Changes in conditional net survival and dynamic prognostic factors in patients with newly diagnosed metastatic prostate cancer.

Abstract

247 Background: The treatment strategy for patients with newly diagnosed metastatic hormone naïve prostate cancer (mHNPC) has changed in recent years. Thus, an accurate assessment of prognosis is critical. Conditional net survival provides the more appropriate method of estimating survival from cancer. The purpose of this study was to identify predictive factors associated with conditional net survival in patients with mHNPC initially treated with androgen deprivation therapy (ADT). Methods: The medical records of 605 consecutive patients with mHNPC who initially received ADT were retrospectively reviewed. The Pohar Perme estimator was used to calculate conditional net cancer-specific survival (CSS) and overall survival (OS) for up to five years subsequent to the diagnosis. Using multiple imputation, proportional hazard ratios for conditional CSS and OS were calculated with adjusted Cox regression models. Results: During follow-up (median, 2.95 years), 208 patients died, 169 from progressive prostate cancer. At baseline, the 5-year CSS and OS rates were 65.5% and 58.2%, respectively. The overall conditional 5-yearnet OS rate at baseline was 0.582, and the overall conditional 5-year net OS rates for patients who survived for1, 2, 3, 4, and 5 years were 0.566 (−0.16), 0.615 (+3.3), 0.550 (−0.32), 0.702 (+1.2), and 0.811 (+2.29), respectively. Conditional 5-year net CSS and OS survival gradually increased for all the patients. In patients given a 5-year survivorship, the conditional 5-year net CSS and OS rates improved to 0.906 and 0.811, respectively. Only the extent of disease score (EOD) ≥2 remained a prognostic factor for CSS and OS up to 5 years; as survival time increased, other variables were no longer independent prognostic factors. Conclusions: The conditional 5-year net CSS and OS in patients with mHNPC gradually increased; thus, the risk of mortality decreased with increasing survival. The patient’s risk profile changed over time. EOD remained an independent prognostic factor for CSS and OS after 5-year follow-up. Conditional net survival can play a role in clinical decision-making, providing intriguing information for cancer survivors.