Abstract
The ctDNA plasma testing is one of the methods to examine biomarkers for lung adenocarcinoma in order to detect a mutation of epidermal growth factor receptor (EGFR) gene. The advantages of ctDNA testing over tissue biopsy and lung tumor cytology include less invasive, faster result, cheaper, and minimum risk of complication for the patient. We analyzed and compare the detection of EFGR mutation in peripheral blood plasma (liquid biopsy) with cytological specimens of patients with lung adenocarcinoma. We conducted ctDNA plasma testing in 124 lung adenocarcinoma patients who visited our hospital from January to December 2018. The ctDNA testing results were compared with the results of EGFR detection from the previous cytological specimen examination. Most of the patients were males, aged 55-59 years, nonsmokers, and had stage IVA lung adenocarcinoma, with most metastasis found in the pleura. We found a correlation between EGFR prevalence with nonsmoking status and patient's age. The ctDNA plasma testing detected 27.4% common EGFR mutation and 72.6% wild-type EGFR. The figures of EGFR mutation detection from cytological specimens were 47.6% and 52.4%, respectively. Compared to cytological specimens, the EGFR mutation detection in ctDNA had a sensitivity of 48.3%, with a specificity of 90.9%, PPV of 82.35%, NPV of 66.7%, and 70.97% concordance rate. EGFR mutation with cytological specimen examination was more accurate than ctDNA.