Evaluation of the Prognostic Nutritional Index in Conjunction with Lung Cancer Stage and PET-CT SUVmax

Lung cancer is among the malignancies with the highest mortality rates globally, where nutritional and immune status significantly influence disease progression and prognosis. The study aimed to investigate the relationship of the prognostic nutritional index (PNI) with both the maximum standardized uptake value (SUVmax), measured by positron emission tomography-computed tomography, and the clinical stage of lung cancer.

Patients who underwent fiberoptic bronchoscopy and were diagnosed with lung cancer at the Department of Pulmonology, Kütahya Health Sciences University, between January 1, 2022 and May 31, 2025, were retrospectively evaluated. A total of 241 patients diagnosed with lung cancer via bronchoscopy were evaluated; of these, 205 patients diagnosed with non-small-cell lung cancer (n = 205) were assessed according to stage.

A total of 241 lung cancer patients were included; the mean age was 68.35±8.52 years and 95.0% were male. The mean PNI was 41.41±9.50 and the mean primary tumor SUVmax was 10.53±5.22. PNI and primary tumor SUVmax showed a very weak negative association that did not reach statistical significance (Spearman ρ = -0.127; P = 0.055). Clinical stage was positively associated with SUVmax (ρ = 0.253; P < 0.001) and negatively associated with PNI (ρ = -0.186; P = 0.007).

Higher clinical stage was associated with higher primary tumor SUVmax and lower PNI. The association between PNI and SUVmax was weak and not statistically significant; therefore, it should not be considered clinically discriminative on its own. PNI may serve as an adjunctive indicator of nutritional and immune status, but prospective studies with survival outcomes and multivariable adjustment are required before it can be used as a prognostic or staging tool.