Non-invasive early detection of malignant pulmonary nodules by FISH-based sputum test

Abstract

Background: Early detection decreases lung cancer mortality. The Target-FISH Lung Cancer Detection (LCD) Test is a non-invasive test designed to detect chromosomal changes (deletion or amplification) via Fluorescence in situ Hybridization (FISH) in sputum specimens from persons suspected of having lung cancer. We evaluated the performance of the LCD test in patients with highly suspicious pulmonary nodules who were scheduled for a biopsy procedure.

Methods: Induced sputum was collected from patients who were scheduled for biopsy of a solitary pulmonary nodule (0.8-3 cm) in one of 6 tertiary medical centers in the US and Israel. The lung cancer detection (LCD) Test combined sputum cytology and Target-FISH analysis on the same target cells and the results were compared to the pathology. Participants with non-surgical negative biopsy results were followed for 2 years to determine their final diagnosis.

Results: Of the 173 participants who were evaluated, 112 were available for analysis. Overall, the LCD test had a sensitivity of 85.5% (95% CI, 76.1-92.3), specificity of 69% (95% CI, 49.2-84.7) and an accuracy of 81.3% (95% CI, 72.8-88). The positive and negative predictive values (PPV, NPV) were 88.8% and 62.5%, respectively. The LCD test was positive in 9 of 11 lung cancer patients who had an initial negative biopsy.

Conclusions: In a cohort of patients with highly suspicious lung nodules, the LCD test is a non-invasive option with good sensitivity and a high positive predictive value. A positive LCD test reinforces the need to aggressively pursue a definitive diagnosis of suspicious nodules.

Keywords: Early detection; Fluorescence in situ hybridization; Induced sputum; Lung cancer; Pulmonary nodule.