Comparison of digital rectal examination and biopsy results with the radical prostatectomy specimen

Purpose: Digital rectal examination is integral to staging prostate cancer. Ultrasound guided biopsy establishes the diagnosis, and it may provide use ful information regarding disease grade and extent. Treatment decisions are largely based on information gained from digital rectal examination and bi opsy but this information is only useful if it correlates with the radical prostatectomy specimen and prognosis. We correlated digital rectal examinat ion and transrectal ultrasound guided biopsy results with a detailed analys is of the radical prostatectomy specimen. Materials and Methods: The accuracy of an abnormal digital rectal examinati on for predicting the location and extent of cancer was assessed in 89 pati ents thought to have clinical stage T2 disease. We evaluated 155 patients w ith clinical stages Tie and T2 disease to correlate the location of positiv e biopsies with the tumor site in the prostate. Radical prostatectomy speci mens were completely sectioned at 2 mm. intervals, and tumor extent and loc ation were recorded. Results: In 85 patients a unilateral lesion was suspicious on digital recta l examination, that is stage cT2. The final pathological review revealed ca ncer on the suspicious side in 82 cases (96%) with tumor confined to the sa me lobe in only 23 (27%), bilateral disease in 59 (69%) and tumor confined to the contralateral lobe in 3 (4%). In 4 patients with a palpable bilatera l abnormality a bilateral lesion was confirmed on final pathological evalua tion. Digital rectal examination demonstrated a 36 and 31% incidence of ext racapsular tumor extension and positive surgical margins, respectively, on the clinically benign side. In 100 patients only unilateral biopsy was posi tive. The final pathological evaluation revealed cancer in the biopsy posit ive side in 95 cases (95%) with tumor confined to the ipsilateral lobe in o nly 26 (26%), bilateral disease in 69 (69%) and tumor confined to the contr alateral lobe in 5 (5%). In 46 of the 55 patients (84%) with bilateral posi tive biopsies tumor involved both sides but the pathologist did not identif y cancer in both lobes in 9 (16%). While 100 patients had a unilateral nega tive biopsy, analysis of the prostatectomy specimen revealed carcinoma in t he benign lobe in 74 (74%). Moreover, extracapsular tumor extension and a p ositive surgical margin were observed on the biopsy negative side in 31% of the patients. The degree to which digital rectal examination and biopsy re sults confirmed the final pathological evaluation was assessed using the ka ppa statistic, which revealed only slight agreement with each factor. The c orrelation of digital rectal examination and biopsy results with the locati on of extracapsular extension and positive margins was evaluated by the Spe arman coefficient of correlation, which indicated poor agreement. When pati ents with unilateral versus bilateral positive biopsy were compared with re spect to prognostic parameters, the difference was statistically significan t for initial serum prostate specific antigen, the percentage of surface in volved by tumor, biopsy and final Gleason scores, and the incidence of extr acapsular extension of tumor. Conclusions: Digital rectal examination and the interpretation of prostate biopsy are not accurate clinical tools for defining the location and extent of prostatic carcinoma. Bilateral positive biopsy may be useful as an adju nct to the current clinical staging system.