Quantification of prostatic cancer metastatic disease using prostate-specific antigen.

The serum prostate-specific antigen (PSA) of 58 men with benign prostatic hypertrophy (BPH) and 17 men with carcinoma of the prostate (CaP) was correlated with the weight of prostatic tissue resected at transurethral prostatectomy (TURP). A significant correlation was identified between the weight of resected BPH tissue and the serum PSA (p less than or equal to 0.001; r = 0.54). No such correlation was seen in the CaP patients. By arbitrarily dividing the serum PSA by the prostate weight, it was possible to devise an index. This index corrected PSA in relation to prostatic size and unlike PSA in isolation did not differ significantly between normal controls and those with BPH. The index in CaP was significantly greater than that of either controls or BPH (p less than or equal to 0.001). Furthermore the index of metastatic CaP (M1) was significantly higher than that of nonmetastatic disease (MO) (p = 0.05). The higher index found in CaP would seem to be related to the bulk metastatic tumor, either manifest or occult. Comparing the index of CaPs to that found in normal and benign disease (a constant) offers a possible means of estimating the extent of local and metastatic tumor mass.