GRADING INACCURACIES IN DIAGNOSTIC BIOPSIES REVEALING PROSTATIC ADENOCARCINOMA - IMPLICATIONS FOR DEFINITIVE RADIATION-THERAPY

Purpose: A critical determinant of prognosis in prostate cancer is gra de of disease. Historically, this has been determined by biopsy of the prostate using transperineal, transrectal, or transurethral approache s. Several reports in the literature reveal that these biopsies often underestimate the histologic grade of the tumor when compared with sub sequent radical prostatectomy specimens.Methods and Materials: Data fr om the literature were analyzed to assess the magnitude of this bias t owards undergrading. Grade of biopsy specimens (well-differentiated = Gleason scare 2-4; moderately differentiated = Gleason 5-7; poorly dif ferentiated = Gleason 8-10) were correlated with the ultimate prostate ctomy grade, Analysis was made of tendency to undergrade specimens usi ng strict criteria of data inclusion for needle biopsies, and more rel axed criteria for all types of prostate biopsies. Results: Grading acc uracy from needle biopsies was 71%, with 23% undergraded and 6% overgr aded. A chi-square test on equal chance of under- vs. overgrading yiel ded p = 0.022. Grading accuracy from needle, open perineal, and transu rethral biopsies was 65%, with 23% undergraded and 12% overgraded. A s imilar chi-square test yielded p = 0.007. In both cases, there appears to exist a significant bias towards undergrading. Conclusions: In add ition to other well-documented factors that confound comparisons betwe en radiation therapy and surgical series in carcinoma of the prostate, grade migration exists as well. The equivalence of radiation therapy and surgery with respect to overall survival in this disease is accomp lished despite these biases.