Purpose: To project and compare clinical outcomes of adjuvant radiation soon after radical prostatectomy for locally advanced prostate cancer vs. initial observation with salvage radiation delivered at early prostate specific antigen recurrence.
Methods: A state-transition Markov model was constructed to modify the published results of randomized studies of observation vs. adjuvant radiation such that the observation patients were given salvage radiation at early prostate specific antigen recurrence. Transition probabilities and utility inputs were drawn from randomized controlled trials of adjuvant radiation and cohort studies of salvage radiation and calibrated to validate the model against the reference articles. Outcomes of prostate specific antigen recurrence-free probability, metastasis-free survival, overall survival and projected quality-adjusted life expectancy were modeled through 10 years. Sensitivity analysis and probabilistic sensitivity analysis were performed.
Results: At 10 years, observation with early salvage radiation yields similar results compared to adjuvant radiation for the outcomes of freedom from prostate specific antigen recurrence (53% and 52%, respectively), metastasis-free survival (72% and 70%, respectively) and overall survival (74% and 74%, respectively). Findings were robust to sensitivity analyses and probabilistic sensitivity analyses. After adjusting for the disutility of radiation therapy, observation with early salvage radiation was slightly superior to adjuvant radiation through 10 years (7.0 and 6.2 quality-adjusted life years, respectively).
Conclusion: This decision analysis model suggests that for patients with locally advanced prostate cancer after radical prostatectomy, a strategy of initial observation with salvage radiation given at early prostate specific antigen recurrence yields cancer control and survival outcomes similar to adjuvant radiation while minimizing the morbidity of radiation.
Candidate for the Lee B. Lusted Student Prize Competition