Negative predictive value of pleural fluid cytology in patients with a background of cancer

Abstract

Background: The diagnostic yield for malignancy of pleural fluid (PF) cytology in patients with pleural effusion (PE) is well known but there is scarce data in the setting of patients who developed a PE and have a prior diagnosis of cancer. Aim: The aim of our study was to evaluate the negative predictive value (NPV) of cytological examination of the PF in patients who had a background of cancer and developed PE. Method: This was a retrospective, descriptive analysis of consecutive patients who developed PE, between January 2015 to December 2017, and had a background of cancer in the Oxford Pleural Unit. Follow-up was made until death or at least one year. Results: 152 patients were included (79 -51.9%- women; mean age 71±12). 75 (49.3%) patients had a malignant PE; 48.0% of these cases were diagnosed by cytology. Sensitivity of cytological diagnoses on PE was 57.3%, specificity 100%, positive predictive value 100%, and NPV 70.6%. A background of breast cancer was the most common (39 cases) and malignancy was identified in 26 patients (66.6%) whose PF cytology was positive in 22. For patients with prior breast cancer the sensitivity of the cytological samples was 84.6% and NPV was 76.4%. Conclusion: The negative predictive value of pleural effusion cytology in patients with prior diagnosis of cancer is moderate, however, this technique confirmed the diagnosis in approximately one half of the patients with malignant pleural effusion. The negative predictive value of pleural effusion cytology in the setting of patients with previous breast cancer was slightly higher but remains insufficient to make clinical decisions as a stand alone test. Acknowledgement: European Respiratory Society (CTF201804-00345)