Black men, particularly men of West African descent, are nearly twice as likely to be diagnosed with prostate cancer than Caucasian men, and three times more likely than Asian men. They are also twice as likely as Caucasian men to die from the disease.
These disparities are among the largest in cancer. What is driving them?
Researchers are learning that ancestry may play an important role. Similar to the way people of Ashkenazi Jewish descent are more likely to harbor genetic differences that increase the risk of breast and ovarian cancer, people of West African descent appear to have an elevated genetic risk of prostate cancer.
The findings about the role of genetics in prostate cancer do not explain away the disparities. There are many other factors involved, including health care access, socioeconomics, and environmental exposures. But they do suggest that Black men have been left out of the science that guides care, an example of the effects of institutional racism. By conducting more inclusive research studies, Dana-Farber researchers are working to develop screening and treatment guidelines that are appropriate for diverse populations, including Black men.
“It is particularly disturbing that the same group that is at higher risk for aggressive prostate cancer is also screened for the disease less often, is referred for curative treatment less often, and is included much less often in the important clinical trials that have helped us establish guidelines,” says Mark Pomerantz, MD, clinical director of the Lank Center for Genitourinary Oncology at Dana-Farber. “We are working to change that.”
By conducting more inclusive research studies, Dana-Farber researchers are working to develop screening and treatment guidelines that are appropriate for diverse populations, including Black men.
Learning from diversity
Timothy Rebbeck, PhD, a prostate cancer researcher at Dana-Farber, has been examining prostate cancer disparities through the lens of genetics for nearly 25 years. He and others have found that the genetic susceptibilities for developing prostate cancer are highest in men of African descent, and even higher for people of West African descent.
The findings are relevant to some people who identify as Black in the U.S. because West Africa is where many African American ancestors originated.
“There’s a lot of variation when it comes to genetics,” says Rebbeck. “But being of African descent puts you at higher risk.”
Genetics explains a relatively large proportion of prostate cancer risk. Historically, however, large-scale studies that researchers use to predict an elevated risk of cancer, called genome-wide association studies, have not included many people of African descent. They predominantly included men of European descent. According to Rebbeck’s research, those studies don’t do a good job of predicting risk in people from other groups because their data doesn’t include genomes from other groups.
To develop genetic cancer risk assessments that apply to and benefit everyone, Rebbeck and others are conducting research that includes people from a more diverse set of backgrounds and ancestries, with a focus on African and African American men.
“We have an opportunity to learn from this variation, this diversity across groups,” says Rebbeck. “If we develop a prediction score, or a treatment algorithm, or any guideline based on inclusive data, it will be applicable to the broadest population and not just one group.”
Higher risk, earlier screening
The American Cancer Society recommends that Black men consider screening for prostate cancer at age 45. This is 5 years earlier than the age recommended for groups with a lower risk.
In recent history, experts relaxed prostate cancer screening recommendations due to concerns that the test, which measures prostate specific antigen (PSA) levels in the blood, was leading to false positives and potential overtreatment. That trend is reversing based on more recent evidence, and PSA screening is back on the rise.
“We want to make sure that the pendulum swings back, particularly for men of African and especially West African ancestry,” says Pomerantz.
PSA testing, however, is another area of research where there is an urgent need for inclusive, diverse data. According to Rebbeck, the genetic variability that increases the risk of prostate cancer may also affect PSA-levels. A PSA level that is considered normal for one risk group might be high or low for another.
“There are likely differences that would affect recommendations and guidelines around screening results, but current guidelines are still not based on sufficient guiding evidence,” says Rebbeck. “It’s the usual answer: We need more research.”
Rebbeck has a series of studies underway to understand how multiple factors, including genetics and obesity, influence PSA levels. “To have Black men participate in that research is going to be critical to understand and address prostate cancer disparities,” says Rebbeck.
Seeking equitable care
While genetics may contribute strongly to disparities in the incidence of prostate cancer, access to care — such as finding a specialist, getting an appointment and a treatment plan, and having that care covered by insurance — appears to be a prime driver of the outsized prostate cancer mortality rates for Black men.
Many studies, including one underway by Rebbeck now, suggest that Black men diagnosed with prostate cancer have similar outcomes to other groups when they have the same access to quality care.
“The studies suggest that we can largely eliminate the disparity in mortality among men who were diagnosed with prostate cancer because those differences are very much related to getting the right care at the right time,” says Rebbeck.
To receive quality care for prostate cancer, says Pomerantz, it’s important to find a prostate cancer sub-specialist if possible. A sub-specialist will have a deep understanding of the many possible treatment options and will understand how to personalize treatment and provide the best chances of better outcomes.
“Once the person gets in the door, when everyone is treated equally, outcomes are the same,” says Pomerantz.