Active surveillance would be reasonable for managing low-risk prostate cancer in a 65-year-old man who has a preference for that approach over initial treatment, according to the findings of a decision analysis based on a simulation model.
In a hypothetical cohort of 65-year-old men with a new diagnosis of clinically localized, low-risk prostate cancer, the quality of life benefits and risks of active surveillance and three initial treatment strategies, including brachytherapy, intensity modulated radiation therapy (IMRT), and radical prostatectomy were compared. Active surveillance with IMRT in the event of disease progression was associated with the greatest quality-adjusted life expectancy (QALE), which was the main outcome measure, Dr. Julia H. Hayes of Dana-Farber Cancer Institute, Boston, and her colleagues found.
Active surveillance, which includes close monitoring with serial prostate-specific antigen measurements, digital rectal examinations, and biopsies with treatment at progression or by patient choice, was associated with 11.07 quality-adjusted life-years (QALYs), compared with 10.57 for brachytherapy, 10.51 for IMRT, and 10.23 for radical prostatectomy, the investigators report in the Dec. 1 issue of JAMA.
"The difference between the most and least effective initial treatment was 0.34 QALYs, or 4.1 months of QALE. In contrast, active surveillance provided 6.0 additional months of QALE, compared with brachytherapy, the most effective initial treatment," they wrote (JAMA 2010;304:2373-80).
Inputs for the simulation model, including probabilities and utilities – the weights assigned to individuals’ preferences for a particular health state – were estimated from a systematic literature review. The base case assumption of relative risk of prostate cancer-specific death for initial treatment vs. active surveillance was a "conservative but reasonable" 0.83, but even at an assumed relative risk as low as 0.6, active surveillance remained associated with the highest QALE, they said.
However, although active surveillance was favored over initial treatment even at varied estimates of prostate cancer-specific death and progressive diseases during active surveillance, the result was "highly dependent on the utility individuals place on living under active surveillance compared with having been treated," the investigators said.
This indicates that the decision whether to pursue active surveillance must be individualized, taking into account patient preference, they said.
The findings are important, given that in 2009, 70% of the 192,000 men diagnosed with prostate cancer in the United States will have had clinically localized, low-risk disease, yet more than 90% will have undergone initial treatment, the investigators said, noting that the majority of treated men experience at least one adverse effect from treatment.
Up to 40% of men newly diagnosed with prostate cancer meet the criteria for active surveillance, but that approach is used infrequently.
"Barriers to its use have included concerns about long-term disease outcomes, the perception that most men will ultimately undergo treatment, and concerns about the quality of life of men who elect active surveillance," they wrote.
The findings of this study – though limited only to 65-year-old men and by the limitations inherent in the literature used to derive model inputs, suggest that active surveillance in patients with low-risk disease has the potential to mitigate overtreatment.
"However, the finding that the optimal strategy is sensitive to utility weights is evidence that the decision whether to pursue active surveillance must be individualized. Models that incorporate individual patient utilities should be developed to assist patients and their caregivers to estimate the risks and potential benefits of active surveillance before making this decision," the investigators concluded.
This study was supported by grants from the National Cancer Institute and the Department of Defense, and by a Young Investigator’s Award to Dr. Hayes from the Prostate Cancer Foundation. Blue Shield of California Foundation also supported the study through funding to the Institute for Clinical and Economic Review, with which some study authors are affiliated.