Estimated Cause-specific Survival Continues to Improve Over Time in Patients With Chondrosarcoma

Abstract

Conditional survival measures change in the risk of mortality given that a patient has survived a defined period of time. This has yet to be reported for chondrosarcoma of bone. This information should be of interest to the clinician and helpful in counseling patients with chondrosarcoma. Our questions include the following: (1) Does the conditional survival of patients with local/regional chondrosarcoma improve with each additional year of survival? (2) Does the conditional survival of patients with metastatic chondrosarcoma improve with each additional year of survival? (3) Does tumor location, use of radiation, or patient age affect conditional survival? (4) Can chondrosarcoma ever be considered cured? We used the Surveillance, Epidemiology, and End Results Program database maintained by the National Cancer Institute to identify 2138 patients with chondrosarcoma of bone from 1973 to 2009. We used an actuarial life table analysis to explore differences in 5-year cause-specific survival estimates conditional on 1 to 5 years of survival. The cohort was stratified by grade, location (axial versus extremity), use of radiation, and age. Finally, we expanded the analysis to include survival estimates 20 years after diagnosis conditional on survival for 5 and 10 years. The estimated survival for all grades of local/regional chondrosarcoma improved from baseline with each year of survival after diagnosis. At 5 years after diagnosis, local/regional Grade 1 chondrosarcoma displayed higher conditional survival than Grade 2 and 3 local/regional chondrosarcoma (97.2% [95% confidence interval {CI}, 95.2%-98.4%] versus 92.8% [95% CI, 89.5%-95.0%], p = 0.006 and 83.8% [95% CI, 69.9%-91.7%], p = 0.012). Estimated survival improved from baseline with each year of survival for all grades of metastatic chondrosarcoma. Conditional survival estimates for Grade 3 axial tumors failed to improve from baseline to 5 years after diagnosis (52.9% versus 70.2%, p > 0.05) compared with Grade 3 extremity tumors at baseline and 5 years after diagnosis (58.1% versus 95.8%, p < 0.0001) The 20-year conditional survival estimates reveal that a cancer-specific risk of mortality exists even 10 years after diagnosis, suggesting that although the conditional survival increases considerably over time, it cannot be considered cured. The 5-year conditional survival estimate for patients with chondrosarcoma improved with each additional year of survival regardless of grade, site, age, or use of radiation. At 10 years after diagnosis, deaths attributable to cancer were still present, and patients should be aware of this small long-term risk. Level II, prognostic study. See the Instructions for Authors for a complete description of levels of evidence.