Differential prognostic impact of comorbidity in head and neck cancer

BACKGROUND: The aim was to investigate how the effect of comorbid illnesses on survival is modified by other prognostic factors in head and neck cancer. METHODS: A population-based retrospective cohort study involved 221 patients residing in 1 primary health care district (population about 700,000) in whom head and neck carcinoma was diagnosed between January 1, 1986, and December 31, 1996. Data on clinical characteristics and survival were obtained from patient charts. Comorbidity was classified according to Charlson score. RESULTS: At 3 years, the risk of death was significantly higher among the patients with high comorbidity status (score 3 or higher) (adjusted hazard ratio 2.1, 95% confidence interval 1.2-3.7). The excess risk associated with comorbidity, however, was confined to the subjects aged under 65 years and those with tongue or laryngeal tumors or stage I-II cancer. CONCLUSION: To assess the prognostic significance of comorbidity for an individual patient with head and neck cancer, age, tumor site, and cancer stage must be considered.