Eosinophil percentage elevation as a prognostic factor for overall survival in patients with metastatic renal cell carcinoma treated with tyrosine kinase inhibitor

BACKGROUND: We tried to investigate the prognostic significance of post-treatment eosinophil percentage(Eo %) in metastatic renal cell carcinoma(mRCC) patients undertaking sorafenib. RESULTS: The median OS for the entire sorafenib treatment period was 21.9 months (95% CI: 17.2–25.9 months). Of the 282 mRCC patients, 101 patients experienced an elevated post-treatment Eo % within two months. Median OS of post-treatment Eo % elevated group and non-elevated group were 42.9 months and 16.8 months(p=0.000). After adding post-treatment Eo % into a modified MSKCC model or Heng's model, 43 and 41 patients were reclassified into favorable group, 5 and 9 patients were reclassified to intermediate group respectively. METHODS: mRCC patients treated with sorafenib from 2006 to 2015 in were evaluated. Pre- and post-treatment Eo % were assessed. Oncologic outcomes were analyzed by overall survival and tumor response rate. Predictive parameters were assessed in a Cox proportional hazard model. CONCLUSIONS: Our study demonstrates that an early elevation of Eo % after sorafenib treatment is a strong predictor of good prognosis. Eo % can be a good supplementary for prognostic models using pre-treatment parameters.