This article discusses the highly controversial topic of prostate cancer screening with experts Charles P. Vega, MD, PhD, clinical professor in family medicine at the University of California, and Gabe Rivera, MD, hematologist/oncologist.
PSA Screening, To Do or Not to Do?
Dr. Vega: In 2012, there were 240,000 prostate cancer patients in the United States, and more than 28,000 patients lost their lives as a result. American men have a 16.5 percent chance of developing prostate cancer in their lifetime.
When prostate cancer screening is mentioned, the most iconic PSA screening quickly comes to mind. But PSA screening has performed quite poorly in two important trials. In the Prostate, Lung, Colorectal, and Ovarian Cancer (PLCO) Cancer Screening Trial, PSA screening was not associated with any mortality benefit – even for mortality due to prostate cancer alone.
Another study completed several years ago – the European Randomized Study of Screening for Prostate Cancer (ERSPC) – found that screening led to a 20 percent reduction in the relative risk of death from prostate cancer. But it takes a large number of people to participate in screening – exactly 1 death from prostate cancer for every 1,410 people screened.
The purpose of cancer screening is not just to detect cancer, but more importantly to reduce morbidity and mortality. My question then is, should we or should we not be screened for prostate cancer anymore?
Dr. Rivera: PSA screening is one of the most controversial screening tests available, and physicians are likely to miss patients because of their low PSA values (e.g., 2.0 ng/mL.) The two studies Dr. Vega mentioned used different cutoff values; ERSPC used a median cutoff value of 3.0 ng/mL, while PLCO used a value of 4.0 ng/mL. Even without considering the selection of cutoff values, there is still the possibility of prostate cancer at both ends of the range of values.
It boils down to the fact that PSA levels are a weaker marker, but like mammography, they are all that can be used at this stage.
Since PSA screening is a less useful marker for prostate cancer, is it helpful to clinicians or not? I think it does. Just like mammography for breast cancer in women 40-49 years of age, the use of PSA screening is an individualized decision.
There are significant risks associated with patients undergoing PSA screening. Patients may require a biopsy, and there are many potential complications that can occur during the screening and treatment process (including radiation). These risks are highly valued, and patients may ask themselves, “Is this a painless cancer that won’t kill me? Will I pass away for other reasons?”
The physician needs to communicate with the patient through firm but gentle conversation that a low PSA value is not very useful in determining whether the patient will develop prostate cancer in the future.
High PSA values (≥10ng/mL) are of greater concern. According to the NCCN guidelines, patients with high PSA values and other risk factors should be advised to undergo biopsy. Age is the primary risk factor for prostate cancer, and race is also a risk factor but is controversial.
African Americans, in particular, tend to have higher levels of PSA and also have a higher incidence of prostate cancer. However, these associations have not been confirmed by randomized controlled trials. We must complete such a trial so that we can evaluate whether PSA screening is associated with an absolute decrease in mortality in the US population.
Another risk factor is whether the patient carries the BRCA1 and BRCA2 genes, and they contribute to a slightly elevated risk. These risk factors will guide the physician on what to do, but still need to be discussed with the patient, who must decide for themselves whether to undergo this screening.
It is likely reasonable to screen men aged 50 and older. As with breast cancer, their life expectancy is greater than 5 years.
Is PSA feasible as a marker?
Dr. Vega: Yes, if life expectancy is less than 5 years, we would have to question the value of any kind of cancer screening.
I’m intrigued by the idea of using PSA as a marker because it’s sensitive, it’s not perfect but it’s pretty good, especially at high PSA values.
For those patients with low PSA levels, some observations suggest that men under 56 years of age with PSA levels below the median have less than a 1% risk of eventually developing metastatic prostate cancer.
Another investigation looked primarily at PSA screening in men aged 60 years. Those men with PSA less than 2.0 ng/mL were still at risk of developing cancer, but their cancer-related mortality was quite low. However, for those men with PSA levels above 2.0 ng/mL, the positive predictive value of continuous screening [A7] becomes very high. In order to detect prostate cancer, the number of people who need to be screened is sufficiently small that screening 23 people can prevent 1 death from prostate cancer.
If a patient has been well thought out and has decided to be screened year after year and the PSA value is always in the range of 1 to 2 ng/mL, the physician may consider discontinuing screening. This is because the numbers found in these years suggest that the overall risk of the patient developing cancer and affecting a happy life over the course of his or her lifetime is quite low.
This is the end result reached by shared participatory decision making. Because the U.S. Preventive Medicine Task Force (USPSTF) opposes prostate cancer screening in its recommendations, I would put it at the end of my maintenance of health recommendations – on a fairly long list of all the cancer screenings, vaccinations and other screenings and exams we should do for our patients, with prostate cancer screening being the last item .
Prostate Health Rumors You can often hear a lot of rumors about prostate health at work in general, especially about sex drive and erectile function. Prostate cancer can cause erectile dysfunction, but many people with prostate cancer also have obesity, diabetes, high blood pressure and a number of other risk factors that can lead to erectile dysfunction. Having PSA screening does not necessarily lead to better libido and sexual function. This is something that is worth observing in our usual practice.
When it comes to prostate cancer screening, are there any other practices you can think of?
Dr. Rivera: Rectal screening deserves a brief mention. There is no clear evidence in many studies that this is the test to do, and rectal exams have been juxtaposed with PSA levels, yet PSA screening alone is sufficient.
There are many more exact factors that we need to know that will raise PSA values. For example, acute prostatitis can cause a transient increase in PSA levels within 48 hours, but you can still deal with it. If a patient has acute prostatitis or urinary retention, you will need to wait 6-8 weeks until the symptoms disappear and make sure the course of antibiotics has been completed before checking the PSA level.
We hope that neither the clinician nor the patient will become worried just because a test happens to be needed. If it is implied that there is a problem, it should probably be redone some time later.
Dr. Vega: I don’t want to perform a rectal exam on an asymptomatic patient. These tests do not provide much benefit and can cause rare complications, such as abscesses or. Fingers are also not the most sensitive screening tool.
We are not saying that prostate cancer screening is not useful at all. Prostate cancer is a very serious disease that claims thousands of lives each year. We can prevent it with proper and timely treatment. However, for most men, many will work with their doctors to make the decision to have PSA screening. We currently have few tools to move it to the top of the recommendation list in terms of maintaining and promoting health.
Recognizing the limitations of screening and informing patients so they can make the best decision is important and will play an important role for the foreseeable future.