Prognostic nutritional index as a predictor of survival in stage IV lung cancer undergoing palliative radiation therapy

The Prognostic Nutritional Index (PNI), calculated from serum albumin and lymphocyte count, reflects nutritional and immunological status and has been associated with prognosis in various cancers. However, its prognostic value in patients undergoing palliative radiation therapy remains unclear. We retrospectively analyzed 147 patients with stage IV lung cancer who received palliative radiation therapy at our institution between June 2015 and December 2023. Patients with prior radiation therapy or missing pre-treatment blood test data were excluded. PNI was calculated using the formula: 10 × serum albumin (g/dL) + 0.005 × lymphocyte count (/mm 3 ). Overall survival was measured from the initiation of radiation therapy. Cutoff values for PNI were determined by receiver operating characteristic analysis. Cox proportional hazards models were used for univariate and multivariate analyses. Median follow-up was 5.6 months. The PNI cutoff value was 35.5. Median survival time was significantly longer in the high-PNI group (12.5 months) than in the low-PNI group (3.0 months) (p < 0.001). Low PNI, radiotherapy delivered at disease progression, and poor performance status (3–4) were independently associated with worse overall survival. PNI was significantly associated with survival in stage IV lung cancer patients receiving palliative radiation therapy. As a simple and objective biomarker, PNI may help estimate patient prognosis.