New study explores the role of genetics in prostate cancer

When compared to other groups, certain ethnic and racial groups tend to suffer more often, and fare worse, from common ailments.

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Such health disparities can occur in prostate cancer, in which the disease risk is around 75% higher, and this disease is more than twice as fatal in Blacks when compared to Whites. But despite this fact, Whites are usually overrepresented as research participants, rendering these variations hard to figure out and, eventually, address.

Keeping this aspect in mind, researchers from the USC Center for Genetic Epidemiology and the Institute for Cancer Research in London headed a research work that brings together information from most of the genomic prostate cancer studies worldwide.

The study, which includes over 200,000 men of Asian, African, European, and Hispanic ancestry from across the globe, is the largest and most diverse genetic analysis to be ever performed for prostate cancer—and potentially for any other type of cancer.

The study was recently reported in the Nature Genetics journal.

The authors of the study detected a total of 86 new genetic variations that raise the risk of prostate cancer, which was not discovered before. This brings the total number of risk loci for prostate cancer to 269.

The researchers used a model to assess the risk of prostate cancer based on the interaction of these genetic factors and demonstrated that on, an average, men of African ancestry inherit around twice the risk of prostate cancer when compared to men of European ancestry, whereas men of Asian ancestry inherit around three-quarter the risk of their white equivalents—proof that genetics certainly play some role in the differences in how frequently prostate cancer occurs in various racial groups.

The study also represents a step toward using precision medicine for early detection.

Our long-term objective is to develop a genetic risk score that can be used to determine a man’s risk of developing prostate cancer. Men at higher risk may benefit from earlier and more frequent screening, so the disease can be identified when it’s more treatable.”

Christopher Haiman, ScD, Study Corresponding Author and Professor of Preventive Medicine, Keck School of Medicine of USC

Haiman is also the director of the USC Center for Genetic Epidemiology.

Study tackles health disparities

Jonathan W. Simons, MD, president, and chief executive officer of the Prostate Cancer Foundation, has praised the research’s potential in boosting health equity. The foundation financially supports Haiman’s other studies that led to the RESPOND initiative investigating the disease among African American men.

“PCF believes that Dr. Haiman’s research findings will lead to more effective prostate cancer precision screening strategies for men of West African ancestry,” stated Simons. “PCF is certain that identification of these very high-risk individuals will make a positive impact on this significant health care disparity.”

Along with his collaborators, Haiman used genomic datasets from various nations, such as the United Kingdom, the United States, Ghana, Japan, and Sweden, to compare 107,247 men afflicted with prostate cancer to a control group that comprises a total of 127,006 men. By examining a spectrum of ethnicities and races, the authors of the study aimed to make the genetic risk score handier for more numbers of individuals.

We not only found new markers of risk, but also demonstrated that, by combining genetic information across populations, we were able to identify a risk profile that can be applied across populations. This emphasizes the value of adding multiple racial and ethnic populations into genetic studies.”

Christopher Haiman, ScD, Study Corresponding Author and Professor of Preventive Medicine, Keck School of Medicine of USC

Risk score could contribute to better screening

Existing screening guidelines for prostate cancer indicate that people who are 55 and older with average risk can opt to take the prostate-specific antigen (PSA) test in consultation with their doctors. High levels of PSA are linked to prostate cancer; however, the PSA test has a tendency to identify slow-growing tumors. With extensive use, it usually results in needless treatments.

The PSA test’s value as a screening tool would grow if it were selectively deployed to track individuals found to be at elevated risk for prostate cancer—which is where the genetic risk score could play a role. Individuals who are at particularly high risk for prostate cancer may even start screening before age 55.

To translate the present study findings into better early detection of prostate cancer, a large-scale clinical trial would be required.

Most important, unlike previous screening trials, this one would need to be more representative of the diversity we see in the world. No population should get left behind.

Christopher Haiman, ScD, Study Corresponding Author and Professor of Preventive Medicine, Keck School of Medicine of USC