Prevalence and prognostic impact of comorbidities and peripheral blood indices in sarcomas

Background: The prognostic impact of comorbidities in patients with sarcomas is not well defined. The aims of this study were to examine the implications of comorbidities and abnormal peripheral blood indices in patients with sarcomas.

Methods: A population-based database was assembled to extract patients with sarcoma in Hong Kong between January 2004 and March 2018. Charlson's Comorbidity Index (CCI) score and prevalence of comorbidities, neutrophil, lymphocyte and platelet counts at diagnosis were assessed. The prognostic values of CCI, neutrophil-lymphocyte (NLR) and platelet-lymphocyte ratios (PLR) were estimated using Cox proportional hazard models. Restricted cubic spline plots were used to explore the association of baseline NLR and PLR with all-cause and cancer-specific mortality.

Results: Among 3358 eligible patients with sarcomas, 52.2% died after a median 26 months of follow-up. The most common comorbidities were diabetes mellitus (9.8%) and cerebrovascular disease (4.8%). Patients with higher CCI had higher mortality (CCI=3 vs CCI=2; HR 1.49; 95% CI 1.19 to 1.87; p<0.01; CCI ≥7 vs CCI =2; HR 3.20; 95% CI 2.62 to 3.92; p<0.001). Abnormal NLR and PLR levels were associated with higher all-cause mortality (NLR: HR 1.698, p<0.001, 95% CI 1.424 to 2.025; PLR: HR 1.346, p<0.001, 95% CI 1.164 to 1.555) and cancer-related mortality (NLR: HR 1.648, p<0.001, 95% CI 1.341 to 2.024; PLR: HR 1.430, p<0.001, 95% CI 1.205 to 1.697).

Conclusions: This is the largest population-based soft-tissue or bone sarcoma cohort worldwide. Comorbidities have significant negative prognostic impact on the survival of patients with sarcomas. Moreover, NLR and PLR are robust prognostic factors, and abnormal NLR and PLR have negative effects yet non-linear effects on survival.