The Detection Of ALK And ROS1Rearrangments In Lung Adenocarcinomas

Backgroud:The methods to detect molecular targets of lung carcinoma include immunohistochemistry, FISH and RT-PCR, all of these methods have their advantanges and disadvantanges.The pupose of our research is to detect ALK and ROS1rearrangements in lung carcinoma by using these methods, in order to assess the sensitivity and specificity, and to provide evidence to the classification and detection of personalized therapy.Methods:The research consists of two parts:The first part is to detect ALK rearrangements in lung ADCs. We tested297cases by using IHC and FISH. Ventana IHC and RT-PCR assay were applied to evaluate ALK-fusion status in the discordant cases of FISH and IHC. The association of ALK (+) with clinicopathological characteristics was statistically analyzed.The second part is to detect ROS1rearrangements in lung ADCs. The cases include two parts:The first part is to test218lung ADCs (EGFR/KRAS/ALK mutation were tested before, and all were negative) cases for ROS1rearrangements by using IHC and FISH. The second part is to test463lung ADCs (unselected cases) cases for ROS1rearrangements by using IHC, the positive and suspected cases using FISH analysis further. According to the previous experimental results, we selected60cases (including positive cases) to analyze by RT-PCR assay. The association of ROS1(+) with clinicopathological characteristics was statistically analyzed.Results:The first part:Among297cases,44(14.8%),36(12.6%) were ALK (+) by IHC and FISH. Taking FISH analysis as a standand, IHC had100%sensitivity and81.8%specificity for detecting ALK (+).8ALK-expressed cases were ALK (-),5cases of which had ALK fusion detected by RT-PCR analysis.3of these5cases showed ALK expression using Ventana IHC assay. ALK (+) was associated with younger age and lymph node metastasis in this Chinese lung adenocarcinomas patient cohort. About the histologic subtypes of ALK (+) cases, the cases with mucin production were the highest, the proportion was82.1%(32/39), followed by acinar and solid type, the proportion was71.8%(28/39) and33.3%(13/39), respectively.The second parts:Among218selected cases,7(3.2%),6(2.8%) was ROS1(+) by IHC and FISH, respectively. Among unselected cases,9(1.9%),7(1.5%) was ROS1(+) by IHC and FISH, respectively. According to the previous experimental results,20cases were ROS1(+) by RT-PCR analysis. Taking FISH analysis as a standand, the sensitivity and specificity of RT-PCR was100%and85.1%, respectively. There was no significance with statistical analysis. About the histologic subtypes of ROS1(+) cases, the cases with acinar type were the highest, the proportion was87.5%(14/16), followed by papillary and micropapillary type, the proportion was62.5%(10/16) and50%(8/16), respectively.Conclusion:The advantages of low cost and100%sensitivity allow conventional IHC to serve as a robust diagnostic tool for screening patients with ALK (+) and ROS1(+). For cases in which ALK or ROS1were weakly expressed, or discorded by IHC and FISH analysis, RT-PCR is necessary as a diagnostic test for ALK-fusion and ROS1-fusion detection.