Systemic immune-inflammation index predicts survival in patients with resected lung invasive mucinous adenocarcinoma

The prognostic-related factors of lung invasive mucinous adenocarcinoma(IMA) are unclear because of its rarity. Various inflammation-based biomarkers were reported to predict the survival of malignant diseases. This study aims to explore the prognostic significance of the systemic immune-inflammation index(SII), which is calculated using absolute platelet, neutrophil, and lymphocyte counts, among patients with invasive mucinous adenocarcinoma.

From January 2015 to December 2019, 106 patients were identified as having IMA accepted radical resection and enrolled in the retrospective study. We analyzed the overall survival and disease-free survival using the Kaplan-Meier method and log-rank test. Receiver operating characteristic curve was used to find the optimal SII cut-off values for survival. A Cox regression model was carried out for multivariable analyses.

The study cohort included 53 men and 53 women, with a mean age of 60 years (range 29 to 78 years, median 61 years). The median SII measured before surgery was 378.47 (range: 79.87-1701.97). ROC analyses revealed that the optimal cut-off values of SII was 379.43 for predicting both OS and DFS. An elevated SII (≥379.43) was observed in 52 patients (49.1 %), and was associated with younger age (P = 0.02), advanced T staging (P = 0.042), lymph node metastasis (P = 0.018) and pneumonic-type IMA (P = 0.018). Multivariable analysis showed that SII and pneumonic-type IMA were independent prognostic predictors of OS and DFS in radically resected IMA patients (P < 0.05).

High SII is correlated with worse outcome and can be a novel prognostic biomarker for IMA patients accepted radical surgery.