Comorbidity and survival of Danish patients with colon and rectal cancer from 2000–2011: a population-based cohort study

OBJECTIVE: To evaluate recent trends in the prevalence and impact of comorbidity on colorectal cancer (CRC) survival in the Central Region of Denmark. MATERIAL AND METHODS: Using the Danish National Registry of Patients, we identified 5,777 and 2,964 patients with a primary colon or rectal cancer, respectively, from 2000 through 2011. We estimated survival according to Charlson Comorbidity Index scores and computed mortality rate ratios (MRRs) using Cox proportional hazard regression analysis, adjusting for age and sex. RESULTS: More than one-third of CRC patients had comorbidity at diagnosis. During the study period, 1-year survival increased substantially in colon cancer patients with Charlson score 0 (72% to 80%) and modestly for Charlson score 3+ patients (43% to 46%). Using colon cancer patients with Charlson score 0 as reference, adjusted 1-year MRRs in patients with Charlson score 3+ were 2.19 (95% confidence interval [CI]: 1.57–3.05) in 2000–2002 and 2.56 (95% CI: 1.96–3.35) in 2009–2011. One-year survival after rectal cancer improved from 81% to 87% in patients with Charlson score 0 and from 56% to 60% in Charlson score 3+. Corresponding MRRs in patients with Charlson 3+ were 2.21 (95% CI: 1.33–3.68) in 2000–2002 and 3.09 (95% CI: 1.91–5.00) in 2009–2011 using Charlson score 0 as reference. Five-year MRRs did not differ substantially from 1-year MRRs. CONCLUSION: Comorbidity was common among CRC patients and was associated with poorer prognosis. We observed improved survival from 2000 to 2011 for all comorbidity levels, with least improvement for colon cancer patients with comorbid conditions.