Significance of preoperative parameters for predicting tumor volume in nonpalpable prostate cancer

Preoperative parameters were assessed for their usefulness in predicting tumor volume in 26 cases of nonpalpable prostate cancer. The number of positive biopsy cores was found to be the parameter which predicted most accurately tumor volume in surgical specimens. All 14 patients with multiple positive cores had an index tumor of 0.5 cm3 or more in radical prostatectomy specimens. Only six tumors with a single positive core were substantial. Three of the patients showed a serum level of prostate specific antigen (PSA) of 4.0 ng/ml or more. The pathological stage and prostatectomy Gleason sum could not be predicted accurately by this variable (P>0.05). To predict index tumor volumes of 1.0 cm3 or greater, stepwise logistic regression analysis was conducted, and on the basis of the results it was possible to single out multiple positive biopsies as the only significant variable. The number of positive biopsies appeared reliable for predicting tumor volume of surgical specimens in cases of nonpalpable disease. The presence of significant tumors despite "normal" levels of PSA warrants further investigation of variables that can predict such prostate cancers. An adequate model for predicting significant tumors in oriental male populations should be established using samples of larger size.