Chondrosarcoma: the impact of comorbidity - 30 years of experience from a population-based database including 199 consecutive chondrosarcoma patients

Background: Adjustment for comorbidity when investigating potential prognostic factors, especially in elderly cancer patients, is imperative. Patients diagnosed with chondrosarcoma are elderly and more comorbidity is expected for these patients. Demographic changes are awaited in the future resulting in more and more elderly patients with comorbidity. The aims of this study were to characterize patients with chondrosarcoma treated at a single institute and to evaluate various prognostic factors for survival adjusted for comorbidity. Material and methods: Between 1979 and 2008, 199 patients were treated at the Sarcoma Centre of Aarhus University Hospital, for chondrosarcoma. The incidence was calculated as a WHO age-standardized incidence rate (IR) per million per year. The endpoints were overall mortality and disease-specific mortality. Possible prognostic factors were analyzed for patients with intermediate/high-grade localized tumors by the uni- and multivariate Cox-proportional hazard method. Results: The WHO age-standardized IR in western Denmark in the period 1979-2008 was 2.4/million inhabitants/year (95% CI: 2.2;2.6). The 5-year overall and disease-specific mortality for the 199 patients were 29% (95% CI: 23;36) and 22% (95% CI: 16;27), respectively. The 5-year disease-specific mortality for patients with metastatic disease was significantly higher than for patients with localized disease. The median time to relapse was 2.0 years. Patients who relapse within 1 year after the primary diagnosis have a significantly higher 5-year overall mortality compared to patients who relapse after 1 year. The presence of comorbidity and high-grade tumors were independent prognostic factors for both the overall mortality and the disease-specific mortality of chondrosarcoma patients. Conclusion: Patients with comorbidity had a significantly increased overall mortality and disease-specific mortality. We found that adjusting for comorbidity is important when investigating a cohort of elderly patients.