Use of a surgically derived nomogram to predict high likelihood of Gleason score upgrading for favorable-risk prostate cancer treated with permanent seed brachytherapy.

Abstract

114 Background: Crook et al have reported a 7-year disease-free survival (DFS) of 95.2% in 1,111 men with prostate cancer treated with Iodine-125 permanent seed brachytherapy (BT) at Princess Margaret Hospital. Two nomograms have been developed that estimate the likelihood of Gleason score (GS) upgrading for patients with favorable risk prostate cancer undergoing radical prostatectomy (RP). The purpose of this project was to apply these nomograms to a cohort treated with BT. Methods: Records were examined for all men receiving prostate BT in 2006-7. 217 had favorable risk disease. The likelihood of GS upgrading was predicted using RP-derived nomograms created by Kulkarni et al (PMH, 2007) and Budaus et al (2010). Clinical and pathologic information were available on 208 patients to allow completion of the Kulkarni nomogram, and on 193 patients for the Budaus nomogram. Results: The median age of the BT cohort was 62 years (range 44–77), and the median PSA level 4.68 ng/ml. Clinical stage was T1 in 65%, and 47.6% had positive findings on transrectal ultrasound. Median prostate volume was 33.3 cc (15.0–72.3). Uro-pathology review was available for 93%. 84.1% had extended biopsies, with 40.9% showing prostatic intraepithelial neoplasia and 10.1% inflammation. The median % of positive cores was 25%, with a median maximum % involvement per core of 20%. Two men received androgen deprivation therapy for prostate downsizing. The median predicted likelihood of GS upgrading was 51.6% using the Kulkarni nomogram, and 43.6% using the Budaus nomogram. The median PSA after 3.2 years median follow-up is 0.18 ng/mL. Conclusions: In a population of men with favorable risk prostate cancer treated with BT, the estimated likelihood of GS upgrading using two surgical nomograms was substantial. The study cohort was taken from a larger population of patients treated over 10 years for whom 7-year DFS is 95.2%. This suggests that permanent seed brachytherapy is a highly effective treatment option for patients with favorable risk disease despite unfavorable clinical and pathologic factors. Patients should not be discouraged from brachytherapy on the basis of a high likelihood of GS upgrading. No significant financial relationships to disclose.