PSA Mass Density - A Measure Predicting Prostate Cancer Volume and Accounting for Overweight and Obesity: Related PSA Hemodilution

OBJECTIVE - To test PSA mass density (PSAMD) as a predictor of total tumor volume (TTV) at radical prostatectomy (RP).

METHODS - We conducted a detailed pathologic analysis of 469 RP from men with NCCN low risk prostate cancer who had Gleason score 3+3=6 (Grading group 1) at RP.

We then compared the ability of PSA, PSA density (PSAD), PSA mass (PSAM - absolute amount of PSA in patient's circulation), and PSAM density (PSAM/prostate weight without seminal vesicles) to predict TTV at RP. PSAM was calculated by multiplying plasma volume (estimated body surface [weight,kg(0. 425) * height,m(0. 72) * 0. 007184] x 1. 67) by PSA. Performance of the above measures in different BMI categories was assessed. Kruskal-Wallis test was used to compare the means and Spearman's rank correlation coefficient to assess the correlations.

RESULTS - The 469 men were normal weight (n=129), overweight (n=253), and obese (n=87). Mean age of the patients' was 57. 4 years and PSA 4. 53 ng/ml. Increase of prostate weight with BMI was reflected in PSAM (both p<0. 001) but not in other measures. BMI did not correlate with TTV and PSA. Among PSA, PSAD, PSAM, and PSAMD, PSAMD had the highest correlation with TTV (r=0. 336; p<0. 001). Prostate weight had stronger (negative) association with PSAMD (r=-0. 394; <0. 001) than TTV.

CONCLUSIONS - 8PSAMD is the biochemical measure with the best correlation with TTV at RP. Unlike other measures, it is not affected by BMI related hemodilution. Thresholds should be established to use this more objective measure clinically in surveillance algorithms and in planning radical prostatectomy.

Urology. 2016 Jan 07 [Epub ahead of print]

Oleksandr N Kryvenko, Mireya Diaz, Andres Matoso, Max Kates, Jason Cohen, Gregory P Swanson, Jonathan I Epstein

Departments of Pathology & Laboratory Medicine and Urology, University of Miami Miller School of Medicine, Miami, FL. Vattikuti Urology Institute, Henry Ford Hospital, Detroit, MI. , Department of Pathology, Rhode Island Hospital and Brown University, Providence, RI. , Department of Urology, The Johns Hopkins Medical Institutions, Baltimore, MD. , The Johns Hopkins Medical School, Baltimore, MD. , Department of Radiation Oncology, UT Health Science Center, San Antonio, TX. , Department of Pathology, The Johns Hopkins Medical Institutions, Baltimore, MD; Department of Urology, The Johns Hopkins Medical Institutions, Baltimore, MD; Department of Oncology, The Johns Hopkins Medical Institutions, Baltimore, MD.