Clinicopathological Features of NSCLC Patients Associated With the Chromosome 2p (EML4-ALK)

Because ALK-positive lung cancer constitutes less than 5% of all lung cancers, it is critically important to select those patients who are more likely to have the ALK mutation. Clinical characteristics of patients with mutations in the target gene should also be known, so that the incidence of a given target mutation is established in a specific population. There is not incidence known in Mexican population, but it is believed it is greater.

Lung adenocarcinoma studies. The only inclusion criterion was the availability of tissue for biomarker studies. To identify ALK rearrangements, fluorescence in situ hybridization (FISH) studies were performed on 3 to 4 mm thick paraffin sections from NSCLCs. The commercially labeled Vysis LSI ALK Dual Color (split-apart), break-apart rearrangement probe (Abbott Molecular, Abbott Park, IL) was used to detect any rearrangement involving the ALK gene. The probe hybridizes to band 2p23, on either side of the ALK gene breakpoint. Criteria for probe signal interpretation in at least 200 interphase nuclei were as follow: 1) separated green and orange signals or single red signals identified cells with rearranged ALK; 2) overlapping of red and green signals (yellowish) indicated cells in which ALK was not rearranged. FISH-positive samples for ALK rearrangement were defined as having cells with a clearly separated pair of probe signals, or with \>15% of cells having loss of the 5´(centromeric) probe. The higher threshold for loss is necessary because parts of probes can be lost during sectioning. The aim of our study is to evaluate the utility of IHC with 5A4 and RT-qPCR in the detection of ALK rearrangements in NSCLC compared with the current method of choice, FISH. Further, we report on the demographics, and clinicopathologic features of ALK-rearranged NSCLC in a Latin-American population. Clinical details of these patients were included in a database. Further results will be analyzed with the program SPSS17