Smaller Prostate Size Is Independently Associated with Biochemical Recurrence in Gleason 7 Prostate Cancer
Boris Gershman, Fei Dong, Francis J McGovern, Niall M Heney, W Scott McDougal, Chin-Lee Wu. Massachusetts General Hospital, Boston, MA
Background: Prostate size is associated with a number of negative prognostic indicators. We evaluated the effect of prostate size on biochemical recurrence following radical prostatectomy.
Design: A retrospective review was conducted to identify patients with Gleason 6-10 prostate cancer who underwent radical retropubic prostatectomy at a single institution from 1993 – 1999. Patients were excluded if they received neoadjuvant therapy, had less than 8 weeks of follow-up, or had serum PSA that did not fall below 0.2 ng/ml post-operatively. Biochemical recurrence was defined as a PSA rise to 0.2 ng/ml or greater with a confirmatory value if available. Cox proportional hazards models were used to evaluate for association between variables and biochemical recurrence.
Results: A total of 877 patients underwent surgery with a mean follow-up of 7.5 ± 4.5 years (range 0.2 – 16.3). Mean age, PSA, and prostate weight were 61.0 ± 6.9 years, 7.3 ± 5.5 ng/ml, and 46.7 ± 19.1 grams, respectively. Gleason score was distributed as follows: 6 in 422 patients (48.1%), 7 in 372 patients (42.4%), and 8-10 in 83 patients (9.5%). Using univariate Cox proportional hazards models, older age, higher PSA, higher Gleason score, presence of pT3 or pT4 disease, positive margins, and smaller prostate weight were associated with biochemical recurrence (p < 0.05 for each). After stepwise addition of each variable in a multivariate Cox model, prostate weight lost significance only when Gleason score was included in the model. To assess for effect modification, multivariate Cox models were stratified by Gleason score (Table 1). In this analysis, prostate weight was associated with biochemical recurrence only for Gleason 7 disease, but margin status was associated with recurrence for Gleason 6 disease.
|Gleason 6||Gleason 6||Gleason 7||Gleason 7||Gleason 8-10||Gleason 8-10|
|Prostate weight (grams)||0.985||0.147||0.986||0.023||1.01||0.355|
|pT3+ vs pT2||0.675||0.410||1.42||0.076||1.39||0.302|