Androgen receptor antigen density and S-phase fraction in prostate cancer: a pilot study

Purpose: To determine whether quantitative flow cytometric androgen receptor density expression (MFC ratio) in prostate cancer was associated with S-phase fraction. Methods: Flow cytometry was performed to determine DNA aneuploidy, S-phase fraction, percentage of androgen receptor (AR)-positive cells, and MFC ratio in prostate cancer patients. Results: MFC ratio showed distinct clustering. Eight patients had a low MFC ratio of 1.78-2.74, while 10 patients had high MFC ratios between 4.99 and 6.48. The S-phase fraction had average values of 11.05 vs 4.92 in tumors with high vs low MFC ratio (P<0.01). Conclusion: S-phase fraction was significantly higher in tumors with high AR density.