Background: Over 200000 pleural effusions are attributable to cancer in the UK and USA every year. Cytological examination of pleural fluid classifies about 60% of malignant effusions. Pleural biopsy needs to be done in the remaining cases. We aimed to assess whether CT-guided biopsy is an improvement over standard pleural biopsy in this setting.
Methods: 50 consecutive patients with cytologically negative suspected malignant pleural effusions were recruited. All had a contrast-enhanced thoracic CT scan to assess pleural thickening. Patients were randomly allocated, stratified by baseline pleural thickening, to either Abrams' pleural biopsy (standard care; n=25) or CT-guided cutting needle biopsy (n=25). Sensitivity for pleural malignancy from the biopsy specimen was the primary endpoint, with the patient's clinical outcome after 1 year being the diagnostic gold standard. Analysis was per protocol.
Findings: Three patients did not undergo biopsy. Abrams' biopsy correctly diagnosed malignancy in eight of 17 patients (sensitivity 47%, specificity 100%, negative predictive value 44%, positive predictive value 100%). CT-guided biopsy correctly diagnosed malignancy in 13 of 15 (sensitivity 87%, specificity 100%, negative predictive value 80%, positive predictive value 100%; difference in sensitivity between Abrams' and CT-guided 40%, 95% CI 10-69, p=0.02). Diagnostic advantage was similar in patients proving to have mesothelioma.
Interpretation: Primary use of CT-guided biopsy would avoid doing at least one Abrams' biopsy for every 2.5 CT-guided biopsies undertaken. In cytology-negative suspected malignant pleural effusions, CT-guided pleural biopsy is a better diagnostic test than Abrams' pleural biopsy.