Introduction: Next-generation sequencing (NGS) is the standard of care in the diagnosis of patients with advanced non-small cell lung cancer (NSCLC), but only recently has it become routine in early-stage NSCLC.

Objectives: To identify possible variations of mutations in NGS between stage l-lll and stage lV NSCLC at the time of diagnosis.

Methods: Retrospective study in a Portuguese NGS database. Comparative analysis of NGS results between stage l-lll NSCLC and stage lV NSCLC.

Results: The total population (n=132) consisted of a majority of men (53.8%), a mean age of 64+-10 years, 24% never smokers, 39% ex-smokers, and 36% active smokers. The majority of patients (62%) had a performance status of 1. 57% of patients had stage lV NSCLC at diagnosis, 41.6% had stage l-lll NSCLC at diagnosis, and staging was unknown in 2 patients. Most patients had a pathologic diagnosis of lung adenocarcinoma (92%). Most NGS samples were from bronchial biopsy (33%), surgical pathology (30%), or fine-needle aspiration cytology (16%). When analysing the total population, the most frequent mutation sites were EGFR and K-RAS with 34 patients per mutation site. 26.5% of patients had no mutation in the NGS. In the comparative analysis between stage l-lll NSCLC (n=55) and stage lV NSCLC (n=75), there was no statically significant result in any outcome. However, the stage l-lll NSCL group had more patients without mutations in the NGS (30.9%vs24%, p=.62), a lower percentage of EGFR mutations (18.2%vs32%, p=.11), an equal percentage of K-RAS mutations (20%), more BRAF mutations (9.1%vs2.6%, p=.22), and more patients with more than one mutation.

Conclusions: Stage l-lll NSCLC might have a lower number of EGFR mutations.