For many cancers, the value of screening is well established. As the saying goes, “knowledge is power” and early diagnosis is usually linked with better outcomes. For prostate cancer, this topic has been more controversial. That’s because many of the tumors we discover through screening are what we call indolent tumors – prostate cancers that may never lead to symptoms or require treatment in their lifetime.
The men who are diagnosed with slow growing prostate cancers can potentially be harmed by the label, particularly if they undergo treatment and have long-term side effects as a result.
We have a number of different screening tools available to both detect the presence of prostate cancer and distinguish between the sub-types that don’t require treatment versus those that need to be treated as early as possible. One of the most common and least invasive ways to screen for prostate cancer is through Prostate Specific Antigen (PSA) testing.
PSA is a blood test that since the early 1990s has been widely used to detect prostate cancers and to follow response to treatment. This blood test is frequently incorporated as part of routine blood testing during annual physical exams for men aged 40 or older. PSA values above a “normal” threshold are associated with a greater risk of prostate cancer.
In 2012, the U.S. Preventative Health Task Force (USPSTF) recommended against routine PSA-based prostate cancer screening for healthy men, regardless of age. This recommendation was based, in large part, on results from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, a large randomized trial designed and funded by the National Cancer Institute (NCI) to determine the effect of PSA screening on prostate cancer deaths in the United States. At the time, it was determined that there was no benefit to PSA testing.
Contrary to this landmark study, a new study led by Jim Hu, MD at Weill Cornell Medicine and NewYork-Presbyterian found evidence that now demonstrates that PSA testing can help reduce the number of fatal cases of prostate cancer.
Researchers from the Genitourinary Oncology Program at NewYork-Presbyterian and Weill Cornell Medicine will be presenting their findings at the 2016 American Urology Association (AUA) Meeting on Monday, May 9. They discussed their findings in this week’s New England Journal of Medicine in a letter to the editor questioning the results of the PLCO trial due to limitations in the study’s methodology.
According to this letter, more than 80% of the participants in the PLCO control group (who were not supposed to have PSA tested) reported having had PSA testing within three years of starting the trial or during the trial. Thus the trial was not truly studying men who had not been screened in contrast to those who had been screened.
Dr. Jonathan Shoag, urology resident and lead author on the article further explains, “We demonstrate that the PLCO study did not compare a group of men who received PSA screening to a group of men who were not screened, but compared men who were screened to other men who were screened, and we should therefore reconsider any decisions based on the study.”
While PSA testing isn’t perfect (PSA can rise due to other conditions aside from prostate cancer), it can be a very good screening tool when viewed as one piece of the larger puzzle of what’s going on in the body.
Stay tuned for additional blog updates on the topic. Next week, we’ll have continuing coverage on research from the 2016 AUA meeting, including updates on PSA as a prostate cancer screening tool, other ways to detect prostate cancer, and additional biomarkers that can be used to distinguish between aggressive and non-aggressive prostate cancers.
Together, this information allows us to see a clearer picture of what’s going on in the body in order to increase our cure rates and the number of people we’re able to treat effectively, while simultaneously minimizing interventions for those who don’t need them.