By Charlie Schmidt
Editor, Harvard Medical School Annual Report on Prostate Diseases
During the last decade, more men with favorable-risk prostate cancer that is unlikely to cause symptoms and spread have opted for a monitoring approach called active surveillance (AS) instead of immediate treatment. AS entails routine PSA checks and prostate tumor biopsies, and the cancer is treated only if it progresses. The approach has some drawbacks, especially because repeat biopsies — which are standard for monitoring the cancer’s behavior — are expensive and uncomfortable, and carry a small risk of infection.
Now researchers are concluding that some men on AS don’t need to be re-biopsied as frequently as others. Dr. Matthew Cooperberg, a urologist at the University of California San Francisco, says a one-size-fits-all approach to scheduling biopsies “makes little biological sense,” given that prostate cancer varies so widely in terms of its behavior after diagnosis.
Current protocols call for biopsies every one to three years. But Cooperberg and his colleagues wanted to know if they could identify men who could proceed safely with an even less intensive schedule.
To find out, they reviewed data from two large AS cohorts: one is run by the Canary Prostate Active Surveillance Study, which is ongoing at nine centers in North America; the other is based at UCSF. The team focused on nearly 1,400 men who were diagnosed between 2003 and 2017 and then followed for an average of four years. They identified several factors that predict if a man’s cancer might turn more aggressive: the number of positive biopsy cores at diagnosis; PSA levels at diagnosis, and the rate at which they change over time; and a history of any subsequent negative biopsies after a man has already been diagnosed with prostate cancer.
Plug and play
The researchers incorporated these and other factors into an online model that shows where men fall on the risk spectrum. Findings from the research suggest that “large subpopulations of men might be able to defer additional biopsies and even many interval PSA tests,” the authors wrote. But importantly, the model doesn’t advise men as to whether they should get a biopsy or not. “It’s not a yes or no test,” Cooperberg says. Instead, the calculator “uses all the available information at hand to get a more precise assessment of risk for shared decision-making between a man and his doctor.”
Cooperberg said doctors may eventually use other types of predictive information, such as magnetic resonance imaging or tests for genetic biomarkers, to identify men who might avoid biopsies altogether. These newer tools are currently under investigation and haven’t been endorsed in clinical AS guidelines. “We’d like to do AS without any biopsies at all and tell a significant proportion of men that they’re never going to develop aggressive cancer,” Cooperberg said. “But we’re not there yet.”
“This study underscores the important research that is ongoing to help minimize invasive procedures for clinically localized prostate cancer in men who opt for active surveillance,” said Dr. Marc Garnick, the Gorman Brothers Professor of Medicine at Harvard Medical School and Beth Israel Deaconess Medical Center, and editor in chief of HarvardProstateKnowledge.org. Garnick added that in his practice, patients who have completely stable repeat biopsies for several years, as well as stable prostate MRI studies, are followed with a combination of “PSA values, physical exam, presence or absence of urinary symptoms, and periodic MRI studies.” Under these conditions, additional biopsies are considered if findings from these other tests suggest an increase in cancer activity. The new predictive model, Garnick added, “should provide data that can help inform this decision, with the hope and anticipation that longer-term research will continue to justify less frequent biopsies.”