Easy method of assessing volume of prostate adenocarcinoma from estimated tumor area: using prostate tissue density to bridge gap between percentage involvement and tumor volume.

AIM To determine prostate carcinoma tumor volume in routine pathology practice by using prostate tissue density. METHODS Prostate tissue density was determined experimentally by using picnometry in 57 unfixed prostate tissue fragments of different size. The percentage of prostate involvement was converted to tumor volume using the equation V=m/rho (g/mL). Additionally, all tumor foci were outlined in 46 prostates. A high grade component was also designated. The percent of prostate involvement by the tumor and separately by the high-grade component was determined using the fine grid method (0.9 mm resolution) in all cases. Pathologist's estimated square area method was applied for comparison in 27 cases. All tumor foci were evaluated for Gleason grades. RESULTS Prostate tissue density (rho) was 0.98 or approximately 1.0 (g/mL). Quicker estimated square area method was fully comparable to more laborious fine grid method for determination of percent of prostate involvement. The percentage of prostate involvement by the tumor as measured by the grid method was not significantly associated with the Gleason sum of the tumor. However, the total tumor volume that was calculated from the percent tumor involvement, mass of the prostate, and tissue density was positively associated with the Gleason sum (P=0.035, linear-by-linear association). CONCLUSION Our results show that prostate tissue density can be used to determine prostate carcinoma tumor volume in routine pathology practice.