Comparison of molecular abnormalities in bronchial brushings and tumor touch preparations

Preneoplastic lung lesions and early-stage lung carcinomas are associated with molecular abnormalities. The authors performed a pilot study to evaluate the use of DNA fluorescence in situ hybridization (FISH) probes to ascertain whether these biomarkers can predict nonsmall cell lung carcinoma (NSCLC).

Fourteen bronchial brushings ipsilateral to the tumor (BB/Ts), tumor touch imprints, and touch imprints of the bronchus adjacent to the tumor obtained from 15 patients with early-stage NSCLC were analyzed. The LAVysion multicolor probe set consisting of probes to 5p15, 6, 7p12, and 8q2 and the in-house probes 3p22.1 and 10q22 was used. Using the LAVysion multicolor probe set, 25 epithelial cells were counted and considered positive if > 5 cells were abnormal. Using 3p22.1 and 10q22, > or = 100 nuclei per slide were scored. The results were tabulated as the percentage of cells with deletions compared with the centromeric probes 3 and 10. Greater than 2% of the deletions were positive for 3p22.1 and 10q22. Bronchial washings from patients without lung tumors were used as controls.

The BB/Ts were negative for malignant cells by cytologic evaluation and the LAVysion probe set; however, the combined in-house probes for 3p22.1 and 10q22 tested on BB/Ts predicted cancer in 100% of cancer patients. FISH positivity in the lung cancers was 100% for 3p22.1 deletions, 79% for 10q22 deletions, and 57% for LAVysion probes. When compared with the bronchial epithelium, tumor cells showed a 3.7-fold excess of 3p22.1 deletions, a 2-fold excess of 10q22 deletions, and a 12.6-fold excess of abnormal cells.

The current study indicated that detection of molecular abnormalities in bronchial epithelial cells via FISH was very useful in identifying patients at high risk for developing lung carcinoma. The molecular abnormalities identified in the BB/Ts were detected at elevated levels in the tumor specimens.