Curtis Pettaway, MD, of the University of Texas M.D. Anderson Cancer Center in Houston, and his colleagues recently characterized radical prostatectomy specimens obtained from 37 AA men and 35 white men with nonpalpable prostate cancer (clinical Stage T1c). Both groups were matched for age, clinical stage, serum PSA level, biopsy strategy (six-core or extended strategy), year of surgery, and prostate weight.
All prostatectomy specimens were processed in the same manner, and the total number of tumor foci, zonal distribution, zone of origin of each tumor focus, and zonal origin of the largest focus were determined. Tumor volumes were calculated by computer software that produced 3-D images and determined the volumes of serially sectioned specimens based on planimetric tracings.
Despite similar preoperative prostate biopsy Gleason scores in the AA and white men, prostatectomy Gleason scores of 7 or higher were observed in 78.4% of the AA men compared with 42.8% of white men. Gleason score upgrading in the prostatectomy specimen compared with the pretreatment biopsy specimen occurred in 49% and 26% of the AA and white men, respectively.
The total number of tumor foci and the location of the dominant tumor focus were similar in the AA and white men. Compared with white men, AA men exhibited nonsignificant trends toward distribution of cancer foci in both the peripheral and transition zones (59.5% vs. 42.9%) and cancer in the apex of the radical prostatectomy specimen (89.2% vs. 71.4%).
Tumor volumes calculated for all individual cancer foci were significantly greater in AA than in white men (mean, 1.82 vs. 0.72 cm3). Total tumor volumes by serum PSA less than 5, 5-10, and more than 10 ng/mL were greater in the AA than the white men (mean, 1.02 vs. 0.29 cm3; 1.57 vs. 0.65 cm3; 2.69 vs. 1.19 cm3, respectively).
An analysis of tumor volume per unit of measured serum PSA revealed that AA men had 2.8 times more tumor in the prostate per ng/mL of serum PSA compared with white men. Most men in both cohorts exhibited organ-confined disease, and the mean tumor volume in specimens with organ-confined disease was significantly greater in AA men than in white men (mean, 1.73 vs. 0.53 cm3).
“The detection of higher tumor volumes in African-American men despite adjusting for serum PSA level suggests that, even in patients with clinical Stage T1c disease, the opportunity for cure after surgery may be lower among African-American patients if the same serum PSA threshold for biopsy is used for all races,” the researchers concluded.