BANFF, Alberta—Active surveillance (AS) for low-risk prostate cancer (PCa) is associated with a low risk for progression and very good 10-year cancer-specific survival, according to new findings.

A study presented at the Canadian Urological Association’s 2012 annual meeting by Mark Preston, MD, a urologic oncology fellow at Massachusetts General Hospital (MGH) and Harvard Medical School in Boston, showed that 77% of patients remained intervention-free after five years and 62% had this status after a decade.

Furthermore, a systematic review published online June 7 in European Urology indicated PCa-specific mortality is only about 1% with AS and that just one-third of patients receive secondary therapy after a median of approximately 2.5 years of surveillance.

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Dr. Preston, the lead investigator of the MGH study, said the results are surprisingly similar.

“Our collective work shows that extremely low-risk disease can be safely managed with active surveillance,” Dr. Preston said. “The caveat is that there remains a very small risk of developing metastatic or lethal disease, and so further research is needed to solidify inclusion criteria and indicators for timely intervention.”

Dr. Preston, along with Adam S. Feldman, MD, MPH, the senior investigator on the study, and their colleagues examined the outcomes of 469 men diagnosed with PCa at the MGH between January 1997 and October 2009.

The hospital’s AS criteria are that a patient be a candidate for curative treatment, have a Gleason score of 6 or less—although a score of 7 is acceptable for some low-tumor-volume patients—have no more than three positive cores with less than 20% of each core containing tumor and have a PSA level below 10 ng/mL. The center’s AS protocol which was formalized in 2008 involves PSA testing and a digital rectal examination every four months for one year, followed by these procedures once every six months for two years, then annually. Those on AS also have a repeat 12-core biopsy 12-18 months after diagnosis and additional biopsies at the discretion of the treating physician.

The mean follow-up was 5.6 years and the patients had a mean of 1.5 post-diagnosis biopsies. Three hundred and eight (65.7%) had at least one prostate re-biopsy and 132 (28.1%) had more than one.  On first re-biopsy, Fifty-five (17.9%) experienced an increase in their Gleason score. Fifty-two (16.8%) experienced cancer-volume progression, defined as an increase from less than 33% to 33% or more.

A total of 116 patients (24.7%) had an intervention during follow-up. Of these, 52 (44.8%) had an intervention due to pathologic progression, whereas 35 (30.2%) had a PSA increase and 14 (12.1%) chose to have an intervention because of their own preference. Fifty-four patients (46.6%) underwent external beam radiation therapy. Another 26 patients (22.4%) underwent radical prostatectomy, 19 (16.4%) received androgen deprivation therapy, and 17 (16.4%) had brachytherapy.

At five years post-diagnosis, 77% of the cohort was free from intervention, as was 62% at 10 years. At both five and 10 years, the cancer-specific survival rate was 100%. The overall survival rate was 95% at five years and 88% at 10 years.

The systematic review, by Marc A. Dall’Era, MD, of the University of California-Davis Medical Center in Sacramento, and colleagues included the results of seven large AS series published between 1980 and 2011. The longest median follow-up was 6.8 years. PCa-specific mortality was 0%-1% and up to one-third of the patients received secondary therapy after a median of approximately 2.5 years of surveillance. Most patients were treated for histologic reclassification or rapid increase in PSA, whereas 7%-13% were treated despite no evidence of progression.