A new blood test may help reduce unnecessary prostate biopsies and can detect prostate cancer with similar sensitivity to standard screening in patients across racial and ethnic groups, according to a recent multi-center trial published in the Journal of Clinical Oncology.
Adam B. Murphy, MD, MBA, ‘14 MSCI, ‘10 GME, the Distinguished Professor of Health Equity Research in Urology, was a lead author of the study and the principal investigator of the U.S. clinical site.
Prostate cancer is currently the second-leading cause of death in men in the U.S. and one in eight men will be diagnosed with prostate cancer during their lifetimes, according to the Centers for Disease Control and Prevention. Men who are older, who have a family history of prostate cancer and are African American also have an up to 70 percent higher risk of developing prostate cancer, according to the American Cancer Society.
Prostate cancer risk is typically determined by a digital rectal exam and biomarker screening such as the prostate-specific antigen (PSA) test, which measures levels of the PSA protein in the patient’s blood, followed by a prostate biopsy.
In the current study, Murphy and colleagues aimed to determine if a new blood test that determines prostate cancer risk, the Stockholm3 test, could improve prostate cancer detection in patient from different racial and ethnic groups in the U.S. and also reduce unnecessary prostate biopsies in patients with benign or low-grade prostate cancer.
More than 2,100 patients from 17 clinical sites across the U.S. who underwent prostate biopsies were enrolled. Of the participants, 16 percent were Asian, 24 percent were Black or African American, 14 percent were Hispanic white, and 46 percent were non-Hispanic white.
“The study recruited patients from 17 sites to achieve racial and ethnic diversity to permit a thorough subgroup analysis of accuracy, which is a remarkable thing and that’s how validations should be done,” said Murphy, who is also an associate professor of Preventive Medicine in the Division of Cancer Epidemiology and Prevention and assistant director of Community Outreach and Engagement for the Robert H. Lurie Comprehensive Cancer Center of Northwestern University.
Before the biopsy, patient samples were collected to measure Stockholm3 risk score, which consists of measuring different protein biomarkers, genetic biomarkers and other clinical information to determine each patient’s respective risk score.
The investigators found that the Stockholm3 test reduced benign and low-grade prostate cancer biopsies by 45 percent overall, and between 42 percent and 52 percent across racial and ethnic subgroups.
The team also found that the threshold in Black men was lower to achieve greater than 90 percent detection. The Stockholm3 test also demonstrated a similar sensitivity to the PSA test and nearly three times higher specificity.
“The U.S. is multiracial, multi-ethnic, and very diverse and prostate cancer happens to all men, but it happens to Black men most frequently in this country. I think that validations for prostate cancer biomarkers should follow this model where they have enough to do adequate subgroup analysis because capitalist trends will push companies to get their biomarker test to market fastest, but it may not necessarily be the safest route,” Murphy said. “This study is a model for what should be done when tests are being applied across the general U.S. population, especially in this era of precision medicine and precision oncology.”
This work was supported by the Vetenskapsrådet (Swedish Research Council, 2020-01609; Eklund, Grönberg), Cancerfonden (Swedish Cancer Society, CAN 180649; Eklund, Grönberg), and A3P Biomedical.
