This multicenter pilot observational study aims to assess the feasibility of introducing liquid biopsy at an early stage of the diagnostic pathway for patients with suspected advanced non-small cell lung cancer (NSCLC).

Liquid biopsy is a minimally invasive blood test that can detect tumor-related genetic alterations in circulating nucleic acids. The study will evaluate whether this approach can provide molecular information more rapidly than standard tissue-based testing and how closely the results obtained from blood samples match those obtained from tumor tissue.

Approximately 70 adult patients with radiological evidence of locally advanced or metastatic lung cancer will be enrolled. Participants will undergo a blood draw for liquid biopsy and will continue to follow the standard diagnostic pathway, including tissue biopsy or cytological sampling when indicated.

The results generated within the study are intended for research purposes and will not replace standard diagnostic procedures or independently determine treatment decisions. The findings will be used to identify practical and methodological issues and to support the design of future clinical studies on the plasma-first approach.

Molecular characterization is an essential step in the management of advanced non-small cell lung cancer (NSCLC), as the identification of actionable genomic alterations may guide the selection of targeted therapies. However, tissue-based molecular testing may be delayed or limited by insufficient or poor-quality biological material.

Liquid biopsy allows the analysis of circulating tumor-derived nucleic acids from a peripheral blood sample and may provide molecular information earlier in the diagnostic pathway. The plasma-first approach consists of performing liquid biopsy at an early stage, while the patient continues the standard diagnostic process.

This is a multicenter, prospective, non-pharmacological pilot observational study involving adult patients with radiological suspicion of locally advanced NSCLC not suitable for locoregional treatment or metastatic NSCLC. Eligible patients must have a tissue biopsy or cytological sampling planned but not yet performed, or already performed without an available histopathological diagnosis of NSCLC at the time of enrollment.

Each participant will undergo a peripheral blood draw for liquid biopsy within one week of the first clinical assessment. Plasma-derived circulating nucleic acids will be analyzed using next-generation sequencing (NGS). Participants will then continue the standard diagnostic pathway of the enrolling center, including tissue biopsy or cytological sampling, histopathological diagnosis, PD-L1 assessment, and standard tissue-based molecular profiling.

The study will assess the feasibility of the plasma-first approach and will generate a structured dataset to support the design of future prospective studies. Secondary objectives include evaluating:

• the turnaround time of plasma-based and tissue-based molecular testing;
• the proportion of informative liquid biopsy results;
• the concordance between molecular alterations detected in plasma and tissue samples;
• the performance of different NGS-based approaches for the detection of genomic alterations;
• the tumor fraction in plasma samples and its relationship with molecular and clinical variables;
• the potential organizational and economic implications of integrating liquid biopsy into the diagnostic pathway.

For participants enrolled at the coordinating center, additional exploratory analyses will be performed to estimate tumor fraction and compare two NGS-based analytical approaches.

The results of the liquid biopsy performed within this pilot study are collected for research purposes. They will not replace standard diagnostic procedures and will not independently determine the initiation of treatment. Treatment decisions will remain based on the standard diagnostic and clinical assessment performed according to current clinical practice.

The study plans to enroll approximately 70 participants over a 6-month recruitment period, with an observation period of 12 months and an overall estimated study duration of 18 months.

Inclusion Criteria:

• Age ≥ 18 years.
• Radiological suspicion of locally advanced lung cancer not amenable to locoregional treatment or metastatic lung cancer (stage III-IV).
• Eastern Cooperative Oncology Group (ECOG) Performance Status 0-1.
• Tissue biopsy and/or cytological sampling planned but not yet performed, or already performed without an available histopathological diagnosis of non-small cell lung cancer (NSCLC).
• Written informed consent for study participation and personal data processing obtained before any study-specific procedure.

Exclusion Criteria:

• Previous or current history of non-small cell lung cancer (NSCLC).
• Histopathological diagnosis of NSCLC already available following tissue biopsy.
• Eligibility for surgical removal of tumor tissue.
• Ongoing or previous systemic oncological treatment for lung cancer.

The study population includes adult patients with radiological suspicion of locally advanced lung cancer not suitable for locoregional treatment or metastatic lung cancer. Participants are enrolled before completion of the standard diagnostic pathway, when tissue biopsy or cytological sampling is planned but not yet performed, or has already been performed without an available histopathological diagnosis of NSCLC. Eligible patients are recruited at participating centers during thoracic surgery assessment or the first oncology visit and undergo plasma-based liquid biopsy while continuing the standard diagnostic pathway.

Individual participant data will not be made publicly available. Study data will be pseudonymized and managed in accordance with applicable data protection requirements. Any data sharing among participating centers will be limited to the purposes of the study and regulated through appropriate data transfer agreements. Study results may be disseminated in aggregated form. Any future reuse or sharing of individual-level data for compatible research purposes would require specific institutional approval and compliance with applicable ethical, legal, and data protection requirements.