Our objective was to study the feasibility of detecting chromosomal deletions at 3p22.1 and 10q22.3 by fluorescent in situ hybridization (FISH) and to examine their distribution in different areas of the airway in patients with non-small cell lung cancer.
Brush biopsies from the mainstem bronchus on the normal side contralateral to the tumor (NBB) and mainstem bronchus on the tumor side (TBB) were obtained from 122 patients who underwent surgical resection. Touch preparations from the tumor (TTP), normal lung parenchyma, and bronchi adjacent to the tumor were also obtained. Two FISH assays using probes complementary to 3p22.1 and 10q22.3 were used to detect deletions.
NBB showed a relatively low deletion rate of 3p22.1 and 10q22.3 compared with TTP (p < 0.0001). TBB showed a significantly higher rate of deletions compared with NBB but lower than TTP from the tumor (p < 0.05) for both 3p22.1 and 10q22.3. A significantly higher deletion rate was seen at TTP compared with normal lung parenchyma at both the 3p22.1 and 10 q22.3 (p < 0.0001). Correlations were seen between the deletion rates of TTP and TBB at 3p22.1 (ρ = 0.61, p < 0.0001) and between TTP and bronchi adjacent to the tumor at 10q22.3 (ρ = 0.64, p < 0.0001).
Deletions of the 3p22.1 and 10q22.3 regions can be reliably detected by FISH. As one progresses from the contralateral normal bronchus to the bronchus on the side of tumor and the tumor itself, the percentage of chromosomal deletions increases in a statistically significant fashion. This suggests that, FISH analysis of bronchoscopic brushes may be useful for identifying patients at high risk for developing non-small cell lung cancer.