Background. Comorbid conditions have a significant impact on the actuarial survival of patients with head and neck cancer. However, no studies have evaluated the impact of comorbidity on tumor-and treatment-specific outcomes. This study was performed to evaluate the impact of comorbidity, graded by the Kaplan-Feinstein comorbidity index (KFI) on the incidence and severity of complications, disease-free interval, and tumor-specific survival in patients undergoing curative treatment for head and neck cancer.
Methods. A multi-institutional, retrospective cohort of 70 patients 45 years of age and under with head and neck squamous cell carcinoma (SCC) presenting over an 11-year period was studied.
Results. Advanced comorbidity (KFI grade 2 or 3) was present in 21 patients (30%). Patients with advanced comorbidity did not differ from patients with low-level comorbidity (KFI grades 0 or 1) in sex distribution, race, presence of human immunodeficiency virus (HIV) infection, tobacco use, location of primary lesion, stage at presentation, pathologic differentiation of the tumor, or type of initial treatment. The overall incidence of treatmentassociated complications was similar between the groups (57% versus 49%; p > 0.05), but a higher proportion of patients with advanced comorbidity developed high-grade complications (24% versus 6%; p = .04). The median disease-free interval (11.1 months versus 21.6 months; p = .045) and tumor-specific survival (13.7 months versus 57.6 months; p = .03) was poorer for patients with advanced comorbidity. The effects of comorbidity on survival remained significant even after adjusting for the confounding effects of HIV status and tumor stage (p = .05).
Conclusions. The presence of comorbid conditions has a significant impact on tumor-and treatment-specific outcomes. Although the presence of advanced comorbid conditions is not associated with an increase in the rate of treatment-associated complications, complications tend to be more severe in this population. More importantly, advanced comorbidity has a detrimental effect on the disease-free interval and tumor-specific survival in patients with head and neck cancer, independent of other factors. This suggests that comorbidity may impact on tumor behavior, presumably by altering the host's response to cancer. Accordingly, to be more predictive and reliable, the current staging system for head and neck cancer should include a description of the patient's comorbidity.