Smaller prostate size predicts high grade prostate cancer at final pathology

Purpose: Prostate size may influence the likelihood of detecting high grade prostate cancer at final pathology. We evaluated the association between prostate size and high grade (Gleason score 7 or greater) cancer.

Materials and methods: We analyzed data from 2,880 patients who underwent surgical treatment of prostate cancer between January 2000 and June 2008. Prostate size measured at prostatectomy was compared across a strata of clinical variables (age, body mass index, prostate specific antigen, biopsy Gleason score, clinical stage and year of surgery) and pathological outcomes (final Gleason score, extraprostatic extension, positive surgical margin, seminal vesicle invasion and lymph node involvement). Multivariate logistic regression was used to assess prostate size as a predictor of high grade cancer.

Results: Older age, higher prostate specific antigen and later year of surgery were associated with larger gland size. Small prostate size was associated with high grade prostate cancer as well as extraprostatic extension and positive surgical margins on univariate and adjusted analysis. The probability of high grade disease decreased approximately 15% across the lowest vs highest prostate sizes. On multivariate analysis adjusted for age, race, prostate specific antigen, clinical stage, biopsy Gleason score and date of surgery prostate size was an important predictor of high grade disease (OR 0.94; 95% CI 0.92, 0.97 per 2 gm increments, p <0.001). The area under the ROC curve was 0.82 (95% CI 0.81, 0.84).

Conclusions: Prostate size was inversely associated with the risk of high grade cancer at final pathology. The ability to predict high grade disease could have implications for the management of prostate cancer.