Comorbidity and survival of Danish prostate cancer patients from 2000-2011: a population-based cohort study.

OBJECTIVE

We investigated temporal changes in overall survival among prostate cancer (PC) patients and the impact of comorbidity on all-cause mortality.

METHODS

We conducted a population-based cohort study in the Central Denmark Region (1.2 million inhabitants). Using medical registries, we identified 7,654 PC patients with first-time PC diagnosis within the period 2000-2011 and their corresponding comorbidities within 10 years prior to the PC diagnosis. We estimated 1- and 5-year survival in four consecutive calendar periods using a hybrid analysis and plotted Kaplan-Meier survival curves. We used Cox proportional hazards regression to compute 1- and 5-year age-adjusted mortality rate ratios (MRRs) for different comorbidity levels. All estimates are reported with their corresponding 95% confidence intervals (CI).

RESULTS

The annual number of PC cases doubled over the 12-year study period. Men aged <70 years accounted for the largest proportional increase (from 33% to 47%). The proportion of patients within each comorbidity category remained constant over time. One-year survival increased from 82% (CI: 80%-84%) in 2000-2002 to 92% (CI: 90%-93%) in 2009-2011, while 5-year survival increased from 43% (CI: 40%-46%) to 65% (CI: 62%-67%) during the same time intervals. Improvements in 5-year survival were most prominent among patients aged <80 years and among those with no comorbidity (from 51% to 73%) and medium comorbidity (from 32% to 54%). Improvements in survival were much smaller for those with high comorbidity (from 33% to 39%). The 1-year age-adjusted MRR for patients with high comorbidity (relative to patients with no comorbidity) increased over time from 1.84 (CI: 1.19-2.84) to 3.67 (CI: 2.49-5.41), while the 5-year age-adjusted MRR increased from 1.73 (CI: 1.34-2.23) to 2.38 (CI: 1.93-2.94).

CONCLUSION

Overall survival of PC improved substantially during 2000-2011, although primarily among men with low comorbidity. All-cause mortality was highest among PC patients with high comorbidity, and their relative 1- and 5-year mortality increased over time compared to those without comorbidity.