Shared patient-physician decision-making regarding treatment for prostate cancer detected by prostate-specific antigen screening involves a complex calculus weighing the risk of the cancer and patient life expectancy. We investigated quantifying these competing risks using the probability that the cancer was "overdiagnosed"-i.e., would not have been clinically diagnosed (diagnosed without screening) during the patient's remaining lifetime.
Using an established model of prostate cancer screening and clinical diagnosis, we simulated screen-detected cases and determined whether modeled clinical diagnosis would occur before non-cancer death, which was based on comorbidity-adjusted population lifetables. Logistic regression models were fitted to the simulated data and used to estimate overdiagnosis probabilities given patient age, PSA level, Gleason sum, and comorbidity category. An online calculator was developed to communicate overdiagnosis estimates; face validity and ease of use was assessed by surveying 32 clinical experts.
Estimated probabilities of overdiagnosis ranged 4%-78% across clinicopathologic variables and comorbidity status. Ignoring comorbidity, the estimated probability for a 70-year-old man with PSA 9.4 ng/mL and Gleason 6 is 34%; if he has severe comorbidities, the estimate increases to 51%, a personalization that may help inform the choice between active surveillance and definitive treatment. Based on responses from 20/32 experts, we modified the online calculator's explanation of overdiagnosis and input method for comorbid conditions.
The probability of overdiagnosis is strongly influenced by comorbidity status in addition to age. Personalized estimates incorporating comorbidity may contribute to shared decision-making between patients and providers regarding personalized treatment selection.
The Journal of urology. 2019 May 21 [Epub ahead of print]
Roman Gulati, Sarah P Psutka, Ruth Etzioni
Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington (RG, RE) and Department of Urology, University of Washington , Seattle , Washington (SPP).