Blood Test for Prostate Cancer Reduces Mortality

Early detection may prevent up to 17,000 cases of metastatic prostate cancer a year, if age-specific pre-PSA era incidence rates were to occur in the present day, the number of men whose cancer had already spread at diagnosis would be three times greater.

A retrospective analysis by scientists at University of Rochester Medical Center (Rochester, NY, USA) looked back at the era prior to 1986, when no one was routinely screened for prostate cancer with a PSA test. To analyze the effect of screening on stage of disease at initial diagnosis, they reviewed data from 1983 to 2008 kept by the National Cancer Institute registry, the Surveillance, Epidemiology and End-Results or SEER (Bethesda, MD, USA). They compared SEER data from the pre-PSA era (1983 to1985) to the current era of widespread PSA use (2006 to 2008), and adjusted for age, race, and geographic variations in the USA population.

Approximately 8,000 cases of prostate cancer with metastases at initial presentation occurred in the USA in 2008. Using a mathematical model to estimate the number of metastatic cases that would be expected to occur in 2008 in the absence of PSA screening, the scientists predicted the number would be 25,000. The authors emphasized that the study was observational and has some limitations. In particular, it is impossible to know if the PSA test and early detection is solely responsible for the fewer cases of metastasis at diagnosis in 2008.

Emelian Scosyrev, PhD, an assistant professor of Urology, said, "For some people an earlier stage of cancer at diagnosis may not always translate into better survival. This may happen, for example, in cases when the cancer had already metastasized at the time of screening, but the metastasis remained undetected.” In general, however, the study concluded that massive screening and PSA awareness efforts during the 1990s and early 2000s resulted in substantial shifts toward earlier-stage disease and fewer cases of metastases at diagnosis.

Prostate cancer usually occurs in older men, and is the second leading cause of cancer death in the male population. In 2012 an estimated 241,740 new cases will be diagnosed and 28,000 deaths will occur. Prognosis depends on whether the cancer has spread outside the prostate gland, and the degree to which the cancer cells are abnormal. The study was published on July 30, 2012, in the journal Cancer.

Related Links:
University of Rochester Medical Center
National Cancer Institute