Impact of comorbidity on renal cell carcinoma prognosis: a nationwide cohort study

Background Presence of comorbid diseases at time of cancer diagnosis may affect prognosis. We evaluated the impact of comorbidity on survival of patients diagnosed with renal cell carcinoma (RCC), overall and among younger (<70 years) and older (>= 70 years) patients. Methods We established a nationwide register-based cohort of 7894 patients aged >= 18 years diagnosed with RCC in Denmark between 2006 and 2017. We computed 1- and 5-year overall survival and hazard ratios (HRs) for death according to the Charlson Comorbidity Index (CCI) score. Results Survival decreased with increasing CCI score despite an overall increase in survival over time. The 5-year survival rate of patients with no comorbidity increased from 57% among those diagnosed in 2006-2008 to 69% among those diagnosed in 2012-2014. During the same periods, the survival rate increased from 46% to 62% among patients with a CCI score of 1-2 and from 39% to 44% for those with a CCI score of >= 3. Patients with CCI scores of 1-2 and >= 3 had higher mortality rates than patients with no registered comorbidity (HR 1.15, 95% CI 1.06-1.24 and HR 1.56, 95% CI 1.40-1.73). Patterns were similar for older and younger patients. Particularly, diagnoses of liver disease (HR 2.09, 95% CI 1.53-2.84 and HR 4.01, 95% CI 2.44-6.56) and dementia (HR 2.16, 95% CI 1.34-3.48) increased mortality. Conclusion Comorbidity decreased the survival of patients with RCC, irrespective of age, despite an overall increasing survival over time. These results highlight the importance of focusing on comorbidity in this group of patients.