Comorbidity, age and overall survival in cetuximab-treated patients with advanced colorectal cancer (ACRC)-results from NCIC CTG CO.17: a phase III trial of cetuximab versus best supportive care

Background: The interplay between comorbidity, age and performance status (PS) as predictors of outcome in advanced colorectal cancer (ACRC) is poorly understood. We examined these factors as predictors of treatment toxicity and outcome in cetuximab-treated patients with ACRC. Patients and methods: Comorbidity was independently evaluated using the Charlson Comorbidity Index (CCI), a validated measure of comorbidity based on the presence of medical conditions weighted according to their effect on mortality. CCI score was correlated with clinical and outcome data. Results: Five hundred and seventy-two patients were included; 41% were 65 years and 25% had comorbidities at randomization. In multivariate analysis (MVA) of all covariates, only older age was associated with greater comorbidity (P = 0.008). Overall survival (OS) was significantly better for patients with greater comorbidity in univariate analysis (P = 0.047). Conversely, better PS was associated with better OS in MVA (hazard ratio 1.92 for PS = 2 versus PS = 0, P < 0.0001). Age was not associated with OS (P = 0.13). Elderly patients had significantly less grade 3 vomiting (P = 0.034) but more dyspnea (P = 0.005). Patients with greater comorbidity had significantly less grade 3 vomiting (P = 0.002) but more non-neutropenic fever (P = 0.005). Conclusion: Better PS was associated with improved OS. For patients with good PS, restricting cetuximab use in the setting of significant comorbidity does not appear justified.