ALK Gene In Lung Cancer Patients Bronchoscopic Specimen Testing

PurposeThe incidence of EML4/ALK(echinoderm microtubule-associated proteinlike4/anaplastic lymphoma kinase)gene of non-small cell lung cancer in the Asian population is about10%. We evaluated it in the Chinese people with bronchoscopic samples, analysed the clinicalpathological factors which may impact the detection efficiency, and the characteristics of the patients with ALK-rearranged gene in order to find optimal modality in small biopsy samples.MethodWe collected bronchoscopic samples of lung adenocarcinoma, tested the ALK gene with fluorescent in-situ hybridization(FISH) and immunohistochemistry(IHC), then analysed several factors such as symptom, gross manifestation under bronchoscopy, location of biopsy, the number of biopsy samples and IHC sections, as well as the ratio of tumor cells in order to find out the influential ones for better detection with bronchoscopic samples. Furthermore we also compared the clinicopathological characteristics and the prognosis of patients with different ALK status.ResultWe collected108patients’ clinical data of lung adenocarcinoma, of which92have bronchoscopy biopsy samples. The rate of detection for FISH with bronchoscopic biopsy samples is71.3%(77/108), and the incidence of ALK gene in the Chinese population is7.8%(6/77), which is higher in the left lower lobe and principal bronchus(P=0.004). And the rate of detection tends to increase in the samples with tumor cells more than100(P=0.00).Except for these,we find no other clinicopathological factors can merits the detection. The patients with ALK-rearrangements are younger (P=0.01).And all of them are non-smokers with low pathological differention,but the P value is larger than0.05.The ALK status is irrelevant to gender,clinical stage or the manifestation under bronchoscopy.The sensitivity and specificity of IHC with D5F3monoclonal antibody is50%and100%respectively.ConclusionThe rate of detection for FISH with bronchoscopic biopsy samples is71.3%, and the incidence of ALK gene in the Chinese population is7.8%, which is higher in the left lower lobe, principal bronchus and those with tumor cells more than100. The patients with ALK-rearrangements are younger.The IHC with D5F3provides good specificity,but the sensitivity is not so satisfying.