Prostate-specific Antigen Screening: Still Debated

In May 2012, the US Preventive Services Task Force recommended against routine prostate-specific antigen (PSA) screening for men of any age, but that didn’t settle the issue. The American Urological Association continues to recommend that PSA testing be considered for men between age 55 and 69 years,¹ and more than half of men between age 40 and 74 years say they intend to continue getting PSA tests.²

Mortality from prostate cancer has declined by 40% over the past 25 years, but whether this is due to earlier detection through PSA screening or better treatment is unknown. Now, two recent studies suggest that, in fact, PSA screening has played an important role in reducing prostate cancer deaths.

Regions With More Testing Have Fewer Deaths

In an article published in the Journal of the National Cancer Institute, a research team from Umeå University in Sweden reports that regions of that country where PSA testing is widely used have lower rates of prostate cancer mortality.³

PSA testing was introduced in Sweden in the early 1990s. The researchers examined cancer registries for 14 Swedish counties for the periods of 1990 to 1999 and 2000 to 2009 and found that, in eight counties, there was a marked increase in prostate cancer diagnosis in the earlier time period. The assumption was that this increase in incidence resulted from early adoption of PSA testing.

Analysis of mortality statistics for the later time period revealed that the prostate cancer mortality rate was 19% lower in the counties where PSA testing was more widely used in the 1990s. Metastatic prostate cancer incidence and excess mortality from the disease were also lower.

Assuming that a surge in prostate cancer diagnoses really does reflect more widespread use of PSA screening, the results of this study suggest that regular testing does appear to significantly reduce prostate cancer mortality.

Treatment of Metastatic Prostate Cancer Not a Factor

Detractors of PSA testing argue that the decline in prostate cancer mortality is a result of better treatment options for the disease rather than early detection. Improvements in the treatment of localized prostate cancer are likely responsible for a substantial portion of the decline in prostate cancer mortality, but how changes in the treatment of metastatic disease contribute to this decline is poorly understood.

To investigate this issue, researchers at the University of California at Davis analyzed data on more than 19,000 men who presented with metastatic prostate cancer in California between 1988 and 2009.⁴ Contrary to expectations, overall survival was better for men diagnosed before 1999 than for those diagnosed afterward. Similarly, there was no improvement in disease-specific survival among men diagnosed between 2004 and 2009 compared with those diagnosed between 1988 and 1997.

Thus, changes in the treatment of metastatic prostate cancer during the study period played little role in the decline of prostate cancer mortality. The incidence of de novo metastatic prostate cancer declined by 65% between 1988 and 2009. This stage migration, attributable to widespread PSA screening, most likely accounts for the bulk of the decline in prostate cancer mortality.

Case Not Closed

Although these studies document benefits from PSA screening, neither study addressed the possible harms—most importantly, the complications that may result from unnecessary treatment of indolent prostate cancers. There’s little doubt that PSA testing is overused, as approximately 45% of men older than age 75 years undergo annual PSA testing, though most will die of something else before a prostate tumor causes symptoms. In the future, research may identify risk factors that justify PSA testing, or even might find a more reliable test.

References

Carter HB, Albertsen PC, Barry MJ, et al. Early detection of prostate cancer: AUA guideline. https://www.auanet.org/common/pdf/education/clinical-guidance/Prostate-Cancer-Detection.pdf. Accessed March 28, 2014.
Squiers LB, Bann CM, Dolina SE, et al. Prostate-specific antigen testing: men’s responses to 2012 recommendation against screening. Am J Prev Med. 2013;45(2):182-189.
Stattin P, Carlsson S, Holmström B, et al. Prostate cancer mortality in areas with high and low prostate cancer incidence. J Nat Cancer Inst. 2014;106(3):dju007.
Wu JN, Fish KM, Evans CP, et al. No improvement noted in overall or cause-specific survival for men presenting with metastatic prostate cancer over a 20-year period. Cancer. 2014;120(6):818-823.

Topics:

Male Reproductive Cancers Prostate Cancer