Role of prognostic nutritional index in postoperative radiotherapy for non‐small cell lung cancer

BACKGROUND: The prognostic nutritional index (PNI) is known to be correlated with clinical outcomes in non‐small cell lung cancer (NSCLC) patients. However, its role has not been studied in patients who have undergone postoperative radiotherapy (PORT). This study aimed to investigate the relationship between PNI and survival and recurrence in NSCLC patients with PORT. METHODS: We reviewed 97 stage I–III NSCLC patients who received PORT between January 2006 and December 2016 at our institution. We obtained PNI values for both pre‐RT (within 1 month before PORT) and post‐RT (within 2 months after PORT) by using serum albumin and lymphocyte count. A cutoff value for PNI was determined by the receiver operating characteristic curve (ROC). The median follow‐up period was 52.8 months. RESULTS: The ROC curve of post‐RT PNI exhibited a higher area under the curve (AUC 0.68, cut‐off: 47.1) than that of pre‐RT PNI (AUC 0.55, cutoff: 50.3), so the group was divided into high post‐RT PNI (> 47.1) and low post‐RT PNI ([Formula: see text] 47.1). The five‐year overall survival rate (OS) was 66.2% in the high post‐RT group, compared with 41.8% in the low post‐RT PNI group (p = 0.018). Those with both low pre‐RT and low post‐RT PNI had the worst five‐year OS of 31.1%. Post‐RT PNI (HR 0.92, p = 0.003) was an independent risk factor for mortality. CONCLUSIONS: PNI after PORT was significantly associated with survival. This finding suggests that PNI can be used as a prognostic marker.