Study: Comorbidity Does Not Affect Prostate Cancer–Specific Mortality

September 25, 2017

The presence of more comorbidities had an effect on all-cause mortality, but not prostate cancer-specific mortality, in a large cohort study of men with prostate cancer.

The presence of more comorbidities had an effect on all-cause mortality, but not prostate cancer–specific mortality, in a large cohort study of men with prostate cancer.

“Comorbidity is highly prevalent among patients with cancer and may adversely affect both competing-cause and cancer-specific mortality, depending on the measures of comorbidity and survival,” wrote study authors led by Prabhakar Rajan, MD, PhD, of Barts Cancer Institute in London. “Evidence for an effect in patients with prostate cancer is conflicting.”

The new study included 118,543 men who were diagnosed with prostate cancer in Sweden from 1998 to 2012 and included in the Prostate Cancer Database Sweden. Patients were stratified using the Charlson comorbidity index (CCI) into four groups: CCI 0 included 87,816 patients, CCI 1 included 16,186 patients, CCI 2 included 9,114 patients, and CCI ≥ 3 included 5,427 patients. The full cohort was followed for a median of 8.3 years; results of the analysis were published online ahead of print in the Journal of Clinical Oncology.

In an unadjusted analysis, CCI 1, 2, and ≥ 3 all had a higher rate of both prostate cancer–specific and other-cause mortality compared to CCI 0. The difference was greatest for CCI ≥ 3, with a hazard ratio (HR) for prostate cancer–specific mortality of 1.99 (95% CI, 1.87–2.11; P < .001) and for other-cause mortality of 5.62 (95% CI, 5.40–5.85; P < .001).

After adjustment for patient and tumor characteristics, the effect was lost for prostate cancer–specific mortality for CCI 1 and CCI 2, but remained for CCI ≥ 3, with an HR of 1.15 (95% CI, 1.06–1.25; P < .001). All three CCI groups still had significantly increased risk of other-cause mortality compared to CCI 0.

When the analysis was further adjusted for the type of prostate cancer treatment received, all associations with prostate cancer–specific mortality were lost. Other-cause mortality was still increased as the comorbidity index rose, with the CCI ≥ 3 group having an HR of 3.16 (95% CI, 2.97–3.36; P < .001).

“Overall, our findings suggest that, after adjusting for patient and tumor characteristics, comorbidity does not seem to significantly impact the risk of dying from prostate cancer after radical treatment (radical prostatectomy or radical radiotherapy) or watchful waiting,” the authors wrote.