Objective To investigate the possible significance of tumour dimensional variables, including maximum tumour diameter (MTD), maximum tumour area (MTA) and total tumour volume (TTV), with standard prognostic factors for predicting prostate-specific antigen (PSA) recurrence after radical prostatectomy (RP). Patients and Methods Serial whole sections of the prostate from 164 patients who had RP for localized prostate cancer were investigated. Cox proportional hazards regression models were used for univariate and multivariate analyses to test the relationships between biochemical failure and clinicopathological factors, including tumour dimensional variables. The results were analysed retrospectively to develop a prognostic factor-based model for risk stratification. RESULTS In the univariate Cox proportional hazard model, pathological T stage, Gleason score, perineural invasion, microvascular invasion, positive surgical margins, MTD, MTA and TTV were significantly associated with biochemical failure. In the multivariate Cox proportional hazard model using a stepwise inclusion of these factors, Gleason score, positive surgical margins and MTD were independent indices in association with biochemical failure. Using the three statistically significant variables, the relative risk of biochemical failure could be calculated. Conclusion These results imply that MTD is possibly one of the most important prognostic factors for predicting biochemical recurrence after RP. As calculating the MTD on the section a rapid, simple and objective method, it can be used instead of the TTV calculation. The prognostic factor- based risk stratification might help clinicians to predict biochemical failure after RP.
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