The influence of cardiovascular morbidity on the prognosis in prostate cancer. Experience from a 12-year nationwide Danish population-based cohort study

We conducted a cohort study of patients with incident prostate cancer registered in the Danish Cancer Registry from 1997 through 2008. We identified patients diagnosed with IHD or stroke prior to the date of prostate cancer diagnosis in the Danish National Patient Registry. We constructed Kaplan-Meier curves to analyze time to death and Cox regression was used to estimate hazard ratios (HRs) to compare mortality rates by preexisting IHD or stroke status, adjusting for age, stage, comorbidity, and calendar period.Of 30,721 prostate cancer patients, 4,276 (14%) had preexisting IHD and 1,331 (4%) preexisting stroke. Crude 1- and 5-year survival rates were 85% and 44% in men without preexisting IHD or stroke, 81% and 36% in men with preexisting IHD, and 78% and 27% in men with preexisting stroke. Adjusted HRs were 1.05 (95% CI 1.00-1.10) for patients with IHD and 1.20 (95% CI 1.12-1.30) for patients with stroke compared with patients without preexisting IHD or stroke.Preexisting IHD had minimal impact on mortality in prostate cancer patients, whereas overall mortality was 20% higher in prostate cancer patients with preexisting stroke compared to those without IHD or stroke. These results highlight the importance of differentiating between various comorbidities.Prostate cancer is the most common malignancy in men and the second most common cause of death from cancer in men in Western countries [1]. In Denmark, prostate cancer accounts for 4% of all deaths in men [2]. The median age of patients with newly diagnosed prostate cancer is above70 years, and a large proportion of these men have coexisting diseases (comorbidities) at the time of prostate cancer diagnosis [3]. Several studies have shown that comorbidity increases mortality in prostate cancer patients [3-6]. In a Danish population-based cohort study of prostate cancer patients diagnosed between 1995 and 2006, comorbidity was present in more than one-third of the patients and was a negative prognostic factor [3]. I