Systemic Inflammatory Index: A Promising Non-Invasive Marker for the Prediction of Response to Neoadjuvant Chemotherapy prior to Cystectomy.

Introduction: The main challenge to the optimal use of neoadjuvant chemotherapy (NAC) is the difficulty in selecting patients who may or may not benefit from NAC. Our aim in this study was to investigate whether the Systemic Inflammatory Index (SII) predicts response to chemotherapy in patients who receive NAC prior to cystectomy.

Methods: We retrospectively analysed the data of patients who underwent NAC followed by cystectomy at our institution between January 2010 and September 2015 and whose 5-year follow-up was completed. All patients who underwent diagnostic biopsy with complete transurethral resection of bladder tumour at our hospital and whose pathology result was muscle-invasive transitional cell carcinoma were included in the study. At least 3 courses of gemcitabine/cisplatin NAC were given to all patients. A pathological response was defined as a reduction in cystectomy to a lower pathological stage after NAC.

Results: The SII was 320.8 ± 51 in the responders and 388.28 ± 50 in the non-responders. SII optimal cut-off of 350 was determined. The sensitivity and specificity of SII in predicting response were found to be 80% and 83%, respectively. Low SII (<350) was found to be a significant predictor of response compared with the other factors on multivariate analysis. The mean overall survival time was 55.4 months in patients with a low SII value and 40.3 months in the high SII group.

Conclusion: SII, together with known clinicopathological factors and newer genetic and molecular markers, can be used to select patients for NAC.