An evidence review of active surveillance in men with localized prostate cancer.

Abstract

Background: Radical prostatectomy and radiation therapy for prostate cancer have side effects and unclear survival benefits for early stage and low-risk disease. Prostate cancer often has an indolent natural history, making observational management strategies potentially appealing.

Purpose: To systematically review the role of active surveillance for triggers to begin curative treatment in men with low-risk prostate cancer. Key Questions address changes in prostate cancer characteristics over time, definitions of active surveillance and other observational strategies, factors affecting the offer of, acceptance of, and adherence to active surveillance, the comparative effectiveness of active surveillance with curative treatments, and research gaps.

Data sources: MEDLINE(®), Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and existing systematic reviews, evidence reports, and economic evaluations.

Study selection: Randomized controlled trials and nonrandomized comparative studies of treatments, multivariable association studies, and studies of temporal trends in prostate cancer natural history. Only published, peer-reviewed, English-language articles were selected based on predetermined eligibility criteria.

Data extraction: A standardized protocol was used to extract details on design, diagnoses, interventions, predictive factors, outcomes, and study validity.

Data synthesis: In total, 80 studies provided information on epidemiologic trends; 56 on definitions of active surveillance; 42 on factors affecting the offer of, acceptance of, or adherence to observational management strategies; and 26 on comparative effectiveness. Increased diagnosis of early-stage prostate cancer due to prostate-specific antigen (PSA) testing, led to an increase in prostate cancer incidence from the mid-1980s to the mid-1990s. The prostate cancer-specific mortality rate decreased for all age groups from the early-1990s to 1999. Currently, patients are diagnosed with earlier stage and lower risk prostate cancers compared to the pre-PSA era. Over time, a lower proportion of men received observational management versus active treatment, even among those with low-risk disease. There was no standardized definition of active surveillance. Sixteen cohorts used different monitoring protocols, all with different combinations of periodic digital rectal examination, PSA testing, rebiopsy, and/or imaging findings. Predictors that a patient received no initial active treatment generally included older age, presence of comorbidities, lower Gleason score, lower tumor stage, lower diagnostic PSA, and lower disease progression risk group. No trial provided results comparing men with localized disease on active surveillance with surgery or radiation therapy.

Limitations: Because of the nonstandardized usages of the terms "active surveillance" and "watchful waiting" and their intended and often mixed (both curative and palliative) treatment objectives, it was difficult to determine which study patients received active monitoring for triggers indicative of curative treatment and which observation for clinical symptoms indicative of palliative treatment.

Conclusions: More men are being diagnosed with early stage prostate cancer. Whether active monitoring with a curative intent is an appropriate option for these men remains unclear. A standard, universally agreed-upon definition of active surveillance that clearly distinguishes it from watchful waiting and other observational management strategies is needed to help clarify scientific discourse on this topic. Ongoing clinical trials may provide information on the comparative effectiveness of active surveillance compared to immediate active treatment, but will require long term followup.