Evaluation of diagnostic utility of Acridine orange staining using fluorescence microscopy in lung cancers: A diagnostic test evaluation

Abstract

Lung cancer causes more deaths than most other cancers. Conventional sputum cytology (CSC) has low diagnostic yield for lung cancer. Thus, there is a need for rapid, accurate and cost-effective test for detecting lung cancers. 1). To study sensitivity, specificity and accuracy of Acridine Orange staining with fluorescence microscopy (AOFM) in detection of lung cancer against histo-pathology and fine needle aspiration cytology (FNAC) results. 2). To compare results of AOFM and CSC in diagnosis of lung cancer.It was a diagnostic test evaluation conducted at a tertiary care institute over a period of 24 months.Sputum samples of 60 patients suspicious of lung cancer were examined using AOFM. After staining with Acridine Orange, exfoliated cells in the sputum samples were categorized as benign or malignant based on the type of fluorescence they emitted when examined under a fluorescence microscope, and results were compared with histo-pathology and/or FNAC reports.Chi-square test, Cohen’s kappa statistic etc.AOFM had sensitivity, specificity and accuracy of 92.31%, 87.67% and 90.24% respectively when compared with histopathology and/or FNAC. P=0.0000026 implies significant difference between sensitivities of AOFM and CSC (30.77%). There was significant difference between AOFM and CSC in context of specificity [P=0.04] and accuracy [P=0.05].AOFM in the patients with suspected lung cancer is a useful ‘first diagnostic test’. It is a rapid pre-screening tool which will reduce cost of cyto-diagnosis in under-served and remote areas.