Transrectal ultrasound and core biopsies for the diagnosis of prostate cancer. A study of pretreatment investigation strategy for patients with suspected prostate cancer.

Abstract

Prostate cancer is the most common malignancy among Swedish men. In order to select patients to appropriate treatment, transrectal ultrasound (TRUS) and guided core biopsies is commonly used. The aim of this study was to define prognostically important factors in prostate cancer and the accuracy of TRUS and core biopsies as diagnostic tools. Fifty-one patients with localized prostate cancer were prostatectomized and followed up after a mean observation time of 73 months. The adverse influence on progression by tumor volume, Gleason grade, seminal vesicle invasion and lymph node metastases was statistically significant in the univariate analyses. However, tumor volume was the only parameter with an independent prognostic impact on progression. It is important to find a diagnostic method which can accurately determine these parameters in the pretreatment work-up. Thirty-four patients with localized prostate cancer were examined with TRUS prior to radical surgery. The ultrasound examination failed to detect 24% of the tumors, and was not reliable for the determination of tumor size and capsular penetration. TRUS can not be used as the sole method for the diagnosis of prostate cancer. Biopsies might improve the results. Ultrasound-guided core biopsies targeting hypoechoic lesions suspicious for prostate cancer in combination with systematic biopsies sampling the whole gland were performed on 251 men. By adding the results of systematic biopsies to the results of target biopsies, additional information was obtained for the detection of cancer, on tumor volume and seminal vesicle invasion. Grading was not improved. By taking multiple TRUS-guided biopsies considerable trauma is inflicted to the patient. A 1.2-mm cutting needle is commonly used for sampling. A thinner needle may possibly cause less pain. It was shown that a 0.9-mm core biopsy needle can be used without compromising diagnostic accuracy. The results obtained with two thinner needles, 0.8- and 0.7-mm, were unsatisfactory. Complications following TRUS-guided biopsies are infections, bleeding and urinary retention. A total of 347 consecutive men were extensively biopsied. We studied the impact of patient age, final diagnosis, number of biopsies taken, and different regimes for prophylactic norfloxacin treatment. The administration of antibiotics for 3 days, when the first dose was given before the examination began, was the only parameter statistically associated with a reduced risk for complications. Multiple biopsies can be taken without an increased risk for complications if prophylactic antibiotic treatment is given.