Significance of Noninvasive Diagnosis of Prostate Cancer with Cytologic Examination of Prostatic Fluid

Objectives: While reassessing the value of exfoliative cytologic examination of prostatic fluid (PF) for the diagnosis of prostate cancer, we found that PF is easily obtained with transrectal ultrasonography during prostate biopsy and that cytologic examination of PF is useful for the diagnosis of prostate cancer. Methods: The cohort included 53 consecutive patients who underwent transrectal prostate biopsy from May through September 2005. Patient age was 66.7 ± 7.24 years, and the mean concentration of prostate-specific antigen (PSA) was 15.1 ± 25.8 ng/ml. The PF for cytologic examination was obtained before biopsy, and Papanicolaou's staining was performed. The results of cytologic examination are expressed as class 1 to 5. Results of cytologic examination and prostate tissue pathologic examination were analyzed. Patient age, PSA levels, total prostate volume (TPV), and PF volume were compared with cytologic class by means of analysis of variance. Results: The mean PF volume was 378.4 ± 245.3 μl, and the mean TPV was 38.0 ± 18.8 ml. The numbers of patient in classes 1 to 5 were 1 (1.9%), 37 (69.8%), 11 (20.7%), 1 (1.9%), and 3 (5.7%), respectively. Pathologic examination showed 23 (43.4%) cases of cancer, 27 (50.9%) cases of benign prostatic hyperplasia, and 3 (5.7%) cases of high-grade prostatic intraepithelial neoplasia. All three patients with class 5 results had prostate cancer (Gleason score, 7 to 10). All 9 patients with a PSA level greater than 16 ng/ml had biopsy-proven cancer, and 3 of these 9 patients (33.3%) were in cytology class 5. Therefore, PF cytologic examination showed a specificity of 100% and a sensitivity of 33.3% in patients with PSA levels higher than 16 ng/ml. The cytologic classes differed in PSA levels (F=8.271, P=0.000) but not in patient age, TPV, or PF volume. Conclusions: Exfoliative cytologic examination of PF is a valuable, noninvasive method for detecting prostate cancer, especially in patients with high PSA levels.