[Detection of ALK positive pulmonary adenocarcinoma using immunostaining]

Although ALK-positive lung cancer cases have been recently reported, it is impossible to detect using only morphology technique. Furthermore, though RT-PCR and FISH techniques can be used for detection, they are not practical for screening. We investigated whether ALK-positive lung cancer could be detected using a conventional immunostaining method. Resected lung adenocarcinoma samples from 88 nonsmoker cases were selected and screening was performed using ALK immunostaining in 24 cases that did not have the EGFR or k-ras mutation. We found that the optimal staining condition was treatment using a water bath and detection with a Novo Link Polymer Detection System (Leica microsystems). Of the 24 cases examined, ALK expression was found in 4, of which ALK separated signals were found in 3 using a FISH method. No separated signals were seen in cases with negative immunostaining findings. Detection by immunostaining was found useful for ALK mutated lung cancer cases, though the pretreatment and detection methods utilized are important.