PREDICTORS OF FIRST REPEAT BIOPSY CANCER DETECTION WITH SUSPECTED LOCAL STAGE PROSTATE CANCER

Abstract

We determine demographic and tumor related predictors of repeat biopsy cancer detection in men with suspected stage T1c-2 prostate cancer. The study population included 298 consecutive men with suspected stage T1c-2 prostate cancer who had a benign prostate biopsy at 1 institution between January 1, 1992 and April 1, 1999 and underwent 1 repeat biopsy. Mean age plus or minus standard deviation was 66.8+/-6.7 years for 133 black (55%) and 165 white (45%) patients. Clinical measures included determination of high grade prostatic intraepithelial neoplasia in benign biopsy specimens, Gleason score of malignant biopsy specimens, prostate specific antigen (PSA), PSA density, annualized interbiopsy PSA change, percent free PSA (201 cases) and PSA velocity (171). Cancer was detected on repeat biopsy in 80 cases (27%). Significant differences between patients with benign and malignant repeat biopsies included age (p = 0.001), PSA density (p = 0.0001), percent free PSA (p = 0.0001) and PSA velocity (p = 0.009). High grade prostatic intraepithelial neoplasia in an initial benign biopsy was not predictive of cancer in repeat biopsy (p = 0.12). Multiple logistic regression analysis of all cases showed that age (p = 0.002) and PSA density (p = 0.0002) were independent predictors of cancer. Subset multiple logistic regression analysis modeled with age, PSA density and percent free PSA demonstrated that age (p = 0.002) and percent free PSA (p = 0.0001) were significant independent predictors of malignancy. Subset multiple logistic regression analysis modeled with age, PSA density, percent free PSA and PSA velocity revealed that age (p = 0.02) and percent free PSA (p = 0.0003) were significant independent predictors of cancer. There were no significant differences between the Gleason scores of cancers detected on repeat biopsy compared to 587 stage T1c-2 cancers detected on initial biopsy during the study period (p = 0.09). PSA, PSA density, percent free PSA and PSA velocity were not significantly different among men without a cancer diagnosis who had high grade neoplasia in 1 or 2 benign biopsies. Greater than 25% of this population of select patients with suspected stage T1c-2 prostate cancer had malignancy detected on repeat biopsy. Percent free PSA was the most powerful predictor of cancer. High grade prostatic intraepithelial neoplasia was not a predictor of repeat biopsy cancer detection and PSA functions were similar among men without cancer who did and did not have high grade neoplasia in 1 or more benign biopsies. This finding suggests that high grade prostatic intraepithelial neoplasia may not be a reliable indicator of clinically significant existing prostate cancer.