Purpose: We determined the prevalence of and risk factors for carcinoma in patients with 1 previously negative prostate biopsy.
Materials and methods: Transrectal ultrasound guided prostate needle biopsies were repeated in 130 men. Risk factors analyzed included age, pathological result of initial biopsy, inter-biopsy interval, prostate specific antigen (PSA), PSA density, PSA velocity, digital rectal examination, abnormal transrectal ultrasound and family history of prostate cancer.
Results: A total of 39 patients (30%) had positive biopsies for cancer. Univariate analysis revealed that PSA more than 20 ng./ml. and abnormal transrectal ultrasound were more frequent in men with positive second biopsies. Using multivariate logistic regression analysis only PSA more than 20 ng./ml. was a significant risk factor (adjusted odds ratio 4.48, 95% confidence interval 1.02 to 20.1). We determined the incidence of carcinoma in patients who represent the lowest risk group as defined by PSA less than 10 ng./ml., PSA density less than 0.15 mg./ml./cm.3, PSA velocity less than 0.75, ng./ml. per year, no prostatic intraepithelial neoplasia plus negative transrectal ultrasound, digital rectal examination and family history. Of 21 patients who fit this cohort 5 (23.8%) had carcinoma on repeat biopsy.
Conclusions: A significant false-negative rate for initial transrectal ultrasound guided prostate biopsies exists. Baseline risk in lowest risk patients is sufficiently high such that one cannot define a subset of patients for whom repeat biopsy is unnecessary. We recommend repeat biopsy in all patients who meet the criteria for a transrectal ultrasound guided biopsy and in whom the initial biopsy is negative.