Circulating Cell-Free DNA in Neuroendocrine Lung Tumors: Preliminary Data from a Prospective Surgical Series

Pulmonary neuroendocrine tumors (PULMONARY NETs) are heterogeneous tumors ranging from well-differentiated to highly aggressive neoplasms. The aim of this study is to prospectively test pre-operative circulating free DNA (cfDNA) in PULMONARY NET patients undergoing surgery and evaluate its relationship to clinicopathological features. From February to December 2024, 136 patients with suspected primary lung cancer underwent pre-operative blood sampling, of whom 21 were diagnosed with PULMONARY NETs. Total cell-free nucleic acid extraction was performed using the Genexus Purification System (Thermofisher). cfDNA was quantified using a fluorometric assay with the Qubit dsDNA HS Assay kit (Thermofisher) and a capillary electrophoresis-based assay (cell-free DNA ScreenTape kit) on the Tape Station 4200 systems (Agilent). A cfDNA quality assessment was also obtained (cfDNA sizing and % cfDNA). Most patients had Stage I (18/21.85.7%) typical carcinoids (16/21.76.2%). Nodal involvement was detected in one patient (0.5%). Six months after surgery, all patients were alive without recurrence. Larger tumors presented higher levels of cfDNA. The mean tumor size in patients with cfDNA > 40 ng was 266 mm (±16.7 mm), compared to 13.2 mm (±7.3 mm) for cfDNA < 40 ng (p-value = 0.018). Higher levels of cfDNA were observed in patients with pStages greater than IA (p-value = 0.007). Although limited by a small sample group and biases of a surgical series, we observed that larger/advanced PULMONARY NETs presented higher cfDNA levels pre-operatively.