The association between tumour density and prostate cancer recurrence following radical prostatectomy

Abstract

Purpose: Tumour density (TD) may be an independent prognosticfactor in men with prostate cancer. The purpose of this study wasto evaluate the association between prostate cancer TD and recurrencefollowing radical prostatectomy.Materials and Methods: Between 1995 and 2007, 645 patientsfrom The Ottawa Hospital or Memorial Sloan-Kettering CancerCenter who had cancer and prostate volumes measured from radicalprostatectomy specimens. Tumour density was defined as therelative tumour to prostate volume (tumour volume/prostate volume)and recurrence was defined as a prostate-specific antigen(PSA) >0.2 ng/mL and rising, or postoperative use of radiation orhormonal therapy. Associations between TD and recurrence areadjusted for preoperative PSA, prostatectomy Gleason sum, tumourstage and margin status.Results: Median follow-up was 40.8 months. Tumour density wasassociated with preoperative PSA, Gleason sum, tumour stage andsurgical margin status (all p < 0.0001). As a continuous variable,TD predicted recurrence-free survival (adjusted HR 1.34 per 10%increase in TD; p = 0.04). As a categorical variable, the groupof patients with a TD of >10% had a 2.7 times greater hazard ofrecurrence compared to patients with a TD <5% (95%CI 1.41,5.19; p = 0.003). Despite the independent association betweenTD and recurrence, the clinical value of TD remains in question asthe discriminative performance (area under the curve) of predictivemodels only improved from 0.865 to 0.876.Conclusions: Prostate cancer TD is associated with known prognosticfactors and is also independently predictive of recurrencefollowing radical prostatectomy.