Abstract
BackgroundThe purpose of this study was to identify predictive factors associated with conditional net survival in patients with metastatic hormone‐naive prostate cancer (mHNPC) initially treated with androgen deprivation therapy (ADT).MethodsAt nine hospitals in Tohoku, Japan, 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 5 years subsequent to the diagnosis. Using multiple imputation, proportional hazard ratios for conditional CSS and OS were calculated with adjusted Cox regression models.ResultsDuring a median follow up of 2.95 years, 208 patients died, of which 169 died due to progressive prostate cancer. At baseline, the 5‐year CSS and OS rates were 65.5% and 58.2%, 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.ConclusionsThe 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.
Highlights
Prostate cancer is the most common malignancy in men and the sixth leading cause of cancer‐related death worldwide.[1]
After the baseline survival estimation, the conditional net cancer‐specific survival (CSS) and overall survival (OS) rates gradually increased with time
extent of disease score (EOD) ≥2 remained an independent factor for CSS and OS, whereas other well‐known prognostic factors had lost their statistical significance as prognostic factors by 5 years after the administration of androgen deprivation therapy (ADT) therapy
Summary
Prostate cancer is the most common malignancy in men and the sixth leading cause of cancer‐related death worldwide.[1]. Conditional survival analysis has been applied to assess the prognosis for a number of cancers, including metastatic cancers[13,14]; only a small number of studies have investigated conditional survival for prostate cancer, especially metastatic prostate cancer.[15,16] Net survival, which measures the survival that would be observed if the only possible cause of death was the disease of interest, provides the most appropriate method of estimating survival from cancer.[17,18] The newly developed Pohar Perme estimator has been shown to provide unbiased net survival estimates that are more accurate than classical relative survival estimates.[19] there is little evidence regarding estimates of conditional survival using an unbiased Pohar Perme estimator in cancer populations.[20,21] In this multicenter retrospective cohort study, we evaluated changes in conditional net survival in patients with mHNPC initially treated with ADT, at time points from 1 to 5 years after the initial diagnosis, using the Pohar Perme estimator. We evaluated the impact of potential prognostic factors on CSS and OS in this study population
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