STAGING OF EARLY PROSTATE-CANCER - A PROPOSED TUMOR VOLUME-BASED PROGNOSTIC INDEX

Current staging of early prostate cancer separates patients into two g roups: those with palpable and non-palpable tumors. Such staging relie s on digital rectal examination in making this separation, despite the low sensitivity, low specificity, and low positive predictive value o f this method. As an alternative, tumor volume may be useful for stagi ng because of its powerful prognostic ability and its potential to be assessed clinically due to recent advances in imaging techniques such as transrectal ultrasound. In this study, we evaluate the utility of t umor volume in predicting progression of early prostate cancer based o n the composite published evidence from nine pathologic studies of ser ially-sectioned prostates. Logistic regression revealed that tumor vol ume was a good positive predictor of all measures of tumor progression . There was a 10 percent probability of capsular invasion in tumors me asuring about 0.5 cm3, 10 percent probability of seminal vesicle invas ion in tumors measuring about 4.0 cm3; and 10 percent probability of m etastases in tumors measuring about 5.0 cm3. These composite results s uggest that tumor volume is a significant predictor of cancer progress ion. A volume-based prognostic index is proposed as an adjunct to stag ing for early prostate cancer.