Comparison of Tumor Tissue, CTCs and ctDNA in EGFR Mutations of Non-Small-Cell-Lung-Cancer (NSCLC) Patients


Student thesis: Doctoral Thesis

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Award date16 Jan 2023


Since a lot of targeted therapies are available as treatment strategies, molecular tests are frequently used in the selection of treatment plans for various cancers. The invasive nature of the specimen collection procedures and inadequacy of the tissue samples have imposed limitations on the detection of the molecular rivers in formalin-fixed paraffin-embedded (FFPE) specimens of tissues. On the other hand, using plasma samples from cancer patients is getting increasingly popular, as the plasma sample collection procedure is less invasive and furthermore, the tumor heterogeneity problem can be well tackled. A liquid biopsy for the detection of mutation drivers in a non-solid biological sample, such as body fluid and blood, provides more flexibility and advantages over the conventional tissue biopsy. The most practical minimal invasive mutation drivers are circulating tumor DNA (ctDNA), cell free DNA (cfDNA) and circulating tumor cells (CTCs). These mutation drivers play a significant role in understanding the metastasis and tumorigenesis, which exhibit more in-depth information of the tumor development during disease treatment and progression. Despite all the advantages, liquid biopsy is still a slow process in clinical routine practice. The major obstacles include a lack of consensus on the technical approach for the detection of circulating markers; difficulty in standardizing the pre-analytical and analytical procedures to obtain reliable results; expensive technology limiting its accessibility to patients, and a relatively long turn-around time required which does not meet the needs of urgent requests. The aim of the research project is to isolate, recover and evaluate the performance of tissue molecular results and molecular characterization of plasma CTCs and ctDNA by using a next generation sequencing (NGS) of lung cancer gene profile. It was done by using a leading microfluidic inertia-focusing technology-based method, the Cellomics CTC100 for the isolation of circulating tumor cells (CTCs). Since lung cancer is the major cause of cancer morbidity and mortality rates in both men and women, the focus was on the outcome of epidermal growth factor receptor (EGFR) mutations of lung cancer samples. The research had two stages. In stage I, tissue samples from one batch of 10 non-small-cell lung cancer (NSCLC) patients by real time PCR (RT-PCR) were used to compare the tissue molecular characterization by NGS. In stage II, same batch of 10 NSCLC tissue samples from stage I by RT-PCR were used to compare the blood based ctDNA and CTCs EGFR results by NGS. Blood samples were collected simultaneously for ctDNA and CTCs analysis at the same time. Although there was a limitation on the size of patient samples, results from the tissue NGS and plasma ctDNA EGFR mutation analysis are encouraging. The research data indicated that the stage I study revealed high concordance rate with overall 90% (9/10) of tissue based RT-PCR with NGS comparison for EGFR mutation. The positive concordance rate is 86% (6/7) and negative concordance rate is 100% (3/3). While in stage II of comparison between tissue RT-PCR to plasma ctDNA, we have an overall 70% concordance rate with sensitivity and specificity of 57% (4/7) and 100% (3/3) respectively. Whereas, for tissue RT-PCR to CTCs comparison, the overall concordance rate is 45% (4/9) with 43% (3/7) sensitivity and 50% (1/2) specificity only. A proposed modified workflow with detection of tissue molecular by RT-PCR, NGS and plasma ctDNA is highly suggested, since genetic mutation and allelic frequency provide significant means of treatment selection and cancer burden information.

    Research areas

  • Circulating tumor cells, Cell free DNA, Non-small-cell-lung-cancer, Tumor tissue, Next generation sequencing