Does larger tumor volume explain the higher prostate specific antigen levels in black men with prostate cancer-Results from the SEARCH database

Objectives: To assess whether larger tumor volume in black men explains higher presurgical PSA levels versus white men with prostate cancer. Methods: We retrospectively analyzed 1904 men from the Shared Equal Access Regional Cancer Hospital database who underwent radical prostatectomy from 1990 to 2013. Geometric mean of tumor volume and preoperative PSA for each race were estimated from multivariable linear regression models. Results: There were 1104 (58%) white men and 800 (42%) black men. Black men were younger (60.2 vs. 62.9 years, p< 0.001) had a higher PSA (6.7 vs. 6.0 ng/mL, p< 0.001), more positive margins (47 vs. 38%, p< 0.001), and seminal vesicle invasion (13 vs. 9%, p=0.007). White patients had higher clinical stage (p< 0.001) and greater median tumor volume (6.0 vs. 5.3 gm, p=0.011). After multivariable adjustment (except for PSA), white men had smaller mean tumor volumes (5.2 vs. 5.8 gm, p=0.011). When further adjusted for PSA, there was no racial difference in mean tumor volume (p=0.34). After multivariable adjustment, black men had higher mean PSAs vs. white men (7.5 vs. 6.1 ng/mL, p< 0.001). Results were similar after further adjusting for tumor volume: black men had 16% higher mean PSAs versus white men (7.4 vs. 6.2 ng/mL, p< 0.001). Conclusions: In this study of men undergoing radical prostatectomy at multiple equal access medical centers, racial differences in tumor volume did not explain higher presurgical PSA levels in black versus white men. The exact reason for higher PSA values in black men remains unclear.