Support for the use of objective comorbidity indices in the assessment of noncancer death risk in prostate cancer patients.

Abstract

Prostate cancer management involves a balance between the risks of cancer death against those from other causes. To evaluate the performance of several comorbidity indices in predicting comorbid death in a prostate cancer radiotherapy cohort. 2,131 men with localised prostate cancer treated with radical radiotherapy between 1999 and 2007 were studied. Tumour features, androgen deprivation usage, age, number of prescription medications (PMN) and Adult Comorbidity Evaluation-27 Index (ACE-27) were recorded. Death from prostate cancer (DPC) and death from other causes (DOC) were analysed as competing causes of death using a competing risks model, with discrimination assessed using the concordance index. ACE-27 scores correlated with patient's PMN (median PMN = 2). Tumour features were independent of ACE-27 scores. Estimated cumulative incidences of DOC and DPC at 10 years were 16.4% and 7.7% respectively. In the low/intermediate risk group (n = 1026) there was a 3.4-fold predominance of DOC inside 10 years (cumulative incidence: 15.8% DOC vs 3.4% DPC). High-risk men had approximately equal rates of DPC and DOC at 10 years. Multivariable analysis showed age, ACE-27 score ≥ 1 and PMN to have significant associations with DOC (P < 0.002 for all). A multivariable model incorporating all 3 variables resulted in C-Index = 0.646. Age, ACE-27 score and PMN act as independent prognostic factors for DOC in prostate cancer patients and can improve patient's life expectancy prediction.