Background: While older age is associated with higher tumor grade, it is unknown whether comorbid disease burden has a similar, independent association. We sought to evaluate the impact of comorbid disease burden on tumor grade at diagnosis as indicated by biopsy Gleason score.
Methods: We conducted an observational cohort study of 1260 men newly diagnosed with non-metastatic prostate cancer from 1998 to 2004 at two Veterans Affairs Medical Centers. Multivariable ordinal and multinomial logistic regression were used to evaluate the association between Charlson Comorbidity Index score and biopsy Gleason score.
Results: Men with Charlson scores of 2 (odds ratio (OR) 1.8, P<0.001) and 3+ (OR 1.8, P<0.001) had significantly greater odds of higher Gleason scores, compared with men with Charlson scores of 0. In a multinomial logistic regression model predicting Gleason 7 vs ⩾6, only men with Charlson scores of 2 (OR 1.6, P=0.01) had greater odds of having a Gleason 7 tumor, compared with those with Charlson scores of 0. In a multinomial logistic regression model predicting Gleason 8-10 vs ⩽6, those with Charlson scores of 1 (OR 1.6, P=0.047), 2 (OR 2.8, P=0.01) and 3+ (OR 2.9, P=0.001) had higher odds of having a Gleason 8-10 tumor.
Conclusions: Moderate-to-heavy comorbid disease burden at diagnosis may be associated with high tumor grade, independent of age, and is a stronger predictor of Gleason 8-10 than Gleason 7 disease.