Prevalence and prognostic impact of comorbidity in soft tissue sarcoma: a population-based cohort study

Comorbidity is an important prognostic factor for survival in other cancers, but the importance in soft tissue sarcoma has not yet been clarified. The aims of this study were to examine the prevalence of comorbidity in soft tissue sarcoma patients, and estimate the impact of comorbidity on overall and disease-specific mortality.

Overall, 1210 adult patients with soft tissue sarcoma in the extremities or trunk wall were identified through the Aarhus Sarcoma Registry, a validated population-based database. Information on comorbidity was obtained through the National Patient Registry, and a Charlson's Comorbidity score was calculated for each patient. The prevalence of comorbidity was assessed overall, as well as according to age and year of diagnosis. Overall and disease-specific mortality rates according to level of comorbidity were computed. The prognostic value of comorbidity was estimated using crude and adjusted Cox proportional hazard models.

The overall prevalence of comorbidity was 25%. The prevalence increased with increasing age, and patients with comorbidity had a larger proportion of adverse prognostic factors when compared to patients without comorbidity. The five-year disease-specific mortality was 26% (95% CI 24-29) for patients without comorbidity, compared to 33% (95% CI 24-42), 41% (95% CI 32-50), and 44% (95% CI 33-55) for patients with mild, moderate, and severe comorbidity, respectively. After adjusting for age, sex, stage, tumor size, depth, grade, surgical margin, radiotherapy, and chemotherapy, comorbidity was independently associated with an increased overall and disease-specific mortality.

Patients with comorbidity had significantly increased overall and disease-specific mortality compared to patients without comorbidity, even when adjusting for important prognostic factors including age.