Purpose: Needle biopsy Gleason scores are often upgraded after pathological examination of the prostate following radical prostatectomy. It has been suggested that larger prostates would be associated with a greater risk of upgrading since a smaller percentage of the gland is sampled and, thus, the highest grade disease would more likely be missed, assuming an equal number of cores is taken from similar locations. We examined the likelihood of clinically relevant upgrading after radical prostatectomy as a function of transrectal ultrasound volume.
Materials and methods: We examined the association between transrectal ultrasound volume and upgrading (higher Gleason score category in the radical prostatectomy specimen than in the biopsy) in 586 men treated with radical prostatectomy between 1995 and 2006 in the SEARCH database who underwent at least a sextant biopsy using multivariate logistic regression. Transrectal ultrasound volume was categorized as 20 or less (in 71), 21 to 40 (in 334), 41 to 60 (in 123) and greater than 60 cm(3) (in 58). Gleason score was examined as a categorical variable of 2-6, 3 + 4 and 4 + 3 or greater.
Results: Overall 138 cases (24%) were upgraded, 80 (14%) were downgraded, and 368 (62%) had identical biopsy and pathological Gleason sum groups. Larger transrectal ultrasound volume was significantly associated with decreased likelihood of upgrading (p trend <0.001). For transrectal ultrasound volumes greater than 60, 41 to 60, 21 to 40 and 20 cm(3) or less, the estimated multivariate adjusted probability of upgrading was 12.6%, 27.5%, 36.4% and 45.5% for Gleason 2-6 tumors, and 6.1%, 8.5%, 18.9% and 20.9% for Gleason 3 + 4 tumors, respectively.
Conclusions: Larger transrectal ultrasound volumes were at decreased risk for clinically significant upgrading after radical prostatectomy. This fact should be kept in mind when deciding on treatment decisions for men with apparently low grade prostate cancer on biopsy.