2021 Volume 60 Issue 2 Pages 75-85
The recent advent of targeted cancer therapy has led to widespread implementation of molecular testing such as next-generation sequencing. Companion diagnostics are very important for predicting response to and adverse events for specific chemotherapeutic agents. Liquid-based cytology (LBC) allows immunohistochemistry, fluorescence in situ hybridization, and polymerase chain reaction to be performed. In our laboratory, two feasibility studies were done to validate the use of LBC materials. First, cytological materials were obtained from surgical specimens of 40 lung adenocarcinomas (ADC) and fixed using CytoRichTM Red. Twenty cases (50%) were positive for epidermal growth factor receptor (EGFR) mutation. Anaplastic lymphoma kinase gene rearrangement and c-ros oncogene 1 gene rearrangements were each identified in one case (2.5%) with companion diagnostics. Second, the CobasTM EGFR Mutation Test ver. 2 was performed on each sample (LBC, formalin-fixed paraffin-embedded tissue or plasma) obtained by bronchoscopic examination from the 20 ADC with positive immunohistochemistry results. EGFR mutations were identified in eight cases (40%) using LBC, seven cases (35%) using formalin-fixed paraffin-embedded samples and four cases (20%) using plasma. These results suggest that LBC would be suitable for use in subtyping and molecular testing in clinical practice.
