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Most men with prostate cancer have positive 5-year outcomes with active surveillance
Most men with clinically localized prostate cancer remained on active surveillance for 5 years without disease reclassification or adverse pathology at surgery, according to findings from a prospective multicenter study.
The goal of the Canary Prostate cancer Active Surveillance Study (PASS) — which opened for enrollment in 2008 in response to growing evidence of the overtreatment of prostate cancer — is to identify biomarkers for prostate cancer outcomes.
Daniel W. Lin
Daniel W. Lin, MD, professor and chief of urologic oncology at University of Washington in Seattle, and colleagues conducted the first analysis of clinical factors associated with outcomes of 905 men (median age, 63 years) enrolled in the study. Eighty-seven percent of the men met National Comprehensive Cancer Network criteria for very low risk or low risk cancer at diagnosis.
Median follow-up from diagnosis was 28 months (interquartile range, 33.5 months). During that time, 24% of the patients experienced tumor grade and/or volume reclassification. From that group, 53% started treatment whereas 31% remained on active surveillance.
Median time free of treatment was 10 years.
Overall, 19% of the patients eventually received treatment, 68% of whom did so due to having an adverse reclassification. The other 32% opted for treatment without disease reclassification.
Results of a multivariable analyses showed adverse reclassification appeared associated with the percentage of biopsy cores with cancer (P = .01), BMI (P = .04) and PSA density (P = .04).
One hundred three patients (11.4%) subsequently received a radical prostatectomy, the most common form of treatment in the study. Patients underwent a mean of 2.5 biopsies (range, 1-7) prior to surgery.
Thirty-four percent of men who underwent prostatectomy had an adverse pathology at surgery, which the researchers defined as primary Gleason pattern 4-5, extraprostatic extension, seminal vesical invasion or lymph node metastasis.
However, researchers observed no significant relationship between risk classification at diagnosis and adverse pathology at surgery. Of the patients with adverse pathology, 37% had very low risk disease at diagnosis, 32% had low-risk disease and 40% had intermediate- or high-risk disease.
Using Kaplan-Meier estimates, the researchers determined the probability of remaining on active surveillance at 2 years after diagnosis was 88%. At 5 years the probability was 71%, and at 10 years the probability was 50%.
“We demonstrate that in a diverse clinical setting, active surveillance delays or avoids active treatment with a median time free of treatment of over 5 years, consistent with results from single-center studies,” Lin and colleagues wrote. “Interestingly, a substantial proportion of patients who experience disease reclassification on active surveillance do not opt for primary treatment, while many patients without reclassification opt for curative treatment over a relatively short period of follow-up.”
Possible limitations of the study included the inability to understand the impact of active surveillance on disease-specific endpoints such as prostate cancer metastasis or mortality due to short follow-up. Similarly, reclassification in active surveillance to a higher-grade disease is often representative of under-sampling during the initial biopsy.
“At the time of diagnosis, clinical characteristics alone do not completely distinguish indolent prostate cancers from those cancers that may benefit from early intervention, as evidenced by equal rates of adverse prostatectomy pathology between very low, low and intermediate risk disease at diagnosis,” the researchers concluded. “Better tools are needed to improve risk stratification.
“The PASS biorepository will allow for validation of biomarkers to identify patients who may be better managed with treatment, versus men whose long-term prognosis allows a less-intensive follow-up schedule and provide greater confidence in the appropriateness of a non-treatment management strategy.” – by Anthony SanFilippo
Disclosure: The study was funded by the Canary Foundation, the NCI and the NIH. HemOnc Today was unable to obtain a list of the researchers’ relevant financial disclosures at the time of reporting.