This prospective, multicenter, real-world observational study aims to evaluate the clinical outcomes of first-line atezolizumab monotherapy in patients with stage IV non-small cell lung cancer (NSCLC) with PD-L1 tumor cell expression ≥50% and no targetable mutations. The study aim to determine how atezolizumab performs in routine clinical practice with respect to survival, treatment response, and safety outcomes in this patient population in Türkiye.

This study is a prospective, multicenter, observational study designed to generate real-world evidence on the routine first-line use of atezolizumab in patients with advanced non-small cell lung cancer (NSCLC) who exhibit high PD-L1 expression and have no targetable mutations. The study does not impose any protocol-mandated procedures or intervention requirements, and all assessments, treatments, and follow-up visits are carried out according to local standards of care at each participating center.

Data will be collected prospectively from routine medical records and will include information typically obtained during standard clinical management, such as imaging assessments, laboratory results, performance status evaluations, treatment exposure, and safety monitoring. Clinical outcomes will be analyzed to describe real-world treatment patterns, variations in clinical practice, and survival and safety trends in a national cohort. Approximately 150 patients are expected to be enrolled to ensure adequate precision in estimating long-term outcomes within this population.

Inclusion Criteria:

• Signed informed consent form.
• Diagnosis of stage IV non-small cell lung cancer.
• Male or female patients aged 18 years or older.
• Patients who have been prescribed atezolizumab in accordance with routine clinical practice and the locally approved indication in Türkiye.
• Patients who have received up to 3 cycles of atezolizumab at the screening visit.

Exclusion Criteria:

• Patients who are not receiving atezolizumab for the treatment of lung cancer according to standard of care and the approved indication.
• Known or suspected hypersensitivity to atezolizumab.
• Pregnant or breastfeeding women.

Adult patients with stage IV non-small cell lung cancer receiving first-line atezolizumab as part of routine clinical practice at participating oncology centers in Türkiye. The study population reflects real-world patients treated according to local standards of care.