Prognostic Significance of the LSUVmax–IPI Composite Score on Overall Survival in Metastatic Non–Small Cell Lung Cancer

Background Non–small cell lung cancer (NSCLC) is often diagnosed at metastatic stages, and overall prognosis remains poor. Reliable biomarkers reflecting both tumor metabolism and systemic inflammation are needed. This study investigates the prognostic significance of the LSUVmax–IPI composite index in metastatic NSCLC. Methods A total of 137 metastatic NSCLC patients who underwent pre-treatment 18F-FDG PET/CT were retrospectively analyzed. LSUVmax–IPI was calculated as SUVmax × IPI, and patients were categorized using a cut-off value of 4.4. Clinical, laboratory, metabolic, and survival variables were compared. Overall survival (OS) and progression-free survival (PFS) were analyzed using the Kaplan–Meier method. Results Patients with LSUVmax–IPI > 4.4 had significantly higher metabolic activity and inflammatory markers. Median OS was 28 months in the ≤ 4.4 group and 16 months in the > 4.4 group (p = 0.002). PFS showed a trend toward shorter duration in the > 4.4 group, though not statistically significant (p = 0.098). Conclusions LSUVmax–IPI is a practical prognostic index reflecting both tumor aggressiveness and systemic inflammation. Higher scores were strongly associated with poorer OS. Further validation in prospective studies is required.