What Are the Best Preoperative Predictors of Tumour Volume on Radical Prostatectomy?
D Sidhu, J Zhang, A Yilmaz, K Trpkov. Calgary Laboratory Services and University of Calgary, Calgary, AB, Canada
Background: Tumour volume (TV) is becoming an important parameter to assess on radical prostatectomy because it is a potential predictor of prostate cancer outcome. In the current practice of prostate specific antigen (PSA) driven biopsies using extended gland sampling, there is a need to reassess the preoperative variables that most reliably predict final TV on prostatectomy.
Design: We retrospectively collected the preoperative clinical and biopsy data in 1754 corresponding prostatectomies performed in our institution between 07/2000 and 06/2007. Prostate needle biopsies were performed using ten-core sampling. Preoperative clinical parameters included: age, gland volume, PSA, PSA density, digital rectal exam and ultrasound abnormalities. Biopsy parameters included: Gleason score, total percent core involvement (TPC), number of positive cores (NPC), high-grade prostatic intraepithelial neoplasia and perineural invasion. All prostatectomies were completely sampled. TV was routinely quantitated as a percentage of gland involvement by visual estimation. Given that TV was not distributed normally, it was transformed to the natural logarithmic scale, which resulted in better agreement with the linear regression assumptions. The relationship between TV and each of the pre-operative clinical and biopsy variables was assessed by the Spearman rank correlation coefficient. Univariate and multiple linear regression analyses were used to determine potential preoperative predictors of TV (natural logarithmic transformation) on prostatectomy.
Results: Highest Spearman correlation coefficient was found for TPC 0.55 (p<0.001), NPC 0.52 (p<0.001), PSA density (0.38 (p<0.001) and biopsy Gleason score 0.27 (p<0.001). Gland volume had a negative correlation with TV on prostatectomy (0.27; p<0.001). On univariate analysis, log TPC, NPC, gland volume, log PSA, PSAD, biopsy Gleason Score, perineural invasion and abnormal digital rectal exam were all statistically significant (all p<0.001). The final predictive multivariate model included only the following preoperative variables: log TPC, gland volume, log PSA and NPC (all p<0.001).
Conclusions: Although several preoperative variables were statistically significant on univariate analysis, only log TPC, gland volume, log PSA and NPC were identified as predictors of TV (natural log-transformation) on prostatectomy in the final multivariate analysis. TPC and NPC were the two strongest preoperative predictors of final TV on prostatectomy with Spearman correlation coefficients of 0.55 and 0.52, respectively.
Category: Genitourinary (including renal tumors)
Wednesday, March 11, 2009 9:30 AM
Poster Session V # 127, Wednesday Morning