Measurement of prostate-specific antigen in serum as a screening test for prostate cancer. N Engl J Med 1991; 324: 1156-61.
3. Corrections. N Engl J Med 1991; 325: 1324.
4. PHE (2016). Advising well men aged 50 and over about the PSA test for prostate cancer: information for GPs
5. European Association of Urology 2018. Guidelines on Prostate Cancer