Analisa Sensitivitas Pemeriksaan Imunohistokimia dengan Gold Standar RT-PCR pada Pasien Adenokarsinoma dengan Mutasi ROS-1

Abstract

Background: ROS1 gene mutation is one of the actionable targets in non-small cell lung carcinoma (NSCLC), particularly the adenocarcinoma subtype. Early detection of this mutation is crucial for determining appropriate therapy. While RT-PCR remains the gold standard for ROS1 detection, immunohistochemistry (IHC) is often used as a screening method due to its accessibility and rapid processing time. This study aimed to evaluate the sensitivity and specificity of IHC compared to RT- PCR in detecting ROS1 mutations. Methods: This was a diagnostic cross-sectional study conducted at RSUP H. Adam Malik and RSU Santa Elisabeth Medan between December 2022 and December 2023. A total of 90 patients with NSCLC adenocarcinoma who met the inclusion and exclusion criteria were enrolled. Collected data included clinical characteristics and results of ROS1 testing using RT-PCR and IHC. The validity of IHC was assessed by calculating sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy, using RT-PCR as the reference method. Results: Among the 90 patients, 8 (8.9%) were ROS1-positive by RT-PCR and 7 (7.8%) were ROS1-positive by IHC. The sensitivity of IHC compared to RT-PCR was 42.9%, specificity was 94%, PPV was 37.5%, and NPV was 95.1%. The overall diagnostic accuracy of IHC was 90%. Most patients were male (66.7%), with a mean age of 56.46 years, and the majority were former smokers (67.8%). Conclusion: Immunohistochemistry shows high specificity and negative predictive value, making it a reasonably effective screening tool for ROS1 detection. However, its low sensitivity and positive predictive value indicate that IHC should not be used as a standalone diagnostic method for determining ROS1 status.