Use of prostate-specific antigen and tumor volume in predicting needle biopsy grading error

To study the discrepancy between histologic grades of needle biopsy and prostatectomy specimens and to define the potential role of prostate-specific antigen (PSA), PSA density, and tumor volume in predicting the tumor grade.

Histopathologic grades on needle biopsy and subsequent radical prostatectomy specimens were compared in 135 patients with clinically organ-confined prostate cancer. The frequency of undergrading (difference of one or more grades) by needle biopsy was then compared to PSA, PSA density, and other preoperative parameters.

The frequency of undergrading by one level was 45% using the M. D. Anderson Hospital (MDAH) system and 47% using the Gleason system. When the tumor grades were classified into two categories, undergrading rates of 26% (low to high grade by the MDAH system) and 21% (moderately well to poorly differentiated by the Gleason system) were noted. Serum PSA and PSA density correlated with the grading error rate: the higher the PSA and PSA density values, the higher the biopsy undergrading rate. PSA showed a significant correlation with undergrading (P = 0.0019). Undergrading occurred in 32% of patients with a PSA more than 4 and 10 ng/mL or less and in 47% of those with a serum PSA more than 10 ng/mL. In all cases when the PSA was 4 ng/mL or less, the needle biopsy results correctly predicted the final tumor grade category. Tumor volume was not associated with frequency of undergrading.

The ability to predict tumor grade can be enhanced by considering the serum PSA value.