Comorbidity, treatment and mortality: a population based cohort study of prostate cancer in PCBaSe Sweden

Purpose: We examined associations among comorbidity, treatment decisions and mortality in patients with prostate cancer.

Materials and methods: A total of 77,536 men diagnosed with prostate cancer between 1997 and 2006 were identified in PCBaSe Sweden from the National Prostate Cancer Register of Sweden. Logistic, Cox and competing risk regression were used to assess associations among Charlson comorbidity index, treatment and mortality. The Charlson comorbidity index was categorized into no (0), mild (1) and severe comorbidity (2+).

Results: In men with low risk prostate cancer 5,975 of the 13,245 (45.1%) patients without comorbidity underwent radical prostatectomy compared to 256 of the 1,399 (18.9%) men with severe comorbidity. Following adjustment for age and period of diagnosis, radical prostatectomy was less likely to be offered to men with severe comorbidity (OR 0.48, 95% CI 0.41-0.55). In men with high risk prostate cancer, radiotherapy was more common (range 7.7% to 21.3%) than radical prostatectomy (range 3.0% to 11.2%) regardless of comorbidity burden. All cause and competing cause but not prostate cancer specific mortality were increased in men with severe comorbidity (all cause HR 1.99, 95% CI 1.93-2.05; competing cause sHR 2.66, 95% CI 2.56-2.78; prostate cancer specific sHR 0.98, 95% CI 0.93-1.03). The cumulative probability of prostate cancer death given no death from competing causes was significantly higher in men with severe comorbidity in all risk groups (p<0.01).

Conclusions: Comorbidity affects treatment choices, and is associated with all cause, competing cause and conditional prostate cancer specific mortality. An increased conditional prostate cancer specific mortality in men with severe comorbidity may reflect less aggressive treatment, impaired tumor defense, lifestyle factors and poor general health behavior.