The Role Circulating Tumor DNA (ctDNA) in the Diagnosis and Prediction of Lung Tumors

1–2 Despite advances in treatment strategies, lung tumors show clinical variability and traditional detection methods, involving imaging technologies (X-ray, CT scanning) or invasive tissue biopsy, which are far from perfect for early diagnosis and accurate prognosis of diseases. Thus, there is an increasing demand for non-invasive biomarkers that will enable early diagnosis and risk stratification. Circulating tumor DNA (ctDNA), a subset of cell-free DNA shed into the blood by tumor cells, is an attractive marker for representing tumour burden and molecular features. The purpose of the current study was to assess the diagnostic and prognostic significance of ctDNA in suspected lung tumor patients. Materials and Methods: This cross-sectional diagnostic study was carried out in Al-Forat Al-Awsat Oncology Center, Al-Najaf City-Iraq from March 2025 to September 2025. Seventy (70) patients with clinical and radiological suspicion of lung tumours were recruited. Peripheral blood samples obtained before final diagnostic studies. On the basis of histopathologic examination and/or chest computed tomography, 38 patients had lung tumors and 32 did not; these comprised control subjects. Serum levels of circulating tumor DNA were measured, blood carcinoembryonic antigen (CEA), and neuron-specific enolase (NSE) were detected. ctDNA levels were significantly elevated in tumor-positive cases when compared to those that are negative (p < 0.002). The multivariate logistic regression analysis showed that ctDNA was an independent factor for lung cancer (p < 0.001). Receiver operating characteristic (ROC) curve analysis further verified the high diagnostic value of ctDNA, with an area under the curve (AUC) being 0.89, and sensitivity and specificity were 86.8% and 81.3%, respectively at an optimal cut-off value. It was concluded that circulating tumor DNA is an extremely informative non-invasive biomarker with significant diagnostic value and with prognostic impact in lung neoplasms. The ketone body ability of differentiation in conjunction with conventional tumor markers could enhance the sensitivity and specificity of the diagnosis and have a role as a basis for the personalized decision in lung cancer.