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ORAL 39 - Potential Biomarkers for CT Screening (ID 149)
- Event: WCLC 2015
- Type: Oral Session
- Track: Screening and Early Detection
- Presentations: 1
ORAL39.02 - Early Detection of Lung Cancer by a FISH-Based Sputum Test (ID 711)
16:45 - 18:15 | Author(s): R. Batra
Early detection represents an important opportunity for decreasing lung cancer mortality. Lung cancer screening with low-dose CT scanning is plagued by a high false-positive rate and non-invasive adjuncts that improve diagnostic accuracy or serve as a pre-screen may be helpful. This study evaluated the performance of a sputum based lung cancer detection (LCD) test that utilizes fluorescence in-situ hybridization (FISH) to detect chromosomal alterations at the 3p22.1 and 10q22.3 loci caused by a cancerous process.
At 5 international centers, between March 2012 and July 2014, induced sputum samples were collected from 173 subjects with 8-30 mm solitary pulmonary nodules, where imaging and other subject characteristics mandated biopsy. At least 50 lower respiratory tract cells were required for analysis. The LCD Test, performed at one of 3 reference labs, enabled a combined analysis of sputum cytology and Target-FISH analysis on the same cell using an FDA approved imaging analysis system (BioView Duet™). The LCD test was considered positive if at least 7.5% of the target cells had an abnormal FISH pattern. The results of the LCD were then compared to the clinical pathology. Subjects with an initial non-surgical negative biopsy result were followed for up to 2 years to determine their final diagnosis.
There were 116 subjects who met the inclusion criteria, had a pathologic diagnosis of lung cancer if the nodule was malignant, and produced adequate sputum for analysis. Seventy-two subjects were diagnosed with lung cancer from the initial biopsy, 7 had definitive negative surgical biopsies, and 37 subjects were classified as indeterminate due to non-surgical negative biopsies. Initial positive concordance was 86.1% (62/72) and initial negative concordance was 71.4% (5/7). From the initial 37 indeterminate negative subjects, additional clinical analyses during the follow up period enabled a definitive classification for 23 subjects: 11 were diagnosed with lung cancer and 12 were reclassified as definitive negative. From this group the LCD test had a positive concordance of 81.8% (9/11) and a negative concordance of 91.7% (11/12). Overall, sensitivity was 85.5% (71/83), specificity was 84.2% (16/19), positive predictive value was 95.9%, and negative predictive value was 57.1%. Fourteen indeterminate negative subjects are still being clinically monitored. The test performance for nodules of 8-20mm was as good as the results for 21-30mm nodules.
In a cohort of patients with a high risk of lung cancer, the LCD test had a high positive predictive value. A positive LCD test could potentially lead to an earlier intervention in a nodule that might otherwise have been monitored for growth. An adequate cancer resection might then be accomplished by segmental resection rather than lobectomy in smaller lesions. The LCD test may be useful as a decision support tool at critical points in the management of solitary pulmonary nodules detected by screening CT scans in subjects at high risk for lung cancer.
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