Screening for early prostate cancer detection may reduce the rate of newly diagnosed metastatic disease.
In a published study researchers evaluated the incidence of a men receiving a diagnosis of metastatic prostate cancer at their initial prostate cancer diagnosis using data extracted from the Surveillance, Epidemiology, and End Results (SEER) Program database. Their analysis was of men diagnosed with advanced prostate cancer at diagnosis, not of early-stage disease that then progressed and became metastatic.
In this perspective study, which was published in the New England Journal of Medicine, the authors describe trends in metastatic prostate cancer diagnosis prior to and more than a decade after the widespread use of the Prostate-Specific Antigen (PSA) test came into general use. They found that the incidence of initial diagnoses of metastatic prostate cancer fell by approximately 50% within 7 years of the start of the widespread use of PSA tests in 1990.
One of the study researchers, Dr. Welch indicated “the rapid uptake of PSA screening led to a dramatic spike in overall prostate cancer diagnoses during the early 1990s — one that’s unrivaled in US cancer data.”
In their discussion, the study authors postulated that the many interventions we have made to reduce prostate cancer risk as well as the reductions in environmental carcinogens might contribute to a reduction in the incidence of metastatic prostate cancer, but they believe that “it’s hard to imagine another factor [other than PSA screening] changing and exerting an effect so quickly.”
Prostate cancer expert Anthony V. D’Amico, MD, PhD, who was not involved study agreed. “The initial spike in all prostate cancer incidence following PSA screening was due to the test identifying all the undiagnosed clinically occult disease missed on digital rectal examination. Earlier detection of prostate cancer means that diagnosis of metastatic disease at presentation is less likely to occur.”
Dr. D’Amico also said that, “Because prostate cancer is generally a slow-growing disease, picking it up early through annual PSA screening would be expected to reduce the occurrence of late-stage metastatic disease.”
According to Dr. D’Amico, the recommendation of the United States Preventive Task Force against PSA screening is likely to reverse this trend in the incidence of initial metastatic disease being diagnosed. We should expect to see an increasing number of men initially diagnosed with metastatic, or advanced prostate cancer.
The stark reality of D’Amico’s is best summed up when he said, “We will not see this for another 7 years, but expect death rates to incline in 7 years, given that the survival curves from the European Randomized Study of Screening for Prostate Cancer and Gotenberg where PSA-based screening studies started to separate in favor of PSA screening approximately 7 years following randomization to PSA screening vs usual care.”
N Engl J Med. Published online October 28, 2015.