The impact of comorbidity on outcome in 12 623 Danish head and neck cancer patients: a population based study from the DAHANCA database.

BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) is primarily caused by smoking and alcohol. Besides having a carcinogenic effect, smoking also leads to other diseases and thus contributes to a high prevalence of comorbidities among HNSCC patients. Furthermore, the world population is becoming older resulting in more elderly patients with HNSCC. The aim of this study was to investigate the prevalence and impact of comorbidity in a retrospective nationwide population-based study of all Danish HNSCC patients diagnosed from 1992 to 2008. MATERIAL AND METHODS: A total of 12 623 patients diagnosed with HNSCC in the period from 1992 to 2008 were identified through the Danish Head and Neck Cancer group (DAHANCA) database. By linking to the Danish registers, information on somatic comorbidity present prior to the HNSCC diagnosis was obtained and adapted to the Charlson Comorbidity Index (CCI). The influence of comorbidity on overall survival and cancer specific death was evaluated and the type and prevalence of comorbidity described. RESULTS: In total, 36% of patients had comorbidity according to CCI. Increasing age was significantly associated with increasing CCI. In multivariate analyses, the CCI score remained a strong independent prognostic factor for overall survival, the HR being 1.16 (95% CI 1.08; 1.25), 1.34 (1.22; 1.46), 1.63 (1.51; 1.80) for patients with CCI score 1, 2, and 3+, respectively. The CCI score did not influence cancer specific death. CONCLUSION: Comorbidity is common among HNSCC patients and has a negative prognostic impact on overall survival. Cancer specific death was not affected by comorbidity suggesting that patients die from their comorbidities rather than their cancer. In the future, more elderly patients with comorbidity will require treatment which will demand a change in the healthcare system with a multidisciplinary approach required in order to take care of both their cancer and their comorbidities.