Conditional survival is greater than overall survival at diagnosis in patients with osteosarcoma and Ewing's sarcoma

Abstract

Background: Conditional survival is a measure of the risk of mortality given that a patient has survived a defined period of time. These estimates are clinically helpful, but have not been reported previously for osteosarcoma or Ewing's sarcoma. Questions/purposes: We determined the conditional survival of patients with osteosarcoma and Ewing's sarcoma given survival of 1 or more years. Methods: We used the Surveillance, Epidemiology, and End Results (SEER) Program database to investigate cases of osteosarcoma and Ewing's sarcoma in patients younger than 40 years from 1973 to 2009. The SEER Program is managed by the National Cancer Institute and provides survival data gathered from population-based cancer registries. We used an actuarial life table analysis to determine any cancer cause-specific 5-year survival estimates conditional on 1 to 5 years of survival after diagnosis. We performed a similar analysis to determine 20-year survival from the time of diagnosis. Results: The estimated 5-year survival improved each year after diagnosis. For local/regional osteosarcoma, the 5-year survival improved from 74.8% at baseline to 91.4% at 5 years - meaning that if a patient with localized osteosarcoma lives for 5 years, the chance of living for another 5 years is 91.4%. Similarly, the 5-year survivals for local/regional Ewing's sarcoma improved from 72.9% at baseline to 92.5% at 5 years, for metastatic osteosarcoma 35.5% at baseline to 85.4% at 5 years, and for metastatic Ewing's sarcoma 31.7% at baseline to 83.6% at 5 years. The likelihood of 20-year cause-specific survival from the time of diagnosis in osteosarcoma and Ewing's sarcoma was almost 90% or greater after 10 years of survival, suggesting that while most patients will remain disease-free indefinitely, some experience cancer-related complications years after presumed eradication. Conclusions: The 5-year survival estimates of osteosarcoma and Ewing's sarcoma improve with each additional year of patient survival. Knowledge of a changing risk profile is useful in counseling patients with time. The presence of cause-specific mortality decades after treatment supports lifelong monitoring in this population. Level of Evidence: Level II, prognostic study. See the Instructions for Authors for a complete description of levels of evidence. © 2013 The Association of Bone and Joint Surgeons®.