The prognostic impact of comorbidities on renal cancer, 1995 to 2006: a Danish population based study

Comorbid disease in patients with renal cancer may affect renal cancer prognosis. We estimated the risk of 1 and 5-year mortality in patients with renal cancer in northern Denmark by comorbidity status.

We performed a cohort study tracking mortality in all patients with an incident diagnosis of renal cancer between 1995 and 2006 in a population of 1.6 million residents in northern Denmark. Using hospital discharge data before cancer diagnosis we calculated Charlson comorbidity index scores (0, 1-2 or 3+) in patients with renal cancer as well as absolute survival and relative mortality estimates according to comorbidity level.

We identified 2,315 patients with renal cancer, of whom 950 (41%) had comorbidity. The prevalence of comorbidity tended to increase during the study period with the rate in patients with a score of 3+ increasing from 9% to 13%. The 5-year relative mortality rate was lower in patients with a positive Charlson index score with mortality almost twice as high in those with a score of 3+ and 1.2-fold higher in those with a score of 1-2 compared to mortality in those with no comorbidity. Generally similar patterns were observed for 1-year relative mortality.

Comorbidity is common in patients with renal cancer and it is a negative prognostic factor.