Background: There is a need to better identify those patients with prostate cancer who may not benefit from treatment because they will die of other causes before their cancer becomes symptomatic. We sought to identify which comorbid illnesses are the most important to consider when advising patients about treatment options.
Methods: We conducted a population-based case-cohort study of patients diagnosed and treated for cure with radiotherapy or prostatectomy in Ontario, Canada between 1990 and 1998. Cases consisted of a random sample of 587 patients who died within 10 years of a cause other than prostate cancer. The comparison cohort consisted of 1655 patients randomly selected from all treated patients in the Ontario Cancer Registry (OCR). Data were collected from medical charts at the treating hospital or cancer centre and supplemented from physician office charts as needed. The sampling frame and some key variables were obtained using the OCR linked to electronic clinic and census data. Analyses were stratified by treatment type: radiotherapy or surgery. In addition to investigating the role of separate comorbid illnesses, we calculated patient’s total comorbidity burden using the Cumulative Illness Rating Scale (CIRS).
Results: The most common causes of death were heart disease (36.6%) and respiratory disease (18.4%). Overall, the disease ultimately causing death was identified as a comorbid illness (at cancer diagnosis) in 51.1% of cases; this proportion was 92.6% for cases dying of respiratory disease and 37.2% for heart disease deaths. Across both treatment groups and after controlling for age, comorbid disease was statistically significantly associated with at least a 2-fold increase in the risk of death in those with: moderate to severe cardiac, severe hematopoietic, moderate to severe respiratory, severe lower GI, and moderate to severe liver disease. For both the radiotherapy and surgery groups, each increment on the CIRS scale (range 0-25) was associated with a 13% increase in the risk of dying after controlling for age.
Conclusions: We identified those illnesses known at prostate cancer diagnosis that will be most likely to lead to an early death among patients being curatively treated for prostate cancer. The results have important implications for selection of patients who might avoid unnecessary cancer treatments that are associated with serious sequelae.

Back to Final Program