Sextant prostate biopsies predict side and sextant site of extracapsular extension of prostate cancer

PURPOSE: We examined the ability of sextant prostate biopsies in combination with other preoperative data to predict side and sextant site of prostate cancer extracapsular extension in a large cohort of patients. MATERIALS AND METHODS: We examined 223 contemporary cases of prostate cancer managed by radical prostatectomy. Using logistic regression analysis, we determined whether patient age, Gleason score, clinical stage, prostate specific antigen, number of positive sextants, biopsy location or percent of biopsy cores positive for cancer in a sextant site, side and overall gland was predictive of location of pathological extracapsular extension into periprostatic tissue. RESULTS: Of 41 of the 223 (18%) patients with nonorgan confined disease extracapsular extension was localized to 45 sextant sites in 36 (apex 8, mid 22, base 15) while only side of extension was known in 5. In a multivariate analysis the best predictors of the risk of extracapsular extension on a side were average percent biopsy cores positive for cancer overall 15 or greater (odds ratio 8.4, p <0.0001) and average from 3 ipsilateral biopsies 15 or greater (odds ratio 7.4, p <0.0001). When used in combination these 2 factors yielded a model with a positive predictive value of 37% and a negative predictive value of 95%. Sextant specific percent biopsy cores positive for cancer was predictive of risk of extracapsular extension in a sextant (odds ratio 2.5, p = 0.020). CONCLUSIONS: Our data demonstrate that average overall and per side percent biopsy cores positive for cancer is a significant predictor of risk of extracapsular extension on a side. Sextant specific percent biopsy cores positive for cancer is predictive of sextant site of extension. The high negative predictive value of the side specific model identifies patients who are good candidates for nerve sparing surgery.