Prostate cancer is the second leading cause of cancer death among American men. In 2013, nearly 250,000 men will be diagnosed with prostate cancer and more than 32,000 men will die from prostate cancer across the United States. In Georgia, it is estimated that 7,360 men will be diagnosed and 1,080 will die. With alarming statistics such as these, we want every advantage possible in our fight with this disease.
Over the last few years, the topic of PSA testing as a screening tool for prostate cancer has been under heavy debate in the medical community. PSA (prostate specific antigen) is a protein produced by the prostate gland and its levels can be measured by a simple blood test. A higher number could indicate prostate cancer, but the test doesn’t differentiate between an aggressive, fast-growing cancer, and one that is so slow-growing it wouldn’t threaten a man’s life.
On January 8, Emory University School of Medicine’s Department of Medicine Grand Rounds took on an unusual format: a debate between Otis Brawley, MD and John Petros, MD on the validity of PSA testing as a prostate cancer screening tool.
Dr. Otis Brawley is a professor of hematology and medical oncology and chief medical officer for the American Cancer Society. He kicked off the debate asserting that research demonstrates PSA testing to be unreliable, possibly leading to too many diagnoses and unnecessary treatment for prostate cancer.
Dr. John Petros is a professor of urology who treats prostate cancer patients, and he argues that after looking at other studies (more details below), the PSA test is a tool that has helped save lives by detecting prostate cancer in its early stages.
Less than a year ago, a “grade D” rating for PSA screening was issued by the U.S. Preventive Services Task Force, stating that PSA testing offers more harm than good due to complications from PSA-test-driven treatment such as incontinence and blood clots. Despite not ruling out its use, Dr. Brawley is in agreement with the assessment of the U.S. Preventive Services Task Force and says he’s not convinced the PSA test saves lives. As he puts it, “Pretend you are offered the choice of taking a pill that will double the risk of prostate cancer diagnosis from 10 to 20 percent, but could decrease risk of prostate cancer death by one fifth: from 3 to 2.4 percent. [...] Do you feel lucky?” Brawley quipped.
To counterpoint Dr. Brawley’s assertion, Dr. Petros cited the National Cancer Institute’s epidemiology data, which indicates the rate of metastatic prostate cancer has substantially dropped over the last few decades due to prostate cancer being diagnosed earlier on. Dr. Petros also discussed research conducted in Sweden and Austria, which shows significant drops in prostate cancer-related mortality as a result of PSA testing.
Despite their differing views on the validity and use of PSA testing as a prostate cancer screening tool, there are five things Dr. Brawley and Dr. Petros agree on:
- The PLCO study, a NCI-sponsored randomized clinical trial to examine the effects of screening on cancer-related mortality, was flawed. In particular, the “control” arm had a substantial rate of PSA testing.
- Brawley said: “Some cancers that are detected early do not pose a threat and do not need to be treated.” Similarly, Petros said: “Prostate cancer can be low risk if safely observed, but high risk forms are lethal. We need to focus on cancers that matter.”
- PSA testing should be performed in the context of a physician-patient relationship, with men making an informed decision about the value of the information they will receive and the associated risks.
- Vans in supermarket parking lots – more broadly, community- or employer-based screening — are not the ideal setting for PSA testing.
- Biomarkers that are better than PSA alone are needed. Brawley said: “We need a 2013 definition of prostate cancer, informed by genomics, rather than going by what Virchow decided prostate cancer looks like under the microscope 160 years ago.”
In regards to the last point, Dr. Petros added that more sophisticated tests than PSA have already been developed. The prostate health index, which measure levels for three types of PSA and is also more cancer-specific is a good example. Research is currently being conducted at Emory by Carlos Moreno and Dr. Petros to help further this goal. To build on the research they’ve already performed around a panel of biomarkers that can predict prostate cancer outcomes after prostatectomy, Moreno and Dr. Petros will seek to evaluate in coming months whether the same biomarkers could be useful on prostate biopsy samples. The results of this research are expected to help inform treatment option decision making regarding the use of surgery versus radiation.
For now, Petros is an advocate of initiating a conversation about PSA screening with patients 50 and older, or younger if they are at risk for the disease. He believes the decision to have routine PSA testing, follow-up tests and prostate cancer treatments, is a very individualized process.
“It comes down to, what do you tell the man standing in front of you?” he said. “You have to consider where they are in life and what their goals are, and that varies with every man.”