This study investigates the impact of sarcopenia and the CRP-TyG Index (CTI) on immunotherapy outcomes in patients with metastatic non-small cell lung cancer (NSCLC). Medical records of 115 adult patients treated with immune checkpoint inhibitors at Ankara Etlik City Hospital between November 2022 and December 2024 will be retrospectively analyzed. Sarcopenia will be determined from CT-based skeletal muscle index (SMI) measurements at the L3 vertebral level. SMI will be calculated as skeletal muscle area (cm²) divided by height squared (m²), with sex-specific cut-offs (≤52.4 cm²/m² for men, ≤38.5 cm²/m² for women). CTI will be calculated from CRP, triglycerides, and fasting glucose values. Primary outcome is objective response rate (ORR, RECIST 1.1). Secondary outcomes include 1-year progression-free survival (PFS), 1-year overall survival (OS), treatment duration, and adverse events (CTCAE v5.0).
Metastatic non-small cell lung cancer (mNSCLC) is among the leading causes of cancer-related mortality worldwide. Immune checkpoint inhibitors (ICIs) targeting PD-1/PD-L1 have improved survival outcomes, yet responses remain heterogeneous. Prognostic biomarkers such as sarcopenia and systemic inflammation-metabolism indices may help optimize patient selection. This retrospective, single-center cohort study will analyze 115 adult patients with mNSCLC treated with ICIs at Ankara Etlik City Hospital between November 2022 and December 2024. Sarcopenia will be assessed from computed tomography (CT) imaging at the L3 vertebral level by calculating skeletal muscle index (SMI = skeletal muscle area \[cm²\] / height² \[m²\]). Patients will be classified as sarcopenic if SMI ≤52.4 cm²/m² for men or ≤38.5 cm²/m² for women. Both baseline and 3-month CT scans will be analyzed to assess dynamic changes (ΔSMI). The CRP-TyG Index (CTI) will be calculated as: TyG = ln \[triglycerides (mg/dL) × fasting glucose (mg/dL) / 2\] CTI = 0.412 × ln \[CRP (mg/L)\] + TyG Patients will be categorized into low- and high-risk groups using the published cut-off of 4.78. The primary endpoint is objective response rate (ORR, RECIST v1.1). Secondary endpoints include 12-month progression-free survival (PFS), overall survival (OS), treatment duration, adverse events (graded by CTCAE v5.0), and sarcopenia dynamics. Associations between CTI and sarcopenia will also be explored. Statistical analyses include multivariable logistic regression for ORR and Cox proportional hazards models for PFS/OS, adjusting for age, sex, and ECOG status. This study aims to integrate radiological (sarcopenia), biochemical (CRP, triglycerides, glucose), and clinical outcomes to determine whether sarcopenia and CTI can serve as practical prognostic markers for immunotherapy in real-world mNSCLC patients.
Study Type
OBSERVATIONAL
Enrollment
155
Retrospective analysis of patients with metastatic non-small cell lung cancer (mNSCLC) who received standard-of-care immune checkpoint inhibitors, including PD-1 and PD-L1 inhibitors (e.g., nivolumab, pembrolizumab, atezolizumab, durvalumab). Patients received these agents as part of routine clinical practice; no experimental intervention was administered in this study.
Etlik City Hospital Medical Oncology Department
Ankara, Yenimahalle, Turkey (Türkiye)
Etlik City Hospital Radiology Department
Ankara, Yenimahalle, Turkey (Türkiye)
Objective Response Rate (ORR)
Proportion of patients achieving complete response (CR) or partial response (PR) according to RECIST 1.1 criteria, based on radiological evaluation.
Time frame: Baseline to 12 months after initiation of immunotherapy
Progression-Free Survival (PFS)
Time from initiation of immunotherapy to disease progression or death from any cause, whichever occurs first.
Time frame: Baseline to 12 months
Overall Survival (OS)
Time from initiation of immunotherapy to death from any cause.
Time frame: Baseline to 12 months
Treatment Duration
Duration of immunotherapy treatment, measured from initiation to discontinuation for any reason.
Time frame: Baseline to end of treatment (up to 12 months)
Adverse Events (Toxicity Profile)
Incidence and severity of treatment-related adverse events, graded according to CTCAE version 5.0.
Time frame: Baseline to 12 months
Sarcopenia Status at Baseline
Skeletal Muscle Index (SMI = skeletal muscle area \[cm²\] / height² \[m²\]) measured at L3 level. Minimum value: near 0 (exceptionally low muscle mass) No theoretical maximum, but typical range: \~20-80 cm²/m² Lower values indicate worse muscle status. Cut-offs: ≤52.4 cm²/m² (men), ≤38.5 cm²/m² (women) define sarcopenia.
Time frame: At baseline (0 months)
Sarcopenia Status at 3 Months
Skeletal Muscle Index (SMI) at 3-month CT scan. SMI reassessed at \~3 months. Same cut-offs as above. Same cut-offs as baseline (≤52.4 cm²/m² for men, ≤38.5 cm²/m² for women).
Time frame: 3 months after initiation of immunotherapy
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