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Active surveillance feasible for majority of favorable-risk prostate cancers
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An increasing number of men with low-risk or very-low-risk prostate cancer have elected to forgo immediate treatment in favor of active surveillance, according to the results of a cross-sectional study conducted in Sweden.
These data may provide justification for an increased move toward active surveillance in the United States, according to the researchers.
“A decade ago, only 10% of low-risk patients in the United States were managed conservatively,” Stacy Loeb, MD, MSc, assistant professor of urology and population health at NYU Langone Medical Center, told HemOnc Today. “This has increased to about 40% to 50% in some regions, but that is still much lower than the trends we are seeing in Sweden.”
Curative treatment for prostate cancer can result in reduced quality of life due to sexual and urological adverse events. Despite these risks, a majority of American men with favorable-risk prostate cancer elect to have immediate curative therapy rather than undergo active surveillance.
“We interviewed U.S. physicians who treat prostate cancer to identify barriers surrounding active surveillance in this country,” Loeb said. “Some of the themes that they expressed were the fact that long-term data on the safety of active surveillance only recently became available, so many were uncomfortable with this strategy until they confirmed it was safe. Some physicians suggested that their urological training included a greater emphasis on procedural skills than noninterventional management. Other possible barriers in the United States include concerns about medico-legal risk, financial incentives and patient preferences.”
Loeb and colleagues accessed the National Prostate Cancer Register of Sweden — which captures data on 98% of prostate cancer cases diagnosed in Sweden — to conduct a population-based study of active surveillance among men diagnosed with favorable-risk disease from 2009 to 2014.
The classification of favorable-risk prostate cancer included:
- very low risk (clinical stage, T1c; Gleason score, 6; PSA level, < 10 ng/mL; PSA density, < 0.15 ng/mL/cm3; and < 8 mm total cancer length in 4 positive biopsy cores);
- low risk (clinical stage, T1 or T2; Gleason score, 6; PSA level, < 10 ng/mL); and
- intermediate risk (clinical stage, T1 or T2; Gleason score, 7; PSA level, 10-20 ng/mL).
The researchers identified 32,518 men (median age, 67 years) diagnosed with very-low-risk prostate cancer (n = 4,693), low-risk prostate cancer (n = 15,403) or intermediate-risk prostate cancer (n = 17,115).
From 2009 to 2014, use of active surveillance increased among men of all ages with very-low-risk prostate cancer (57% vs. 91%; P < .001) and low-risk prostate cancer (40% vs. 74%; P < .001).
The researchers observed a small decrease in active surveillance and watchful waiting among men with intermediate-risk prostate cancer during the study period (26% vs. 25%).
The greatest increases in active surveillance among men with very-low-risk prostate cancer and low-risk prostate cancer occurred after 2011.
By 2014, 88% of men aged 50 years to 59 years with very-low-risk prostate cancer chose active surveillance as their management option, as did 95% of men aged 60 years to 69 years and 84% of men aged 70 years or older.
Among men with low-risk prostate cancer in 2014, active surveillance use increased to 68% of men aged 50 years to 59 years; 79% of men aged 60 years to 69 years; and 67% of men aged 70 years or older.
Nineteen percent (n = 561 of 3,030) of men with intermediate-risk disease chose active surveillance in 2014. The use of active surveillance among men with intermediate-risk disease remained low at all points.
However, the researchers observed an increase in active surveillance from 2009 to 2014 among a subset of men with a Gleason score of 6 and PSA levels between 10 ng/mL and 20 ng/mL (31% vs. 59%).
Factors associated with active surveillance included single marital status, diagnosis at an academic hospital, diagnosis during a later study year and older age.
The researchers acknowledged study limitations, including the lack of consensus on a definition of active surveillance in men aged 70 years or older, as well as a lack of follow-up data.
“Many patients in the United States fear the ‘C’ word, and it’s important they understand that prostate cancer is really a wide spectrum in which many low-risk cases can be managed with upfront active surveillance,” Loeb said. “We hope that our study from Sweden will show patients and providers in other countries that this is a growing, accepted option, and we encourage other men diagnosed with low-risk prostate cancer to discuss this option with their doctor.”
A broader understanding of which patients should be considered for active surveillance may increase the strategy’s recognition in the United States, particularly among men with intermediate-risk disease, Matthew R. Cooperberg, MD, MPH, Helen Diller Family chair in urology and associate professor of urology, epidemiology and biostatistics at University of California, San Francisco, wrote in a related editorial.
“Particularly given changes in pathology grading practices over the years, active surveillance is increasingly recognized as a safe alternative for carefully selected men with low-volume, Gleason 3 + 4 tumors, as reflected in the ASCO guidelines,” Cooperberg wrote. “This recommendation is based on findings from academic cohorts supporting the intermediate-term oncologic safety of active surveillance, but remains relatively uncommon in the United States. Broader use of advanced imaging and genomic testing may identify more men with Gleason 3 + 4 tumors eligible for surveillance.”
The shift in thinking toward personalized medicine could extend to active surveillance.
“Of course, many men starting on surveillance will ultimately need treatment, but these decisions can be much more personalized — based on longitudinal PSA data, serial biopsy results, genomics, imaging, as well as simply on repeated counseling — after a period of observation during which the risk for cancer progression is very low,” Cooperberg wrote. “A default assumption that most low-risk prostate cancers do not need immediate treatment would completely shift the balance of benefits and harms for prostate cancer early detection efforts, and it will prove invaluable in reframing the ongoing national debate regarding optimal screening policy.” – by Cameron Kelsall
For more information:
Stacy Loeb, MD, MSc, can be reached at stacyloeb@gmail.com.
Disclosures: The researchers and Cooperberg report no relevant financial disclosures.
Perspective
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Mark Stein
This study by Loeb and colleagues confirms that active surveillance has become an accepted form of management for men with low-risk and very low-risk prostate cancer. In Sweden, more than 65% of men with low-risk prostate cancer opted for active surveillance.
This study does not, however, provide additional data regarding outcomes of men being managed with this treatment strategy. Further data from this cohort will provide insight into the outcomes of patients managed with active surveillance. Ongoing research seeks to determine the molecular features of men most likely to have progression on active surveillance, and how to optimally monitor patients undergoing active surveillance to minimize patient discomfort while remaining vigilant for disease progression.
Disclosure: Stein reports no relevant financial disclosures.
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