Prediction of non-muscle-invasive bladder cancer recurrence during intravesical BCG immunotherapy by use of peripheral blood eosinophil count and percentage: a preliminary report

Objectives To determine whether there is an association between blood eosinophil count and percentage with the recurrence of nonmuscle invasive bladder cancer (NMIBC) during Bacillus Calmette-Guérin (BCG) maintenance therapy with our preliminary results. Methods A total of 53 patients with NMIBC underwent BCG immunotherapy between January 2015 and September 2018, and met our inclusion criteria were included in the study. The parameters age, gender, smoking status, comorbidity, blood neutrophil, lymphocyte and eosinophil counts, blood eosinophil percentage, previous single postoperative intravesical chemotherapy instillation, tumor characteristic, and total and maintenance dose numbers of BCG were extracted from our medical records and compared between patients with response and with recurrence. Results Blood eosinophil count and percentage were significantly higher in patients with recurrence compared to patients with response (0.263 ± 0.37 vs. 0.0134 ± 0.021, p = 0.01 and 0.31 ± 0.29 vs. 0.17 ± 0.27, p = 0.01). Other parameters were similar in patients with recurrence and response. Receiver-operating characteristic analysis showed a considerable diagnostic value of blood eosinophil count and percentage in the prediction of bladder cancer recurrence during BCG immunotherapy. Conclusion Blood eosinophil count and percentage in patients with NMIBC can predict the disease recurrence during the BCG immunotherapy. Our research raised new questions and assumptions about the role of eosinophils during BCG immunotherapy.