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N5 The use of CT in the staging of prostate cancer

      Introduction and Objectives

      According to current guidelines, patients af Herlev Hospital, Denmark, with intermediate or high risk prostate cancer (PC), who may be candidates for curative treatment, undergo pelvic lymphadenectomy (PLA) in order to detect lymph node metastases. Prior to this, an abdominal CT is performed in order to spare the patients with positive lymph nodes on CT unnecessary invasive PLA.
      Objective: To assess the usefulness of CT in the staging procedure of PC.

      Material and Methods

      All patients with PC who had an abdominal CT in 2008 were reviewed. Furthermore, all patients with PC, who had a radical prostatectomy (RP) with PLA and patients who underwent PLA prior to external beam radiation (EBR) or brachytherapy (BT) were reviewed. The two groups were crossed, and the results from PLA were correlated to the CT findings.

      Results

      171 patients had PLA. There were no patients who had CT that did not undergo PLA. The prevalence of lymph node metastases after PLA was 22.2%. In the group of patients who had RP or were scheduled for BT (85 patients with generally localised PC), the prevalence was 9.9%. In the group scheduled for EBR (generally locally advanced PC), the prevalence was 35.7%. 5 patients (2.9%) had positive CTs, 3 true positive and 2 false positive. The sensitivity, specificity, positive predictive value and negative predictive value of CT was thus 7.9%, 98.5%, 60%and 78.9%. Fine needle aspiration biopsy (FNAB) was only performed in 1 of the cases of positive CTs, showing no metastases. In none of the cases in this study did CT result in avoiding PLA. In 17 patients (9.9%), CT revealed unexpected pathologic findings, which were succeeded by other invasive or non-invasive examinations.

      Conclusions

      The sensitivity of CT in this study is extremely low, corresponding to earlier findings. CT does not meet the demands of a meaningful diagnostic tool for this group of patients. The disadvantages are obvious: Exposition to unnecessary radiation, prolongation of the time of treatment and redundant expenses. We propose that CT should consequently not be performed in the staging of PC.