Analysis of the risk factors for incidental carcinoma of the prostate in patients with benign prostatic hyperplasia.

PURPOSE To determine the occurrence of incidental carcinoma of the prostate, its characteristics, and the risk factors for this diagnosis in a group of patients surgically treated for benign prostatic hyperplasia. METHODS The study comprised a retrospective analysis of 218 patients. After surgical treatment, patients with the finding of incidental carcinoma of the prostate were compared to those without this finding. The preoperative variables analyzed were patient age, digital rectal examination, PSA, PSA density, prostate volume, and preoperative prostate biopsy. We also determined the sensitivity, specificity, positive predictive value, and negative predictive value of digital rectal examination and PSA for the finding of incidental carcinoma of the prostate at surgical specimen analysis. RESULTS Thirteen (6.2%) out of the 218 patients presented incidental carcinoma of the prostate. Eight (61.5%) of these tumors were classified as T1a and 5 (38.5%) as T1b. Only advanced age (P = 0.003) and the presence of a suspect digital rectal examination (P = 0. 016) were statistically related to the findings of the surgical specimen analysis. The sensitivity, specificity, positive predictive value, and negative predictive value for the diagnosis of incidental carcinoma were 23.0%, 96.6%, 30.0%, and 95.2% for a suspect digital rectal examination and 85.0%, 34.1%, 7.5%, and 97.2% for a PSA greater than 4.0 ng/mL. The accuracy for these methods was 92.2% and 37.1%, respectively. CONCLUSIONS Advanced age and the presence of a suspect digital rectal examination represent the most important risk factors for the diagnosis of an incidental carcinoma of the prostate. However, the low positive predictive values reflect the weak correlations among these variables.