Surveillance of Low-Risk Prostate Cancer Tripled

SAN FRANCISCO — Conservative management using active surveillance or watchful waiting has now become the most common strategy for men with low-risk prostate cancer across the U.S., a new study suggested.

In response to national guidelines from 2010 that advocated conservative management for low-risk disease, use of active surveillance/watchful waiting increased from 14.5% that year to 42.1% in 2015 (P<0.001 for trend), Brandon Mahal, MD, of Dana-Farber Cancer Center in Boston, and colleagues reported.

Across the same 5-year period, use of radical prostatectomy dropped from 47.4% to 31.3% while use of radiotherapy dropped from 38% to 26.6% in these low-risk prostate cancers (both P<0.001 for trend), they wrote in JAMA.

“What we know from high-level evidence is that conservative management of low-risk prostate cancer is associated with a very favorable prognosis,” Mahal said in a statement. “Many men with low-risk disease are able to be spared the toxicity of treatment so it’s an important discussion to have between clinicians and patients.”

In contrast, and without any change in the guidelines, use of radical prostatectomy for the treatment of higher-risk disease increased from 38.0% to 42.8% during this time, while use of radiotherapy in this risk group dipped from 60.1% to 55.0% (both P<0.001 for trend).

“This shift in management patterns away from radiation therapy toward more radical prostatectomy is not supported by any recent high-levels studies,” Mahal added. “This finding is provocative and may be a focal point of debate.”

The results will be presented here later this week during a poster session at the Genitourinary Cancer Symposium.

Stacy Loeb, MD, of NYU Medical Center in New York City, told MedPage Today that there is no reason to believe that the slight increase in radical prostatectomy for high-risk localized prostate cancer is inappropriate, given that guidelines clearly indicate that surgery is a “gold standard” treatment option for men with this disease.

But while Loeb, who was not involved in the study, said it was “encouraging” that there has been an increase in the use of conservative management for low-risk prostate cancer in recent years, she felt it was “concerning” that only 42% of patients with low-risk disease were being managed conservatively in 2015.

In her own study of patients in the U.S. Veterans Affairs healthcare system, 72% of men with low-risk prostate cancer under the age of 65 were being managed conservatively in 2015, and 79% of those ages 65 and older. So by comparison, the numbers in the current study are actually quite modest, Loeb said.

“National guidelines state that active surveillance is the recommended strategy for most men with low-risk prostate cancer,” she emphasized. “These trends are intriguing, but follow-up studies are needed to determine what the reasons are behind the selection pattern seen in each risk group, and why in fact more men [in the low-risk group] are not choosing active surveillance.”

The analysis of U.S. trends in prostate cancer management from Mahal’s group was based on data from the Surveillance, Epidemiology, and End Results (SEER) Prostate Active Surveillance/Watching Waiting database, and included all men diagnosed with localized prostate cancer from 2010 to 2015 where management type was known (N=164,760).

Patients initially treated with active surveillance or watchful waiting were designated as being conservatively managed unless definitive therapy was offered within a year of diagnosis, at which point patients were categorized as having been treated with definitive therapy. In the total cohort, 12.7% were managed conservatively, 41.5% were treated with radiotherapy, and 45.8% were treated with radical prostatectomy.

Interestingly, the group of men diagnosed with prostate cancer in 2015 were both older (median age 65 vs 64) and less likely to have low-risk disease (24.5% vs 34.2%) compared with the 2010 cohort. This translated into higher median prostate-specific antigen (PSA) levels at diagnosis, 6.7 ng/mL in 2015 compared with 6.0 ng/mL in 2010 (P<0.05 for all). Low-risk prostate cancer was classically defined as those with T1c-T2a tumors, PSA level <10 ng/mL, and Gleason 6 disease.

For men with intermediate-risk disease, the use of active surveillance/watchful waiting also increased, from 5.8% in 2010 to 9.6% in 2015 (P<0.001 for trend). At the same time, the use of radical prostatectomy in these patients decreased slightly, from 51.8% to 50.6% (P=0.004 for trend), as did the use of radiotherapy, from 42.4% to 39.8% (P<0.001 for trend).

Unsurprisingly, few men with high-risk disease were treated conservatively at either time point; management with active surveillance/watchful waiting remained stable at 1.9% in 2010 and 2.2% in 2015.

Limitations of the study included a lack of data on compliance with conservative management as well as information regarding the use of neoadjuvant androgen deprivation therapy.