Limitations of serum prostate specific antigen in predicting peripheral and transition zone cancer volumes as measured by correlation coefficients

Abstract

Purpose: We reexamined the relationship between preoperative serum prostate specific antigen (PSA) and prostate cancer volume in 290 patients who underwent radical prostatectomy.

Materials and methods: Serum samples from 290 consecutive patients were remeasured with the automated monoclonal-monoclonal Tosoh AIA-600 assay. These values were correlated with individual cancer volume by measuring Pearson correlation coefficients (r).

Results: Cancer was noted in the transition zone in 31 patients and in the peripheral zone in 259. Of the peripheral zone cancers 133 (51.4%) were organ confined and 126 (48.6%) were nonorgan confined, including 12 (9.5%) with histologically confirmed lymph node metastasis (stage D1). The 259 peripheral zone cancers had a correlation coefficient with PSA (r = 0.499, p < 0.0001). After distributing the 259 cases into cancer volume groups we found a large overlap in mean preoperative serum PSA, including 65 with 50% or greater Gleason grade 4 or 5 disease (r = 0.508). The correlation coefficients of cancer volume with PSA in 133 organ confined cancers, 114 nonorgan confined cancers without lymph node metastases and 12 nonorgan confined cancers with positive lymph nodes were 0.382, 0.438 and 0.363, respectively. The 31 transition zone cancers showed a correlation coefficient with PSA (r = 0.81). After excluding 2 cases with extreme PSA and cancer volume the correlation coefficient decreased (r = 0.077).

Conclusions: Even when remeasured with an automated monoclonal-monoclonal assay serum PSA alone is unable to predict preoperatively cancer volume or distinguish between organ and nonorgan confined cancer in peripheral and transition zone tumors of the prostate.