Active surveillance for low-risk prostate cancer, which involves forgoing immediate treatment, has increased threefold since such "conservative" management was recommended by major guidelines in the United States.
Specifically, the practice of active surveillance or watchful waiting (AS/WW) increased from 14.5% in 2010 to 42% in 2015, when it became the most common approach for the management of low-risk prostate cancer.
The new figures were published online February 11 in JAMA and were also presented at the Genitourinary Cancers Symposium (GUCS) 2019 in San Francisco, California.
The increase in AS/WW over time is "encouraging," said lead author Brandon A. Mahal, MD, a radiation oncologist at the Dana-Farber Cancer Institute in Boston, Massachusetts. This "suggests that clinicians are better adhering to current recommendations and guidelines," and this will reduce rates of overtreatment, he told Medscape Medical News.
However, another expert was surprised that the reported numbers are so low.
"Despite these positive trends, it is concerning that as of 2015, still only 42% of low-risk patients were being managed conservatively," said Stacy Loeb, MD, a urologist at NYU Langone Health in New York City, in an email to Medscape Medical News.
Loeb and colleagues recently reported much higher rates: 72% of men younger than 65 years and 79% of men 65 or older with low-risk prostate cancer seen in the US Department of Veterans Affairs health system were managed conservatively in 2015.
How could two studies from the United States have such different findings?
The data sources — and what they reflect in terms of treatment settings — could be the explanation, said both Mahal and Loeb.
The new findings are derived from the Surveillance, Epidemiology and End Results (SEER) Prostate Active Surveillance/Watchful Waiting database. These patients were managed in a variety of settings. On the other hand, Loeb's VA study is from just one healthcare system.
Mahal also pointed out that the VA study included a proxy for AS/WW via administrative codes, but not a validated AS/WW variable, which was embedded in the custom SEER database.
Still, Loeb pressed her point that the newly reported rate of AS/WW is still low — given what can be achieved.
Other findings reinforce her argument. For example, data from the National Prostate Cancer Registry of Sweden showed that 74% of men with low-risk prostate cancer there were managed with active surveillance in 2014.
Another Emerging Trend
Mahal and colleagues, most of whom are also radiation oncologists from Boston institutions, also highlight another trend that emerged from 2010 to 2015 in the United States: for patients with higher-risk prostate cancer, management patterns shifted toward more use of radical prostatectomy and away from use of radiotherapy.
This shift "does not coincide with any new level 1 evidence or guideline changes," they point out.
The rate of surgery increased by 5% for high-risk prostate cancer, while the rate of radiotherapy declined by 5%.
This "downstream effect" of AS/WW on both surgery, which is performed by urologists, and radiotherapy, which is performed by radiation oncologists, needs further examination, the authors state.
"This finding is provocative and may be a focal point of debate," said Mahal in a press statement.
"Further studies will be needed to determine whether this trend continues and what forces may be driving this trend," he added.
In sum, the authors wonder: what is happening in the full treatment landscape of prostate cancer now that AS/WW is taking root?
For their study, the investigators analyzed initial management trends among patients with either low-, intermediate-, or high-risk prostate cancer in the SEER custom database during the 5-year study period.
They found that, overall, among 164,760 men, 20,879 (12.7%) received AS/WW management, 68,350 (41.5%) underwent radiotherapy, and 75,531 (45.8%) underwent radical prostatectomy.
As would be expected, surgery and radiotherapy declined in use over the study period among men with low-risk prostate cancer (n = 50,302).
As noted above, in men with low-risk disease, use of AS/WW increased nearly threefold, from 14.5% to 42.1%, from 2010 to 2015 (P < .001 for trend), while radical prostatectomy decreased from 47.4% to 31.3% (P < .001 for trend), and radiotherapy decreased from 38.0% to 26.6% (P < .001 for trend).
Similar patterns of AS/WW increasing and the other two treatments decreasing held among men with intermediate-risk disease.
However, as noted, something unexpected was found among men with high-risk prostate cancer (n = 32,622).
The investigators report that AS/WW use remained stable (1.9% to 2.2%) from 2010 to 2015 (P = .08 for trend), whereas treatment with radical prostatectomy increased from 38.0% to 42.8% (P < .001 for trend), and radiotherapy use decreased from 60.1% to 55.0% (P < .001 for trend).
The authors end their letter by observing that the study only investigated initial management patterns. "How the trends will translate into clinical outcomes is unknown," they conclude.
The study was supported by multiple sources, including the Wood Family Foundation, the Baker family, the Freedman family, Fitz's Cancer Warriors, and David and Cynthia Chapin. Many of the study authors have financial ties to industry, including companies with prostate cancer–related products.
Genitourinary Cancers Symposium (GUCS) 2019.
JAMA. Published online February 11, 2019. Full text
Follow Medscape senior journalist Nick Mulcahy on Twitter
For more from Medscape Oncology, follow us on Twitter
Source : https://www.medscape.com/viewarticle/908947