Should prostate cancer screening guidelines differ by race?
Should we recommend earlier prostate cancer screening for Black men, given that they have a much higher rate of prostate cancer mortality? We examine the pros and cons of this question raised by a new modeling study in the New England Journal of Medicine.
Benefits and harms of prostate cancer screening
Prostate cancer screening is most commonly done using the prostate specific antigen (PSA) test, a blood test that looks for high levels of a protein that may indicate prostate cancer. PSA testing became very popular after its development in the late 1980s, which led to an enormous increase in the number of prostate cancers being found (this is known as the “incidence” of cancer).
However, millions of these were not cancers that would have grown or led to harm, leading to significant overdiagnosis and overtreatment. Because of these tradeoffs, the US Preventive Services Task Force (USPSTF) recommends that patients and doctors have a shared decision making conversation about the risks and benefits before undergoing screening, and that men over age 70 should not be screened.
How often do overdiagnosis and overtreatment occur? In 2009, researchers at the VA outcomes group and Dartmouth Institute for Health Policy and Clinical Practice, H. Gilbert Welch and Peter Albertson, quantified the excess incidence and mortality benefits in the years since prostate cancer screening was introduced. They estimated that between 1986 and 2005, American men were 23 times as likely to be overdiagnosed and 18 times as likely to be overtreated as they were to avoid death from prostate cancer.
In a new study in NEJM Evidence, Dr. Spyridon P. Basourakos, urologist at New York-Presbyterian Hospital, and colleagues updated this analysis using data up to 2016. They found that because prostate cancer tends to move very slowly, adding more years of data to the analysis provides a more favorable cost-benefit analysis. That is, the incidence of prostate cancer increases a lot in the first years after screening is implemented, but the benefits may not be realized until years down the line.
In this update, Basourakos et al. estimate that men were 14 times as likely to be overdiagnosed and 11 times as likely to be overtreated as they were to avoid a prostate cancer death (assuming that half of the mortality benefit can be attributed to screening). While this is certainly a more beneficial calculation than that of Welch et al., it’s important to put this into context.
According to the latest evidence review on prostate cancer screening from the USPSTF, 20% of men treated for prostate cancer develop long-term urinary incontinence, and 67% of men treated will experience long-term erectile dysfunction. That means that from 1986-2016, men were more than twice as likely to have urinary incontinence and more than seven times as likely to experience erectile dysfunction unnecessarily as they were to avoid death from prostate cancer. These risks must be taken into consideration during conversations between doctors and patients about screening.
Pros of tailoring risk adjustment by race
However, the risk and benefit calculation for prostate cancer screening was not the same for all men, Basourakos et al. found. Looking just at Black men, who have an elevated risk of prostate cancer and prostate cancer death, the rate of overdiagnosis and overtreatment was lower compared to men of all races. Black men were 12 times as likely to be overdiagnosed and 9 times as likely to be overtreated than they were to avoid cancer death.
In light of these results, Basourakos et al. suggest that we should “reconsider the utility of PSA-based prostate cancer screening, particularly for Black men.” Currently, the USPSTF acknowledges that Black men are at higher risk of cancer than white men, but does not have different screening recommendations based on race.
In an accompanying editorial in NEJM Evidence, Welch and Dr. Adewole S.Adamson, dermatologist at the University of Texas in Austin, explain the pros and cons of race-based cancer recommendations.
Tailoring screening recommendations by race has several upsides. Recommending screening for the highest-risk populations is a good way to maximize the benefits and minimize harms. We currently do this based on race and sex for most cancers, as well as other risk factors such as smoking history for lung cancer screening.
In the absence of race-based screening recommendations, the trend has been to recommend more screening for everyone, even patients at lower risk. For example, in 2020 the USPSTF lowered the recommended starting age for colon cancer screening from 50 to 45, in part due to a higher incidence of colon cancer among African Americans. However, by recommending screening for all younger people we may actually increase health disparities: If more low-risk younger people who already have access to health care start getting screened earlier, that leaves fewer practitioners to care for higher-risk people who could benefit more.
Caveats for race-based screening
However, creating race-based prostate cancer screening guidelines is not so straightforward, Welch and Adewole write. First, adding race as a risk factor without understanding what causes these disparities is dangerous, because it may perpetuate the idea of race as a biological construct rather than a social construct.
“Injecting race into screening recommendations would seem to reinforce the false notion that race is a biologic construct that is relevant to clinical decision-making, rather than a sociopolitical one.”Dr. Gil Welch and Dr. Adewole Adamson, NEJM Evidence
One example of how this can go wrong is the standard algorithm for determining kidney function. The algorithm automatically produces a higher value for anyone identified as Black, because it is based on the assumption that Black people naturally have more creatine in their blood. By using race as a blanket adjustment instead of using patients’ actual creatine levels, the algorithm not only contributes to delays in needed care for Black patients with kidney disease, but it also perpetuates the idea of race as a biological, rather than social definition.
When it comes to prostate cancer risk, studies show that social factors–not biological factors– appear to the be the culprit behind health disparities. Black men are less likely than men of other races to have regular access to high-quality healthcare. According to two studies comparing prostate cancer outcomes for Black men in the Veteran’s Affairs health system, racial disparities in prostate cancer mortality disappeared with comparing cohorts that had similar access to care and standards of treatment. Given the recent effort of doctors to remove race from clinical algorithms, adding race back into a screening recommendation seems to be a step backwards.
Incorporating race into screening guidelines also brings up practical questions, Welch and Adamson point out. Should people in racial groups with lower prostate cancer mortality be advised to get screened less? What about people who identify as multiracial — how often should they get screened? These questions should be figured out before creating additional screening categories based on race.
Missing the bigger picture
All of this focus on prostate cancer screening guidelines misses a more important point, Welch and Adewole write. The disparities in prostate cancer deaths are a result of structural racism — we should be dedicating more energy to ensuring regular access to medical services, improving guideline-concordant cancer care, and addressing the social determinants of health in communities of color that may contribute to cancer. To address disparities only by lowering the screening age is like dealing with a sinking boat by bailing it out without trying to fix the hole.
While Black men have an elevated risk of prostate cancer, this cancer is not close to the biggest health risk for this group. The median age of death from prostate cancer for Black men is higher than all other types of cancer, and is actually four years higher than the average life expectancy of Black men in the US. Lives saved from prostate cancer is incredibly important, but closing racial health disparities will require much more than focusing on this type of cancer.
As Welch and Adamson write, “If we were really serious about addressing life-expectancy disparities, we would focus less on disease among old persons… and more on supporting the young, particularly children and their parents. In addition, we would focus less on further expanding medical care, and more on addressing the social determinants of health.”